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Resolution 237-20151 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 MONROE COUNTY, FLORIDA MONROE COUNTY BOARD OF COUNTY COMMISSIONERS RESOLUTION NO. 237 - 2015 A RESOLUTION OF THE MONROE COUNTY BOARD OF COUNTY COMMISSIONERS ADOPTING FEMA P -499, "HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION" DATED DECEMBER 2010 AS REQUIRED PURSUANT TO MONROE COUNTY CODE SECTION 122 -2(C) WHEREAS, Monroe County is currently a participating community in the National Flood Insurance Program (NFIP) and is working on internal County policies to improve upon its interpretation of NFIP regulations; and WHEREAS, Monroe County desires to become eligible to enter FEMA's Community Rating System (CRS); and WHEREAS, Monroe County Code Section 122 -2(c), in part, requires that in interpreting other provisions of this chapter, the building official shall be guided by the current edition of FEMA's 44 CFR, and FEMA's interpretive letters, policy statements and technical bulletins as adopted by resolution from time to time by the board of county commissioners; NOW, THEREFORE, BE IT RESOLVED BY THE BOARD OF COUNTY COMMISSIONERS OF MONROE COUNTY, FLORIDA: Section 1. Pursuant to Monroe County Code Section 122 -2(c), the Board hereby adopts FEMA P -499, "Home Builder's Guide to Coastal Construction" dated December 2010, a copy of which is attached hereto. Section 2. The Clerk of the Board is hereby directed to forward one (1) certified copy of this Resolution to the Building Department. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 t '7 BOARD OF COUNTY COMMISSIONERS OF MONROE COUNTY, FLORIDA BY: Ma r T)--A .7 L. Kolhage MONROE COUNTY ATTORNEY PROVED AS FORM: STEVEN T. WILLIAMS ASSISTANT COUNTY ATTORNEY Date PASSED AND ADOPTED by the Board of County Commissioners of Monroe County, Florida, at a regular meeting held on the 16 of September, 2015. Mayor Danny L. Kolhage Yes Mayor pro tem Heather Carruthers Yes Commissioner Sylvia Murphy Yes Commissioner George Neugent Yes Commissioner David Rice Yes x1:- ` ` - .r<4' 4 r Al _... _. .-- ' 4. . 1,r4 ,.. ,, T 411, 11111 Home Builder's Guide • to Coastal Construction Technical Fact Sheet Series FEMA P-499 / December 2010 c epRT 5 /T Vf4 F FEMA y o��1ND se' Coastal Construction Fact Sheet Series HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. G.1 Introduction FEMA has produced a series of 37 fact sheets that provide technical guidance and recommendations con- cerning the construction of coastal residential buildings. The fact sheets present information aimed at improving the performance of buildings subject to flood and wind forces in coastal environments. The fact c sheets make extensive use of photographs and drawings to illustrate National Flood Insurance Program 0 (NFIP) regulatory requirements, the proper siting of coastal buildings, and recommended design and m construction practices, including structural connec- tions,the building envelope, utilities,and accessory structures. In addition, many of the fact sheets in- Note: The fact sheets have been divided into 10 clude lists of additional resources that provide more different categories,which represent various build- information about the topics discussed. ing components or aspects of the construction process. Fact sheets are numbered first by the Available Fact Sheets category and then followed by a number to rep- resent the fact sheet within the category. Future The following 37 fact sheets are also available on the updates to the guide will include fact sheets us- FEMA website (www.fema.gov) as Adobe® Portable ing these categories and will allow the user to add Document Format(PDF)files and as plain text(.txt)files. new fact sheets within the category without requir- You must have Adobe® Reader to view the PDF files. ing the entire guide to be reprinted. Revisions to The latest version of Adobe Reader is recommended. individual sheets will include a letter behind the Download the free Reader from www.adobe.com. numbers to represent each successive update. Category 1 — General Fact Sheet No. 1.1, Coastal Fact Sheet No. 1.3,Using a Dig- And Building Successes and Fail- Imerlbre ""� ital Flood Insurance Rate Map _�=_ ___ ures — Explains how coastal , (DFIRM) — Explains the pur- -� - ----" construction requirements ' pose of Flood Insurance Rate -may Rome =... �,"� differ from those for inland am Maps (FIRMs) and Digital r construction, and discusses Flood Insurance Rate Maps -_- .---- the characteristics that make = Y'� (DFIRMs); highlights features R: for a successful coastal res- : —_- —` that are important to coastal idential building. Includes builders, including flood zones design and construction recommendations for and flood elevations; and ex- achieving building success. plains how to obtain FIRMs, DFIRMs, and Flood ,, ,,., Fact Sheet No. 1.2,Summary of Insurance Studies (FISs). Coastal Construction Require- r Fact Sheet No. 1.4, Low- -• - ments and Recommendations est Floor Elevation — Defines "` for Flood Effects — Summa- £ _ -;-__ "lowest floor," discusses ben- rizes recommendations for _= __ efits of exceeding the NFIP s=z=- exceeding NFIP regulatory emmr� ii minimum building elevation mammon requirements for new con- _''-__ requirements, identifies corn- . . struction and for repairs, -uw--.L1 u1- mon construction practices remodeling, and additions. ;" "Wi that are violations of NFIP Topics include building foundations, enclosures regulations, which result in below the Base Flood Elevation (BFE), use of significantly higher flood insurance premiums; nonstructural fill, use of space below the BFE, and discusses the NFIP Elevation Certificate. utilities, certification requirements, and repairs, Also includes a copy of the certificate. remodeling, and additions. Cross-references to related fact sheets are provided. JUt OvpA��F~fin FEMAG.1: COASTAL CONSTRUCTION FACT SHEET SERIES HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 6 AND SEE 12 10 `' _ Fact Sheet No. 1.5,V Zone De- Category 2 — Planning sign Certification - Explains_-- `--cam the certification requirements Fact Sheet No. 2.1, How Do for structural design and " _ methods of construction in V Siting and Design Decisions ..erne-:---2 i r i i- —�-�► Affect the Owner's Costs?- E-- --_ Zones. Also includes a copy - 1- _ wr: =_-_ -� r Discusses effects of planning, __,-�- of a sample certificate and siting, and design decisions ..:.�- explains how to complete it. tr on coastal home costs. Topics -E;_ include initial, operating, and Fact Sheet No. 1.6, Design- . . long-term costs; risk deter- ing for Flood Levels Above the urination; and the effect on -_--= BFE - Recommends design costs of meeting and exceeding code and NFIP and construction practices design and construction requirements. w that reduce the likelihood of o s Fact Sheet No. 2.2, Selecting — twill flood damage in the event . . D1 that flood levels exceed the ----- — a Lot and Siting the Building- Presents guidance concerning .,O. BFE. It includes illustrations Et_ i lot selection and building sit- of appropriate construction -z. ing considerations for coastal practices and information on the insurance ben- s -_= residential buildings. Topics efits of building above the BFE. . _." include factors that constrain Fact Sheet No. 1.7, Coastal sIMA siting decisions, coastal set- Building Materials - Provides back lines, common siting _= -y" guidance and best practices problems, and suggestions for builders, design- on the selection of building ers, and owners. -- __ : materials used for coastal a`" '',-- construction. Flood, wind, cor- Category 3 — Foundations Nt rosion, and decay resistance .„,,, are discussed, including pro Fact Sheet No. 3.1, tection recommendations. Foundations in Coastal Areas- lam` Explains foundation design sT�\t� �`i criteria and describes foun- NomTrdi:MnulBwNu:g Fact Sheet No. 1.8, Non-Tradi- = :_2_,_-- m tional Building Materials and Eta:, =- --C dation types suitable for .._ Systems - Provides guidance X =-=___ coastal environments. Also aT= on alternative building ma ¢ _: -_ - addresses foundations for } terials and techniques and s"�,,' ems- high elevation coastal areas _ their application in coastal (e.g., bluff areas). 4 .� environments. It includes dis- -g_ ==-= Fact Sheet No. 3.2, Pile Design .„. cussions of Engineered Wood pi_ g Products, Structural Insulated __,__;- and Installation- Presents ba- Panels, Insulating Concrete Forms, Prefabricat _-=_ - sic information about pile ed Shear Walls and Moment Frames, Sprayed : = € err= design and installation, in- Closed-Cell Foam Insulation, Advanced WallI = _`VA� cluding pile types, sizes Framing, and Modular Houses. - and lengths, layout, installa- tion 41-w t tion methods, bracing, field Fact Sheet No. 1.9, Moisture .`� cutting, connections, and veri- fying Barrier Systems - Describes fying capacities.== _: the moisture barrier system, === explains how typical wall mois- �Pik �.� Fact Sheet No.3.3,Wood Pile-to- e- `� " Beam Connections-Illustrates ture barrier systems work,and discusses common problems -_ - typical wood-pile-to-beam associated with moisture bar .= connections; presents ba- = =- ' t sic construction guidance rier systems. le_7.Fe. .. for various connection meth- r._ ods, including connections •— for misaligned piles; and illus- trates pile bracing connection ` techniques. I 4.4 • G.1: COASTAL CONSTRUCTION FACT SHEET SERIES 2 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Reinlamed M.umn PK. Fact Sheet No. 3.4, Reinforced Category 5 —Wall Systems _ " `°`° _ _ Masonry Pier Construction- Provides an alternative to Fact Sheet No. 5.1, House- v-- 0 piles in V Zones and A Zones """`" -.`.Y___ '� wrap- Explains the function __ in coastal areas where soil ,i of housewrap, examines its _, :r _ properties preclude pile in- NI attributes, and addresses =_ems =- -- stallation, but the need for �_- _ common problems associat- .,,,,, an "open foundation sys- -=_i �__�== - ed with its use. Topics include tern" still exists. Includes =-iA housewrap vs. building paper recommendations for good masonry practices in gym. `�` coastal environments. •.---- and housewrap installation. k„,n..,;,,nw;,,, Fact Sheet No. 3.5, Founda- Ra..f Wd, J Fact Sheet No.5.2,Roof-to-Wall - tion Walls- Discusses and "'"'�"Fl and Deck-to-Wall Flashing- _-= -,e7 illustrates the use of foun- Emphasizes the importance - - G= dation walls in coastal %'' of proper roof and deck flash c - ` buildings. Topics include foot __ ing, and presents typical and 0 z= � ing embedment, wall height, - -- �� enhanced flashing techniques -' materials and workmanship, ^ _:__ �� for coastal homes. - lateral support,flood openings •„ ----_------ ' and ventilation requirements, and interior grade elevations for crawlspaces. ,,JN,g�nw��,. Fact Sheet No. 5.3, Sid- H.gh Nb ing Installation in High-Wind - Regions- Provides basic de- Category 4 — Load Paths z = `==`-— sign and installation tips for =L- Y various types of siding for Fact Sheet No. 4.1, Load - -__ high wind regions, including Paths- Illustrates the con- ;" 4 vinyl, wood, and fiber cement :-: �= cept of load paths and :---�----- and discusses sustainable �i highlights important connec- t- design issues. =. tions in a typical wind uplift ,._= I load path. Fact Sheet No. 5.4 Attachment =::::: of Brick Veneer in High-Wind Re- •M.. - gions-Provides recommended practices for installing brick ...,o,..--, Fact Sheet No. 4.2, Masonry veneer that will enhance wind --_ = Details- Illustrates important `-T== resistance in high wind re- _-- ,_, roof-to-wall and wall-to-foun- Examples of proper ,- • gions. p p p �IL dation connection details , installations and brick veneer _--, for masonry construction in tie spacings are provided. a g coastal areas. Topics include load paths, building materi Or Cate 6 Openings S "'� - als, and reinforcement. Category - p g %SIMI"..M Door Fact Sheet No. 6.1, Window Fact Sheet No. 4.3, Use of '" and Door Installation- Pres- lira Let‘ Connectors and Brackets- -- _:=== ents flashing detail concepts _________'=4 Illustrates important building -r= _ for window and door openings connections and theproper F provide- r ar_=,� L .�� that adequate resis use of connection hardware i x tance to water intrusion in 4---4- ? throughout a building. gray-a_ coastal environments, do not depend solely on sealants,are integral with secondary weath- er barriers (e.g., housewrap), and are adequately attached to the wall. Topics include the Ameri- can Society for Testing and Materials (ASTM) Standard E 2112 and specific considerations concerning pan flashings, Exterior Insulation Fin- ishing Systems, frame anchoring, shutters, and weatherstripping. G.1: COASTAL CONSTRUCTION FACT SHEET SERIES HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 6 1210 Fact Sheet No. 6.2, Protection hips and ridges, tile installation on critical and of Openings - Shutters and essential buildings, and quality control. ;T, _� Glazing- Presents informa- tion about the selection and ",mn;,� Kwic e°��,n Fact Sheet No. 7.5, Minimiz- installation of storm shutters �,,RI:��ndRfl . ing Water Intrusion through K":".` _=Y-.'•= - Roof Vents in High-Wind Re- -.� -`` F and impact-resistant glazing =- __- : _ "__= gions— Describes practices a and other types of opening -- protection in windborne de- _ for minimizing water intrusion bris regions. Shutter types , __ through roof vent systems, addressed include temporary plywood " -'-""- which can lead to interior p y panels; , 1-�- �7 - temporary manufactured panels; permanent, ,„w• _ - damage and mold growth in manual closing; and permanent, motor-driven. high-wind regions. Topics in- clude soffit vents, ridge vents, gable end vents, w Category 7 - Roofing off-ridge vents, gable rake vents, and turbines. o G 5 - Fact Installation- Roo M h",W R.`..,." Fact Sheet No. 7.6, Metal Roof Fact Sheet No. 7.1, Roof ",.IR,•,•" g - Systems in High-Wind Re- ents information about proper gions- Presents design and � �; installation guidance for met- ---- ,,=1 roof sheathing installation ,E �_: al roofing systems that will and its importance in coastal - enhance wind-resistance in _ construction; also discuss- �: :16 -—= es fastening methods that ..:-- - high-wind regions. Discus- _ _== ------ sions on sustainable design j„�, will enhance the durability of a building in a high-wind options are included. area. Topics include sheathing types and layout methods for gable-end and hip roofs,fastener se- Category 8 - Attachments lection and spacing,the treatment of ridge vents and ladder framing, and common sheathing at- In,hmim awl Raitawn, Fact Sheet No. 8.1, Enclosures and Breakaway mistakes. � Walls- Dis- cusses requirements and Fact Sheet No. 7.2, Roof Un- r recommendations for enclo- R.I I1,.kAn mrni her --. '.p'uh sh,°It " fi derlayment for Asphalt Shingle ' ' �-- 0 sures and breakaway walls Roofs- Presents recommend- for their use below the BFE. It ^- 7. ! ed practices for the use 'ram___ includes a diagram of a compli- of roofingunderlayment =� -__ _ y •mi4 ant wall system and examples 7 -- as an enhanced second- — of systems that have either re- men! ' ary water barrier in coastal suited in increased damages u•y `-- environments. Optional instal- or increased flood insurance premiums. lation methods are illustrated. Fact Sheet No. 8.2, Decks, 'yJ,h Shingle Roofing(.. Fact Sheet No. 7.3, Asphalt Pools, and Accessory Struc- "'Rh""` Shingle Roofing for High-Wind tures- Summarizes NFIP Regions- Recommends prac- 5-' Ji requirements, general guide T tices for installing asphalt roof = lines, and recommendations i j shingles that will enhance the -> =s concerning the construction wind resistance of roof coy- z= _-, and installation of decks, ac- erin s in high-wind, coastal ""'�='�` °T�--'_ g g ,,,,„ cess stairs and elevators, i,:,,, regions. Issues include in- swimming pools, and acces- stallation at hips, eaves, and sory buildings under or near coastal residential ridges; shingle characteristics; weathering and buildings. durability; and wind resistance. „o ,,,;h,k Fact Sheet No. 8.3, Protecting R,..1,,,,'.•. Fact Sheet No. 7.4,Tile Roofing � Utilities- Identifies the spe- "'"''"""'"""' for High-Wind Areas- Pres- cial considerations that must flia -__= ents design and construction 'MNbe made when installing utility `Y i guidance for tile roofing attach- = .O equipment, such as fuel, sew- a= =ira ment methods. Topics include age, and water/sewage lines uplift loads, uplift resistance, _ - in a coastal home, and pres- 7. _ special considerations con- ., , ents recommendations for cerning tile attachment at utility protection. G.1: COASTAL CONSTRUCTION FACT SHEET SERIES 4 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Category 9 - Repairs Category G - Guide Fact Sheet No. 9.1, Repairs, Fact Sheet No. G.1- Technical ' -In' Remodeling, Additions, and Fact Sheet Guide Retrofitting - Flood- Outlines ` -.` I .. - NFIP requirements for repairs, _-ti -_ = remodeling, and additions, __F ;=____ _ _"_,- and discusses opportunities -== T-T for retrofitting in coastal flood - ice, - -- hazard areas. Also presents Ir.- , recommendations for exceed- ing the minimum NFIP requirements. Definitions -. of "substantial damage" and "substantial inn- R Fact Sheet No. G.2, References provement" are included. �z, _' and Resources- Lists referenc !7 -.-_ es that provide information C MAUI,Rcmoddm,: Fact Sheet No. 9.2, Repairs, `ems relevant to topics covered by v �dJnvn.ami rtn,li�i�. v.,,„, Remodeling, Additions, and the Home Builder's Guide to m �*"' -- Coastal Construction technical -;� Retrofitting - Wind-d Outlines -� —.-�- requirements and makes fact sheets. ---- _ = "best practice" recommenda- -- -- �-_. i tions for repairs, remodeling, _.,-3:;, -_-_,-,—n= and additions, and discusses ' „ opportunities for retrofitting in coastal high wind areas. FEMA P-499 Home Builder's Guide to Coastal Construction— 2005 to 2010 Crosswalk Category Category Code Sheet Title 2005 Edition Fact Sheet No. Guide G 1 Technical Fact Sheet Guide General 1 1 Coastal Building Success and Failures 1 Summary of Coastal Construction Requirements General 1 2 2 and Recommendations for Flood Effects General 1 3 Using a Digital Flood Insurance Rate Map 3 (DFIRM) General 1 4 Lowest Floor Elevation 4 General 1 5 V Zone Design Certification 5 General 1 6 Designing for Flood Levels Above the BFE New General 1 7 Coastal Building Materials 8 General 1 8 Non-Traditional Building Materials and Systems New General 1 9 Moisture Barrier Systems 9 Planning 2 1 How Do Siting and Design Decisions Affect the 6 Owner's Costs? Planning 2 2 Selecting a Lot and Siting the Building 7 Foundations 3 1 Foundations in Coastal Areas 11 Foundations 3 2 Pile Design and Installation 12 Foundations 3 3 Wood Pile-to-Beam Connections 13 Foundations 3 4 Reinforced Masonry Pier Construction 14 Foundations 3 5 Foundation Walls 15 G.1: COASTAL CONSTRUCTION FACT SHEET SERIES HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 6 12/10 Category Category Code : Sheet Title 2005 Edition Fact Sheet No. Load Paths 4 1 Load Paths 10 Load Paths 4 2 Masonry Details 16 Load Paths 4 3 Use of Connectors and Brackets 17 Wall Systems 5 1 Housewrap 23 Wall Systems 5 2 Roof-to-Wall and Deck-to-Wall Flashing 24 Wall Systems 5 3 Siding Installation in High-Wind Regions 25 Wall Systems 5 4 Attachment of Brick Veneer in High-Wind Regions New w Openings 6 1 Window and Door Installation 22 ti - Openings 6 2 Protection of Openings- Shutters and Glazing 26 C3 Roofing 7 1 Roof Sheathing Installation 18 Roofing 7 2 Roof Underlayment for Asphalt Shingle Roofs 19 Roofing 7 3 Asphalt Shingle Roofing for High-Wind Regions 20 Roofing 7 4 Tile Roofing for High-Wind Areas 21 Roofing 7 5 Minimizing Water Intrusion through Roof Vents in New High-Wind Regions Roofing 7 6 Metal Roof Systems in High-Wind Regions New Attachments 8 1 Enclosures and Breakaway Walls 27 Attachments 8 2 Decks, Pools, and Accessory Structures 28 Attachments 8 3 Protecting Utilities 29 Repairs 9 1 Repairs, Remodeling,Additions and Retrofitting- 30 Flood Repairs 9 2 Repairs, Remodeling,Additions and Retrofitting- 30 Wind Guide G 2 References and Resources 31 NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER G.1: COASTAL CONSTRUCTION FACT SHEET SERIES 6 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Coastal Building Successes and Failures HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 1.1 Purpose: To discuss how coastal construction requirements are different from those for inland construction. To discuss the characteristics that make for a successful coastal building. C) m Is Coastal Construction That Different From m Inland Construction? D A well-built but poorlysited buildingcan be under- ment short answer is yes, building in a coastal environ- ment is different from building in an inland area: mined and will not be a success (see Figure 1). Even if a building is set back or situated farther Flood levels,velocities, and wave action in coast- from the coastline, it will not perform well (i.e., will al areas tend to make coastal flooding more not be a success) if it is incapable of resisting high damaging than inland flooding. winds and other hazards that occur at the site (see Figure 2). Coastal erosion can undermine buildings and de- stroy land, roads, utilities, and infrastructure. .Y -+ Wind speeds are typically higher in coastal areas :p and require stronger engineered building connec- tions and more closely spaced nailing of building i _ sheathing, siding, and roof shingles. doi. . / ., - •••• • S. • Wind-driven rain, corrosion, and decay are f lb\ re- quent concerns in coastal areas. In general, homes in coastal areas must be designed ;S• ) and built to withstand higher loads and more extreme ;; - -,,,,- V conditions. Homes in coastal areas will require more maintenance and upkeep. Because of their expo- sure to higher loads and extreme conditions, homes Figure 1. Well-built but poorly sited building. in coastal areas will cost more to design, construct, maintain, repair, and insure. • 1 Building Success �� r • 'ti :7 " ,i In order for a coastal buildingto be considered a _ b '� "success," four things must occur: ,. vikt 'aElm i The building must be designed to withstand _ ;' . = coastal forces and conditions. * ' :'1'I 1 _ 41 r� .,'{1• ttllii The building must be constructed as designed. " - rpi f'� ��,�. z � The building must be sited so that erosion ".� �.. does not undermine the building or render it uninhabitable. The building must be maintained/repaired. Figure 2. Well-sited building that still sustained damage. o,,e i 4 i o 1.1: COASTAL BUILDING SUCCESSES AND FAILURES '+!' FEI\4.A HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 44‘`�ND SELv 12/10 What Should Owners and Home Builders Expect From a "Successful" Coastal Building? In coastal areas, a building can be considered a success only if it is capable of resisting damage from coastal hazards and coastal processes over a period of decades. This statement does not imply that a coastal residential building will remain undamaged over its intended lifetime. It means that the impacts of a design-level flood, storm,wind, or erosion event(or series of lesser events with combined impacts equivalent to a design event) will be limited to the following: The building foundation must remain intact and functional. The envelope (walls, openings, roof, and lowest floor) must remain structurally sound and capable of minimizing penetration by wind, rain, and debris. The lowest floor elevation must be sufficient to prevent floodwaters from entering the elevated < building envelope during the design event. W The utility connections (e.g., electricity, water, sewer, natural gas) must remain intact or be re- z stored easily. 0 The building must be accessible and usable following a design-level event. Any damage to enclosures below the Design Flood Elevation (DFE)* must not result in damage to the foundation, the utility connections, or the elevated portion of the building. Recommended Practice 6 8 0 2 O Siting— Site buildings away from eroding shorelines and high-haz- ard areas. 11 O Building Form—Flat or low-sloped porch roofs, overhangs, and ;,, , .- - gable ends are subject to in- creased uplift = �— in high winds. Buildings that are both tall and narrow are � _ -- - - - � � — — subject to over- �1I turning. Each of ,\, these problems can be overcome through the de- -- sign process, but each must receive 0 special attention. In 3 the design process,choose moderate-sloped hip roofs (4/12 to 6/12) if possible. © Lowest Floor Elevation— Elevate above the DFE or finish enclosed areas below the DFE (owners the bottom of the lowest horizontal structur- tend to convert these areas to habitable uses, al member supporting the lowest floor. Add which is prohibited under the National Flood "freeboard" to reduce damage and lower flood Insurance Program and will lead to additional insurance premiums. flood damage and economic loss). O Free of Obstructions— Use an open foundation. © Foundation— Make sure the foundation is deep Do not obstruct the area below the elevated enough to resist the effects of scour and portion of the building. Avoid or minimize the erosion; strong enough to resist wave, cur- use of breakaway walls. Do not install utilities rent, flood, and debris forces; and capable of 1.1: COASTAL BUILDING SUCCESSES AND FAILURES 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 transferring wind and seismic forces on upper Mechanical and Utilities— Electrical boxes, HVAC stories to the ground. equipment, and other equipment should be el- Connections— Key connections include roof ® evated to avoid flood damage and strategically Osheathing, roof-to-wall, wall-to-wall, and walls- located to avoid wind damage. Utility lines and to-foundation. Be sure these connections are runs should be installed to minimize potential constructed according to the design. Bolts, flood damage. screws, and ring-shanked nails are common re- Quality Control—Construction inspections and quirements. Standard connection details and g quality control are essential for building suc- nailing should be identified on the plans. cess. Even "minor" construction errors and Exterior Walls—Use structural sheathing in high- defects can lead to major damage during high Owind areas for increased wall strength. Use wind or flood events. Keep this in mind when tighter nailing schedules for attaching sheath- inspecting construction or assessing yearly ing. Care should be taken not to over-drive maintenance needs. m pneumatically driven nails. This can result in Recommended practice and guidance concerning the z loss of shear capacity in shearwalls. topics listed above can be found in the documents referenced in these fact sheets and in many trade D Windows and Glass Doors— In high wind areas, publications (e.g., The Journal of Light Construction, O use windows and doors capable of withstand- htto://www.jlconline.com). ing increased wind pressures. In windborne debris areas, use impact-resistant glazing or shutters. Flashing and Weather Barriers—Use stronger Will the Likelihood of Success (Building connections and improved flashing for roofs, Performance) Be Improved by Exceeding O walls, doors, and windows and other openings. Minimum Requirements? Properly installed secondary moisture barriers, States and communities enforce regulatory require- such as housewrap or building paper, can re- ments that determine where and how buildings may duce water intrusion from wind-driven rain. be sited, designed, and constructed. There are of- Roof—In high wind areas, select appropriate roof ten economic benefits to exceeding the enforced coverings and pay close attention to detailing. requirements (see box). Designers and home build- O Avoid roof tiles in hurricane prone areas. ers can help owners evaluate their options and make informed decisions about whether to exceed these Porch Roofs and Roof Overhangs— Design and tie requirements. Q down porch roofs and roof overhangs to resist uplift forces. Building Materials— Use flood-resistant materi- • als below the DFE. All exposed materials should be moisture-and decay-resistant. Metals should Benefits of Exceeding Minimum have enhanced corrosion protection. Requirements Reduced building damage during coast- al storm events Reduced building maintenance Longer building lifetime Reduced insurance premiums* Increased reputation of builder * Note:Flood insurance premiums can be reduced up to 60 percent by exceeding minimum siting, design, and construction prac- tices. See the V Zone Risk Factor Rating Form in FEMA's Flood Insurance Manual(htto:J/www.fema.gov/nfio/manual.shtm). NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER ti 1.1: COASTAL BUILDING SUCCESSES AND FAILURES HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12/10 Summary of Coastal Construction Requirements and Recommendations HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 1.2 0 Purpose: To summarize recommendations for exceeding National Flood Insurance Program(NFIP) regulatory requirements concerning coastal construction. D r Key Issues New construction* in coastal flood hazard areas (V Zone and A Zone) should be designed using the engi- neering standards (ASCE 24 and ASCE 7) or the International Residential Code (IRC), as applicable. Best practices must exceed the minimum NFIP requirements and must meet, or exceed,all community zoning and building code requirements. Repairs, remodeling,and additions must always meet NFIP and building code requirements for the part of the structure impacted. Should these costs exceed 50 percent of the fair market value of the structure, the entire building must be brought to local floodplain management and building code compliance. Engineering standards ASCE 24-05 and ASCE 7-10 are more stringent in V Zones than in A Zones,to pro- tect against the increased flood, wave, flood-borne debris, and erosion hazards typical of V Zones. For added protection,it is strongly recommended that buildings in flood zones that are subject to break- ing waves between 1.5 and 3 feet as well as erosion and scour be designed and constructed to V Zone standards. These coastal areas, mapped as A Zones, may be subject to damaging waves and erosion and are often referred to as "Coastal A Zones." Buildings in these areas are typically constructed to the minimum NFIP A Zone requirements and have at least a 1-percent-annual-chance of sustaining major damage or being destroyed. This regulatory standard is known as the base flood. Buildings constructed to minimum NFIP A Zone standards and subject solely to shallow flooding(i.e., not subject to breaking waves greater than 1.5 feet or erosion) are still subject to flood damage and should be built with a first floor elevation above the BFE (usually at least one foot or greater), which is referred to as "freeboard." Following the recommendations in the following table will result in less damage to the building and may reduce flood insurance premiums (see the V Zone Risk Factor Rating Form in FEMA's Flood Insurance Manual(http://www.fema.gov/nfip/manual.shtm). * For floodplain management purposes, new construction refers to structures for which construction be- gan on or after the effective date of adoption of the community's floodplain management ordinance. Substantial improvements,repairs of substantially damaged buildings,and some enclosures must meet the same floodplain management ordinance and building code requirements as new construction where such ordinances and codes have been adopted by the community. The following table summarizes NFIP regulatory requirements and recommendations for exceeding those requirements for both (1) new construction and (2) repairs, remodeling, and additions. OF'4�\E1. J ' ° FEmA 1.2: COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS ;iF44HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 10 ND5 LJ� 12/10 Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone M, Coastal Additional Resources V A Structural Fill Prohibited Requirement: Requirement: IBC: 1804.4,App.G 401.1, Compaction where Compaction where App.G 401.2 NFIP 60.3(e)(6) used;protect against used;protect against IRC: R322.3.2 scour and erosion. scour and erosion. J ASCE: ASCE 24 Sec.2.4 Q Other: FEMA TB#5 I _ W z Solid Foundation Prohibited Requirement: Requirement: IBC: 1612.5.1 u.i Walls [see Fact Flood vents must be Where used,the walls IRC: R322.2.3 Sheet Nos.3.1, installed to equalize must allow floodwaters pressures(see Fact to pass between or ASCE: ASCE 24 Sec.2.5, 3.5] Sheets Nos.3.5 and through the walls using ASCE 7 Sec.5.4.4.2 8.1). flood openings(see NFIP 60.3(c)(3) Fact Sheets Nos.3.5 Other: FEMA TB#5, FEMA Recommendation: and 8.1). 550 An open foundation system should be used. Open Foundation Recommendation: Recommendation: Recommendation: IBC: 1803.5.5 [see Fact Sheet Site new construction Open foundations Open foundations are IRC: R322.3.3 landward of the long- are recommended in recommended in A No. 3.1] term erosion setback Coastal A Zones. Zones. ASCE: ASCE 7 Sec.5.4.4.1, e 5 and landward of the ASCE 24 Sec 4.5.5 NFIP 60.3(e)(5) area subject to erosion and 60.3(c)(5) during the 1%coastal Other: FEMA TB#5 flood event. Requirement: All new construction shall be landward of the reach of the mean high tide; alteration of sand dunes and mangrove stands that increases the potential of flood damage is prohibited. Lowest Floor Not Applicable Recommendation: Requirement: IBC: 1603.1.7, 1612.5 Elevation(not in Elevate the bottom of Top of floor must be at IRC: R105.3.1.1, R322.2.1, a V Zone) the lowest horizontal or above BFE. R322.1.5 structural member at, [see Fact Sheet or above, BFE. ASCE: ASCE 24 Sec. 1.5.2, No. 1.5] Requirement: Top ASCE 24 Sec.2.5,ASCE 24 of floor must be at or Ch.5,ASCE 24 Ch.7 NFIP 60.3(C) above BFE. Other: FEMA TB#5 Bottom Lowest Requirement: Recommendation: Recommendation: IBC: 1603.1.7, 1605.2.2, Horizontal Bottom of the lowest Follow the V Zone The minimum 1605.3.1.2, 1612.4, 1612.5.2 Structural horizontal structural building elevation recommendation is IRC: R322.3.2 member of the first requirement. to follow the Coastal Member floor must be at, or A Zone requirements. ASCE: ASCE 24 Sec.4.4, [see Fact Sheet above,the BFE(see Users should consider ASCE 24 Sec.2.5,ASCE 24 Fact Sheet No.1.5). following V Zone Ch.5 No. 1.4] recommendations for Other: FEMA 55, FEMA TB the lowest horizontal NFIP 60.3e #8, FEMA TB#5 ( )(4) structural member elevation to further minimize the risk of flood damage. 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS 2 of 10 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone rrn, Coastal 1111 Additional Resources V A A Foundation Orientation Requirement: Recommendation: Recommendation: IBC: see ASCE 24 of Lowest Elevate the bottom of If the orientation of Follow the Coastal A IRC: R322.3.2 Horizontal the lowest horizontal the lowest horizontal Zone recommendation. structural member at, structural member ASCE: ASCE 24 Sec 4.4 Structural or above, BFE. is parallel to the Member expected direction of Other: FEMA TB#5 0 waves,elevate the m bottom of the member z to or above BFE; If m the orientation of the lowest horizontal structural member is perpendicular to the expected direction of waves, elevate the bottom of the member to BFE plus one foot. Diagonal bracing for decks,stairways, balconies and other attached structures should also be elevated at,or above,the BFE. Freeboard Requirement: Recommendation: Recommendation: IBC: see ASCE 24 [see Fact Sheet No NFIP requirement, Freeboard is Freeboard is IRC: R322.2.1, R322.3.2 but freeboard is recommended in recommended in A Nos. 1.1, 1.4] required by IRC and Coastal A Zones. Zones. ASCE: ASCE 24 Sec.2.3 ASCE. Note: Per ASCE 24-05 Note: One foot above one foot of freeboard BFE is required per required for Risk IRC R322.2.1 Item#2 Category II structures. for Coastal A Zones. Enclosures Not Applicable Recommendation: Recommendation: IBC: 1203.3.2, 1403.5, Below the BFE If an enclosure is If an enclosure is 1612.4, 1612.5.1 (not in a V Zone) constructed, use constructed, use IRC: R322.2.2, R408.7 breakaway walls, open breakaway walls,open lattice,or screening(as lattice,or screening(as ASCE: ASCE 24 Sec.2.6, required in V Zones). required in V Zones). ASCE 24 Sec 4.6 Requirement: Requirement: Other: FEMA TB#1 If an area is fully If an area is fully enclosed,the enclosed,the enclosure walls must enclosure walls must be equipped with be equipped with openings to equalize openings to equalize hydrostatic pressure; hydrostatic pressure; the size, location, and the size, location, and covering of openings covering of openings governed by regulatory governed by regulatory requirements. requirements. Enclosures Prohibited,except Not Applicable Not Applicable IBC: 1403.5, 1403.6, 1612.4, Below the BFE for breakaway walls, 1612.5.2 (not in V Zones) open wood lattice,and IRC: R322.3.2, R322.3.4, screening. R322.3.5 [see Fact Sheet No.8.1] ASCE: ASCE 24 Sec.4.6, ASCE 7 Sec.C5.3.3 NFIP 60.3(c)(5) Other: FEMA 55, FEMA TB #5, FEMA TB#9 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 10 12/10 Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone rr, Coastal11111 Additional Resources V A A Foundation , ,.•mw.. Non Structural Requirement: Recommendation: Recommendation: IBC: 803.11.1 Fill Allowed for minor Follow the V Zone fill Follow the V Zone fill IRC: R322.14.2, R322.3.2 landscaping and site requirement. requirement. drainage as long as the ASCE: ASCE 24 Sec 1.5.4, fill does not interfere 45.4 with free passage of Other: FEMA TB#5 Q flood waters and debris CC beneath the building,or LU cause changes in flow Wdirection during coastal 0 storms that could result in damage to buildings. Use of Space Requirement: Requirement: Requirement: IBC: 110775,G105.7(5), Below BFE Allowed only for Allowed only for Allowed only for 801.5, G103.5, G103.8 parking, building parking, building parking,building [see Fact Sheet access,and storage access,and storage access,and storage IRC: R309.3, R322.1, No. 8.1] R322.1.2, R322.1.3, R322.1.4, R322.1.4.1, R322.2.1, R322.2.2, R322.3.2, R322.3.5 ASCE: ASCE 24 1.5.2, 2.6, 2.6.1, 2.6.2.1, 2.6.2.2,4.6, 4.6.1,4.6.2 itie Sanitary Sewer IBC: 1403.6,App.G 401.3 NFIP 60.3(a)(6)(i) R P.3001?3, R P3101.502 2 and 60.3(a)(6)(ii) ASCE: ASCE 24 Sec.73.4 Other: FEMA 348, FEMA TB#4 Utilities Requirement: Requirement: Requirement: IBC: 1403.6, 1612.4, [see Fact Sheet Must be designed, Electrical, heating, Electrical, heating, App.G 701 No. 8,3] located, and elevated ventilation, plumbing, ventilation,plumbing, IRC: R322.1.6, IFGC 301.11, to prevent flood and air-conditioning and air-conditioning R G2404.7, R P2601.3, waters from entering equipment and other equipment and other R P2602.2, R M1301.1.1, NFIP 60.3(a)(3) and accumulating in service facilities to service facilities to (iv) components during be designed and/or be designed and/or R M1701.2, R M1601.4.9. flooding.Utility lines located as to prevent located as to prevent R M1201.6, R M2001.4, must not be installed water from entering or water from entering or R M2201.6 or stubbed out in accumulating within accumulating within ASCE: ASCE 24 Ch.7 enclosures below BFE the components during the components during Other: FEMA 348, FEMA unless flood proofed to periods of flooding. periods of flooding. TB#4 the extent practicable. Recommendation: Follow the V Zone utility recommendation Certification Permits Requirement: Requirement: Requirement: IBC: App.G 101.3,App.G V Zone certificate, Elevation Certificate. Elevation Certificate. 103.App.G 104 NFIP 60.3(b)(1) Breakaway Wall certificate,and IRC: R104.2, R105,App. E, Elevation Certificate. App.J ASCE: ASCE 24 Sec.4.6. ASCE 7 Sec.C5.3.3 Other: FEMA EMI IS-9 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS 4 of 10 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION I Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone rai, Coastal 1111 Additional Resources V A A Certification Elevation Requirement: Recommendation: Recommendation: IBC: 110.3.3.1603.1.7, 1612.5 The lowest horizontal Follow the V Zone The minimum IRC: R106.1.3, R322.1.2, NFIP 60.3(b)(5)(i) structural member building elevation recommendation is R322.1.5, R322.2.1 and 60.3(e)(2) must be at, or above, requirement. to follow the Coastal BFE;electrical, Requirement: A Zone requirements. ASCE: ASCE 24 Sec. 1.5.1, 0 heating, ventilation, Top of lowest floor Users should consider 1.5.2, 4.4 rrl plumbing, and following V Zone must be at,or above, air-conditioning recommendations for m BFE;electrical equipment and other the lowest horizontal service facilities heating, ventilation, structural member (including ductwork) plumbing,and elevation to further must be designed air conditioning minimize the risk of and/or located so equipment and other flood damage. as to prevent water service facilities from entering or (including ductwork) Requirement: accumulating within must be designed Top of the lowest the components and/or located so floor must be at, during flooding(see as to prevent water or above, BFE; Fact Sheet Nos. from entering or electrical heating, 1.4,1.5,8.3) accumulating within ventilation,plumbing, the components and air conditioning during flooding (see equipment and other Fact Sheet Nos. 1.4 service facilities 8.3) (including ductwork) must be designed and/or located so as to prevent water from entering or accumulating within the components during flooding (see Fact Sheet Nos. 1.4, 8.3) Structure Requirement: Recommendation: Recommendation: IBC: 1604.1,1604.2, 1604.3 Registered engineer Follow the V Zone Follow the V Zone IRC: R301.1, R301.1.3,R301.2 or architect must requirement. requirement. certify that the design ASCE: ASCE 7 Sec. 1.3.1.3.3 and methods of construction are in accordance with an accepted standard of practice for meeting design requirements described under General Requirement (see Fact Sheet No. 1.5) 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 10 12/10 Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone rev Coastal1111 Additional Resources V A A Certification Breakaway Walls Requirement: Recommendation: IBC: 1612.5 (2.3) [see Fact Walls must be designed Breakaway walls are IRC: R322.3.4 Sheet Nos. 1.5, to break free under recommended with larger of the following an open foundation ASCE: ASCE 24 Sec.4.6.1, 8.1] (also see allowable stress design in lieu of solid walls;if 4.6.2, 2.6.1.1,ASCE 7 Sec. Enclosures loads: (1)design wind breakaway walls are 5.3.3 CC load, (2)design seismic used and enclose an W Below BFE) load, or(3) 10 psf, area,flood openings Other: FEMA TB#5, FEMA Z acting perpendicular to are required(see Fact TB#9 W NFIP 60.3(e)(5) the plane of the wall; Sheet Nos.3.1, 3.5). if loading intended to cause collapse exceeds 20 psf using allowable stress design,the breakaway wall design shall be certified;when certification is required, a registered engineer or architect must certify that the walls will collapse under a water load associated with the Base Flood and that the elevated portion of the building and its foundation will not be subject to collapse, displacement,or lateral movement under simultaneous wind and water loads. Openings in Not Applicable Requirement: Requirement: IBC: 1203.4.12,G1001.4 Below-BFE Walls Unless the number and Unless the number and IRC: R322.2.2 size of the openings size of the openings [see Fact meet regulatory meet regulatory ASCE: ASCE 24 Sec.2.6.1. Sheet Nos. 3.1, requirements,a requirements, a 2.6.2.1, 2.6.2.2 3.5] (also see registered engineer or registered engineer or Other: FEMA TB#1 Enclosures architect must certify architect must certify that the openings that the openings Below BFE) are designed to are designed to automatically equalize automatically equalize NFIP 60.3(c)(5) hydrostatic forces on hydrostatic forces on the walls by allowing the walls by allowing automatic entry and automatic entry and exit of flood waters. exit of flood waters. Repairs,Remodeling,and Additions[See Fact Sheet No.9.1] Substantial Requirement: Recommendation: Recommendation: IBC: 1612.1. 1612.2, 3403.2, Improvements Must meet current Follow the V Zone Elevate bottom of 3404.2, 3405.2, 3405.3, and Repairs NFIP requirements requirement for building lowest horizontal 3405.4 concerning new elevation and open structural member to IRC: R322.1.6, R322.3.1 of Substantial construction in V foundations. or above BFE. Damage Zones except for siting Requirement: Requirement: ASCE: ASCE 24 Sec.4.3, landward of mean high Must meet current Must meet current ASCE 7 Sec. 1.6 NFIP 60.3(e)(5) tide(see Fact Sheet NFIP requirements NFIP requirements Other: FEMA P-758 Nos. 1.4, 1.5, 2.2, 3.1, and 60.3(c)(5) 3.5 8.1, 8.3). concerning new concerning new construction in A Zones construction in A Zones (see Fact Sheet Nos. (see Fact Sheet Nos. 1.4, 3.1, 3.5, 8.1,8.3). 1.1, 3.1, 3.5, 8.1, 8.3) 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone rra Coastal1111 Additional Resources V A A Repairs,Remodelh,.,�.� _� ,.e o e _ • Lateral Additions Requirement: Recommendation: Recommendation: IBC: 3403.2, 3412.2.3, That Constitute Both the addition and Follow V Zone Elevate bottom of 3405.3 Substantial the existing building requirement for lowest structural IRC: R322.3.1 must meet current building elevation and member of the addition Improvement NFIP requirements open foundations for to or above BFE(same ASCE: ASCE 7 Sec. 1.6 concerning new the addition and the for the existing building ,#1 FEMA Other: TB r11 NFIP 60.3(e)(5) construction in V Zones existing building. if it is elevated). FEMA TB TBFE #1A TB#9, m (see Fact Sheet Nos. Requirement: Requirement: FEMA 550 m 1.4, 1.5,2.2,3.1,3.5, Only additions Only additions 8.1,8.3). must meet current must meet current NFIP requirements NFIP requirements concerning new concerning new construction in A Zones construction in A Zones (see Fact Sheet Nos. (see Fact Sheet Nos. 1.4, 1.5, 3.1, 3.5, 8.1, 1.4,2.2, 3.1, 3.5, 8.1, 8.3), provided the 8.3), provided the existing building is not existing building is not subject to any work subject to any work other than cutting an other than cutting an entrance in a common entrance in a common wall and connecting wall and connecting the existing building the existing building to the addition;if any to the addition;if any other work is done to other work is done to the existing building it the existing building it too must meet current too must meet current NFIP requirements for NFIP requirements for new construction in A new construction in A Zones. Zones. Lateral Additions Recommendation: Recommendation: Recommendation: BC: 3403.2, 3412.2.3, 3405.3 That Do Not Make addition Follow V Zone Elevate bottom of IRC: R322.3.1 Constitute compliant with current requirement for lowest horizontal NFIP requirements for building elevation and structural member to ASCE: ASCE 7 Sec. 1.6 Substantial V Zone construction. open foundations for or above BFE(same Other: FEMA TB#1, Improvementthe addition and the for existing building P Requirements: existing building. if it is elevated) (see FEMA TB#5, FEMA TB#9, Post-FIRM existing Fact Sheet No. 1d) FEMA 550 NFIP 60.3(e)(5) building—the Requirements: and 60.3(c)(5) addition must meet Post-FIRM existing Requirements: NFIP requirements building—the addition Post-FIRM existing in effect at time the must meet NFIP building—the addition building was originally requirements in must meet NFIP constructed. Pre-FIRM effect at the time the requirements in existing building— building was originally effect at the time the NFIP requirements constructed(see Fact building was originally concerning new Sheet Nos.1d, le,2b, constructed(see Fact construction are not 3a, 3e, 8a,8c).Pre- Sheet Nos. 1d, 1 e, 2b, triggered(see Fact FIRM existing building 3a,3e, 8a, 8c). Pre- Sheet Nos.1d, 1e,2b, --NFIP requirements FIRM existing building 3a,3e, 8a, 8c) concerning new -- NFIP requirements construction are not concerning new triggered. construction are not triggered. 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 7 of 10 I 12/10 Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone r73 Coastal Additional Resources V A A Repairs, Remodeli a a .,, a a ` o'"s `o.9.1] Vertical Additions Requirement: Recommendation: Recommendation: IBC: 3405.3.1, 3405.4, That Constitute Entire building Follow V Zone Elevate bottom of 3405.5 Substantial must meet current requirements for lowest horizontal IRC: N/A NFIP requirements building elevation and structural member to Improvement concerning new open foundations. or above BFE(same ASCE: N/A construction in V Zones for existing building if it Requirement: ct NFIP 60.3(e)(5) (see Fact Sheet Nos. Entire building is elevated) (see Fact Zand 60.3(c)(5) 18d' 1 e,2b,3a' 3e'8a' must meet current Sheet No. 1 d). W NFIP requirements Requirements: concerning new Post-FIRM existing construction in A Zones building—the addition (see Fact Sheet Nos. must meet NFIP 1 d, 1 e, 2b, 3a,3e, 8a, requirements in 8c). effect at the time the building was originally constructed(see Fact Sheet Nos.1 d, le,2b, 3a,3e, 8a,8c).Pre- FIRM existing building NFIP requirements concerning new construction are not triggered. Vertical Additions Recommendation: Recommendation: Recommendation: IBC: 3405.3.1, 3405.4, That Do Not Make the addition Follow the V Zone Elevate bottom of 3405.5 Constitute compliant with current requirement for lowest horizontal IRC: N/A NFIP requirements for building elevation and structural member Substantial V Zone construction. open foundations for at, or above, BFE ASCE: N/A Improvement Requirements: the existing building. (same for the existing Post-FIRM existing Requirements: building f it is elevated) (see Fact NFIP 60.3(e)(5) building—the addition Post-FIRM existing Sheet must meet NFIP buildingthe addition No. 1.4). and 60.3(c)(5) — requirements in must meet NFIP Requirements: effect at the time the requirements in Post-FIRM existing building was originally effect at the time the building—the constructed.Pre- building was originally addition must meet FIRM existing building constructed(see NFIP requirements NFIP requirements Fact Sheet Nos.1.4, in effect at the time concerning new 1.5,2.2, 3.1, 3.5, the building was construction are not 8.1,8.3).Pre-FIRM originally constructed triggered(see Fact existing building-- (see Fact Sheet Nos. Sheet Nos. 1.4, 1.5, NFIP requirements 1.4, 1.5, 2.2,3.1, 3.5, 2.2,3.1,3.5,8.1,8.3). concerning new 8.1, 8.3).Pre-FIRM construction are not existing building-- triggered. NFIP requirements concerning new construction are not triggered. 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS 8 of 10 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12n0 1 Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone Mg Coastal11111 Additional Resources V A A Repairs,Remodeling,an• Ad•!ions ESee Fact Sheet No. 91 Elevating on New Requirement: Recommendation: Recommendation: IBC: 1808.1, 1808.2, 1808.3. Foundation New foundation Follow the V Zone Elevated bottom of 1808.6. 1808.6.1 must meet current requirement for building lowest horizontal IRC: R401.1, R401.2, R401.3, NFIP requirements elevation and open structural member to or NFIP 60.3(e)(5) R401.4, R401.4.1 concerning new foundations. above BFE(see Fact 0 and 60.3(c)(5) construction in V Sheet No. 1 d). ASCE: ASCE 24 Sec. 1.5.3, m Zones;the building Requirement: New 1.5.3.1, 1.5.3.2, 1.5.3.3,ASCE Z must be properly foundation must Requirement: New 7 Sec. 1.6 rll meet current NFIP foundation must connected and DJ anchored to the new requirements meet current NFIP Other: FEMA 550, FEMA TB D concerning new requirements #1, FEMA TB#5 r- foundation. construction in A concerning new Note: Repairing Zones;the building construction in A a foundation that must be properly Zones;the building does not constitute connected and must be properly a substantial anchored to the new connected and improvement does foundation. anchored to the new not require current foundation. compliance, but compliance to the year of construction. Enclosures Requirement: Recommendation: Recommendation: IBC: 1612.1, 3404.2 Below Buildings— Both the enclosure and Follow the V Zone Elevated bottom of 9 IRC: R322.1, R322.1.8. When Enclosure the existing building requirement for building lowest horizontal R322.3.5 must meet current elevation and open structural member at, Constitutes NFIP requirements foundations. or above, BFE(see ASCE: ASCE 24 Sec.4.6, a Substantial for new construction Requirement: Both Fact Sheet No. 1.4). ASCE 7 Sec. 1.6 Improvement in V is Nos.es 1.4,ee Fact the enclosure and the Requirement: Both Other: FEMA TB#5, FEMA p Sheets 1.5, 2.2,3.1,8.1, 8.3). existing building must the enclosure and the TB#9 NFIP 60.3(e)(5) meet current NFIP existing building must and 60.3(c)(5) requirements for new meet current NFIP construction in A Zones requirements for new (see Fact Sheets Nos. construction in A Zones 1.4, 1.5, 2.2, 3.1, 8.1, (see Fact Sheets Nos. 8.3). 1.4, 1.5,2.2, 3.1, 8.1, 8.3). Enclosures Recommendation: Recommendation: Recommendation: IBC: 1612.1, 3404.2 Below Buildings— Make the enclosure Construct only Install flood openings IRC: N/A When Enclosure compliant with current breakaway enclosures; in the enclosure;do not NFIP requirements install flood openings convert the enclosed ASCE: ASCE 24 Sec.4.6 Does Not for new V Zone in the enclosure;do not space to habitable use. Other: FEMA TB#1, Constitutes construction. convert the enclosed Requirement: Post- FEMA TB#5, FEMA TB#9 a Substantial Requirement: Post- space to habitable use. FIRM existing building Improvement FIRM existing building Requirement: Post- —the enclosure —the enclosure FIRM existing building must meet NFIP NFIP 60.3(e)(5) must meet NFIP --the enclosure requirements in requirements in must meet NFIP effect at the time the and 60.3(c)(5) effect at the time the requirements in building was originally building was originally effect at the time the constructed.Pre- constructed.Pre- building was originally FIRM existing building FIRM existing building constructed.Pre- --NFIP requirements --NFIP requirements FIRM existing building concerning new concerning new -- NFIP requirements construction are not construction are not concerning new triggered(see Fact triggered(see Fact construction are not Sheet Nos.3.5, 8.1). Sheet No.8.1). triggered(see Fact Sheet Nos.3.5,8.1). 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 9 of 10 12/10 Coastal Construction Requirements and Recommendations V Zone Coastal A Zone A Zone M, CoastalIIII Additional Resources V A A Repairs,Remodeling,and'Ad d Itlons ee ract She • et No. •91 Reconstruction Requirement: Recommendation: Requirement: IBC: 1810.1.2, 105.1, K103.1 of Destroyed or Where the entire Follow the V Zone Where the entire IRC: R105.1,AJ501.3, Razed Buildingbuilding is destroyed, requirement for building is destroyed, AJ501.4,AJ501.5.1,AJ501.5, damaged,or building elevation and damaged, or AJ501.5.1,AJ501.5.2, .J purposefully open foundations. purposefully AJ501.5.3,AJ501.5.3.1, cC Requirement: Where AJ501.5.3.2,AJ501.5.3.3, Q NFIP 60.3(8)(5) demolished or razed, demolished or razed, W and 60.3(c)(5) the replacement the entire building is the replacement AJ501.5.3.4 AJ501.5.3.5, building must building must Z meet current NFIP destroyed,damaged, meet current NFIP AJ501.6,AJ501.7,AJ501.8, W or purposefully AJ501.8.1,AJ501.8.2, requirements demolished or razed, requirements AJ501.8.3 concerning new concerning new the replacement construction in V construction in A ASCE: N/A building must Zones,even if it is meet current NFIP Zones,even if it is Other: FEMA 550 built on the foundation requirements built on the foundation from the original from the original building(see Fact concerning new building (see Fact Sheet Nos.1.4, 1.5, construction in A Sheet Nos.1.4,9.1). 9.1). Zones, even if it is built on the foundation from the original building(see Fact Sheet Nos.1.4, 9.1). Moving Existing Requirement: Recommendation: Recommendation: IBC: 3410.1 Building Where the existing Follow the V Zone Elevate bottom of building is moved to requirement for lowest horizontal IRC: AE102.6 NFIP 60.3(e)(5) new location or site, building elevation and structural member at, ASCE: ASCE 7 Sec. 1.6 the relocated building open foundations. or above, BFE(see Other: FEMA 550 and 60.3(c)(5) must meet current Fact Sheet No. 1.4). NFIP requirements Requirement: Where concerning the existing building Requirement: Where construction in V is moved to new the existing building Zones(see Fact location or site,the is moved to new Sheet Nos.1.4, 1.5, relocated building location or site,the 9.1). must meet current relocated building NFIP requirements must meet current concerning NFIP requirements construction in A concerning Zones(see Fact construction in A Sheet Nos.1.4, 9.1). Zones(see Fact Sheet Nos.1.4, 9.1). Manufactured Housing General IRC: R322.1.9,App.AE101 ASCE: Not Applicable Other: FEMA 85 NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER ti 1.2: SUMMARY OF COASTAL CONSTRUCTION REQUIREMENTS AND RECOMMENDATIONS 10 of 10 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Using a Digital Flood Insurance Rate Map (DFIRM) HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 1.3 Purpose: To explain the purpose of Flood Insurance Rate Maps(FIRMS), Digital Flood Insurance Rate Maps(DFIRMs), highlight features that are important to coastal builders, and explain how to obtain FIRMs, DFIRMs, and Flood Insurance Studies (FISs). What Is a FIRM? Flood-prone areas are studied by engineers and hydrologists I FIRM r— �:. R�M�MI�W that specialize in analysis of streams, rivers, tidal shorelines, .,CA,rtv, ,a and their adjacent floodplain or coastal area. These publishedMOW studies, known as the community's FIS, provide detailed infor- ':;COMM •�•® 1_ mation on the study area that facilitates the creation of flood `r°°"°°' '"" maps. FISs are usually produced for the highest risk streams, most rivers, and almost all coastal reaches. w== '`4� _ q rwasa1r ��s FEMA has mapped flood hazards for nearly 20,000 communi- -,: = ties in the United States, most commonly on FIRMs. Most of -_ =-_._ the nation's FIRMs were converted during the past five years ;.1: r through the Map Modernization Program into a digital prod- ,,,RS , uct that depicts flood-prone areas for a community. These are ""E'"ER 1 ;� 14--- known as Digital Flood Insurance Rate Maps, or DFIRMs. — u Effective October 1, 2009, FEMA discontinued the distribution of paper maps. Paper FIRMs were replaced with DFIRMs. The FIRM for "` gam �� your specific site can be viewed online and reproduced by creating a „`its' - printable FIRMette1 that can be downloaded to a personal computer. ''=' ' 7—) DFIRMs show the delineation of the Special Flood Hazard Areas(SFHAs) — land areas subject to inundation by a flood that has a 1-percent prob- ability of being equaled or exceeded in any given year(hence, the terms "1-percent-annual-chance flood" and "100-year flood"). SFHAs are shaded on the DFIRM and are divided into different flood zones, depending on the nature and severity of the flood hazard. DFIRM datasets have been provided to your local community and are available for viewing at the local National Flood Insurance Program (NFIP) coordinator's office. FIRMs and DFIRMs Are Used By: Communities, to regulate new construction* (e.g.,foundation type, lowest floor elevation, use of the enclosed areas below the lowest floor). Designers and Builders, to determine flood hazards and plan new construction per community ordi- nance and code requirements. Lenders, to determine whether flood insurance is required for federally backed mortgages. Insurance Agents,to establish flood insurance premiums. Land surveyors and engineers,to complete National Flood Insurance Program (NFIP) elevation certif- icates (see Fact Sheet No. 1.4, Lowest Floor Elevation). * Note that new construction may include some additions,improvements,repairs,and reconstruction.Consult the community about substantial improvement and substantial damage requirements. 1 FIRMettes are user-selected portions of flood maps available through the FEMA Map Service Center. ?ARTAf J y ° FEMA 1.3: USING A DIGITAL FLOOD INSURANCE RATE MAP (DFIRM) ` � HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 4 t�ND SEC 12/10 Why Are FIRMs and DFIRMs Important? Flood Hazard Zones in Coastal Areas FIRMs and DFIRMs show the boundaries of mod- eled flood hazard areas in a community. (See the sample DFIRM that follows) Zone V: Areas closest to the shoreline includ- SFHAs shown on the maps are used to set flood ing the Primary Frontal Dune (PFD), subject to insurance rates and premiums. storm wave action, high-velocity flow, and ero- The 1-percent-annual-chance flood elevations sion during 100-year storm events. Elevations and flood depths shown on FIRMs and DFIRMs are not provided. are the minimum regulatory elevations on which community floodplain management ordinances Zone VE: Base Flood Elevations (BFEs) are pro and building codes are based. vided on the DFIRM and an additional hazard can be present associated with storm waves _j The information shown on these maps can af- greater than 3 feet and including the PFD. BFEs fect the design and construction of new build- are derived from detailed analyses shown in wings and infrastructure, the improvement and the FIS. z repair of existing buildings, and additions to W existing buildings (see Fact Sheet Nos. 1.2, Zone A: Areas subject to flooding during the Summary of Coastal Construction Requirements 1-percent-annual-chance flood. Flood conditions and Recommendations for Flood Effects,and 8.3, are less severe than in Zone V and MOWAs due Protecting Utilities). to lower wave forces. Because detailed anal- ysis has not been performed, BFEs and flood What Are Flood Zones and Base Flood depths are not provided. Elevations, and How Do They Affect Coastal Zone AE: Depicts BFEs on the DFIRM. Further Buildings? details are provided in the FIS on areas where hydrology and hydraulic modeling was per- BFEs are typically shown on DFIRMs for riverine formed to determine flood hazard risk. flood zones (Zone A, AE, AO, and AH) and coast- al flood zones (Zone V and VE). The BFE Is the Area of Moderate Wave Action (MOWA): Area predicted elevation of flood waters and wave ef- landward of Zone V, or landward of an open fects during the 1-percent-annual-chance flood coast without a mapped Zone V. During base (also known as the base flood). The BFE is ref- flood conditions, the potential wave height in erenced to the vertical datum shown on the this area is between 1.5 and 3 feet above the DFIRM. Most have been updated to the 1988 1-percent-annual-chance stillwater flood depth. North American Vertical Datum. While this area is not specifically labeled on the DFIRM panel, this is the area between the The minimum lowest floor elevation and the LiMWA and the VE/AE zone boundary. In many foundation type and design for new construc- codes and standards it is referred to as the tion* are determined by the BFE and flood zone, "Coastal A Zone." as required in the community's floodplain man- agement ordinance and building code (see Fact Zone AO: Areas subject to shallow flooding or Sheet Nos. 1.4, Lowest Floor Elevation, and 3.1, sheet flow during the 1-percent-annual-chance Foundations in Coastal Areas). This ordinance, flood. If they appear on a coastal DFIRM they along with the most current DFIRM and FIS, are will most likely be found on the landward slopes adopted by resolution to meet NFIP participation of shoreline dunes and overtopped structures. requirements. Use of these tools supports com- Flood depths, rather than BFEs, are shown for munity planning, zoning, and building inspection Zone AO. programs that require specific structure design and new construction* in high-hazard coastal Zone AH:Areas subject to inundation by 1-percent- floodplains. annual-chance shallow flooding (usually areas of ponding) where average depths are between Some communities have adopted higher standards 1 foot and 3 feet. for coastal construction (e.g., lowest floor elevations above the BFE [freeboard], restrictions on foundation Zone X: Areas with a lower probability of types, and enclosures in Zone A). Builders should flooding (<1%); these areas are generally not consult their local jurisdiction for details. regulated through community floodplain man- agement ordinances and building codes due to their lower predicted risk of flooding. * Note that new construction may include some additions,improve- ments,repairs,and reconstruction.Consult the community about substantial improvement and substantial damage requirements. 1.3: USING A DIGITAL FLOOD INSURANCE RATE MAP (DFIRM) 2 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12,10 Sample DFIRM r rrlrll ID 1 This map is a portion of the DFIRM for the Town of Oyster Bay F� PANEL owsG and the City of Glen Cove in Nassau County, New York. Several iiiilii important things to note are highlighted: FIRM Q FLOOD NBURAKE RATE IMP Iz The community identification number is 360465 for Glen Cove and 'C for NASSAU COUNTY,NEW YORK 360483 for Oyster Bay. III, • CONTAINS: The panel number is 19.Note that an Index Map is available showing NIjIP COMMUNITY Min all DFIRM panels for all communities within Nassau County. " I ,dr 13LE11 360465 Z OYSTER IAY,TO ' 9' 360483 I SI 'Q 0 The effective date of the DFIRM is September 11,2009. �' z NOTE. m ;1 G M wEU•IG iE, 'DF YEd SOE TOE D6O1.n$7EO OMME DD III; --. rt.,RG CtACT Of.2E2 MOOR SUBSEQUENT > 1 I' PANE i 366 C , MAP Sa 1NCEX FOR FIRM PMtEL LAYOUT) Ill Nome to User TEE r.aar�Rr rrort teem FEYr M I: I YFEE Rtrn t+eo E Rr tEEFrt Ea DEa�mI►aaaTrr I * aft.Fhaea be bud co tame wEFelleD arM The map scale is shown ill; •a•d.«••,.., along with shorelines, - fork. NUMBER roads, flood zones,and '<L '~ t E BFEs. (The scale and north s- 19G arrow are usually shown in �'� v. k� -',E- iz the"Key to the Map-along - -- _ F I� 4RD,T0 the left edge of the DFIRM.) Q SEPTEMBER 11.2009 1 Federal I nter¢cnr%\IanXo nttni AUK)) :•:t:. . The Limit of Moderate 52MW2 a:;11:::*` °� Wave Action-or LiMWA-is WU ` ' shown with a dashed black MR cenDIT.40 BFEs across the and white line.This is the ,1 4. - '..0,:::;.:Sva DFIRM section area subject to damaging 3 9ra* j ), shown range from waves between 1.5-3 feet ;i` �, 11 to 19 feet.The above the stillwater BFE. f datum (not shown 1 . P3 •- in this sample) i '- •. is the 1988 North T , e. American Vertical S. I Z. EAE � .7 SL4,1i)D a Otn�11'rD ZONE AE 1' � . • � � .tE�tsr Datum. EE i7 I'. 0t ZONE AE t[ OF o• • E.,J vwvEAEnO , - to I' fir. '"' OTNEEWIEE PROTECTED AREA ONE CIO ;.j•- - W, t D Es�uAKwFeD►Eea~i »E tir I L I r ( 1 : '� •'•L JAe /" II •C3.1 20NE AE (",,..--- - jp, 8 Q /y,.� i EL gt, 360465 `/ LIMIT OF MODERATE u - .ZONE AE • .. .. v LAVE ACTION Zone X has a less than 1-percent chance of flooding;therefore,floodplain ordinance and most flood-related building code requirements are not in effect for this area.However,use of the building standards described in these fact sheets is recommended due to the area's proximity to coastal waters and wind. 1.3: USING A DIGITAL FLOOD INSURANCE RATE MAP (DFIRM) HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 4 12/10 Is There Anything Else I Should Know About Where Can I Get FIRMs, DFIRMs, Flood Coastal Flood Hazard Areas and Flood Studies, and Other Information? Elevations? Many DFIRMs are digital conversions of FIRMs Community floodplain administrator.The community's produced during the past few years without im- DFIRMs and its local floodplain management regula- proved analysis of flood hazards.While some cor- tions, should be on file and available for viewing at rections were made,the maps may not accurate- the office of the community floodplain administrator. ly represent coastal flood hazards. Sections 7.8 FEMA's Map Information eXchange, or FMIX. This and 7.9 of FEMA's Coastal Construction Manual (FEMA-55,2005)describe how coastal flood haz service center serves as a one stop shop for a ards are mapped and how to determine whether variety of information, products, services, and coastal FIRMs reflect present-day flood hazards. tools that support the National Flood Insurance Program. To contact a FEMA Map Specialist, please DFIRMs do not incorporate the effects of long- call 1-877-FEMAMAP (1-877-336-2627) or email wterm shoreline erosion. This information should FEMAMapSpecialist@riskmapcds.com. DFIRMs and Z be obtained from other sources. FISs can be accessed at www.msc.fema.gov. Index w sheets and specific FIRM panels can be viewed on- Recent post-storm investigations and studies line at the FEMA Map Service Center website by have shown flood forces and damage in Areas entering either a parcel address or the specific of Moderate Water Action (MOWAs) or Coastal DFIRM panel number, if known. A user-selected por- A Zones can be very similar to those in Zone V. tion of flood maps (called a FIRMette) such as the Some communities have adopted DFIRMs that previous sample can be created,saved,and printed. show MOWAs as a white line on the DFIRM that An effective tutorial on interpretation and use of the depicts the LiMWA. Although DFIRMs (and mini- old FIRM product is available at www.FloodSmart. mum NFIP building standards) do not differenti- gov. While not specific to the newer DFIRM platform, ate between Zone A in coastal areas and Zone the tutorial defines basic flood hazard map termi- A in riverine areas, builders should consider us- nology and will be helpful to those less experienced ing Zone V foundation and elevation standards for with using flood hazard maps. new construction in the MOWA. These flood zones are depicted as white boundaries on DFIRMs where communities are encouraging use of Zone V standards in MOWAs. Many communities and states require that the lowest floor elevations are above the BFE, offer- ing an additional level of protection known as Freeboard. The term used to describe the higher elevation level is Design Flood Elevation (DFE). Many property owners have voluntarily construct- Information regarding FIRMs, DFIRMs, FISs, ed their buildings with the lowest floor several and related products can also be obtained from feet above the BFE because of the potential for FEMA through FMIX at: flood waters to exceed the BFE and enter the building. Flood insurance is not available in ar- FEMAMAP (1 877 336 2627) eas designated as being in the Coastal Barrier Or Resource System (CBRS). Only structures con- structed prior to the designation of the area as FEMAMapSpecialist@riskmap.cds.com being in the CBRS are allowed to purchase fed- eral flood insurance. NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 1.3: USING A DIGITAL FLOOD INSURANCE RATE MAP (DFIRM) 4 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12'10 Lowest Floor Elevation HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 1.4 Purpose: To describe the benefits of exceeding the National Flood Insurance Program (NFIP)minimum elevation requirements;to identify common construction practices that violate NFIP regulations, which result in significantly higher flood insurance premiums;and to discuss the NFIP Elevation Certificate. Why Is the Lowest Floor Elevation Important? 0 In riverine and other inland areas, experience has shown that if the lowest floors of buildings are not elevated above the flood level,these buildings and their contents will be damaged or destroyed. In coastal areas, wave m action causes even more damage, often destroying enclosed building areas below the flood level (and any D building areas above the flood level that depend on the lower area for structural support). Once waves rise r— above the lowest structural member in V Zones or Coastal A Zones,the elevated portion of the building is likely to be severely damaged or destroyed. Recommended Lowest Floor Elevations* Because of the additional hazard associated with wave action in V Zones and in Coastal A Zones, it is rec- ommended that the elevation requirements of ASCE 24 (that exceed the minimum elevation requirements of the NFIP) be followed: The bottom of the lowest horizontal structural member of a building in the V Zone is elevated 1 foot or more above the Base Flood Elevation (BFE) (i.e., add freeboard). The lowest horizontal structural member of a building in the A Zone in coastal areas is elevated 1 foot or more above the BFE (i.e., add freeboard). Recommended Practice: rya A • V A Zones in Coastal Areas: V Zones: Subject to Breaking Waves and Erosion During the Base Flood Bottom of Lowest Horizontal Structural Member Lowest Horizontal Structural Member Above BFE(Freeboard) Above BFE(Freeboard) Bottom of Top of Lowest Lowest Horizontal Floor Structural Member BFE � BFE _lFreeboard v"// U'/, A-Zone Building(Open Foundation) V-Zone Building(Open Foundation) * NFIP minimum elevation requirements:A Zones-elevate top of lowest floor to or above BFE;V Zones-elevate bottom of lowest hori- zontal structural member to or above BFE. In both V Zones and A Zones,many people have decided to elevate a full story to provide below-building parking,far exceeding the elevation requirement. See Fact Sheet No. 1.2 for more information about NFIP minimum requirements in A Zones and V Zones. EQN��F� J 9 FEMA 1.4: LOWEST FLOOR ELEVATION HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 2 41ND SEL 12/10 What Does FEMA Consider the Lowest Floor? Do not modify building plans to create habitable The lowest floor means "the lowest floor of the space below the intended lowest floor. Doing so will Put the building in violation of floodplain manage- lowest enclosed area, except for unfinished or ment ordinances and building code requirements. flood-resistant enclosures used solely for park- ing of vehicles, building access, or storage." Also, this space cannot be converted to living space after the certificate of occupancy is awarded. If the lowest enclosed area is used for anything other than vehicle parking, building access, or FEMA Elevation Certificate storage, the floor of that area is considered the The NFIP requires participating communities to adopt lowest floor. Such prohibited use will violate NFIP a floodplain management ordinance that specifies requirements, resulting in drastically increased minimum requirements for reducing flood losses. flood insurance premiums. Communities are required to obtain and maintain Note that any below-BFE finished areas, includ- a record of the lowest floor elevations for all new ing foyers, will violate NFIP requirements, may and substantially improved buildings. The Elevation wsustain unreimbursable flood damage,and make Certificate (see the following pages) allows the com- Z the building subject to increased flood insurance munity to comply with this requirement and provides W premiums. insurers the necessary information to determine flood insurance premiums. The floor of a basement (where "basement" means the floor is below grade on all sides) will A licensed surveyor, engineer, or architect must com- always be the lowest floor, regardless of how the plete, seal, and submit the Elevation Certificate to space is used. Basements are prohibited from the community code official. Not placing the lowest being constructed in V Zones and A Zones un- supporting horizontal members and the first floor less the basement is elevated to or above the of a building at the proper elevation in a coastal flood elevation or a basement exception has area can be extremely costly and difficult to correct. been granted. Following the carpenter's adage to measure twice, but cut once, the elevation of the building must be Walls of enclosed areas below the BFE must checked at several key stages of construction. Note meet special requirements in coastal areas (see that multiple Elevation Certificates may need to be Fact Sheet No. 8.1, Enclosures and Breakaway submitted for the same building: a certificate may Walls; TB 5, Free-of-Obstruction Requirements be required when the lowest floor level is set(and be- (2008); and TB 9, Design and Construction Guid- fore additional vertical construction is carried out); a ance for Breakaway Walls Below Elevated Coastal final certificate must be submitted upon completion Buildings (2008)). However, it should be empha- of all construction prior to issuance of the certifi- sized that in no instance are basements recom- cate of occupancy. mended in Coastal A Zones. The Elevation Certificate requires that the following Construction Practices and the Lowest Floor information be certified and signed by the licensed Constructing the lowest floor at the correct elevation professional (surveyor/engineer/architect) and is critical. Failure to do so can result in a building signed by the building owner: being built below the BFE. As a result, construction Name and address of property owner. work can be stopped, certificates of occupancy can be withheld, and correcting the problem can be ex- NFIP flood zone and elevation from a Digital pensive and time-consuming. Here are some helpful Flood Insurance Rate Map (DFIRM) and/or FloodInsurance Study (FIS). tips to consider when constructing the lowest floor: After the piles have been installed and the low- GPS coordinates. est horizontal structural supporting members Adjacent grade elevation. have been installed, have a licensed profession- al engineer, architect, or surveyor validate the in- Lowest horizontal structural supporting member tended elevation of the lowest floor before the elevation. piles are cut off. This should be noted on the Elevation of certain floors in the building. Elevation Certificate. Lowest elevation of utility equipment/machinery. Alternatively, after the piers or columns have been constructed, the intended elevation of the The Elevation Certificate provided in this fact sheet lowest floor should be validated during an in- expires March 31, 2012. Updated versions can be spection by the licensed professional and noted found at http://www.fema.gov/business/nfip/forms. on the Elevation Certificate prior to installation shtm. The Elevation Certificate and instructions are of the lowest horizontal structural supporting available on FEMA's website: http://www.fema.gov/ members. pdf/nfi p/elvicert.pdf. 1.4: LOWEST FLOOR ELEVATION 2 of 2 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12;10 V Zone Design and Construction Certification HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 1.5 Purpose: To explain the certification requirements Completing the V Zone Design Certificate for structural design and methods of construction There is no single V Zone certificate used on a na- in V Zones. tionwide basis. Instead, local communities and/or m states have developed their own certification pro- z Structural Design and Methods of cedures and documents. Registered engineers and m Construction Certification architects involved in V Zone construction projects D should check with the authority having jurisdiction r- As part of the agreement for making flood insurance regarding the exact nature and timing of required available in a community,the National Flood Insurance certifications. Program (NFIP) requires the community to adopt a floodplain management ordinance that specifies min- Page 2 shows a sample certification form. It is intend- imum design and construction requirements. Those ed to show one way that a jurisdiction may require requirements include a certification of the structural that the certification and supporting information be design and the proposed methods of construction provided. In this example,the certification statement (a similar documentation requirement appears in the can address both design and proposed methods of 2009 IRC,Section R322.3.6). It is recommended that construction and breakaway wall design. the design professional use ASCE 24 and ASCE 7 as appropriate engineering standards. Specifically, NFIP regulations and local floodplain Required Certifications in V Zones management ordinances require that: Designed and constructed to 1. A registered professional engineer or architect resist floatation, shall develop or review the structural design, collapse,and specifications, and plans for the construction. ❑ ❑ lateral movement 2. A registered professional engineer or architect shall certify that the design and methods of Lowest floor construction to be used are in accordance with elevation accepted standards of practice in meeting these Breakaway wall criteria: The bottom of the lowest horizontal structur- al member of the lowest floor (excluding the pil- ings or columns) is elevated to, or above, the Base Flood Elevation (BFE). Other Certifications Required in V Zone The pile or column foundation and structure at- Breakaway Wall Design,by a registered profes- tached thereto is anchored to resist flotation,col- sional engineer or architect (see Fact Sheet lapse, and lateral movement due to the effects No. 8.1, Enclosures and Breakaway Walls) of wind and water loads acting simultaneously on all building components. ASCE 7-10, Minimum "As Built" Lowest Floor Elevation, by a sur- Design Loads for Buildings and Other Structures, veyor, engineer, or architect (see Fact Sheet provides guidelines on different load combina- No. 1.4, Lowest Floor Elevation) tions, which include flood and wind loads. The V Zone Design certification should take into consideration the NFIP Free-of-Obstruction require- ment for V Zones: the space below the lowest floor must be free of obstructions (e.g., building element, equipment, or other fixed objects that can transfer flood loads to the foundation, or that can cause flood- waters or waves to be deflected into the building), or must be constructed with non-supporting breakaway walls, open lattice, or insect screening. (See NFIP Technical Bulletin 5 and Fact Sheet No. 8.1, Enclosures and Breakaway Walls.) O4,4 A�r1EA z ° FEMA1.5:V ZONE DESIGN AND CONSTRUCTION CERTIFICATION HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 2 AND 12/10 • Note: The V Zone design certificate is not a substitute for the NFIP Elevation Certificate (see Fact Sheet No. 1.4, Lowest Floor Elevation),which is required to certify as-built elevations needed for flood insurance rating. V ZONE DESIGN CERTIFICATE Name Policy Number(InsuranceCo.Use) Building Address or Other Description Permit No. City State Zip Code SECTION I: Flood Insurance Rate Map (FIRM) Information Community No. Panel No. Suffix FIRM Date FIRM Zone(s) CC SECTION II: Elevation Information Used for Design (NOTE: This section documents the elevations/depths used or specified In the design-it does not document surveyed elevations lW and is not equivalent to the as-built elevations required to be submitted during or after construction.] 1. FIRM Base Flood Elevation(BFE) feet* 2. Community's Design Flood Elevation(DFE) feet* 3. Elevation of the Bottom of Lowest Horizontal Structural Member feet* 4. Elevation of Lowest Adjacent Grade feet* 5. Depth of Anticipated Scour/Erosion used for Foundation Design feet 6. Embedment Depth of Pilings or Foundation Below Lowest Adjacent Grade feet *Indicate elevation datum used in 1-4: ❑NGVD29 ❑NAVD88 ❑Other SECTION III:V Zone Design Certification Statement I certify that: (1) I have developed or reviewed the structural design, plans, and specifications for construction of the above- referenced building and(2)that the design and methods of construction specified to be used are in accordance with accepted standards of practice**for meeting the following provisions: • The bottom of the lowest horizontal structural member of the lowest floor(excluding piles and columns) is elevated to or above the BFE. • The pile and column foundation and structure attached thereto is anchored to resist flotation, collapse, and lateral move- ment due to the effects of the wind and water loads acting simultaneously on all building components.Water loading values used are those associated with the base flood***.Wind loading values used are those required by the applicable State or local building code.The potential for scour and erosion at the foundation has been anticipated for conditions associated with the base flood, including wave action. SECTION IV: Breakaway Wall Design Certification Statement NOTE.This section must be certified by a registered engineer or architect when breakaway wails are designed to have a resistance of more than 20 psf(0.96 kN/m2)determined using allowable stress design] I certify that: (1) I have developed or reviewed the structural design, plans, and specifications for construction of breakaway walls to be constructed under the above-referenced building and (2)that the design and methods of construction specified to be used are in accordance with accepted standards of practice**for meeting the following provisions: • Breakaway wall collapse shall result from a water load less than that which would occur during the base flood***. • The elevated portion of the building and supporting foundation system shall not be subject to collapse, displacement, or other structural damage due to the effects of wind and water loads acting simultaneously on all building components(see Section III). SECTION V: Certification and Seal This certification is to be signed and sealed by a registered professional engineer or architect authorized by law to certify structural designs. I certify the V Zone Design Certification Statement (Section III) and the Breakaway Wall Design Certification Statement(Section IV,check if applicable). Certifier's Name License Number Title _ Company Name Address Place Seal Here City State Zip Code Signature Date Telephone 1.5:V ZONE DESIGN AND CONSTRUCTION CERTIFICATION 2 of 2 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Designing f Flood Levels Above the BFE HOME BUILDER'S GUIDE TO COASTAL CON STRUCTION Technical Fact Sheet No. 1.6 Purpose: To recommend design and construction practices that reduce the likelihood of flood damage in the event that flood levels exceed the Base Flood Elevation (BFE). 0 m Key Issues z m BFEs are established at a flood level, includ- The cost of adding freeboard at the time of home D ing wave effects, that has a 1-percent chance construction is modest, and reduced flood insur- r- of being equaled or exceeded in any given year, ance premiums will usually recover the freeboard also known as the 100-year flood or base flood. cost in a few years' time. Floods more severe and less frequent than the 1-percent flood can occur in any year. Flood levels during some recent storms have ex- ceeded BFEs depicted on the Flood Insurance . Rate Maps (FIRMs), sometimes by several feet. - - __ In many communities, flooding extended inland, well beyond the 100-year floodplain (Special - III � Flood Hazard Area [SFHA]) shown on the FIRM = •. (see Figure 1). 6!► . Flood damage increases rapidly once the el- r - evation of the flood extends above the lowest �' �� floor of a building, especially in areas subject to — coastal waves. In V Zones, a coastal flood with rk a_ �--- y ' a wave crest 3 to 4 feet above the bottom of the floor beam (approximately 1 to 2 feet above Figure 1. Bridge City.Texas,homes were flooded dur- the walking surface of the floor) will be sufficient ing Hurricane Ike,even though they were constructed to substantially damage or destroy most light- outside the SFHA and in Zone B.The flood level was frame residential and commercial construction approximately 4'above the closest BFE. (see Figure 2). Wilir There are design and construction practices that _.. , can eliminate or minimize damage to buildings `' when flood levels exceed the BFE. The most .ik, common approach is to add freeboard to the t_ .. design (i.e.,to elevate the building higher than i imi required by the FIRM). This practice is outlined II in American Society of Civil Engineers (ASCE) 24- 'I:05, Flood Resistant Design and Construction. _1 II • There are other benefits of designing for flood 10 r r<' levels above the BFE: reduced building damage t 1 i t 1 and maintenance, longer building life, reduced + IL = t . ;, flood insurance premiums, reduced period of ; r � � time in which the building occupants may need �, . .- _'11, v• 1 to be displaced in the event of a flood disas- ter (and need for temporary shelter and assis Figure 2.Bolivar Peninsula,Texas,V Zone house tance), reduced job loss, and increased reten constructed with the lowest floor(bottom of floor beam) at the BFE(dashed line).The estimated wave tion of tax base. crest level during Hurricane Ike (solid line) was 3' to 4' above the BFE at this location. QiyP Rtq GNING FOR D LEVELS VE THE BFE � � FEIN4Ii . HOME B 1.6: UILDER'S GUIDE OTO COASTAL CONSTRUCTION1 of 8 �,„.SFt. j 12/10 I How High Above the BFE Should a Building If the 50Oyear stillwater elevation (feet North be Elevated? American Vertical Datum of 1988 [NAVD] or Ultimately, the building elevation will depend on sev- feet National Geodetic Vertical Datum of 1929 eral factors, all of which must be considered before [NGVD]) is not available, a rule of thumb can be a final determination is made: used to approximate it as 1.25 times the 100- The accuracy of the BFE shown on the FIRM: year stillwater elevation (feet NAVD or feet NGVD). If the BFE is suspect, it is probably best to ele- The 500-year wave crest elevation can be ap- vate 3 or more feet above the BFE; if the BFE is proximated as 1.25 times the BFE. deemed accurate, it may only be necessary to el- evate a couple of feet above the BFE. If historical high water levels are above the Flood Insurance Rate Maps and Flood Risk Q BFE, the historical high water levels should be Hurricanes Ivan (2004), Katrina (2005), Rita (2005), cc considered in building elevation decisions. and Ike (2008) have demonstrated that constructing w z Availability of preliminary Digital Flood Insur- a building to the minimum National Flood Insurance w ance Rate Maps (DFIRMs): As new Flood Insur- Program (NFIP) requirements—or constructing a 0 ance Studies (FISs) are completed, preliminary building outside the SFHA shown on the FIRMs—is DFIRMs will be produced and available for use, no guarantee that the building will not be damaged even before they are officially adopted by those by flooding. communities. This is due to two factors: 1) flooding more severe Future conditions: Since the FIRM reflects con- than the base flood occurs, and 2) some FIRMs, par- ditions at the time of the FIS, some owners or ticularly older FIRMs, may no longer depict the true jurisdictions may wish to consider future condi- base flood level and SFHA boundary. tions (such as sea level rise, subsidence, wet- Even if the FIRM predicted flood levels perfect- land loss, shoreline erosion, increased storm ly, buildings constructed to the elevations shown frequency/intensity, and levee settlement/fail- on the FIRM will offer protection only against the ure) when they decide how high to elevate. 1-percent-annual-chance flood level (BFE). Some State or local requirements: The state or local coastal storms will result in flood levels that exceed jurisdiction may require a minimum freeboard the BFE, and buildings constructed to the minimum through its floodplain management requirements elevation could sustain flood damage. The black line or building code. in Figure 3 shows the probability that the level of the flood will exceed the 100-year flood level during time Building code requirements: The International periods between 1 year and 100 years; there is an Building Code (IBC) requires buildings be de- 18 percent chance that the 100-year flood level will signed and constructed in accordance with ASCE be exceeded in 20 years, a 39 percent chance it will 24. ASCE 24 requires between 0 and 2 feet of be exceeded in 50 years, and a 51 percent chance freeboard, depending on the building impor- it will be exceeded in 70 years. As the time period tance and the edition of ASCE 24 referenced.1 increases, the likelihood that the 100-year flood will The 2009 International Residential Code (IRC) be exceeded also increases. requires 1 foot of freeboard in V Zones and in Coastal A Zones. Figure 3 also shows the probabilities that floods of other severities will be exceeded. For example, tak- Building owner tolerance for damage, displace- ing a 30-year time period where there is a 26 percent ment,and downtime: Some building owners may chance that the 100-year flood level will be exceeded wish to avoid building damage and disruption, and a 6 percent chance that a flood more severe and may choose to elevate far above the BFE. than the 500-year flood will occur. In V Zones and A Zones, FEMA 499 recommends considering elevation of residential structures to the Elevation Recommendation 500-year flood elevation, or to the requirements of ASCE 24-05, whichever is higher. FEMA 499 recommends new and reconstructed residential buildings be elevated above the effec- tive BFEs with freeboard equal to that specified in ASCE 24-05, plus 3 feet. When new DFIRMs are available and adopted, 499 additionally rec- ommends new and reconstructed residential 1 The 1998 edition of ASCE 24 is referenced by the 2003 edition of the buildings be elevated to or above the freeboard IBC,and requires between 0 and 1 foot of freeboard.The 2005 edition g of ASCE 24 is referenced by the 2006 and 2009 editions of the IBC, elevation specified by ASCE 24-05. and require between 0 and 2 feet of freeboard. 1.6: DESIGNING FOR FLOOD LEVELS ABOVE THE BFE 2 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 FIRMs depict the limits of flooding,flood Probability of a Flood Exceeding the n-Year Flood Level elevations, and flood zones during the During a Given Period of Time base flood. As seen in Figure 3,buildings elevated only to the BFEs shown on the 100% - � FIRMs have a significant chance of being 90% flooded over a period of decades. Users 0 8o°%° should also be aware that the flood lim- a 70°i° its, flood elevations, and flood zones soi° shown on the FIRM reflect ground eleva- w 50% tions, development, and flood conditions o 4o°i° at the time of the FIS.2 .a 3 0% 20% 2 FIRMs do not account for the o_ 10% C) following: 0% z 0 10 20 30 40 50 60 70 80 90 100 m Shoreline erosion, wetland loss, Period of Time(years) subsidence, and relative sea 10- r flood �100- r flood 200 r flood r level rise Y Y Y Upland development or f 50-yr flood —4-150-yr flood t-500-yr flood topographic changes Degradation or settlement of Figure 3. Probability that a flood will exceed the n-year flood level levees and floodwalls over a given period of time. Changes in storm climatology (Note:this analysis assumes no shoreline erosion,and no increase in sea level or storm frequency/severity over time.) (frequency and severity) The effects of multiple storm events Thus,what was once an accurate de- 90 piction of the 100-year floodplain and 80 - flood elevations may no longer be so. V Zone a) 70 (No Obstruction) 60 Consequences of Flood Levels o 50 Exceeding the BFE 40 Buildings are designed to resist most 30 A Zone environmental hazards (e.g., wind, a_ (Two-Story Without seismic, snow, etc.), but are generally 20 Basement) designed to avoid flooding by elevat- 10 • ing the building above the anticipated 0 flood elevation. The difference in design -2 -1 0 1 2 3 4 5 6 7 8 9 1011 12 1314 15 16 17 18 19 20 21 22 approach is a result of the sudden on- Depth in Feet Relative to set of damage when a flood exceeds Bottom of Lowest Horizontal Structural Member* the lowest floor elevation of a build- ing. Unlike wind—where exposure to a *Assumes distance between top of floor and bottom of lowest wind speed slightly above the design horizontal structural member=2'for A Zone buildings. speed does not generally lead to se- vere building damage—occurrence of a Figure 4. Flood depth versus building damage curves for V Zones and flood level even a few inches above the riverine A Zones. lowest floor elevation generally leads to (SOURCE:FEMA 55,COASTAL CONSTRUCTION MANUAL). significant flood damage. Therefore, the recommendation is to add freeboard. This is especially true in cases where waves accompany coastal flooding. Figure 4 illustrates the expected flood damage (expressed as a percent of a building's pre-damage market value)versus flood depth above the bottom of the lowest horizontal structural member supporting the lowest floor(e.g., bottom of the floor beam), for a building in a V Zone and for a building in a riverine A Zone.3 2 Sections 7.8.1.3 and 7.9 of FEMAs Coastal Construction Manual(FEMA 55, 2000 edition)provide guidance on evaluating a FIRM to determine whether it still provides an accurate depiction of base flood conditions,or whether it is obsolete. 3 Since the normal floor reference for A Zone buildings is the top of the lowest floor,the A Zone curve was shifted for comparison with the V Zone curve. 1.6: DESIGNING FOR FLOOD LEVELS ABOVE THE BFE HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 8 12/10 One striking difference between the two curves is that a flood depth in the V Zone (wave crest elevation) 3 to 4 feet above the bottom of the floor beam (or approximately 1 to 2 feet above the top of the floor) is sufficient to cause substantial (>50 percent) damage to a building. In contrast, A Zone riverine flooding (without waves and high velocity) can submerge a structure without causing substantial damage. This difference in building damage is a direct result of the energy contained in coastal waves striking buildings—this type of damage was identified in Texas and Louisiana following Hurricane Ike (see Figure 5). In cases where buildings are situated behind levees, a levee failure can result in rapid flooding of the area. Buildings near a levee breach may be exposed to high velocity flows,and damages to those buildings will likely be characterized by the V Zone damage curve in Figure 4. Damages to buildings farther away from the breach will be a result of inundation by floodwaters, and will likely resemble the A Zone curve in Figure 4. Q CC o tz -- -- - — - � ale 111111 LLI ,i.T t tit.> • r 1 In I ' Ill it 4'- It !! 1 p , , 14 . - 1 Vft, 40, ' ,' .7.7- __ ,..____ AA Figure 5.Hurricane Ike damage to buildings.The upper left and upper right photos are of buildings that were close to the Gulf of Mexico shoreline and subjected to storm surge and large waves above the lowest floor.The lower left photo is of a building close to Galveston Bay shoreline and subjected to storm surge and small waves.The lower right photo is of a Cameron Parish,Louisiana,school that was approximately 1.3 miles from the Gulf shoreline.but subjected to storm surge and small waves. General Recommendations damage to wood floor systems, floor coverings, The goal of this fact sheet is to provide methods to and lower walls during the design flood,and may lead to mold growth and contamination damage minimize damage to buildings in the event that coast- (see Figure 6). al flood levels rise above the BFE. Achieving this goal will require implementation of one or more of the fol- In V Zones and A Zones, use a DFE that results lowing general recommendations: in freeboard (elevate the lowest floor above the In all areas where flooding is a concern, inside BFE) (see Figure 7). and outside the SFHA, elevate the lowest floor In V Zones and A Zones, calculate design loads so that the bottom of the lowest horizontal struc- and conditions (hydrostatic loads, hydrodynamic tural member is at or above the Design Flood loads,wave loads,floating debris loads, and ero- Elevation (DFE). Do not place the top of the low- sion and scour) under the assumption that the est floor at the DFE, since this guarantees flood flood level will exceed the BFE. 1.6: DESIGNING FOR FLOOD LEVELS ABOVE THE BFE 4 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12,10 • • , .. Toward Flood Source '1 {` 5 100-year Bottom of tt ty Wave Crest Lowest Horizontal �` �'"�•, • ,` r• • Elevation(ABFE) ' —Structural Member Freeboard G�yl l�' 1 �-. KP:= 100-Year - ---- -- Stillwater Elevation ts. ` 7.441PCIA11.4111041 I /, \YA II. 0 , . . m -' Exceeding NFIP Elevation Requirements in Coastal A Zones and V Zones Z m Figure 6. Mold and biological/chemical contamination J7 are also concerns when flood levels rise above the Figure 7. Recommended construction in Coastal A D I— lowest floor.Contamination may result in the build- Zone and V Zone. ing being irreparable or,at least,make the cleanup, restoration,and repairs more expensive and time- consuming. Toward Ocean In an A Zone subject to moderate waves (1.5 to 3.0 feet high) and/or erosion (i.e. •Coastal A Historcal Wave • Top of ' Crest Elevation Lowest Floor Zone), use a pile or column foundation (see Fig- I R Crawlspace 1// I 1 ure 7). 1 Foundation Outside the SFHA (in Zone B, Zone C, and Zone __ _1 ___ ___ __ ___ ___ ___ __ X),adopt flood-resistant design and construction practices if historical evidencereviewf the Historical Stillwater p es or a o Flood Depth odwnings a ersr Fl available flood data shows the building could be _Historical Stillwater Elevation damaged by a flood more severe than the base (Above 100-year Stillwater) flood (see Figure 8). Note:A pile or column foundatation may be best. Design and construct buildings in accordance with the latest model building code (e.g., IRC Figure 8. Recommended construction in Zone B,Zone or IBC), ASCE 7-10, Minimum Design Loads for C,and Zone X. Buildings and Other Structures and ASCE 24-05, Standard for Flood Resistant Design and Con- struction as applicable. Use the pre-engineered foundations, as applica- New and replacement manufactured homes should be installed in accordance with the pro ble,which are shown in FEMA 550, Recommend ed Residential Construction for the Gulf Coast: visions of the 2009 edition of the National Fire on Strong and Safe Foundations. Protection Association (NFPA) 225, Model Man- Buildingufactured Home Installation Standard. The stan- Use strong connections between the foundation dard provides flood, wind, and seismic-resistant and the elevated building to prevent the building installation procedures. It also calls for elevat- from floating or washing off the foundation, in ing manufactured homes in A Zones with the the event that flood levels do rise above the low- bottom of the main chassis frame beam at or est floor. above the BFE, not with the top of the floor at the BFE. FEMA P-85, Protecting Manufactured Homes Where additional freeboard is prohibited or not from Floods and Other Hazards provides addition- provided use flood damage-resistant building al guidance on proper manufactured home siting materials and methods above the lowest floor. and installation. For example, consider using drainable, dryable interior wall assemblies (see Figure 9). This al- lows interior walls to be opened up and dried after a flood above the lowest floor, minimizing damage to the structure. 1.6: DESIGNING FOR FLOOD LEVELS ABOVE THE BFE HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 8 1 12 10 Figure 9. Recommended wet Batt Insulation floodproofing techniques for .. . Above Gap ritil NI interior wall construction.The i following flood damage-resistant ii � PreSSuretreated IFNI materials and methods will Lumbher prevent wicking and limit flood r damage: Elevated 1)construct walls with horizontal Outlets gaps in wallboard; ri 2) use non-paper-faced gypsum _. wallboard below gap,painted --r with latex paint; 111' *board ' —J � Q 3) use rigid,closed-cell ►I! Gap in lboard ell l _) fi insulation in lower portion of to Prevent,�ffficking W walls; z 2-- 4) use water-resistant flooring Non-paper-faced �Rery ble with waterproof adhesive;and , Gypsum .Via -nCo 5) use pressure treated wood Wallboard t framing Rigid, Closed-cell i/4-Imo (SOURCE: LSU AGCENTER AND COASTAL Insulation CONTRACTOR MAGAZINE). Water-resistant Flooring Drained Cavity Exterior Rigid 1x4 Furing Exterior Rigid Brick Veneer Insulation Fiber cement Insulation f Non-paper faced Siding , Non-paper-faced °' i Gypsum Sheathing / I Gypsum Sheathing I z Latex Paint Latex Paint 1 • ./Non-paper-faced Non-paper-faced Gypsum Wallboard Gypsum Wallboard Uninsulated Steel or Pressure-treated I Uninsulated Steel or Pressure-treated Wood-framed Wall Wood-framed Wall Membrane or Trowel-on Membrane or Trowel-on Vapor Barrier(Class 1) Vapor Barrier(Class 1) Figure 10. Recommended flood-resistant exterior cavity wall construction.The following materials and methods will limit flood damage to exterior cavity walls: 1) use brick veneer or fiber-cement siding,with non-paper-faced gypsum sheathing (vinyl siding is also flood- resistant but is less resistant to wind damage); 2)provide cavity for drainage; 3) use rigid,closed-cell insulation; 4) use steel or pressure-treated wood studs and framing;and 5) use non-paper-faced gypsum wallboard painted with latex paint (SOURCE:COASTAL CONTRACTOR MAGAZINE AND BUILDING SCIENCE CORPORATION1. 1.6: DESIGNING FOR FLOOD LEVELS ABOVE THE BFE 6 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12 1ll I Drained Cavity Exterior Rigid Brick ,` Insulation Figure 11. Recommended flood- Veneer ': resistant exterior mass wall Concrete construction. The following BlockI materials and methods will limit d� flood damage to exterior mass ,411111P; Pil � � walls: -4— 1 use concrete masonr with Painted ) yStucco stucco or brick veneer(provide 0drainage cavity if brick veneer is used); 2) use rigid,closed-cell insulation; 3) use steel framing;and 4) useDnon-paper-faced gypsum wallboard rrliNon-paper-faced painted with latex paintm Gypsum Wallboard (Source: Coastal Contractor Magazinewith Latex Pai and Building Science Corporation). D r Uninsulated Membrane or Steel-framed Wall Non-paper-faced Trowel-on Vapor Barrier Gypsum Wallboard (Classl) with Latex Paint Other Considerations premiums can be cut in half by elevating a home 2 As previously stated, in addition to reduced building feet above the BFE, saving several hundred dollars damage, there are other reasons to design for flood per year in A Zones, and $2,000 or more per year levels above the BFE: in V Zones. In V Zones, savings increase with added freeboard. Reduced building maintenance and longer build- A comprehensive study of freeboard (American ing life. Institutes for Research, 2006) demonstrated that Reduced flood insurance premiums. adding freeboard at the time of house construction Reduced displacement and dislocation of build- is cost-effective. Reduced flood damage yields a ing floods (and need for tempo- benefit-cost ratio greater than 1 over a wide range ing occupantsshelter a afterd floods of scenarios, and flood insurance premium reduc- tions make adding freeboard even more beneficial Until flooded, many homeowners and communities to the homeowner. Reduced flood insurance premi- do not think about these benefits. However, one of ums will pay for the cost of incorporating freeboard the most persuasive (to homeowners) arguments for in a house in a V Zone in 1 to 3 years; for a house elevating homes above the BFE is the reduction in an- in an A Zone, the payback period is approximately nual flood insurance premiums. In most cases,flood 6 years. Flood Insurance Premium Reductions Can Be Significant Example 1:V Zone building, supported on piles Example 2:A Zone building, slab or crawlspace or piers, no below-BFE enclosure or obstruction. foundation (no basement). $200,000 building $250,000 building coverage, $100,000 contents coverage, $75,000 contents coverage. coverage. Floor Elevation Above BFE Reduction in Annual Flood Floor Elevation Above BFE Reduction in Annual Flood Premium* Premium* 1 foot 25% 1 foot 39% 2 feet 50% 2 feet 48% 3 feet 62% 3 feet 48% 4 feet 67% 4 feet 48% * Compared to flood premium with lowest floor at BFE 1.6: DESIGNING FOR FLOOD LEVELS ABOVE THE BFE HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 7 of 8 12/10 1 Additional Resources and References American Institutes for Research. 2006. Evaluation of the National Flood Insurance Program's Building Standards, (http://www.fema.gov/library/viewRecord.do?id=2592) ASCE. 2005. Minimum Design Loads for Buildings and Other Structures. ASCE 7-05. ASCE. 2005. Standard for Flood Resistant Design and Construction. ASCE 24-05. Coastal Contractor Magazine. July 2006. Low Country Rx: Wet Floodproofing. Drainable, dryable assemblies made with water-tolerant materials help speed recovery from deeper than-expected floods, by Ted Cushman, (http://www.coasta'contractor.net/cgi-bin/issue.pl?issue=9) FEMA. 2000. Coastal Construction Manual. FEMA 55. (ordering information at: http://www.fema.gov/pdf/ plan/prevent/nhp/nhp_fema55.pdf) FEMA. 2009. Mitigation Assessment Team Report, Hurricane Ike in Texas and Louisiana: Building Performance cc Observations, Recommendations, and Technical Guidance. FEMA P-757. (available at: http://www.fema.gov/ library/viewRecord.do?id=3577) FEMA. 2009. Protecting Manufactured Homes from Floods and Other Hazards. FEMA P-85, (http://www.fema. gov/library/viewRecord.do?fromSearch=fromsearch&id=1577) FEMA.2010.Recommended Residential Construction for the Gulf Coast,Building on Strong and Safe Foundations. FEMA 550, (http://www.fema.gov/library/viewRecord.do?id=1853) LSU AgCenter. 1999. Wet Floodproofing. Reducing Damage from Floods. Publication 2771, (http://www.lsuag- center.com/NR/rdonlyres/B2B6CDEC-2B58-472E-BBD9-OBDEBOB29C4A/26120/pub2771Wet6.pdf) NFPA. 2009. Model Manufactured Home Installation Standard. NFPA 225, (http://www.nfpa.org/about- thecodes/AboutTheCodes.asp?DocNum=225&cookie_test=1) NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 1.6: DESIGNING FOR FLOOD LEVELS ABOVE THE BFE 8 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Coastal Building Materials HOME BUILDER'S GUIDE TO COASTAL CON'TRUCTION Technical Fact Sheet No. 1.7 Purpose: To provide guidance and best practices on selecting building materials to use for coastal construction. Key Issues This fact sheet will cover special con- rilikke .. 1 ° siderations that must be made when ' ) selecting building materials for a coast- Z al building. The harsh environment mm requires that more substantial building . materials be used and more care tak- . f' D en when using these materials in order l - i c, , 1 B to ensure durability, hazard resistance, and reduce maintenance. The materials discussed can be used when dealing ; with both flood and wind hazards. Other factors such as corrosion and decay re- • , sistance will also be covered. Although '.'r - !44. inft- proper design is a key element it will be for naught if the proper materials are not _ selected. This fact sheet is also intend- '=' ed to provide the reader an idea of what the best practice should be when se- lecting a material for a coastal building. Select building materials that can endure periodic flooding. The following are some key consider- ations when screening materials. Materials and construction methods in a coast- Flood-Resistant Materials al environment should be resistant to flood and Flooding accounts for a large percentage of the dam- wind damage, wind-driven rain, corrosion, moss- age caused by a coastal storm,which is why building ture, and decay (due to sunlight, aging, insects, materials must be flood damage-resistant. The NFIP chemicals, temperature, or other factors). defines a flood damage-resistant material as "any Ease of installation or the ability to properly in- building material capable of withstanding direct and stall the material should be a major consider- prolonged contact (i.e., at least 72 hours) with flood- ation for the selection of materials. waters without sustaining significant damage (i.e., All coastal buildings will require maintenance requires more than cosmetic repair)." The cost of and repairs (more so than inland construction) cosmetic repair should be less than the cost of re- - use proper materials and methods for re- placing building materials. Although flood-resistant pairs, additions, and other work following initial materials typically refer to areas below the BFE,they construction (see Fact Sheets Nos. 9.1, Repairs, may be appropriate in areas above the BFE in order Remodeling, Additions and Retrofitting - Flood to limit the amount of damage caused by wind-driven and 9.2, Repairs, Remodeling, Additions and rain. All building materials below the BFE must be Retrofitting- Wind). flood damage-resistant, regardless of expected or historic flood duration. The durability of a coastal home relies on the types of materials and details used to construct it. For flood- Section 60.3(a)(ii)of the National Flood Insurance related information, see NFIP Technical Bulletin 2, Program (NFIP) regulations requires that all new Flood Damage-Resistant Material Requirements for construction and substantial improvements in Buildings Located in the Special Flood Hazard Areas flood-prone areas be constructed with materials in accordance with the National Flood Insurance below the Base Flood Elevation (BFE) that are Program 8/08. For other natural hazards, see the resistant to flood damage. (See Fact Sheet No. Institute for Business and Home Safety Fortified...for 9a for a definition of"substantial improvement.") Safer Living®Builder's Guide. .„�gAl1FH 1.7: COASTAL BUILDING MATERIALS ;` e:'' ;•-q � FEMA HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 6 4gND 00' 1 12/10 The following are examples of flood-resistant The following are examples of materials that are un- materials: acceptable below the BFE: Lumber: Preservative-treated or naturally dura- Normal, water-soluble adhesives specified for ble wood as defined in the International Building above-grade use or adhesives that are not resis- Code. Naturally durable wood includes the heart- tant to alkali or acid in water, including groundwa- wood of redwood, cedar, black locust, and black ter seepage and vapor. walnut. Materials that contain paper-based materials, Concrete: A sound, durable mix, and when ex- wood-based materials, or other organic materi- posed to saltwater or salt spray, made with a sul- als that dissolve or deteriorate, lose structural fate-resisting cement,with a 28-day compressive integrity, or are adversely affected by water. strength of 5,000 psi minimum and a water ce Sheet-type floor coverings (e.g., linoleum, vinyl) ment ratio not higher than 0.40—such mixes are J usually nominally more expensive and rarely add or wall coverings (e.g., wallpaper) that restrict oaC significant cost to the project (consult ACI 318 drying of the materials they cover. w 02, Building Code Requirements for Structural Materials that become dimensionally unstable w Concrete and Commentary by the American when subject to wetting and drying. C� Concrete Institute). Reinforcing steel used in Materials that absorb water excessively or main- concrete or masonry construction in coastal ar- eas should not be left exposed to moisture and tain a high moisture content after submergence. should not be stored on bare ground. The rein- Wiring, outlets, and electrical components not forcing steel should be free from rust and clear- designed to be flood resistant. It is important to ances should be maintained as shown on the de- locate any materials like these above the expect- sign drawings. ed floodwater elevation. When this is not possi- Masonry: Reinforced and fully grouted. If left un ble, it is important to allow for the isolation of filled, then masonry block cells can create a res— ervoir that can hold water and can make the ma- Flood insurance will not pay a claim for damages to sonry difficult to clean following a flood. finish materials located in basements or in enclosed Structural Steel: Coated to resist corrosion. areas below the lowest floor of elevated buildings, even if such materials are considered to be flood Insulation: Plastics, synthetics, and closed-cell damage-resistant. NFIP claims for damages below foam, or other types approved by the local build- the BFE are limited to utilities and equipment, such ing official. as furnaces and water heaters. This table lists examples of flood-resistant materials used in coastal homes. Location of Material Use Name of Material Piles and Posts Preservative-treated round, tapered wood piles:square-cross section piles;or wood posts. Piers Reinforced concrete or concrete masonry units (CMU) (see the section"Flood- Resistant Materials"and Fact Sheet No.3.4, Reinforced Masonry Pier Construction). Foundation Walls Reinforced concrete or CMU, or wood that is preservative-treated for foundation or marine use (see Fact Sheet No.3.5, Foundation Walls). Solid sawn timbers and glue-laminated timber products, either naturally durable wood Beams or preservative-treated for above ground exposure;built-up members preservative- treated for ground contact. Decking Preservative-treated or naturally durable wood Framing Sawn lumber or manufactured lumber that is preservative-treated or naturally durable wood if in close proximity to the ground. Exterior Sheathing Plywood that is marine grade or preservative-treated, alkaline copper quaternary (ACQ) or copper azole (C-A) Plywood that is marine grade or preservative treated, alkaline copper quaternary Subflooring (ACQ) or copper azole (C-A). (Although providing additional freeboard is recommended, as a redundant hazard mitigation measure, a flood-resistant material can also be considered for the subflooring). 1.7: COASTAL BUILDING MATERIALS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Location of Material Use Name of Material Siding Vinyl siding, fiber cement siding, or heartwood of naturally durable species (see Fact Sheet No. 5.3, Siding Installation in High-Wind Regions). Latex or bituminous cement formed-in-place, clay, concrete tile, pre-cast concrete, epoxy formed-in-place, mastic flooring, polyurethane formed-in-place, rubber sheets, rubber tiles with chemical-set adhesives, silicone floor formed-in-place, terrazzo, Flooring vinyl sheet-goods, vinyl tile with chemical-set adhesives, preservative-treated lumber or lumber from naturally durable wood. (Some tile types attached with ordinary mastic or thin set mortar may not be flood resistant and should be avoided.Verify with a manufacturer that a flooring material is flood-resistant.) Cement board, brick, metal, cast stone in waterproof mortar, slate, porcelain, glass, Walls and Ceilings glass block, clay tile, concrete, CMU, preservative-treated wood, naturally durable C) wood, marine grade plywood, or preservative-treated plywood. Metal doors, either hollow, wood core, and foam-filled core should be evaluated Doors after exposure to salt water flooding. Fiberglass, wood core doors may be another r— alternative to consider. Insulation Sprayed polyurethane foam (SPUF) or closed-cell plastic foams Trim Preservative-treated or naturally durable wood or artificial stone, steel, or rubber Although the materials listed are considered flood- Tie-down connectors used throughout struc- resistant materials, some sidings and wall coverings ture (from roof framing to foundation — see may need to be removed from framing members fol- Fact Sheet Nos. 4.1, Load Paths and 4.3, Use of lowing a flooding event in order to allow the system Connectors and Brackets) to properly dry. For more information on repair tech- niques after a flood, see FEMA 234, Repairing Your Wider framing members (2x6 instead of 2x4) Flooded Home (08/92). As hurricanes in recent years have proven, even well- Many jurisdictions will provide a list of approved flood- selected materials can fail if not installed properly. resistant materials that can be used in their local Proper installation requires attention to detail, fol- coastal environments. Check these lists and include lowing the manufacturer's recommended installation all proposed construction and materials in approved procedures, and proper maintenance. When select plans. ing a material or building component it is important to consider the level of difficulty required to properly Wind-Resistant Materials install the material. Improper installation of materi- als may expose the building's systems to wind loads Homes in many coastal areas are often exposed to that the systems were not designed to resist. Also, winds in excess of 90 mph (3-second peak gust). it is important to verify that any special requirements Choose building materials(e.g., roof shingles,siding, were followed and that specialized tools or adhesives windows, doors, fasteners, and framing members) were used. Even a building component that exceeds that are designed for use in high-wind areas. the design requirements can fail if it is installed incorrectly. Examples: Roof coverings rated for high winds (see Roofing Corrosion and Decay Resistance Category, Fact Sheet Nos. 7.1-7.6) Buildings in coastal environments are prone to dam- Double-hemmed vinyl siding (see Fact Sheet No. age from corrosion, moisture-related decay, and 5.3, Siding Installation in High-Wind Regions) termite damage to building materials. Metal corro- sion is most pronounced on coastal homes (within Deformed-shank nails for sheathing attach- 3,000 feet of the ocean), but moisture-related decay ments (see Fact Sheet No. 7.1, Roof Sheathing and termite damage are prevalent throughout coastal Installation) areas. Wind-borne debris resistant glazing (see Fact Sheet No. 6.2, Protection of Openings - Shutters and Glazing) Reinforced garage doors 1.7: COASTAL BUILDING MATERIALS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 6 12/10 Corrosion-Resistant Metals The term corrosion-resistant is widely used but, Preservative-treated wood used in a coastal environ- by itself, is of little help to those specifying or ment often contains chemical preservatives such evaluating materials for use in a coastal home. as Alkaline Copper Quat (ACQ), Copper Azole (CAC), Every material resists corrosion to some extent, Dispersed or Micronized Copper (µCA-C), or Copper or conversely, every material corrodes. Naphthenate (CuN-W). The connectors and fasten- ers used in conjunction with these pressure-treated The real issue is how long will a given material wood products should be properly selected and it serve its intended purpose at a given home?The should be verified that the connectors are compat- answer depends on the following: ible with the wood preservative. According to the The material. 2009 International Residential Code (IRC) R317.3.1 and International Building Code(IBC) 2304.9.5.1 the Where it is used in the home. fasteners should be compatible with the wood pre- Whether installation techniques (e.g., drill- servative per the manufacturer's recommendations. pc ing, cutting, bending) will compromise its w The fasteners shall be hot-dip zinc-coated galvanized resistance. z steel, stainless steel, silicon bronze, or copper. If the w manufacturer's recommendations are not available, Its degree of exposure to salt air, moisture, then corrosion protection in accordance with ASTM and corrosive agents. A 653 type G185 for zinc-coated galvanized steel or equivalent is required. Exceptions to this rule may be Whether maintenance required of the home- owner is performed. noted in the building code. The bottom line:Do not blindly specify or accept a product just because it is labeled corrosion- resistant. Evaluate the nature of the material, its coating type and thickness (if applicable), and its performance in similar environments before determining whether it is suitable for a particular application. For guidance on the selection of metal hardware for use in coastal environments, consult an en- gineer with experience in corrosion protection. For more information about corrosion in coast- al environments, see FEMA Technical Bulletin 8-96, Corrosion Protection for Metal Connectors in Coastal Areas (see the "Additional Resources" section). Recommendations Use hot-dip galvanized steel or stainless steel hardware. Stainless steel hardware is accept- able in virtually all locations, but hot-dip galva- nized hardware may not be appropriate in every location. Reinforcing steel should be protected from corrosion by sound materials (e.g., mason- ry, mortar, grout, concrete) and good workman- ship (see Fact Sheet No. 4.2, Masonry Details). 0 Use galvanized or epoxy-coated reinforcing steel in areas where the potential for corro- sion is high (see Fact Sheet No. 3.4, Reinforced Masonry Pier Construction). • It is important to verify that the connector plate Metals corrode at a much faster rate near the ocean. and the fastener are the same type of met Always use well-protected hardware,such as this con- al. Avoid joining dissimilar metals, especial- nector with thick galvanizing.(For information about ly those with high galvanic potential (e.g., cop- pile-to-beam connections,see Fact Sheet No.3.3, per and steel) because they are more prone to Wood Pile-to-Beam Connections.) corrosion. 1.7: COASTAL BUILDING MATERIALS 4 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1210 1 Metal-plate-connected trusses should not be exposure of end grain cuts, which absorb mois- exposed to the weather. Truss joints near vent ture up to 30 times faster than the sides of a openings are more susceptible to corrosion wood member). and may require increased corrosion protection. Do not use untreated wood in ground contact or Verify the connectors used near any roof vent high-moisture situations. Do not use untreated openings are stainless steel or a minimum of wood in direct contact with concrete. ASTM A 653 type G185 zinc-coated galvanized steel or equivalent. Field-treat any cuts or drill holes that offer paths Due to the potential for galvanic corrosion, stanfor moisture to enter wood members. Field treat- -dard carbon-steel, aluminum, or electroplated ment shall be done per M4-06 of the American Wood Preservers' Association. fasteners and hardware are not recommended for direct contact with preservative-treated wood. For structural uses,employ concrete that is sound, Thedense, and durable; control cracks with welded 0 use of aluminum flashing with many types of treated wood should be avoided. Aluminum will wire fabric and/or reinforcing, as appropriate. m z corrode quickly when in contact with most wood Use masonry, mortar, and grout that conform to m preservatives. Copper flashing in many instanc- the latest building codes. es is the best choice although products such as r- Cavity wall systems (two masonry wall systems vinyl flashing are becoming more common. separated by a continuous air space) should be Moisture Resistance avoided in flood-prone areas since they can fill with water, retain moisture, and be difficult to re- Moisture-resistant materials can greatly reduce pair without a significant level of demolition. maintenance and extend the life of a coastal home. Consider the interior finishes for first floors However, such materials by themselves cannot where floodwaters exceeding the design event prevent all moisture damage. Proper design and in- could cause significant damage (See Fact Sheet stallation of moisture barriers (see Fact Sheet No. No. 1.6, Designing for Flood Levels Above the 1.9, Moisture Barrier Systems) are also required. BFE). It is also important to consider that wind- driven rain can cause damage to interior finishes around door and window openings. :. Termite Resistance 1 Termite damage to wood construction occurs in many 4 coastal areas (attack is most frequent and severe along the southeastern Atlantic and Gulf of Mexico shorelines, in California, in Hawaii, and other tropical areas). Termites can be controlled by soil treatment, termite shields, and the use of termite-resistant '' ' !! materials. 44: r Recommendations '• Incorporate termite control methods into design + � in conformance with requirements of the author- 1, I" ity having jurisdiction. Where a masonry foundation is used and anchor- Wood decay at the base of a wood post supported by age to the foundation is required for uplift resis- concrete. tance,the upper block cores must usually be com- pletely filled with grout, which may eliminate the requirement for termite shields (see Fact Sheet Recommendations No. 3.4, Reinforced Masonry Pier Construction). Control wood decay by separating wood from Use preservative-treated wood for foundations, moisture, using preservative-treated wood, using sills,above-foundation elements,and floor framing. naturally durable wood, and applying protective In areas with infestations of Formosan termites, wood finishes. wood products treated with insect-resistant Use proper detailing of wood joints and con- chemicals or cold-formed steel framing are ma- struction to eliminate standing water and reduce terial options for providing protection against ter- moisture absorption by the wood (e.g., avoid mite damage. 1.7: COASTAL BUILDING MATERIALS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 6 12/10 Additional Resources FEMA. NFIP Technical Bulletin 2-08, Flood-Resistant Materials Requirements. (http://www.fema.gov/plan/pre- vent/floodplain/techbul.shtm) FEMA. NFIP Technical Bulletin 8-96, Corrosion Prttection for Metal Connectors in Coastal Areas. (http://www. fema.gov/plan/prevent/floodplain/techbul.shtm American Concrete Institute. (http://www.aci-int.org/general/home.asp) American Wood Protection Association. (http://www.awpa.com) J W Z 0 NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 1.7: COASTAL BUILDING MATERIALS 6 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12.10 - Tr di i n l Building Nona t o a Materials and Systems HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 1.8 Purpose: To provide guidance on non-traditional building materials and techniques and their appropriate application in coastal environments. G) m Key Issues r Z m Determination of whether a material sIIor system is appropriate for the site- D specific hazards. Evaluation of whether new materials '-4 and construction systems should be '4Y* 0 y resistant to flood and wind damage, -•?-.- i _‘. wind-driven rain, corrosion, mois- ., 15we' ture, and decay. All coastal buildings will require maintenance and repairs (more so q _ than inland construction). When I `� / considering using a non-traditional 'f T�' material or system, it is important I. _ t to ask, "What are some consider- I ations for various new materials and systems?" - — _ _ - Every year, new construction materials are introduced into the market. These Figure 1. Construction of a modular home. building materials cover every part of the home from the foundation system to the roof system. New materials often offer a variety of of these factors include overall hazard resistance benefits — a cost-effective solution, energy efficien- for flood and wind, durability, maintenance, and re- cy, aesthetics, ease of installation, or eco-friendly pair requirements. Additionally, when considering solutions. a particular building component, it is important to This fact sheet will focus on providing information consider the installation and constructability of the component. When selecting a material or a system on building materials and systems that while not being considered traditional materials are not un- for a coastal environment it is important to consid- er available information in addition to technical data common to the industry.The sheet is not intended to from encourage any one material or system, but will pro- considerations are: the manufacturer or supplier. Some examples vide information so that the user can make a more of informed choice about whether something is an ap- Contact the local building official about the ac- propriate material or system for a given situation. ceptability of the material or system. While the fact sheet does not cover all materials, it Review test results on the material or system's provides readers with an idea of what criteria they use in coastal environments. may need to be mindful of when selecting materials Review product code evaluation reports. and systems. While many are reasonable alterna- tives to traditional materials and systems,their uses Review field reports or a history of these materi- should be carefully considered. The same factors als or systems performing well in similar coast- used to consider the applicability of traditional al environments, including experience in high building materials and systems should be used to winds and flooding. determine whether new materials and systems are Review the manufacturer's installation and main- appropriate for use in a coastal environment. Some tenance instructions. �E¢�1Fti 1.8: NON-TRADITIONAL BUILDING MATERIALS AND SYSTEMS of � FEI\4J\ HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 6 �<IWD SEcv I 12,10 Not all materials and systems will be specifically ad- Availability: Certain sizes of Glulam or SCL may dressed by local building code requirements. Some be difficult to obtain. They may require special or- products or systems may be absent from the code dering and fabrication, which may not meet the and may require engineering calculations or studies project schedule for the building. in order to determine that they are appropriate for use in a particular area. Installation: Installation issues include condi- tions for storing materials, dimensional compat- ibility with other materials, and requirements for NOTE: When considering using new materials or use of metal connectors and fasteners to ensure systems, the application of load path connec- accordance with the manufacturer's installation tors should be carefully evaluated. Connectors instructions. should be evaluated by testing to demonstrate adequate performance for their intended appli- Structural Insulated Panels (SIPs) cation. Installation of the connectors should be considered and the ease of installation should Structural Insulated Panels (SIPs) are manufactured CC w be a primary consideration. An improper instal- panels made of a foam insulation core bonded be z lation of a connector can result in significant tween two structural facings. SIPs are commonly w losses in strength. manufactured with OSB facings as discussed in the 02009 International Residential Code (IRC) Section R613.3.2, but are also available with steel, alumi- num, or concrete facings. SIPs can be used for walls System Options (see Figure 2), floors, and roofs, and are compatible Engineered Wood Products with light-framed construction. A variety of Engineering Wood Products (EWPs) are recognized in the model building codes. Examples in- clude wood structural panels such as plywood and oriented strand board (OSB) and products commonly used as columns and beams such as structural glued laminated timber (glulam) and structural composite �� lumber (SCL). Glulam is an engineered, stress-rat- ed product of a timber laminating plant comprised of wood laminations of nominal 2 inches or less in thickness bonded together with adhesive. SCL refers to either laminated veneer lumber (LVL), laminated strand lumber(LSL), or oriented strand lumber(OSL), which are comprised of wood in various forms (e.g., veneer, veneer strands, or flaked strands) and struc- tural adhesive. For floor systems, conventional sawn lumber joists and girders (either solid or built-up) are recognized as flood-resistant. If EWPs are used for Imo orI floor framing they should be either flood-resistant or , 4. 1111111111 I elevated to a height where they are not expected to . ■ be wetted. Figure 2. Construction of a Structural Insulated Panel Advantages: house. EWPs are available in dimensions (length, width, and thickness) that are economical or, in some instances, not possible with sawn lumber. Due to availability of larger sizes, EWPs are able Advantages: to resist greater loads than sawn lumber. SIPs offer an efficient construction method and EWPs are manufactured in a dry condition and quick assembly. Insulation is built-in, and wall openings and utility chases are precut by the are more dimensionally stable than sawn lumber, manufacturer per the building plans, reducing on- which may warp and twist during drying. site coordination and adjustments. Things to consider if building with EWPs: They increase thermal resistance, reducing Cost: While EWPs can be used to offer greater heat gain and loss from the building, which al- spans and exceed the loading properties of con- lows smaller HVAC equipment to be used in the ventional lumber,they cost more. building. 1.8: NON-TRADITIONAL BUILDING MATERIALS AND SYSTEMS 2 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Things to consider if building with SIPs: Evaluate the design loading values of the SIP and verify that the prod • uct is appropriate for the wind load- ing requirements for the building location. - . SIPS are an engineered assembly. -" SIPS should not be used where they • , can be flooded unless the entire as- . .�,.c. sembly has been tested for flood re- sistance. Many SIPs utilize OSB fac- ings. Generally, SIPs should only be used above the base flood ele- vation (BFE) so that they maintain their structural integrity. Refer to IRC . ' R322.1.8 for requirements for flood- resistant materials. Otherwise, if the SIP is exposed to water damage dur- ing flooding, the panel may need to Figure 3. An example of ICF walls and reinforcing steel prior to be opened, allowed to dry out, and placement of the concrete.The forms are left in place following repaired or, in some instances, even placement of the concrete. replaced. As with conventional construction techniques, Advantages: SIPs may sustain windborne debris damage. ICF provides improved energy efficiency and al- This may require cutting out a section of the SIPs lows the use of smaller HVAC equipment than and repairing it with either conventional framing some other construction methods. techniques or a replacement SIP The foam core of SIPs is inert and provides no The concrete and insulation walls are durable food value to termites and other pests. However, and require little maintenance. pests may still nest within the foam. Always in- The combination of thick concrete walls and con- corporate pest control methods into the design tinuous insulation provide significant noise re- in conformance with local jurisdictional require- duction over other construction methods. ments. Some manufacturers sell pre-treated SIPs. ICF provides good wind, windborne debris, and Always use approved connectors and connection flood resistance. methods for panel-to-panel, panel-to-foundation, Things to consider if building with ICFs: and panel-to-roof connections. For guidance on SIPs connections, refer to IRC R613.5. It is im- Special connectors may be required for the con- portant to consider that not all connectors are nection of the roof system, floor system, doors, compatible with SIPs and in some instances and windows. specific connectors may be required in order to maintain the load path. For material and construction requirements for concrete walls, refer to IRC R611. Follow manufacturer's installation instructions and product use requirements in the manufac Exterior foam must be protected from sunlight turer's code evaluation report. and physical damage by the application of an ap- proved exterior wall covering. Refer to IRC 611.4 Insulating Concrete Forms (ICFs) for requirements for stay-in-place concrete forms. ICFs are made of molded expanded polystyrene (MEPS) foam and are used to form cast-in-place ICF foam is inert and provides no food value to concrete walls (see Figure 3). Unlike conventional termites and other pests. However, pests may cast-in-place concrete construction, the ICFs are left still nest within the foam. Always incorporate in place after the concrete cures to provide insula pest control methods into the design in confor tion, an attachment surface for interior and exterior mance with requirements of the authority having finishes, and space to run plumbing and electrical jurisdiction. lines within the wall. In some seismically active areas, constructing large, heavy structures on pile foundations can present significant design challenges. As with any 1.8: NON-TRADITIONAL BUILDING MATERIALS AND SYSTEMS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 6 12 10 construction system, construction in areas sub- Verify that the members and connections used ject to high erosion or scour could present design in the prefabricated sections are designed challenges due to the mass of an ICF structure. for the corrosive, moist coastal environment. Foundation walls built with ICF (with appropriate Preservative treated wood and galvanized or openings) can be an appropriate foundation Sys stainless steel connectors may be required for a tem in an A Zone. In V Zones, open foundation coastal application. systems are required and in Coastal A Zones rec- Not all prefabricated shear wall or moment frame ommended. ICF and other solid foundation walls systems will be allowed in all locations. It is im- are not appropriate to be used in these areas. portant to consider that panel substitutions are Follow manufacturer's installation instructions subject to requirements of the applicable build and product use requirements in the manufac ing code. Refer to IRC R602.10 for more infor turer's code evaluation report. mation on wall bracing requirements. Q Maintaining the load path is important with any cc Prefabricated Shear Walls and Moment Frames system. Because these systems provide later- al al support for the structure, it is important to z Many companies now offer prefabricated shear wall W and moment frames that are pre-designed and avail make sure that the load path will be transferred able in standard sizes.The wall sections and moment through the wall system and transferred down frames (see Figure 4) are connected to the rest of to the lower story of foundation and into the the structural framing with bolted, screwed, or nailed ground. Follow the manufacturer's installation in connections. Sections are ordered and brought to struction and product use requirements in the the site on trucks as one piece or constructed with manufacturer's code evaluation report. either bolted or proprietary connectors. Sprayed Closed-Cell Foam Insulation Advantages: Sprayed closed-cell foam polyurethane insulation is Prefabricated shear walls are often designed to used to fill wall cavities in framed construction (see provide for quick installation and compatibility Figure 5). When sprayed, it expands and hardens with other framing methods, where narrow wall forming a rigid air barrier and acting as a moisture solutions may not be practical with other framing retardant. options. Advantages: Moment frames take the place of shear walls to Sprayed closed-cell foam insulation expands to allow large continuous spaces for windows and fill wall cavities, small holes, and gaps as it ex- other wall openings. Much like the prefabricated pands, producing a rigid barrier that results in re- shear walls they can be assembled quickly and duced energy costs. incorporated into the house framing. It is quick to apply and may require less time to Things to consider if building with prefabricated shear install than conventional batt insulation. walls and ordinary moment frames: It offers acceptable flood resistance, which is Some systems may be limited in their application shown in NFIP Technical Bulletin 2-08, Flood- due to seismic or wind loading requirements. Resistant Material Requirements for Buildings Located in Special Flood Hazard Areas in ac- cordance with the National Flood Insurance ."1171,111111111111N, - . r Program, Table 2. Things to consider if building with sprayed closed-cell i ,�. • _ foam insulation: Tests have shown that sprayed foam insulation can improve the strength of structural framing �I ‘`' v systems and connections. However, structural '`Z �► ,� framing systems and connections must be de- - -, `_ "4 signed and constructed in accordance with all —` " applicable building codes. amipc.... While closed-cell foam is a flood-resistant mate- rial, it should be used in conjunction with preser- vative-treated, or naturally durable, wood or cor- Figure 4. Installation of a prefabricated ordinary rosion-resistant metal framing. moment frame. 1.8: NON-TRADITIONAL BUILDING MATERIALS AND SYSTEMS 4 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION +>! NOTE: Some framing materials such as prefab- ricated wood I-joists (e.g., a prefabricated I-joist constructed with sawn lumber or composite lum- *. a• ber flanges and plywood or OSB webs) should not be used below the BFE or where subject to r--, flooding (see FEMA Technical Bulletin 2 Flood- Damage Resistant Materials Requirements). 4 ty ►:,s t Methods L Advanced Wall Framing 0 1 - I Advanced wall framing refers to methods designed to m , ,�... reduce the amount of lumber and construction waste m # A, ;4 generated during home construction. These methods D I' ' r F include spacing wall studs up at 24 inches on center 1— rather than 16 inches, and using smaller structural headers and single top plates on interior non-bearing walls. t i Advantages: ` In most instances, the primary benefit of such I I techniques is the reduced lumber cost. The increased energy efficiency from the re- duced number of wall studs and increased wall cavity space for insulation. Things to consider if using advanced wall framing 41 techniques: / , Not all wall framing techniques are applicable for hurricane-prone regions. The designer should Figure 5. An example of a wall cavity filed with carefully consider if this is an appropriate con sprayed closed-cell foam insulation, struction method for the area. Increasing wall stud spacing, even when using Closed cell foam should not be confused with larger lumber sizes, can reduce the ability of a wall to resist transverse loads. For more in- other types of insulation. Some varieties of in- formation on designing framed walls to resist sulation on the market may be more cost-effec- transverse loading, refer to IRC R602.10 or IBC tive and more environmentally friendly; however, 2305. many of these products are not considered flood- resistant materials. Testing reports and provi- Construction crews may be unfamiliar with advanced sions of the building code should be consulted wall framing techniques, which may increase con- for applicability in a coastal environment. struction time. Construction plans for advanced framing should be detailed enough for construction Sprayed foam systems (such as those used in crews to recognize differences from conventional a wall system) create an assembly that when in- techniques, and additional training for construction undated by floodwaters may not be easily dried. crews may be required. For this reason, they are not appropriate to use below the BFE and are not considered flood-re- Modular Houses sistant material unless the entire assembly has been determined to be flood-resistant. Modular houses provide an alternative construction method by constructing a traditional wood- or steel- framed house in sections in a manufacturing facility and then delivering the sections to a construction site where they are assembled onto a foundation (see Figure 1). The interior and exterior of the house are finished on site. These houses should not be confused with manufactured homes. Unlike 1.8: NON-TRADITIONAL BUILDING MATERIALS AND SYSTEMS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 6 12/10 manufactured homes, modular homes are required Modular homes are to be constructed to the to meet the same building code requirements as same tolerances and locally enforced building houses constructed on site. codes as traditional site-built homes. The locally Advantages: enforced building code where the house will be sited is the standard to which the modular house Sections can be assembled in a controlled ehvi- shall be constructed. ronment and construction time is less sensitive to poor weather conditions at the house site. The manufacturer needs to be aware of the loca- tion of the house and the materials that should Due to the sections being constructed at a be used in order to resist the site-specific haz- manufacturing facility, materials use is often ards. Building component choices for flood, more efficient and fabrication is more efficient wind, and windborne debris-resistant materials than site-built construction, resulting in reduced should be identified prior to ordering the house costs. and checked before installation begins. Things to consider if using modular houses: Extra care should be taken to verify that modu- W lar components are properly fastened to building z Proper installation of the house is important. W Due to the sections of the house being con- foundations and load path connections are prop- structed in another location, tight construction erly completed to transfer building loads from tolerances with the foundation are important in the roof to the foundation. order for the sections to fit together properly. NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 1.8: NON-TRADITIONAL BUILDING MATERIALS AND SYSTEMS 6 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Moisture Barrier Systems HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 1.9 Purpose: To describe the moisture barrier system, explain how typical wall moisture barriers work, and identify common problems associated with moisture barrier systems. Key Issues Roof Covering 4 • Housewrap or Felt A successful moisture barrier sys- Water,Air, tern will limit water infiltration into Underlayment — m unwanted areas and allow drain- Thermal Energy, Insulation m age and drying of wetted building DJ materials. gOverhan and Vapor -_ Most moisture barrier systems Gutters,Valleys • Control System Vapor Retarder r for walls(e.g.,siding and brick ve- neer) are "redundant" systems, Siding, •which require at least two drain Flashing • Windows age planes (see page 2). Housewrap or building paper(asphalt-saturated felt) will provide an adequate secondary drainage plane. Proper flashing and lapping of housewrap and building paper are critical to a successful moisture barrier system. Sealant should never be substituted for proper layering. The purpose of the building envelope is to control the movement of water,air,thermal energy, and water vapor. The goal is to prevent water infiltration into the interior, limit long-term wetting of the building components, and control air and vapor movement through the envelope. Locations and Causes of Common Water Intrusion Problems Poor water shedding from roof-Use moderate overhangs Improper flashing and damaged housewrap or of 12-16 inches,drip edges,and a gutter system. building paper at wall penetrations- Follow window flashing techniques at every wall penetration. Roof/wall intersection-Install effective kick-out flashing at roof-to-wall intersections,diverter flashing around trapped valleys,and 7\ / Damaged or improperly rake flashing. f installed siding-Follow manufacturer's guidelines. 11111 = a �� Prime all surfaces of wood siding(back-priming)before Flashing around windows- 1__��j��l' Proper lapping is key to leak I-�j� �1,• \� applying top coats. �4 . pig prevention. Do not depend on �� • ,_� ��I sealant for sustained ' �' / protection. Protect flashings _ _ with overlapping wrap. No housewrap or building paper used,or improperly lapped- • Virtually all siding leaks. Use housewrap or building paper to Improper flashing over doors-Proper lapping is shed water. Properly lap material key to leak prevention. Do not depend on sealant so water flows without bucking Door sills-Use pan flashing for sustained protection. Protect flashings with seams.Water must be allowed to prevent damage to subfloor. overlapping housewrap or building paper. to drain out of walls. ' ° FEMA 1.9: MOISTURE BARRIER SYSTEMS E� ` HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 2 12;1() The location of water entry is often difficult to see, and the damage to substrate and structural members be- hind the exterior wall cladding frequently cannot be detected by visual inspection. Proper Lapping Is the Key... Wind and capillary action Gravity moves can move water in any direction. water downward. Proper lap distance Laps should never is the key to limiting cause water flowing water instrusion caused Q downward to "buck" by wind and capillary CC + W over seams. action. Always folllow z 1manufacturer's lap u1 Wind specifications or, if a 0 greater lap is specified Do not count on by the designer,follow sealant to substitute designer's requirements. for proper lapping. Proper lapping of moisture barrier materials is the key to preventing water intrusion. Most water intrusion prob- lems are related to the improper lapping of materials. Usually, flashing details around doors, windows, and penetrations are to blame. If the flashing details are right and the housewrap or building paper is properly in- stalled, most moisture problems will be prevented. Capillary suction is a strong force and will move water in any direction. Even under conditions of light or no wind pressure, water can be wicked through seams, cracks, and joints upward behind the overlaps of horizontal siding. Proper lap distances and sealant help prevent water intrusion caused by wicking action. How a Redundant Moisture Barrier Works Rain u / / / Siding.The siding is the first line of defense,but by no means should it be / / / the only protection from outside moisture. Sidings shed most of the water, 1! /l ♦i / / but some does get through,especially in coastal areas where high winds }./ / can drive rain. :4.1 / Winter (:! - Housewrap or Building Paper. Housewrap or building paper is a • y :. dual-purpose protection layer. It sheds water that gets through the siding and Vapor Drive limits air intrusion from the outside.A unique feature of this barrier is that it • t i.:• sheds water,but allows water vapor to pass through.This permits water / �: : vapor from the inside to pass through without condensing on the framing. .i Wind • \ Sheathing. If structural sheathing is used,it should be protected from • moisture. Prolonged wetting,especially without the ability to drain the Interior moisture and dry out,will damage the sheathing. finish Framing member Vapor Retarder. In cold regions,a vapor retarder is often used on the warm side of the wall cavity to minimize the movement of vapor from the inside of _♦ the building into the wall cavity,where it will condense on the cool framing ....--� members.Vapor retarders are typically used only where the predominant — vapor drive is from the inside to the outside(cold climates). Must be 4IM kept dry NAHB i RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 1.9: MOISTURE BARRIER SYSTEMS 2 of 2 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 How Do Siting and Design Decisions Affect the Owner's Costs? HOME BUILDER'S GUIDE TO COASTAL CON 3TRUCTION Technical Fact Sheet No. 2.1 Purpose: To show the effects of planning,siting, and design decisions on coastal home costs. Costs, Hazards, and Damage Vary With Location _ ■ :. . — L Inland Coastal, Set Back Oceanfront -::,i Homes located farther landward may be less appealing to some Homes located close to the shore may have spectacular r- owners, but will be less prone to views,but are subject to greater risks, more frequent and damage and will cost less to build, more severe damage,and higher construction, maintenance, Z; , insure,and maintain. and insurance costs. Z. - ciiKey Issues When building a coastal home, initial, operating, Operating costs include costs associated with the and long-term costs (i.e., life cycle costs) must use of the building, such as the costs of utilities and be considered. insurance.1 Coastal(especially oceanfront)homes cost more Long-term costs include costs for preventive mainte- to design, construct, maintain, repair, and insure nance and for repair and replacement of deteriorated than inland homes. or damaged building components. Determining the risks associated with a particu- Risk lar building site or design is important. One of the most important building costs to be con- Siting, designing, and constructing to minimum sidered is that resulting from storm and/or erosion regulatory requirements do not necessarily re- damage. But how can an owner decide what level of suit in the lowest cost to the owner over a long risk is associated with a particular building site or period of time. Exceeding minimum design re- design? One way is to consider the probability of a quirements costs slightly more initially, but can storm or erosion occurring and the potential building save the owner money in the long run. damage that results (see matrix). Costs ,,, Probability of Occurrence a, A variety of costs should be considered c Low Medium High when planning a coastal home, not just the construction cost. Owners should be _ Low Low Risk Low Risk Medium Risk aware of each of the following, and con- Medium Low Risk Medium Risk ''''" sider how siting and design decisions a, F will affect these costs: High Medium Risk Initial costs include property evaluation and acquisition costs and the costs of permitting, 1Note: Flood insurance premiums can be reduced up to 60 percent design, and construction. by exceeding minimum siting, design, and construction practices. See the V Zone Risk Factor Rating Form in FEMA's Flood Insurance Manual(http://www.fema.gov/nfip/manual.shtm). FEM g A 2 1: HOW DO SITING AND DESIGN DECISIONS AFFECT THE OWNER'S COSTS? HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 2 ��F4 qND 5E 12/10 Building sites or designs resulting in extreme or high Design risk should be avoided — the likelihood of build How much more expensive is it to build near the ing loss is great, and the long-term costs to the coast as opposed to inland areas? The table be- owner will be very high. Building sites or designs low suggests approximately 10-30 percent more. resulting in medium or low risk should be given preference. What about exceeding minimum design require- ments in coastal areas?The table suggests that Siting the added construction costs for meeting the practices recommended in the Home Builder's Note that over a long period,poor siting decisions are Guide to Coastal Construction (beyond typical rarely overcome by building design. minimum requirements) are nominal. o_ cn Effect of Design on Cost = d Z `O y o _ u) a) tom/) -OO tom'/) V' A: O E = = d I_ to y r•i _ c U V V L c a) -O c tCa a to is >. �o -8 c� c c 0 . .(0 3 As Design Item 5 3 2 co E — +1 Eci, a) (Items with asterisk"*"are required by the ci) to 17 '� a) o E v) illNational Flood Insurance Program(NFIP) o c c �) c c o and/or local building code.) il c`-) ri ¢ c°'c ¢ s - co � � co co A Zone,pile/column foundation 1.1, 1.4, 3.1 High ✓ ✓ V V Zone,pile/column foundation* 1.1, 1 a, 1.5, 3.1 High V V Joists sheathed on underside Low Low V V V Structurally sheathed walls* Medium V Corrosion protection* 1.1, 1.7 Low ✓ ✓ y V Decay protection* 1.1, 1.7 Medium ✓ V V V Hip roof shape 1.1 Low Low V Enhanced roof sheathing connection* 1.1,7.1 Low Low ✓ Enhanced roof underlayment* 72 Low Low V Upgraded roofing materials* 1.1, 73 Medium V V ✓ Enhanced flashing* 1.1,6.1,5.2 Low V V V Housewrap* 1.1, 6.1,5.1 Low V V Superior siding and connection* 5.3 Medium Medium V V Protected or impact-resistant glazing* 1.1, 6.2 MilliiMedium V ✓ Connection hardware* 1.1, 1.7, 4.3 Low V ✓ Flood-resistant materials* 1.1, 1.7 Low V V V Protected utilities and mechanicals* 1.1, 8.3 Low V ✓ V V V Estimated Total Additional Cost($thousands) 15-30 ±5 Low <0.5%of base building cost Estimates are based on a 3,000-square-foot home with a moderate number of windows and special features. Many of the upgraded design features are required Medium 0.5%-2.0%of base building cost by local codes,but the level of protection beyond the code minimum can vary, >2.0°/0 of base building cost depending on the owner's preference. Notes: 2 Added costs when compared to typical inland construction 3 Added initial costs to exceed Code/NFIP minimum requirements NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 2.1: HOW DO SITING AND DESIGN DECISIONS AFFECT THE OWNER'S COSTS? 2 of 2 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Selecting a Lot and Siting the Building HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 2.2 Purpose: To provide guidance on lot selection and siting considerations for coastal residential buildings. Key Issues Purchase and siting deci- sions should be long-term - decisions, not based on present-day shoreline and r = - - conditions. Parcel characteristics, infra- - structure, regulations, envi- - - �;r ronmental factors, and own- i 11 er desires constrain siting -- , D • ,,• options. "- - I II I z 11111 � ` ' � � r, . Conformance with local/ 1 , state shoreline setback 0 lines does not mean build- ings will be "safe." Information about site con- ditions and history is avail- able from several sources. Siting, design, and construction should be considered together (see Fact Sheet No. 2.1),but know that poor lot selection and siting decisions can rarely be overcome by improved design and construc- The Importance of tion. Building failures (see Fact Sheet No. 1.1) are often the result Property Purchase and of poor siting. Siting Decisions The single most common and costly siting mistake made by designers, builders, and owners is failing to con- sider future erosion and slope stability when an existing coastal home is purchased or when land is purchased and a new home is built. Purchase decisions—or siting, design, and construction decisions—based on pres- ent-day shoreline conditions often lead to future building failures. Over a long period of time, owners of poorly sited coastal buildings may spend more money on erosion control and erosion-related building repairs than they spent on the building itself. What Factors Constrain Siting Decisions? Many factors affect and limit a home builder's or owner's ability to site coastal residential buildings, but the most influential is probably parcel size, followed by topography, location of roads and other infrastructure, regulatory constraints, and environmental constraints. Given the cost of coastal property, parcel sizes are often small and owners often build the largest building that will fit within the permissible development footprint. Buyers frequently fail to recognize that siting decisions in these cases have effectively been made at the time the land was platted or subdivided, and that shoreline erosion can render these parcels unsuitable for long-term occupation. In some instances, however, parcel size may be large enough to allow a hazard-resistant coastal building to be sited and constructed, but an owner's desire to push the building as close to the shoreline as possible in- creases the likelihood that the building will be damaged or destroyed in the future. ��4A�1Fti J o FEmA 2.2: SELECTING A LOT AND SITING THE BUILDING m ' HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 2 o��gND S6CJ4 12/10 Coastal Setback Lines —What Protection Do They Provide? Common Siting Problems • Many states require new buildings to be sited at or Building on a small lot between a road landward of coastal construction setback lines,which and an eroding shoreline is a recipe for are usually based on long-term, average annual ero- trouble. sion rates. For example, a typical minimum 50-year • Odd-shaped lots that force buildings close setback line with an erosion rate of 2.5 feet/year to the shoreline increase the vulnerability would require a setback of 125 feet, typically mea- of the buildings. sured from a reference feature such as the dune • Siting a building near the edge of a bluff in crest,vegetation line, or high-water line. creases the likelihood of building loss, be- Building at the 125-foot setback (in this case) does cause of both bluff erosion and changes in not mean that a building will be "safe" from erosion bluff stability resulting from development for 50 years. activities (e.g., clearing vegetation, build- Storms can cause short-term erosion that far ex ing construction, landscaping, changes ceeds setbacks based on long-term averages. in surface drainage and groundwater flow patterns). Erosion rates vary over time, and erosion could • Siting near a tidal inlet with a dynamic surpass the setback distance in just a few years' time. The rate variability must also be known to shoreline can result in the building being determine the probability of undermining over a exposed to increasing flood and erosion given time period. hazards over time. 0 • Siting a building immediately behind an What Should Builders, Designers, and erosion control structure may lead to Owners Do? building damage from wave overtopping and may limit the owner's ability to repair Consult local and state agencies, universities, or maintain the erosion control structure. n- and consultants for detailed, site-specific ero- sion and hazard information. ■ Siting a new building within the footprint of a pre-existing building does not guaran- Look for historical information on erosion and tee that the location is a good one. storm effects. How have older buildings in the area fared over time? Use the experience of oth- ers to guide siting decisions. Siting should consider both long-term erosion Determine the owner's risk tolerance, and reject and storm impacts. Siting should consider parcels or building siting decisions that exceed site-specific experience, wherever available. the acceptable level of risk. Lot* 1 Road Long-Term Erosion Setback and Storm Impact Zone Road Dune * Lot area available for construction will vary Recommended building location on a coastal lot. 1CHB RNAESEARCH Developed in association with the National Association of Home Builders Research Center ENTER 2.2: SELECTING A LOT AND SITING THE BUILDING 2 of 2 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Foundations in Coastal Areas HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 3.1 Purpose: To describe foundation types suitable for coastal environments. Key Issues Foundations in coastal areas should elevate buildings above the Design Flood Elevation (DFE) in accordance with ASCE 24-05, while withstanding flood forces, high winds, scour and erosion, and floating debris in ASCE 7-10. 'Foundations used for inland con- I — "' �' °'� wpm ^,; A'; struction are generally not suitable for coastal construction. Some ex- ‘11\111 amples of foundation systems that `�`` ,have a history of poor performance in erosion prone areas are slab-on \\ � ` — ground, spread footings, and mat(or ! 1 raft) foundations. Deeply embedded pile or column • foundations are required for V Zone -- construction. In A Zones they are Figure 1. Near collapse due to insufficient pile embedment in recommended instead of solid wall, Dauphin Island, Alabama. •. crawlspace, slab, or other shallow (SOURCE:FEMA 549.HURRICANE KATRINA IN THE GULF COAST) -T7 foundations, which are more sus- O ceptible to scour. (For the reference of this document, the term deeply embedded inundation by fast-moving water, breaking waves, means "sufficient penetration into the ground to floating debris, erosion, and high winds). accommodate storm induced scour and erosion Because the most hazardous coastal areas are sub- p and to resist all design vertical and lateral loads ject to erosion, scour, and extreme flood loads, the Z without structural damage.") only practical way to perform these two functions Areas below elevated buildings in V Zones must Is to elevate a building on a deeply embedded and be "free of obstructions" that can transfer "open" (i.e., pile or column) foundation. This ap- flood loads to the foundation and building (see proach resists storm-induced erosion and scour, and Fact Sheet No. 8.1, Enclosures and Breakaway it minimizes the foundation surface area subject to Walls).Areas below elevated buildings in A Zones lateral flood loads. should follow the same recommended principles ASCE 24-05 is recommended as a best practice for as those areas for buildings located in V Zones. flood resistance design and construction, especially in V Zones and Coastal A Zones. This standard has Foundation Design Criteria specific information on foundation requirements for All foundations for buildings in flood hazard areas Coastal High Hazard Areas and Coastal A Zones and must be constructed with flood-damage-resistant it has stricter requirements than the NFIP. Elevation materials (see Fact Sheet No. 1.7, Coastal Building on open foundations is required by the National Flood Materials). In addition to meeting the requirements Insurance Program (NFIP) in V Zones (even when the for conventional construction, these foundations ground elevation lies above the BFE) and is strongly must: (1) elevate the building above the Base Flood recommended for Coastal A Zones. Some states and Elevation (BFE), and (2) prevent flotation, collapse, communities have formally adopted open foundation and lateral movement of the building, resulting from requirements for Coastal A Zone construction. loads and conditions during the design flood event While using the approach of elevation of structures (in coastal areas,these loads and conditions include on pile foundations improves performance and FEMAHOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 st 12/10 minimizes some effects, even a deeply embedded structural support of the building), drainage around open pile foundation will not prevent eventual under- and under buildings, and for the support of parking mining and loss due to long-term erosion (see Fact slabs, pool decks, patios and walkways (2009 IRC Sheet No. 2.2,Selecting a Lot and Siting the Building). Section R322.3.2). These guidelines are consistent with NFIP Technical Bulletin 5, Free-of-Obstruction Performance of Various Foundation Types Requirements for Buildings Located in Coastal High in Coastal Areas Hazard Areas (08/08), which states: "Fill must not prevent the free passage of floodwaters and waves There are many ways to elevate buildings above the beneath elevated buildings. Fill must not divert flood- BFE: fill, slab-on-grade, crawlspace, stemwall, solid waters or deflect waves such that increased damage wall, pier(column), and pile. Not all of these are suit- is sustained by adjacent or nearby buildings." able for coastal areas. In fact, several of them are prohibited in V Zones and are not recommended for Slab-on-Grade: Slab-on-grade foundations are also A Zone construction in coastal areas (see Fact Sheet susceptible to erosion and are prohibited in V Zones 1.2, Summary of Coastal Construction Requirements and are not recommended for A Zones in coastal areas. and Recommendations for Flood Effects). (Note that parking slabs are often permitted below el- evated buildings, but are susceptible to undermining Pile: Pile foundations are recommended for V Zones and collapse.) It is recommended that parking slabs and Coastal A Zones. These open foundations are be designed to be frangible (breakaway) or designed constructed with square or round, wood, concrete, or and constructed to be self-supporting structural slabs steel piles, driven or jetted into the ground, or set capable of remaining intact and functional under into augered holes. Critical aspects of a pile foun- base flood conditions, including expected erosion. For dation include the pile size, installation method and more information, see NFIP Technical Bulletin 5, Free- embedment depth, bracing, and the connections to of-Obstruction Requirements for Buildings Located in the elevated structure(see Fact Sheets Nos. 3.2,Pile Coastal High Hazard Areas (08/08). Installation and 3.3, Wood-Pile-to-Beam Connections). Pile foundations with inadequate embedment will Crawlspace: Crawlspace foundations are prohibited lead to building collapse. Inadequately sized piles in V Zones and are not recommended for A Zone are vulnerable to breakage by waves and debris. construction in coastal areas. They are suscepti ble to erosion when the footing depth is inadequate Fill: Using fill as a means of providing structural to prevent undermining. Crawlspace walls are also support to buildings in V Zones is prohibited be- vulnerable to wave forces. Where used, crawlspace cause it is susceptible to erosion. Also, fill must not foundations must be equipped with flood open- be used as a means of elevating buildings in any ings; grade elevations should be such that water z other coastal area subject to erosion, waves, or fast- is not trapped j in the crawlspace (see Fact Sheets Q moving water. However, minor quantities of fill are Nos. 3.5, Foundation Walls and 8.1, Enclosures and permitted for landscaping,site grading(not related to Breakaway Walls). z D Stemwall: Stemwall foundations are 0 similar to crawlspace foundations in . . tri 11 O .., ' • • construction, but the interior space that A- • would otherwise form the crawlspace is often backfilled with structural fill or sand ``• that supports a floor slab. Stemwall foun- "r • - dations have been observed to perform better during storms than many crawl- space and pier foundations.Although the — - 4 IRC allows for heights of up to six feet, it cAar is usually more economical and a better design choice to use another foundation 1 , system if stemwalls are over a few feet _ in height. During periods of high water backfill, soils may become flooded and % ` .._ -' .� cause damage to the slab. The designer --- .i . .�,. 'i-, 4.: should ensure that this does not cause-'f • s- �_ consolidation of the backfill. In addition, in some soils such as sand, capillary Figure 2. Performance comparison of pier foundations.Piers on action can cause water and moisture discrete footings(foreground)failed by rotating and overturning to affect the slab. Flood openings are while piers on more substantial footings(in this case a concrete not required in a backfilled stemwall mat)survived(Pass Christian,Mississippi) foundation. Stemwall foundations are 3.1: FOUNDATIONS IN COASTAL AREAS 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1- prohibited in V Zones but are recommended in A Foundations in V Zones with Ground Zone areas subject to limited wave action,as long as Elevations Above the BFE embedment of the wall is sufficient to resist erosion and scour (see FEMA 549, Hurricane Katrina in the In some instances, coastal areas will be mapped on Gulf Coast). an NFIP Digital Flood Insurance Rate Map(DFIRM)as Zone V, but will have dunes or bluffs with ground el- Solid Foundation Walls:The NFIP prohibits solid foun- evations above the BFE shown on the DFIRM. During dation walls in V Zones and are not recommended a design flood event, erosion of the bluffs and high for A Zone areas subject to breaking waves or other dunes can be expected at these areas as well as large flood forces—the walls act as an obstruction waves and inundation. Therefore, the ground level to flood flow. Like crawlspace walls,they are suscep- can be expected to be lowered to a point that wave tible to erosion when the footing depth is inadequate forces and loss of soil are a critical factor. The foun- to prevent undermining. Solid walls have been used dations for structures in these V Zone areas with in some regions to elevate buildings one story in high ground elevation are the same as V Zone ar- height. Where used,the walls must allow floodwaters eas with lower ground elevations. Deeply embedded to pass between or through the walls (using flood pile or column foundations are still required in these openings). (See Fact Sheets Nos. 3.5, Foundation areas, and solid or shallow foundations are still pro- Walls and 8.1, Enclosures and Breakaway Walls.) hibited. The presence of a V Zone designation in Pier(column): Pier foundations are recommended for these instances indicates that the dune or bluff is A Zone areas where erosion potential and flood forces expected to erode during the base flood event and are small. This open foundation is commonly con- that V Zone wave conditions are expected after the structed with reinforced and grouted masonry units erosion occurs. The presence of ground elevations atop a concrete footing. Shallow pier foundations are above the BFE in a V Zone should not be taken to extremely vulnerable to erosion and overturning if the mean that the area is free from base flood and ero- footing depth and size are inadequate. They are also sion effects. vulnerable to breakage. Fact Sheet No.3.4,Reinforced Masonry Pier Construction, provides guidance on how Additional Resources to determine whether pier foundations are appropri- FEMA 550, Recommended Residential Construction ate, and how to design and construct them. for the Gulf Coast: Building on Strong and Safe Foundations (July 2006). (http://www.fema.gov/Ii- Foundations for High-Elevation Coastal Areas brary/viewRecord.do?id=1853) Foundation design is problematic in bluff areas FEMA 549, Hurricane Katrina in the Gulf Coast (July TO that are vulnerable to coastal erosion but outside 2006). (http://www.fema.gov/library/viewRecord. C mapped flood hazard areas. Although NFIP require- do?id=1857) z ments may not apply, the threat of undermining is cp not diminished. FEMA, NFIP Technical Bulletin 5, Free-of-Obstruction Moreover, both shallow and deep foundations will fail Requirements for Buildings Located in Coastal High ' 5 Hazard Areas, FIA-TB-5, Washington, DC, August z in such situations. Long-term solutions to the prob- 2008. (http://www.fema.gov/library/viewRecord. lem may involve better siting (see Fact Sheet No. do?id=1718) 2.2, Selecting a Lot and Siting the Building), moving the building when it is threatened, or (where permit- FEMA 232, Homebuilders' Guide to Earthquake ted and economically feasible) controlling erosion Resistant Design and Construction, Washington, through slope stabilization and structural protec- DC, February 2001 (http://www.fema.gov/library/ tion. Additionally FEMA 232, Homebuilders' Guide viewRecord.do?id=2103) to Earthquake Resistant Design and Construction, American Society of Civil Engineers (ASCE/SEI) provides information on foundation anchorage for hill- Standard 7-10: Minimum Design Loads for Buildings side structures. and Other Structures, ASCE 7-10, (http://www.asce. org) American Society of Civil Engineers (ASCE). Flood Resistant Design and Construction, ASCE/SEI 24-05. (http://www.asce.org) fNAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 3.1: FOUNDATIONS IN COASTAL AREAS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 2 10 PileDesign and Installation HOME BUILDER'S GUIDE TO COASTAL CON STRUCTION Technical Fact Sheet No. 3.2 Purpose: To provide basic information about pile design and installation. Key Factors are easily cut and adjusted in the field. Concrete Use a pile type that is appropriate for local and steel can also be used but are less common in residential construction. Concrete piles—may be an conditions. appropriate choice depending upon the pile capacity Piles should resist coastal hazards such as high requirements and elevation needed by the design— winds and flood loads in addition to withstanding are available in longer lengths and are usually erosion and scour. Erosion being the widespread installed by pile driving. Concrete piles tend to have loss of soil and scour being a localized loss of higher strengths and are durable to many factors soil around a building or foundation element due that are in the coastal environment when properly to turbulent water movement. designed and detailed. Steel piles are rarely used Have a registered engineer design piles for ade because of potential corrosion problems. quate layout, size, and length. Use installation methods that are appropriate Pile Size and Length for the conditions. The foundation engineer is the one who determines pile size and length. Specified bearing and penetra- Brace piles properly during construction. tion requirements must be met. Round piles should Make accurate field cuts, and treat all cuts and have no less than an 8-inch tip diameter; square drilled holes to prevent decay. piles should have a minimum timber size of 8 by 8 Have all pile-to-beam connections engineered, inches. The total length of the pile is based on build and use corrosion-resistant hardware (see Fact ing code requirements [see the 2009 International Sheet No. 1.7, Coastal Building Materials). Building Code (IBC) Section 1810 on deep founda- e> tions], calculated penetration requirements, erosion T Pile Types and scour potential, Design Flood Elevation (DFE), O and allowance for cut-off and beam width (see Figure e z The most common pile types used are preservative 1 and Table 1, which is an example of foundation de- treated wood, concrete, and steel. Contractors doing sign results). Substantial improvement in foundation construction in coastal areas typically select preser- performance can be achieved by increasing the mini- O vative treated wood piles for pile foundations. They mum timber size for square piles to 12 by 12 inches z can be square or round in cross section. Wood piles or minimum tip diameter for round piles of 12 inches. CI) Original Original Ground Ground 1111 1 11 11 11II 11 3S \ Erosion P. Erosion Scour and Scour Figure 1. Distinguishing between coastal erosion and scour.A building may be subject to either or both,depending on the building location,soil characteristics,and flood conditions. vp, 3.2: PILE DESIGN AND INSTALLATION FEMA HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 4 lq ND SEA 12/10 Table 1.Example foundation adequacy calculations for a two-story house supported on square timber piles and situated away from the shoreline,storm surge,and broken waves passing under the building,130-mph basic wind speed per ASCE 7-05 (167-mph equivalent ASCE 7-10 basic wind speed for Risk Category 11 buildings),soil=medium dense sand.Shaded cells indicate the foundation fails to meet bending (P)and/or embedment(E)requirements. Pile Embedment Erosion and Pile Diameter, 0 Before Erosion Scour Conditions and Scour 8 inch 10 inch 12 inch Erosion=0, Scour=0 P, E E OK Erosion=0, Scour=2.00 P, E E E 10 feet Erosion= 1, Scour=2.50 P. E E E Erosion= 1, Scour=3.00 P, E E E Erosion= 1, Scour=4.00 P, E P, E E Erosion=0, Scour=0 P OK OK Erosion=0, Scour=2.00 P OK OK 15 feet Erosion= 1, Scour=2.50 P OK OK Erosion=1, Scour=3.00 P OK OK Erosion=1, Scour=4.00 P. E P, E E Erosion=0, Scour=0 P OK OK Erosion=0, Scour=2.00 P OK OK 20 feet Erosion=1, Scour=2.50 P OK OK Erosion=1, Scour=3.00 P OK OK Erosion= 1, Scour=4.00 P P OK Pile Layout hammer. Driving the pile even a few feet helps assure The foundation engineer and designer determine the the pile is achieving some end-bearing capacity and pile layout together. Accurate placement and correc some skin friction. Full depth driving where achiev- pile of misalignedpiles is important. The use of a able provides for a pile foundation that has several z g p advantages that merit consideration. 0 drive template for guiding the pile driving operation greatly increases the accuracy of the pile location and need for difficult remediation. A drive template is a Pile Bracing z temporary guide structure that is installed in a man- The engineer determines pile bracing layout. ner to restrict the lateral movement of the piles during Common bracing methods include knee and diago- driving. The pile template is reused for each row of nal bracing. Knee bracing is an effective method of piles to assure consistent spacing and alignment. Pile improving the performance of a pile system without placement should not result in more than 50 percent creating an obstruction to the flow of water and de- of the pile cross section being cut for girder or other bris from a design event. Because slender bracing is connections. Verify proper pile locations on drawings susceptible to buckling, slender bracing should be before construction and clarify any discrepancies. considered as tension only. Bracing can become an Layout can be done by a licensed design professional obstruction, however, and increase a foundations ex- or surveyor, a construction surveyor, the foundation posure to wave and debris impact. Bracing is often contractor, or the builder. The layout process must oriented perpendicular to the shoreline so that it is always include establishing an elevation for the fin- not struck broadside by waves, debris, and velocity ished first floor. Construction of the first-floor platform flow (see Figure 2). Temporary bracing or jacking to should not begin until this elevation is established align piles and hold true during construction is the (see Fact Sheet No. 1.4, Lowest Floor Elevation). responsibility of the contractor. Installation Methods It is recommended that pile bracing be used only for reducing the structure's sway and vibration for Piles can be driven, augered, or jetted into place. comfort. In other words, bracing should be used to The installation method will vary with soil conditions, address serviceability issues and not strength is- bearing requirements, equipment available, and lo- sues. The foundation design should consider the cal practice. One common method is to initially jet piles as being un-braced as the condition that may the pile to a few feet short of required penetration, occur when floating debris removes or damages the then complete the installation by driving with a drop bracing. If the pile foundation is not able to provide 3.2: PILE DESIGN AND INSTALLATION 2 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12 10 Lateral Forces ► F F Typical Brace Pairs F F �— tic ,s, / N'k Braces loaded in tension (T) resist lateral Forces in opposite direction bring opposite m force(F).Braces loaded in compression(C) braces into play. 0 are not effective. C - -I-I Figure 2.Diagonal bracing schematic. ZO the desired strength performance without bracing detail and good construction practices are critical for then the designer should consider increasing the pile successful performance of the foundation (see Fact size. Pile bracing should only be for comfort of the oc- Sheet Nos. 1.7, Coastal Building Materials, and 3.3, cupants, but not for stability of the home. Wood-Pile-to-Beam Connections). Field Cutting and Drilling Verification of Pile Capacity A chain saw is the common tool for making cuts and Generally, pile capacity for residential construction is notches in wood piles. After making cuts, exposed not verified in the field. If a specified minimum pile areas should be field-treated with the proper wood penetration is provided, bearing is assumed to be ac- preservative to prevent decay. This involves apply- ceptable for the local soil conditions. Subsurface soil ing the preservative with a brush to the cut or drilled conditions can vary from the typical assumed con- holes in the pile until no more fluid is drawn into the ditions, so verification of pile capacity is prudent, wood. particularly for expensive coastal homes. Various methods are available for predicting pile capacity. Connections Consult a local foundation engineer for the most ap- propriateThe connection of the pile to the structural mem method for the site. bers is one of the most critical connections in the structure. Always follow design specifications and use corrosion-resistant hardware. Strict attention to 3.2: PILE DESIGN AND INSTALLATION HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 4 12/10 Additional Resources American Concrete Institute (ACI), 543R-00: Design, Manufacture, and Installation of Concrete Piles (Reapproved 2005), (http://www.concrete.org) American Forest and Paper Association (AF&PA). National Design Specification for Wood Construction. (http://www.afandpa.org) American Society for Testing and Materials (ASTM). Standard Specification for Round Timber Piles, ASTM D25. (http://www.astm.org) American Wood-Preservers Association (AWPA). All Timber Products - Preservative Treatment by Pressure Processes,AWPA C1-00; Lumber, Timber, Bridge Ties and Mine Ties - Preservative Treatment by Pressure Processes,AWPA C2-01; Piles - Preservative Treatment by Pressure Process, AWPA C3-99; and others. (http://www.awpa.com) Pile Buck, Inc. Coastal Construction. (http://www.pilebuck.com) Southern Pine Council (SPC) (http://www.southernpine.com/about.shtml) Timber Pile Council, American Wood Preservers Institute, Timber Pile Design and Construction Manual, (http://www.wwpinstitute.org/pdffiles/TimberPileManual.pdf) z 0 z 0 u_ NAHB RESEARCH I Developed in association with the National Association of Home Builders Research Center CENTER 3.2: PILE DESIGN AND INSTALLATION 4 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12110 • Wood Pile - to - Beam Connections HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 3 Purpose: To illustrate typical wood pile-to-beam connections, provide basic construction guidelines on various connection methods, and show pile bracing connection techniques. Key Issues Verify pile alignment and correct, if necessary, Pile-to-beam connections must: before making connections. 1. Provide required bearing area for beam to Carefully cut piles to ensure required scarf rest on pile. depths. 2. Provide required uplift(tension)resistance. Limit cuts to no more than 50 percent of pile cross section. 3. Maintain beam in an upright position. Use corrosion-resistant connectors and fasten- 4. Be capable of resisting lateral loads (wind ers such as those fabricated from stainless and seismic). steel,or connectors and fasteners with corrosion 5. Be constructed with durable connectors protection such as provided by hot-dip galvanized and fasteners from corrosion-resistant ma- coating(see Fact Sheet No. 1.7, Coastal Building terials or with corrosion protection in ac- Materials). cordance with minimum requirements of Accurately locate and drill bolt holes. the International Residential Code. The level of corrosion protection that can be Field-treat all cuts and holes to prevent decay. expected will vary depending on the type of ri Use sufficient pile and beam sizes to allow prop- wood treatment and fastener type. Make c er bolt edge distances. sure the fastener is compatible with the wood variety selected for construction. Built-up beams should be designed as continuous members and not be broken over the piles. Some 0 homebuilders are using engi- z "r neered wood products, such as glued laminated timber and par- Pile-to-Beam Bolted Connection allel strand lumber, which can �✓ span longer distances without splices. The ability to span Ion- 1 ' .. ger distances without splices Nuts eases installation and reduces fabrication costs. Washers 6:4 Pile ®. Note: Pile-to-beam connections must be ‘14 designed by an engineer. f\ Washers • ik Beam Bolts(typical) Figure 1. Pile-to-beam bolted connection. o�cn�lFro FEMA 3.3:WOOD PILE-TO-BEAM CONNECTIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 6 12/10 Figure 2. Proper pile-to-beam bolted connection. Bolt and Edge Distance on Beam Bolts Beam Beam a ii 4D typical (follow design) II iiii 5D typical (larger spacing between ..I bolts can cause splitting when lumber Illbidries; follow design) 4D typical (follow design) Overcut III Shim gap 7D(minimum) if needed with Bolts typically materials not located at prone to decay centerline of or corrosion pile; an end distance of 7D required for full bolt design value (follow design) Required bearing area to be determined by engineer Connection to Overcut Pile— Shim Used to Provide D=Bolt diameter .11111 I. 4D typical (follow design) Adequate Bearing Beam -I I z O Q D = Bolt diameter Avoid gaps; beam Avoid z should fit tight to overcuts D pile Note: Pile-to-beam O connections must be designed u_ Proper Pile-to-Beam Connection Pile by an engineer. Problem: misaligned piles—some piles are shifted in or out from their intended (design) locations. There are five possible solutions to fix the problem. (See figure 3 and details in figure 4): Option 1— beam cannot be shifted. Option 2 —beam can be shifted laterally and remains square to building. Option 3 —beam can be shifted laterally, but does not remain square to building. Option 4 (not shown) — beam cannot be shifted, and connections shown in this fact sheet cannot be made; install and connect sister piles; an engineer must be consulted for this option. Option 5 (not shown) — beam cannot be shifted, and connections shown in this fact sheet cannot be made; remove and reinstall piles, as necessary. 3.3:WOOD PILE-TO-BEAM CONNECTIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 Figure 3. Connection of misaligned pile. _ `, Intended pile O Actual pile �`, location location String stretched String stretched to establish to establish I I center of beam center of beam String stretched to establish center of beam Q � . 1r Standard connection ts % Standard connection `, Standard (see Detail Al) (see Detail A1) connection . � ,: (see Detail Al) Pile shifted out Bearing sufficient Bearing sufficient Bearing sufficient Connection with • Standard � scabbed member or Standard connection connection r engineered bracket (see Detail Al) s, _ i (see Detail B1 or Cl) (see Detail Al) Pile shifted out Bearing insufficient Bearing sufficient Bearing sufficient 0 TI Standard connection Connection with with opposite side of It.? Standard C ' steel plates) ; connection z see Detail pile notched 0 ( ) Pile (see Detail A2) (se:ri :tau A1) shifted inBearing sufficient;uplift Bearing sufficient sufficient 0 resistance insufficient z Connection with Standard connection scabbed member or i with opposite side ��, � engineered bracket, �`� Standard i of pile notched i with opposite side ; connection Pile I (see Detail A2) i. of pile notched ; (see Detail Al) shifted in`` (see Detail B2 or C2) ik Ii Bearing sufficient Bearing sufficient Bearing insufficient I J I - I I_ I Option 1 Option 2 Option 3 Beam cannot be shifted Beam can be shifted laterally Beam can be shifted laterally,but does and remains square to building not remain square to building Note: Pile-to-beam connections must be designed by an engineer. 3.3:WOOD PILE-TO-BEAM CONNECTIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 6 1 12/10 I Figure 4. Connection details for misaligned piles. Detail Al Standard connection Detail Cl Insufficient bearing- engineered bracket for bearing If b ring area under �� bea is sufficient,a � If bearing area under beam 4 '� ill. is insufficient,install itit star{dard bolted connection can be engineered bracket; used;if bearing area �� ,`�' connection to be designed by is insufficient,install ; an engineer scabbed member .I Bearing Bearing (Detail B1/B2)or sufficient sufficient engineered bracket .I Engineered bracket Detail(C1/C2) r Bearing insufficient Dean Standard connection with pile notched i Detail C2 Engineered bracket with pile on opposite side to avoid overnotching notched on opposite side to avoid ill ii r Fri overnotching I, i ,I i .!!L! ,� I i( I ----- ►b 1 itI. O Detail B1 Insufficient bearing- Detail D1 insufficient uplift capacity- I s■'cabbed member for bearing steel plate(s)for uplift resistance If bearing area under beam is flii Notch side of pile that •� insufficient,deepen notch and '� 1 : leaves the greatest pile ! install scabbed member to I,�i t section;use 1/4"or •IiV achieve bearing;do not overnotch .I L 1 ' Fl thicker galvanized steel (n '11 liar plate(s)to satisfy uplift Z connection resistance requirements;to bedesigned 0 Possible .I - Bearing insufficient shim '� _ by an engineer Q Scabbed member 0 Possible second steel plate Z D 0 Detail B2 Scabbed member with pile notched on Detail D2 Steel plate(s)with pile notched on opposite side to avoid overnotching opposite side to avoid overnotching .�,I- fsi,`iI!—791 I 131' ili! ' Note: Pile' ia to-beam 'i' 15' connections must be designed by c'‘.__,., OLJ an engineer. Connections to misaligned piles (see drawings on figure 3 and details above) 1. The ability to construct the pile-to-beam connections designed by the engineer is directly dependent upon the accuracy of pile installation and alignment. 2. Misaligned piles will require the contractor to modify pile-to-beam connections in the field. 3. Badly misaligned piles will require removal and reinstallation, sister piles, or special connections, all to be determined by the engineer. 3.3:WOOD PILE-TO-BEAM CONNECTIONS 4 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 i Figure 5. Built-up beam connections,knee brace connections,and diagonal brace connections. Approximately 12" i •1( How design) H 1 '1 Approximately 12"(follow design) 7D pical ( / O (follow design) O4 Nails or bolts-1-• • D=Bolt diameter Built-up beam/ Note: Pile Glued laminated timber. Note: Splicing the beam over a pile may increase the required pile diameter because of bolt/nail end distance11111k.-d Lapped Splice(Built-up Beam) requirements on the beam or bolt edge distance requirements on the pile. Countersunk through-bolts or Beam lag screws per design 711.71111111 .: Pile uilt-up beam Knee Brace Note: <IFr Approximately 4' This detail is not (follow design) recommended.The connection shown has reduced capacity, D Minimum may violate bolt edge-distance requirements,and can result in =Bolt diameter a weaker beam. C Beam Bolted at Pile Knee Brace Connection on Square Pile* (Not Recommended) *Knee braces of this type can also be used on notched round piles. • Pile centerline D=Bolt diameter Through-bolt(s)or Diagonal Brace Connections on Round Pile lag screw(s)per designpp,I4 Diagonal 7D for full bolt design value brace (follow design) Alternate faces to ensure adequate bolt end distances i Note: Pile-to-beam connections must be designed by an engineer. 3.3:WOOD PILE-TO-BEAM CONNECTIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 6 Additional Resources American Wood Council (AWC) (http://www.awc. rg) American Institute of Timber Construction (AITC) http://www.aitc-glulam.org) z 0 IL- 0 z D 0 NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 3.3:WOOD PILE-TO-BEAM CONNECTIONS 6 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12 >o Reinforced MasonryPier Construction HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 3.4 Purpose: To provide an alternative to piles in V Zones and A Zones in coastal areas where soil Pier Pier Pile properties and other site conditions indicate that = piers are an acceptable alternative to the usually - - Maximum recommended pile foundation. Examples of ap- - Maximum - depth of — depth of erosion erosion propriate conditions for the use of piers are where - and scour - and scour rock is at or near the surface or where the potential - - for erosion and scour is low. ■ di Key Issues Bedrock The footing must be designed for the soil condi- tions present. Pier foundations are generally not recommended in V Zones or in A Zones in coast- Used only where the potential al areas. for erosion and scour is low or where the pier can be The connection between the pier and its footing anchored to underlying must be properly designed and constructed to terminates or otherins and ctour resist separation of the pier from the footing and terminates erosion and scour overturningdue to lateral (flood, wind, debris) Used where the potential O for erosion and scour is high forces. iC The top of the footing must be below the antici- 1 z pated erosion and scour depth. The piers must be reinforced with steel and fully p grouted. The connection to the floor beam at the top of t Cf) the pier must be through use of properly sized and detailed metal connectors. r I Special attention must be given to the applica- i Loss of tion of mortar and the tooling of all the joints in ,' embedment order to help resist water intrusion into the pier core, where the steel can be corroded. + il - ' _ _ r Special attention must be given to corrosion verturnin Upli pro- tection of joint reinforcement, accessories, an- chors, and reinforcement bars. Joint reinforce- Piers are subject to upward,downward,and horizontal loads. ment that is exposed to weather or the earth Pier reinforcement and footing size are critical to resisting shall be stainless steel, hot dipped galvanized, these loads;therefore,pier and footing design must be or epoxy coated. Wall ties, plates, bars, anchors, verified by an engineer. and inserts exposed to earth or weather shall also be stainless steel, hot dipped galvanized,or Figure 1. In coastal areas,masonry pier foundations epoxy coated. Reinforcement bars shall be pro- are not recommended in V Zones with erodible soils, tected by proper use of masonry cover. or in A Zones subject to waves and erosion — use pile foundations in these areas. OEeA�\E,„ 3.4: RCED MASONRY PIER CONSTRUCTION J :,-- FEII\4A. HOME BUIOLDER S GUIDE TO COASTAL CONS RUCTION 1 of 3 f�''ND SEC. 12'1, Piers vs. Piles iVj,,,,k� - ;:.t I . .T�►Y #'fit ,-;,. T,Y, ; 0 Pier foundations are most appropriate in r - `; P ..1 , T �;., ��" y. areas where: i , .4 Erosion and scour potential are low. Flood depths and lateral forces are .yt • j low. , Soil can help resist overturning of pier. .. The combination of high winds and moist II (sometimes salt-laden) air can have a ....�. igt r damaging effect on masonry construc- mm ; tion by forcing moisture into even the i " ,< 4, smallest of cracks or openings in the masonry joints. The entry of moisture into reinforced masonry construction can lead to corrosion of the steel reinforce- 1 ' ment bars and subsequent cracking and Figure 2. Pier breakage(Long Beach,Mississippi) spalling of the masonry. Moisture resis- tance is highly influenced by the quality of the materials and the quality of the masonry construction at the site. should not be left exposed to weather for exces- sive amounts of time prior to installation. Lap MasonryPractice splices should be properly located and of suf- Good ficient length to meet the standard masonry in- If a masonry pier is determined to be an appropriate dustry details and requirements to sufficiently foundation for a building, there are some practices carry the loads imposed on the structure. that should be followed during construction of the Consider incorporating grade beams into the piers. foundation in order to achieve greater structural Masonry units and packaged mortar and grout stability in the pier system. 07 materials should be stored off the ground and z If the design of the pier system or any details are p covered. unclear, contact a structural engineer or appro- Masonry work in progress must be well protect- priate design professional to clarify the founda- 0 ed from exposure to weather. tion details. z Mortar and grouts must be carefully batched and 0 mixed. The 2009 International Building Code Pros and Cons of Grade Beams (IBC 2009) and 2009 International Residential Grade beams are horizontal structural members cast Code (IRC) specify grout proportions by volume against the ground or"grade." Grade beams can be a for masonry construction. useful foundation method in areas with limited poten- Connectors should be selected that are appro tial for erosion and scour. The type of force resisted priate for masonry to wood connection. It is im by grade beams varies by application, but can range portant to maintain a sufficient load path from from continuous vertical and horizontal loads to axial the building into the ground. The connectors and loads. The grade beams used in this example are fasteners should be a corrosion-resistant mate- used primarily for axial loads generated by stabil rial or have corrosion protection at least equiva ity demands of the piers. The grade beams should lent to that provided by coatings in accordance be placed below the elevation of anticipated eroded with the 2009 IRC. Connectors should be prop- grade so that there is no effect on scour and erosion erly embedded or attached to the pier. Wood in of the supporting soils. contact with masonry pier should be natural- The pros of using grade beams with pier foundations ly durable or preservative-treated. Figure 3 il- are that they: lustrates the importance of maintaining a prop- er load path between the pier and the building's Provide vertical and lateral support. beams. Are less prone to rotation and overturning. Properly sized steel reinforcing bars should be Transfer loads imposed on the elevated home installed throughout the masonry piers. Piers and foundation to the ground below. should be fully grouted and steel reinforcing bars 3.4: REINFORCED MASONRY PIER CONSTRUCTION 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12no Some cons of using grade beams with pier founda- tions are that they: Are grade beams allowed in the V Zone? Are susceptible to erosion and scour if too Yes,although the NFIP states that the lowest hor- shallow izontal structural member is to be constructed above the BFE, it is referring to the lowest hod- Can become obstructions during flood events zontal structural member above erodible grade. and can increase scour Based on this, both grade beams, cross bracing and knee bracing are allowed by the NFIP Grade beams can provide significant structural support to an open foundation system provided they are placed below the expected eroded surface. Age Figure 3. Failure of pier-to-beam connections due to s� wave and flood forces acting on the elevated building .,,r.F- - (Long Beach,Mississippi) ,Y . I Ta 7" 4 .-• c - - -n - O r z 46-- CD SDI cn Additional Resources American Concrete Institute, 2004, SP-66(04): ACI Detailing Manual. (http://www.concrete.org) Concrete Reinforcing Steel Institute. Placing Reinforcing Bars - Recommended Practices, PRB-2-99. (http://www.crsi.org) International Code Council. International Building Code. 2009. (http://www.iccsafe.org) International Code Council. International Residential Code. 2009. (http://www.iccsafe.org) The Masonry Society. 2008. Building Code Requirements for Masonry Structures. TMS 402-08/ACI 530-08/ASCE 5-08. (http://www.masonrysociety.org) The Masonry Society. 2008. Specifications for Masonry Structures. TMS 402-08/ACI 530.1 08/ASCE 6-08. (http://www.masonrysociety.org) NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER W 3.4: REINFORCED MASONRY PIER CONSTRUCTION HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12/10 Foundation Walls HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 3.5 Purpose: To discuss the use of foundation walls in coastal buildings. Key Issues Foundation walls include stem- Connection at top of wall Height sufficient to elevate walls, cripple walls, and other sol- to provide lateral bottom of floor system id walls. support above DFE Foundation walls are prohibited by the National Flood Insurance Program (NFIP) in Zone V.* Floor framing DFE IL-. Use of foundation walls in Zone A in coastal areas should be limit- ed to locations where only shallow - , flooding occurs, and where the po- Air vent; does not Flood-resistant , tential for erosion and breaking not satisfy flood waves is low. materials and opening requirement methods Where foundation walls are used, flood-resistant design of founda- tion walls must consider embed- Bottom of flood ment, height, materials and work- opening no more than 1 manship, lateral support at the foot aboveadjacent e top of the wall,flood openings and • exterior grade ventilation openings, and interior -n grade elevation. lii 0 Interior grade C r about equal Z Foundation Walls —When Are Embedment to to,but no lower CD They Appropriate? resist erosion and scour than,exterior grade (limits ponding Use of foundation walls - such as with beneat floodh building; Z those in crawlspace and other sol- doesn't interfere 411 id-wall foundations - is potentially openings) troublesome in coastal areas for two reasons: (1) they present an obstruc • - tion to breaking waves and fast-moving Foundation walls - flood-resistant design considerations flood waters, and (2) they are typically constructed on shallow footings,which are vulnerable to erosion. For these reasons, their use in coastal areas should be limited to sites sub- * Note that the use of shearwalls below the Ject to shallow flooding, where erosion potential is Design Flood Elevation (DFE) may be permit- low and where breaking waves do not occur during ted in limited circumstances (e.g., lateral the Base Flood. The NFIP prohibits the use of foun- wind/seismic loads cannot be resisted with dation walls in Zone V*. This Home Builder's Guide to a braced, open foundation. In such cases, Coastal Construction recommends against their use minimize the length of shearwalls and the de- in Zone A in coastal areas. Deeply embedded pile or gree of obstruction to floodwaters and waves, column foundations are recommended because they orient shearwalls parallel to the direction of present less of an obstruction to floodwaters and are flow/waves, do not form enclosures). Consult less vulnerable to erosion. the authority having jurisdiction for guidance concerning shearwalls below the DFE. ,,E,AART �i �� 3.5: FOUNDATION WALLS s�' � ' FE]\41\ HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 o�#1�ND SECJ" Design Considerations for Foundation Walls The design of foundation walls is covered by building Flood Openings and Ventilation Openings—Any area codes and standards (e.g., Standard for Residential below the DFE enclosed by foundation walls must Construction in High-Wind Regions, ICC 600-2008, be equipped with openings capable of automati- by the International Code Council). For flood design cally equalizing the water levels inside and outside purposes, there are six additional design consid- the enclosure. Specific flood opening requirements erations: (1) embedment, (2) height, (3) materials are included in Fact Sheet No. 8.1. Flood openings and workmanship, (4) lateral support at the top of are not required for backfilled stemwall foundations the wall, (5) flood openings and ventilation open- supporting a slab. Air ventilation openings required ings, and (6) interior grade elevation. by building codes do not generally satisfy the flood opening requirement; the air vents are typically in- Embedment — The top of the footing should be no stalled near the top of the wall,the flood vents must higher than the anticipated depth of erosion and be installed near the bottom, and opening areas for scour(this basic requirement is the same as that for air flow may be insufficient for flood flow. piers; see figure at right and Fact Sheet No. 3.4). If Interior Grade Elevation — Conventional practice for the required embedment cannot be achieved without crawlspace construction calls for excavation of the extensive excavation, consid- er a pile foundation instead. Height — The wall should be I I high enough to elevate the bottom of the floor system to or above the DFE (see Fact Floor slab DFE Floor framing Sheet No. 1.4). w:. w Materials and Workman- Air vent I Interior grade at ship— Foundation walls can . or slightly above be constructed from many ma- ° " adjacent exterior terials, but masonry, concrete, grade and wood are the most com- ,° Flood--obi I mon. Each material can be 4 opening ,.Q cn specified and used in a man- O ner to resist damage due to moisture and inundation (see Q Fact Sheet No. 1.7). Work- •, . z • manship for flood-resistant r ° . D foundations is crucial. Wood O should be preservative-treat- Floor slab atop backfilled Floor joist system and crawlspace ed for foundation or marine stemwall foundation use (aboveground or ground- contact treatment will not be sufficient). Cuts and holes should be field-treated. Masonry should be reinforced crawlspace and use of the excavated soil to promote and fully grouted (see Fact Sheet No. 4.2 for masonry drainage away from the structure (see left-hand figure details). Concrete should be reinforced and composed on page 3). This approach may be acceptable for non- of a high-strength, low water-to-cement ratio mix. floodplain areas, but in floodplains, this practice can result in increased lateral loads (e.g., from saturated Lateral Support at the Top of the Wall—Foundation soil) against the foundation walls and ponding in the walls must be designed and constructed to with- crawlspace area. If the interior grade of the crawlspace stand all flood,wind, and seismic forces, as well as is below the DFE,NFIP requirements can be met by en- any unbalanced soil/hydrostatic loads. The walls suring that the interior grade is at or above the lowest will typically require lateral support from the floor exterior grade adjacent to the building(see right-hand system and diaphragm, and connections to the figure on page 3). When floodwaters recede,the flood top of the walls must be detailed properly. Cripple openings in the foundation walls allow floodwaters to walls, where used, should be firmly attached and automatically exit the crawlspace. FEMA may accept a crawlspace elevation up to 2 feet below the lowest braced. adjacent exterior grade; however,the community must adopt specific requirements in order for this type of crawlspace to be constructed in a floodplain. 3.5: FOUNDATION WALLS 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12,10 If a stemwall and floor slab system is used, the FEMA. NFIP Technical Bulletin 11-01, Craw/space interior space beneath the slab should be back- Construction. 2001. (http://www.fema.gov/plan/pre- filled with compacted gravel (or such material*. as vent/floodplain/techbul.shtm) required by the building code). As long as the sys FEMA. Recommended Residential Construction for the tem can act monolithically, it will resist most flood Gulf Coast, Building on Strong and Safe Foundations. forces. However, if the backfill settles or washes FEMA 550. 2010. (http://www.fema.gov/library) out, the slab will collapse and the wall will lose lat- eral support. Additional Resources FEMA. NFIP Technical Bulletin 1-08, Openings in Foundation Walls and Walls of Enclosures. 2008. (http://www.fema.gov/plan/prevent/floodplain/ techbul.shtm) Floor framing DFE I. Floor framing f El Interior grade at or Interior grade slightly above adjacent below adjacent exterior grade exterior grade 4 e d.d d 111 !Ill .:1114111.11rawlspace •G e construction: Interior grade elevation for Zone A not subject to breaking waves and erosion NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 3.5: FOUNDATION WALLS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12'10 Load Paths HOME BUILDER'S GUIDE TO COASTAL CCM STRUCTION Technical Fact Sheet No. 4.1 Purpose: To illustrate the concept of load paths and highlight important connections in a wind uplift load path. Key Issues Loads acting on a building follow many paths Member connections are usually the weak link in through the building and must eventually be re- a load path. sisted by the ground, or the building will fail. Failed or missed connections cause loads to be Loads accumulate as they are routed through rerouted through unintended load paths. key connections in a building. Wind uplift pressure Vertical uplift component • LINK 1 • ' High winds lift theers roof upward. Roofing fasteners link the roof cover- ,. ing to the sheathing*,and sheathing ,' fasteners link the sheathing to the ir „,. �,' roof framing members (see Fact 0 Sheet No. 7.1). i�-1 * Although not a structural connection, the I` _ attachment of the roof covering to the roof ---;----- -------- sheathing is an essential part of protecting the building envelope. LINK 2 Accumulated roof load is routed through roof-to-wall connections. 1 Special roof ties connect the roof Design wind framing to the bearing walls(see Fact uplift load pathIII We,, Sheet No. 4.3). 'V LINK 3 Upper walls transfer loads directly to the lower walls. The floor framing is r 0 bypassed by using metal straps or 0 extended exterior sheathing that di- 0 rectly connects upper wall studs to the lower wall studs.A similar con- D nection is used to connect the lower —I g`-�_ �d wall to the main floor beam. I IV� Cn LINK 4 The foundation The accumulated uplift force is trans transfers all building 1 loads to theground. ferred from the main floor beams Main floor i�- to the pile foundation with special v; 1 beams i ' brackets or bolts (see Fact Sheet No. 1 , I ; 3.3). Note: Some of this load is off- Vertical load path from roof to ground on a v, set by the weight of the building. platform-and-pile-construction building.Note:Load paths will vary Note: Horizontal load paths transferring shear depending on construction type and design.Adjacent framing from upper stories to the ground must also be members will receive more load if a connection fails. analyzed. QE4A�1f.L 1a 4.1: LOAD PATHS k•Ne.•?-) FEMA HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 2 44ND SE° 12/10 If a connection fails, an alternative load path will form. If the members and connections in the new load path have inadequate resistance, progressive failure can occur. Loads must be routed around openings, such as windows and doors. Accumulated loads on headbrs are transferred to the studs on the sides of the opening. Uplift From Roof _AA). — LINK An adequate connection must Strap be made between the header and the king stud in order for the load to continue down the path. Header r-- r—Jack stud King stud LINK _ The bottom of a wall could have points of high uplift due to an accumulated load from above. Suitable hardware strap should be installed in the proper locations. Rim joist Load path around a window opening. Strap Load paths can be complex 1 through a connection. It is im- portant that each link within the connection be strong enough to transfer the full design load. The detail at left shows a typi- cal floor-to-pile connection. Uplift loads are transferred through the = Floor joint in the following order. framimg 4 2 0 from upper story to strap Floor if 0 from strap to floor beam O beam Design wind 0 from floor beam to bolts uplift load 3 path 0 from bolts to pile Pile Bolts 0 from pile to ground Load path through a pile connection. NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 4.1: LOAD PATHS 2 of 2 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Masonry Details HOME BUILDER'S GUIDE TO COASTAL COF' STRUCTION Technical Fact Sheet No. 4.2 Purpose: To highlight several important details for Roof framing to interior masonry wall masonry construction in coastal areas. Engineered wood roof trusses, Key Issues designed for interior bearing Continuous, properly connected load paths are es- sential because of the higher vertical and lateral loads on coastal structures. Building materials must be durable enough to with- stand the coastal environment. Masonry reinforcement requirements are more stringent in coastal areas. Roof truss1.1.1111 � Load Paths . Bond beam A properly connected load path from roof to foundation Roof truss anchor i_i is crucial in coastal areas (see Fact Sheets Nos. 4.1 i i and 4.3). The following details show important connec- tions for a typical masonry home. y-y III/ Reinforced i concrete i E masonry wall Roof framing to masonry wall Connector(typical) Roof trusses at 24" on center maximum Oversize washer according to design Pressure-treated (typical) Direct roof truss anchor top plate,as required installed according to (2x4 minimum) manufacturer's 1/2" anchor bolt at ,l specifications r 18" to 24" on center t Reinforced 0 or as specified by T,I bond D design �, beam ►% ` � I Connector installed according to manufacturer's � specifications \41411 t . t � barrier Provide moisture i.� Roof truss anchored ' ` , Roof truss anchored to top plate 1 , f in bond beam �/ Reinforced concrete masonry wall 4 Grout stop 4.2: MASONRY LS a�",1T FE '4i\. HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 f�.IND stc- 12 10 Gable end wall—cut concrete rake beam without looker-type overhang Pressure-treated 2x4 at 24"on center, maximum Roof sheathing Isuill 1 ' i ' 21 I' i • ' i-- 8" concrete Wood rake beam roof Fascia with one truss Soffit , / no.5(M #16) "` 8" overhang j bar minimum, (recommended j j at a minimum depth of 4" maximum) ,' 900 % % Gable end wall —cut masonry rake beam with standard % ,� ladder-type overhang hook 4 I j j Vertical Notch webs 2-3/4" 1/2" anchor bolt wall for reinforcement at 36" on center Concrete % reinforcement maximum,or masonry ; ; according to wall g j % Moisture barrier design 1 t • •IF , Gable endwall connections. .14/ 1 • Cut concrete masonry units to match slope; beam height varies, 8" overhang(recommended maximum) I F 4" minimum • Concrete masonry wall 2x4(minimum pressure-treated wood nailer) 4 Mesh or other grout stop device for cells not reinforced j Standard hook with lap,typical Typical reinforcement,one no. 5(M#16) / or according to design % r L Vertical wall reinforcement, / / as required Grout,as required Durability— High winds and salt-laden air can damage masonry construction. The entry of moisture into large 4 cracks can lead to corrosion of the reinforcement and subsequent cracking and spalling. Moisture resistance is highly dependent on the materials and quality of construction. Quality depends on: Proper storage of material— Keep stored materials covered and off the ground. k- Proper batching—Mortar and grout must be properly batched to yield the required strength. • Good workmanship — Head and bed joints must be well mortared and well tooled. Concave joints and V-joints provide the best moisture protection (see detail above). All block walls should be laid with full mortar coverage on horizontal and vertical face shells. Block should be laid using a "double butter" technique for spreading mortar head joints. This practice provides �� K i/- i j,7J7 for mortar-to-mortar contact as two blocks are laid to- gether in the wall and prevents hairline cracking in the ////� �� /� / ///f/ head joint. Concave Joint V-Joint 4.2: MASONRY DETAILS 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 I Protection of work in progress — Keep work in progress protected from rain. During inclement weather, the tops of unfinished walls should be covered at the end of the workday. The cover should extend 2 feet down both sides of the masonry and be securely held in place. Immediately after the completion of the walls,the wall cap should be installed to prevent excessive amounts of water from directly entering the masonry. Reinforcement: Masonry must be reinforced according to the building plans. Coastal homes will typically re- quire more reinforcing than inland homes. The following figure shows typical reinforcement requirements for a coastal home. One#5 at each end Shear segment Reinforced bond —One#6 minimum at each side Standard 90°hook Beams spanning of shear segments 1 2'minimum `beam continuous of opening having a horizontal at each vertical bar openings r(/ around perimeter dimension greater than 6' (typical) r 'I 1 I I ` I I -� --*---\ One#5 minimum at each Vertical wall reinforcement at 4'to 32'on center, Footing dowels at corners, corner and at each change depending on wall height,design wind speed,and openings wider than 6',and in wall direction roof span;footing dowel not always required ends of shear segments,minimum Masonry reinforcement. Gable Ends: Because of their exposure,gable ends are more prone to damage than are hipped roofs unless the joint in conventional construction at the top of the endwall and the bottom of the gable is laterally supported for both inward and outward forces. The figure at right shows a construction method that uses continuous ma- sonry from the floor to the roof diaphragm with a raked cast-in-place concrete bond beam or a cut masonry bond beam. Standard 90°hook with lap likim 4" minimum Reinforced raked cast-in-place concrete bond beam or cut masonry bond beam ■-1 }■ 2 x 4 minimum f wood nailer with 1/4" anchor bolts 11 0 !1 Continuous gable endwall reinforcement. CJ D —`_Tn ml NNE=.li -- - IC■ 111■�■ Cn J. 1I_-1110-- Foundation at III_1 ,1■--I1.1■-■ one-story building or bond beam at multistory Cleanouts required for grout pour heights greater than 5' unless footing dowel is not required NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER ti 4.2: MASONRY DETAILS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 j 12n o 1 and Use o Connectors B rackets HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 4.3 Purpose: To highlight important building connections and illustrate the proper use of various types of connection hardware. Key Issues Never rely on toe-nailing for uplift connections in high-wind areas In high-wind regions, special hardware is used for most framing connections. Toe-nailing is not an acceptable method for resisting uplift loads in high-wind regions. Hardware must be installed according to the manufacturer's or engineer's specifications. The correct number of the specified fasteners (length and diameter) must be used with connection hardware. Avoid cross-grain tension in connections. Metal hardware must be adequately protected from corrosion (see NFIP Technical Bulletin 8-96). Connections must provide a continuous load path (see Fact Sheet No. 4.1). Fill all nail holes with specified fasteners, Improper connection to unless reduced nailing is specified by design only one member of top plate can lead to failure under uplift loads WI I II cii___/ /(------ deoig0'7.---- The length and diameter of the fasteners must be as specified by the manufacturer or engineer; t.-� some specifications require non-standard nails Proper fasteners must be used with Instead, nail connector connection hardware. to outside face of both top plate . _4,- members,or nail to stud and top plate members �� Bolt, screw,or nail diameter Avoid load path failure Offset bracket and quantity as specified r— vertically to at roof-to-wall connections. ♦- 0 achieve minimum ♦!_ D specified end .- 0 spacing for -AI ♦ ' D bolts i 2 . -- -' t -A* -...„,..... 4: 1l ��0� I d Material to which bracket �� is attached must have adequate thickness fo maximum bracket capacity • Proper bracket connection. Proper strap connection. 4.3: USE OF CONNECTORS AND BRACKETS J 1 )9, FEIVIe\. HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 4 ��41A/E SEC 1 12/10 Truss Member Connections are made with metal plates that connect the individu- Truss plate al partsdesigns.ofPlates a truss tost formbeafully structuralembedded,component.andgaps at Everyjoints joint mustshould be havemini- a connector plate on each face sized and positioned according to engineered mi 4•400 mized (see ANSI/TPI-1 95). a 4 r_. , / 4W , I,� � Truss-to-Truss and Rafter-to-Truss Con- \\ nections are made with metal hangers _ IF ..... specified by the truss designer. 1 Ar. •ee..\, 110.:\I.. Important V .� Coastal environments are conducive to rapid corrosion of metals. / All connection hard- �' 410111.°11 .-ware must be properly 4 protected. Galvanized coatings on readily / Roof-to-Wall Connections available hardware may are made with metal rafter not be adequate or in '/ ties or straps, sometimes compliance with localreferred to as hurricane coastal building codes. straps. These connectors Special-ordered hard- replace toe-nailing ware, re-galvanizing, (► and provide added = field applied coatings, or uplift resistance. Q stainless steel may be The strap should d required. extend above the oi / % centerline of the raf- p '< qe. . . 0 :;01/1- ter or,for the strongest —' oI `' �' connection, • completely •. over the rafter. A stud-to-top-plate connector is also necessary,but it has been omitted here for clarity. • I.Solid wall foundation building Pile foundation building Connection Hardware Applications 4.3: USE OF CONNECTORS AND BRACKETS 2 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION i 12 to .4a.p- Stud-to-Top-Plate Connec- Stud-to-Stud Connec- tions are made with metal tions are made with straps, nailed to the side nailed metal straps, or and/or face of the stua and brackets with threaded the top of the top plate. These a` rods,that connect connections replace toe-nailing or �� one story to end-nailing and provide added uplift the next. resistance. The strap should wrap over the top plate. Imo_. ,..A0 . r/P `' \ Ir • ‘ studs. The ' straps should extend 4 I' the full depth of the header. 1441444%1111%111011 i'A 0 d . ,- I1110. . 1111 I'. -------- '4'1w II Built-up members 01 , , ili, 1 must have adequate 111.," )' nailing to ensure that members resist loads ,• together. For greater uplift resistance,use Important ► / leg I`'� �II ' / ► connectors on both sides of joist. o � IL • These are examples of '' 1*. IIII�� CI typical connectors used in 0 1 I residential construction. I I' / For the required continuous - 0 ! p/ I load path to be maintained, ® :i all connectors used must I Of be adequate to resist the 11,V loads expected to act on them. Stronger connectors may be necessary in areas Joist-to-Beam Connections are made with subject to high winds or ties similar to roof-to-wall connections or with earthquakes. wood blocking. Solid wall foundation building Pile foundation building Connection Hardware Applications 4.3: USE OF CONNECTORS AND BRACKETS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 4 12 10 - Nut and washer e Wall-to-Foundation a^ Connections are Threaded rod Sis to,,, made with metal / brackets or bolts / _ that connect wall � 0 0 studs and/or sill -a plates to founda- Coupling - tion walls, beams, or band joists. Continuous Rod Connections ?i de- are made with a system of 4 threaded rods, couplings, and OSstop /1PP \,,, \ brackets. These connections can be used to tie the roof and walls to band joists and sup- port beams. e oee l \ o o 1'1N (0 1 ' of Anchor(for concrete -r+t foundation as shown o here)or bracket o (for pile foundation) ° - - ° 0 / - Pile Connections are made with I * special brackets, spiked grids, n % bolts, or other types of connectors that attach the main floor beams to the piles. It is extremely impor- tant to follow design specifications for this con- cti (see ``.."--- 11 0 Fact Sheet Sheet No. ' 0 3.3 for further • cn • ¢ �, ' / /' details). •,, ' % • c 4.'- --'. .4 0 , -1 floo Additional Resources American National Standards Institute. National Design Standard for Metal Plate Connected Timber Trusses, ANSI/TPI-1 95. Connection Hardware Applications Solid wall foundation building Pile foundation building NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 4.3: USE OF CONNECTORS AND BRACKETS 4 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12 1,, Housewrap HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 5.1 Purpose: To explain the function of housewrap, examine its attributes, and address common problems associated with its use. Key Issues Housewrap has two functions: . to prevent airflow through a wall and to stop(and drain) liquid wa- ter that has penetrated through the exterior finish. Housewrap is not a vapor retard- er. It is designed to allow water vapor to pass through. • The choice to use housewrapIIIP or building paper depends on the climate and on specifier 1111 ve or owner preference. Both ma- terials can provide adequate .. r protection. ' ■ Housewrap must be installed __ems=_, properly or it could be more det- rimentalthanbeneficial. •• re:� Proper installation, especially in lapping, is the key to successful - housewrap use. Purpose of Housewrap Housewrap serves as a dual-purpose weather bar- housewrap also prevents air movement through the rier. It not only minimizes the flow of air in and out wall cavity,which is beneficial for insulating purposes. of a house, but also stops liquid water and acts as a drainage plane. Housewrap is not a vapor retarder. Housewrap or Building Paper? The unique characteristic of housewrap is that it al- lows water vapor to pass through it while blocking To answer this question, it is important to know liquid water. This permits moist humid air to escape what attributes are most important for a particular from the inside of the home,while preventing outside climate. Five attributes associated with secondary liquid water(rain)from entering the home. weather barriers are: Air permeability-ability to allow air to pass When Should Housewrap Be Used? through Almost all exterior finishes allow at least some wa- Vapor permeability-ability to allow water vapor ter penetration. If this water continually soaks the (gaseous water) to pass through wall sheathing and framing members, problems such as dryrot and mold growth could occur. Housewrap Water resistance- ability to prevent liquid water stops water that passes through the siding and al- from passing through r lows it to drain away from the structural members. In Repels moisture-ability to prevent moisture ct) humid climates with heavy rainfall, housewrap is rec- absorption -< ommended to prevent water damage to the framing. Use in dryer climates may not be as critical, since Durability-resistance to tearing and m materials are allowed to adequately dry, although deterioration cn ciF'4A�\FA. FEI4J\. 51: HOUSEWRAP HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 �qND sic- 12/10 As shown in the following table, the climate where the house is located determines the importance of the attribute. • • s or—Fair—Good—Excellent Product Performance Attribute When it is Important Building Paper Housewrap Air Permeability Windy and cold climates Good Vapor Permeability Hot, humid climates Good Water Resistance Windy and rainy climates Good Excellent Repels Moisture High rainfall Good Good Durability Windy,with possible extended exposure Good Cost Owner preference Excellent In general, housewrap is a good choice for coastal homes. Installing Housewrap Avoid complicated details in the design stage to No matter what product is used (housewrap or prevent water intrusion problems. building paper), neither will work effectively if not When sealant is required: installed correctly. In fact, installing housewrap incor- rectly could do more harm than not using it at all. use backing rods as needed, Housewrap is often thought of and installed as if it use sealant that is compatible with the were an air retarder alone. A housewrap will chan- climate, nel water and collect it whether the installer intends it to or not. This can lead to serious water damage use sealant that is compatible with the ma- if the housewrap is installed in a manner that does terials it is being applied to, not allow the channeled water out of the wall system. surfaces should be clean (free of dirt and The following are tips for successful installation of loose material), and housewrap: discuss maintenance with the homeowner. Follow manufacturers' instructions. Plan the job so that housewrap is applied before Avoid These Common Problems windows and doors are installed. Incomplete wrapping Proper lapping is the key—the upper layer should Gable ends are often left unwrapped, leaving a always be lapped over the lower layer. seam at the low end of the gable. This meth- Weatherboard-lap horizontal joints at least 6 od works to prevent air intrusion, but water that inches. gets past the siding will run down the unwrapped gable end and get behind the housewrap at the Lap vertical joints 6 to 12 inches (depending on seam. Also, it is common for builders to pre-wrap potential wind-driven rain conditions). a wall before standing it. If this is done,the band Use 1-inch minimum staples or roofing nails joist is left unwrapped. Wrap the band joist by in- spaced 12 to 18 inches on center throughout. serting a strip 6 to 12 inches underneath the bottom edge of the wall wrap. In addition, out- Tape joints with housewrap tape. side corners are often missed. Allow drainage at the bottom of the siding. Improper lapping Extend housewrap over the sill plate and founda- This often occurs because the housewrap is tion joint. thought of as an air retarder alone. When apply- -J Install housewrap such that water will never be ing the housewrap, keep in mind that it will be allowed to flow to the inside of the wrap. used as a vertical drainage plane, just like the siding. 5.1: HOUSEWRAP 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12'10 1 Improper integration with flashing around doors and windows- See Fact Sheet No. 6.1. Relying on caulking or self-sticking tape to address improper lapping Sealant can and will deteriorate over time. A lapping mistake cor- rected with sealant will have a limited time of effectiveness. If the homeowner does not per • - form the required maintenance, serious water damage could oc- cur when the sealant eventual- '•� I ly fails. Therefore, do not rely on _ II or tape to correct lapping ..-' lib errors. • i : - - it V,` ,! :, - •' .- D r- r cn cn --I m NAHB K RESEARCH U) Developed in association with the National Association of Home Builders Research Center CENTER 5.1: HOUSEWRAP HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12;io Roof- to - Wall and Deckto - - Wall Flashing HOME BUILDER'S GUIDE TO COASTAL CON 3TRUCTION Technical Fact Sheet No. 5.2 Purpose: To emphasize the importance of proper roof and deck flashing, and to provide typical and en- hanced flashing techniques for coastal homes. Key Issues Housewrap or building paper (minimum) self adhering Poor performance of flash- (do not attach to roof tape) 4"-wide modified bitumen roof tape ing and subsequent water intrusion is a common prob- Shingles ', lem for coastal homes. x,tf Wall sheathing Enhanced flashing tech- *411111/4 }Y 3, niques are recommended in i„ areas that frequently experi- 4111V s Step flashing with 2"to 4' longer vertical ence high winds and driving , leg than normal rain. Note: Stop housewrap ; or building paper Ver/ical leg Water penetration at deck approximately 11/2" ✓ ledgers can cause wood above shingles. dry rot and corrosion of connectors leading to deck collapse. Underlayment Roof sheathing Figure 1. Roof/wall flashing detail. Roof and Deck Flashing Recommendations for Coastal Areas Always lap flashing and other moisture barriers For deck flashing: properly. Follow proper installation sequence to pre- Use increased lap lengths for added protection. vent water penetration at deck ledger (see Do not rely on sealant as a substitute for proper Figure 2). lapping. Leave gap between first deck board and Use fasteners that are compatible with or of the flashing to allow for drainage (see Figure 3). same type of metal as the flashing material. Use spacer behind ledger to provide gap for Use flashing cement at joints to help secure drainage (see Figure 3). flashing. Use stainless steel deck connection At roof-to-wall intersections (see Figure 1): hardware. Use step flashing that has a 2-to 4-inch-Ion- y ger vertical leg than normal. 1— r Tape the top of step flashing with 4-inch-wide � (minimum) self-adhering modified bitumen cn roof tape. See Fact Sheet Nos. 7.2 and 7.3 for rake and m Do not seal housewrap or building paper to eave details. K step flashing. I o 5.2: ROOF-TO-WALL AND DECK-TO-WALL FLASHING , ?J FEIVIA HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 Cq ND stc 12 10 0 Counter flashing Housewrap or Fastener building paper Fastener 1 Level guide line Appoximately 6" ® Housewrap or I building paper Z-flashing#1 J} + e Ledger �, Fastener 0 Counter flashing 4" minimum in high-wind areas ( Counter flashing terminates above Z-flashing#1 horizontal band Fastener in Z-flashing Z-flashing#2 Housewrap or building paper Counter flashing over upper Z-flashing einserted in slit in housewrap or building paper Ledger Nt- - Fastener Counter flashing �i A Fastener ` © Z-flashing#1 (/) Housewrap or building)paper CD CD 0 0 0 0 0 � I Z-flashing#2 Vinyl siding .-- Counter flashing Ledger Fastener ________Z-flashing#2 Z-flashing#1 Deck board Housewrap or M building paper 0 Figure 2 W Installation sequence for deck ledger flash- CO _ . ing Ledger _— Fastener q g } U) J ' Q Z-flashing#1 5.2: ROOF-TO-WALL AND DECK-TO-WALL FLASHING HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 Exterior sheathing Housewrap or building paper Siding Deck board Z-flashing#2 iii Gap for drainage ' ,.i Flashing drip-edge d e • u'ui1iq la/ Housewrap or building paper . Spacer behind ledger . Deck joist I(11/atiori I wall Z-flashing#1 Ledger Figure 3 Deck ledger flashing. D I- (I) -< m NAHB K RESEARCH (n Developed in association with the National Association of Home Builders Research Center CENTER 5.2: ROOF-TO-WALL AND DECK-TO-WALL FLASHING HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12,10 Siding Installation in High - Wind Regions HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 5.3 Purpose: To provide basic design and installation tips for various types of siding that will enhance wind re- sistance in high-wind regions(i.e., greater than 90 miles per hour[mph]basic[gust design] wind speed)'. Key Issues Siding is frequently blown off walls of residential When applying new siding over existing siding, and non-residential buildings during hurricanes. use shims or install a solid backing to create a Also,wind-driven rain is frequently blown into wall uniform,flat surface on which to apply the siding, cavities (even when the siding itself is not blown and avoid creating gaps or projections that could off). Guidance for achieving successful wind per- catch the wind. formance is presented in the following. Coastal buildings require more maintenance To avoid wind-driven rain penetration into wall than inland buildings. This maintenance require- cavities, an effective moisture barrier (house- ment needs to be considered in both the selec- wrap or building paper) is needed. For further in- tion and installation of siding. formation on moisture barriers, see Fact Sheet No. 1.9, Moisture Barrier Systems. For further information on housewrap, see Fact Sheet No. 5.1, Housewrap. Moisture barrier(also known as a water-resistive Always follow manufacturer's installation instruc- tions and local building code requirements. barrier): In the context of residential walls, the moisture barrier is either housewrap or building Use products that are suitable for a coastal en- paper(felt). The moisture barrier occurs between vironment. Many manufacturers do not rate their the wall sheathing and the siding. It is a dual-pur- products in a way that makes it easy to deter- pose layer that sheds water that gets through the mine whether the product will be adequate for siding and limits air flow through the wall. When the coastal environment. Use only siding prod- properly sealed, housewrap is considered an air ucts where the supplier can provide specific in- barrier. Although building paper provides some formation on product performance in coastal or resistance to air flow, it is not considered an air high-wind environments. barrier. Moisture barriers shed water, but they al- low water vapor to pass through them. For buildings located within 3,000 feet of the ocean line, stainless steel fasteners are recommended. Avoid using dissimilar metals together. For further guidance on principles,materials,and The installation details for starting the first (low- procedures for the design and construction of est) course of lap siding can be critical. Loss walls to make them resistant to water intrusion, of siding often begins at the lowest course and see American Society for Testing and Materials proceeds up the wall (Figures 4 and 12). This (ASTM) E 2266, Standard Guide for Design and is particularly important for elevated buildings, Construction of Low-Rise Frame Building Wall where the wind blows under the building as well Systems to Resist Water Intrusion. r cn as against the sides. cn rn 1 The 90 mph speed is based on ASCE 7-05.If ASCE 7-10 is being used,the equivalent wind speed is 116 mph for Risk Category II buildings. v�'p�1Fn. J' FEI4J\ 5.3: SIDING INSTALLATION IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 8 9.4..44ND SECi' 12/10 Vinyl Siding Vinyl siding can be used successfully High-wind siding Standard siding in a coastal environment if properly de- signed and installed. Double Windload Resistance nailing hem Vinyl siding is required by the Inter- national Building Code (IBC) and the International Residential Code (IRC) to comply with ASTM D 3679, Standard Specification for Rigid Poly (Vinyl Chlo- ride) (PVC) Siding. Both the IBC and IRC require static pressure testing over solid Greater locking wall surfaces capable of independently area resisting the design wind pressures to Thicker vinyl approximate loading conditions that oc- cur in 110-mph wind zone areas for a building up to 30 feet in height in Expo- Figure 1. Features of typical high-wind siding and standard siding. sure B.2 Most vinyl siding has also been tested for higher wind pressures and can be used in locations with a higher ba 10111111111 ,07 c:Ap\ - sic wind speed, greater building height, more open exposure, or some combi- nation of these. While vinyl siding wind 1/32" pressure ratings found in most product /Yes X No (about the literature are based on tests of the vinyl — thickness of over an approved sheathing capable of Figure 2. Proper and improper fas- a dime) independently resisting the design wind tener locations. pressures, methods of installation that - rely on a combination of wind resistance Figure 3. Allow 1132" provided by exterior wall sheathing, vinyl be 0.040 to 0.048 clearance between the siding, and interior wall sheathing are available for inches, depending fastener head and the some applications. The design wind pressure or wind on style and design. siding panel. speed for which these products are rated, as well Thinner gauge vinyl as requirements for sheathing behind the vinyl sid- works well for sta- ing are available from product literature, installation ble climates; thicker gauge vinyl is recommended instructions, or listings of agencies such as the Inter- for areas with high winds and high temperature national Code Council (ICC) Evaluation Service. changes. For design wind speeds greater than 110 mph Position nails in the center of the nailing slot per ASCE 7-05, or 139 mph per ASCE 7-10, or, (Figure 2). To allow for thermal movement of the building heights greater than 30 feet, or Exposure siding, do not drive the head of the nail tight C, choose a siding product rated for those con- against the nail hem (unless the hem has been ditions or higher. The manufacturer's product lit specifically designed for this). Allow approxi erature or installation instructions should specify mately 1/32 inch (which is about the thickness the fastener type,size and spacing,and any other of a dime) clearance between the fastener head installation details such as requirements for the and the siding panel (Figure 3). sheathing materials behind the vinyl siding need- Drive nails straight and level to prevent distor- ed to achieve this rating. tion and buckling in the panel. Products that have been rated for high winds typi- Do not caulk the panels where they meet the W cally have an enhanced nailing hem and are some- receiver of inside corners, outside corners, or times made from thicker vinyl (Figure 1). Thick, J-trim. Do not caulk the overlap joints. } rigid panels provide greater wind resistance, Do not face-nail or staple through the siding. withstand dents, and lie flatter and straighter J against the wall. Optimum panel thickness should 2 The 110 mph wind speed is based on ASCE 7-05.If ASCE 7-10 is used,the equivalent wind speed is 139 mph for Risk Category II buildings. 5.3: SIDING INSTALLATION IN HIGH-WIND REGIONS 2 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Use aluminum, galvanized steel, or other corro- sion-resistant nails when installing vinyl siding. Aluminum trim pieces require aluminum or stein- less steel fasteners. : . 1 Nail heads should be 5/16 inch minimum ir1 di- ice" ameter. Shank should be 1/8 inch in diameter. Use the manufacturer-specified starter strip to lock in the first course; do not substitute oth- er accessories such as a J-channel or utility trim (Figure 4) unless specified by the manufacturer. If the manufacturer specifies a particular strip for high-wind applications, use it. Make sure that the starter strip is designed to positively lock the panel, rather than just hooking over a bulge in the strip; field test the interlock before proceed- ing with the installation. Make sure that every Figure 4. Utility trim was substituted for the starter course of siding is positively locked into the pre- strip and the bottom lock was cut off the siding.Siding vious course (Figure 5). Push the panel up into was able to pull loose under wind pressure. the lock from the bottom before nailing rather 1 than pulling from the top. Do not attempt to align siding courses with adjacent walls by installing some courses loosely. 1 - Make sure that adjacent panels overlap proper- ly, about half the length of the notch at the end of the panel, or approximately 1 inch. Make sure • . the overlap is not cupped or gapped, which is caused by pulling up or pushing down on the sid- II% iirtiri.., ing while nailing. Reinstall any panels that have - this problem. 'a. Use utility trim under windows or anywhere the top nail hem needs to be cut from siding to fit around an obstacle. Be sure to punch snap-locks into the siding to lock into the utility trim. Do not overlap siding panels directly beneath a window (Figure 6). At gable end walls, it is recommended that vi- Figure 5. The siding panel was not properly locked into nyl siding be installed over approved sheath- the panel below. ing capable of independently resisting the full design wind pressures rather than over plas- tic foam sheathing or combinations of exterior foam sheathing and interior gable end sheath- ing except as provided for in the IRC Section R703.11.2. Figure 7 depicts the vulnerability of siding on gable end walls not properly sheathed with approved materials capable of independent- ly resisting the full design wind pressures. Install vinyl siding in accordance with manufac- turer's installation instructions and local building D code requirements. Ensure product rating is ap- r propriate for the intended application. r It is recommended that vinyl siding installers be cn certified under the VSI Certified Installer Program Figure 6. Proper detailing around windows and other —I Sponsored by the Vinyl Siding Institute. obstacles is important. Use utility trim,punch snap- m locks into siding,and do not overlap directly beneath a window. r) 5.3: SIDING INSTALLATION IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 8 12 10 Wood Siding Use decay-resistant wood such as redwood, ce- dar, or cypress. See the Sustainable Design sec- tion regarding certified wood. To improve longevity of paint, back-prime wood �w siding before installation. Carefully follow manufacturer's detailing instruc- y.!!tI. `� tions to prevent excessive water intrusion behind ��_ - ' lithe siding. .H — �; For attachment recommendations, see Natural , Wood Siding: Selection, Installation and Finish i? • s ing, published by the Western Wood Products _I=, } L Association. l This publication recommends an air gap between 11 — the moisture barrier and the backside of the siding . i . _ to promote drainage and ventilation. Such a wall Figure Z The vinyl siding at this gable was installed configuration is referred to as a rain screen wall. over plastic foam insulation.Without wood sheathing, See the text box on page 5. the wind pressures on the vinyl are increased.Also, if the siding blows away,the foam insulation is very Follow the installation details shown in Figures vulnerable to blow-off.With loss of the foam insulation, 8a and 8b. (Note: Although these details do not wind-driven rain can freely enter the attic,saturate the show a rain screen, inclusion of vertical furring ceiling insulation,and cause collapse of the ceiling. strips to create a rain screen is recommended.) Wood Wood '' sheathing sheathing '\ Housewrap or building paper !1 <.. i * Self-adhering modified a bitumen flashing Fr Bevel 1 siding 1 Corner Seal joints boards Trim Seal joints Comer boards Self-adhering Tongue and groove horizontal modified bitumen I siding up to 6"wide flashing I Stud IHousewrap or building paper IWood sheathing INails must penetrate solid Iwood 1-1/2"minimum U) Tongue and groove horizontal Ill siding up to 6"wide ~ U7 1 -0—Extra nail (n t J J Q Figure 8a. Wood siding installation details. 5.3: SIDING INSTALLATION IN HIGH-WIND REGIONS 4 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 17 , ';)Wood sheathing " Wood sheathing Housewrap Interior Housewrap or Wood stud or building wall building paper paper finish / Bevel siding 11' Tongue and i groove Vapor retarder horizontal (if needed) siding Lap at 45° Insulation Figure 8b. Wood siding installation details. Pressure-equalized rain screen wall system Pressure-treated or Stud decay-resistant In areas that experience frequent wind-driven rain — furring strips and areas susceptible to high winds, it is recom- _s Wood sheathing mended that a rain screen design be considered 111 ' when specifying wood or fiber cement siding. / Housewrap or (Typical vinyl siding products inherently provide air ri building paper cavities behind the siding that facilitate drainage. Therefore, incorporation of vertical furring strips is normally not applicable to this type of wall coy- 4Bevel siding ering.) A rain screen design is accomplished by installing suitable vertical furring strips between the moisture barrier and siding material (see Figure 9). The cavity facilitates drainage of water from the space between the moisture barrier and backside of the siding and it facilitates drying of the siding and moisture barrier. Furring strip attachment: For 1 by 2 inches furring strips, tack strips in place and use siding nails that are 3/4 inch longer than would be required Figure 9. Pressure-equalized rain screen system. if there were no strips (to maintain the minimally required siding nail penetration into the studs). For thicker furring strips, an engineered attach- ment is recommended. Fiber Cement Siding At the bottom of the wall, the cavity should be Installation procedures are similar to those open to allow water drainage. However,the open- for wood siding, but require specialized cutting ing should be screened to avoid insect entry. blades and safety precautions because of the At the wall/soffit juncture, the top of the cavity dust produced during cutting with power tools. can open into the attic space to provide inlet air Manufacturer's installation recommendations D ventilation, thereby, eliminating soffit vents and should be strictly adhered to, and particular at I- r- their susceptibility to wind driven rain entry. If the tention paid to the painting and finishing recom- r- rain screen cavity vent path is used instead of mendations for a high quality installation. -< cn soffit vents, the depth of the cavity needs to be Always seal field-cut ends according to the man- engineered to ensure that it provides sufficient ufacturer's instructions. Properly gap the inter- m air flow to ventilate the attic. section between siding edges and other building cn components and fill the gap with sealant. 5.3: SIDING INSTALLATION IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 8 12/10 Always consult and follow the manufacturer's Face nailing (Figure 11) instead of blind nailing installation requirements for the needed wind is recommended where the basic (design) wind speed rating or design pressure (refer to the speed is 100 mph or greater. If the local building manufacturer's building code compliance ev al- code or manufacturer specifies face nailing at a uation report). Observe the manufacturer's fas- lower wind speed, install accordingly. tener specifications, including fastener type and Do not leave the underside of the first course ex- size, spacing, and penetration requirements. Do not over drive or under drive. posed or extending beyond the underlying mate- rial (Figure 12). Consider the use of a trim board At gable end walls, it is recommended that fiber to close off the underside of the first course. cement siding be installed over wood sheathing rather than over plastic foam sheathing. Keep blind nails between 3/4 and 1-inch from the top edge of the panel (Figure 10). Be sure to drive nails at least 3/8 inch from butt ends, or use manufacturer-specified joiners. 1 Wood sheathing pi'el. Stud \____________ ' � �- r' I I 1 I .'/ - 61,0 Ni 1 Blind nail ` l r ' I ', I . II ,: , 1 , _____ , , _ . .. _ _ _ , ., 1..„_.,„ : . _ _____ i Housewrap or Siding building paper Figure 12. Blind nailed siding installed with exposed gap at bottom (red circle)is vulnerable to failure. Blind Nail Figure 10. Blind nailing. Sustainable Design Material selection for sustainable sources and Wood sheathing durability Stud ` For wood products, it is best to select material that has been certified by a recognized program such -- as the American Tree Farm System® (AYES), the ;p. ; Forest Stewardship Council (FSC) or the Sustainable ForestryInitiative® Not onlydo these programs '., Face nail � ( )• P g 1 verify that wood is harvested in a more responsible fashion, but they also verify that the use of chemi- I ; cals and genetic engineering of these products is '°° avoided. The following publications discuss sustainable as- u) ` 3/4°-1 pects of vinyl siding: w A Dozen Things You Might Not Know That Make Vinyl Housewrap or Sidin Green (available online at htt vin lsidin u) = Siding building paper g p'// Y g' >- org/greenpaper/090710_Latest_Revised_Green_ _IFace Nail paper.pdf). Q Sidingwith the Environment(available online at http:// Figure 11. Face nailing. www.vinylsiding.org/publications/final_Enviro_ single_pg.pdf). 5.3: SIDING INSTALLATION IN HIGH-WIND REGIONS 6 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1210 Energy Conservation and Air Barriers Uncontrolled air leakage through the building enve- lope is often overlooked. The U.S. Department of Air barrier: A component installed to provide a Energy estimates that 40 percent of the cost of heat- continuous barrier to the movement of air through ing or cooling the average American home is lost 1iue the building envelope. Housewrap is a common to uncontrolled air leakage. In warmer climates, ft is air barrier material for residential walls. Although a lower percentage of loss. An air barrier system can very resistant to airflow, housewrap is very vapor reduce the heating, ventilation, and cooling (HVAC) permeable and therefore is not suitable for use system size, resulting in reduced energy use and as a vapor retarder. demand. Uncontrolled air leakage can also contribute to pre- Vapor retarder: A component installed to resist diffusion of water vapor and provide a continuous mature deterioration of building materials, mold and moisture problems, poor indoor air quality, and corn- barrier to movement of air through the building re- promised occupant comfort. When uncontrolled air envelope. Polyethylene is a common vapor tarder material for residential walls. To determine flows through the building envelope, water vapor whether or not a vapor retarder is needed, refer moves with it. Controlling the movement of moisture by air infiltration requires controlling the air pathways to the appropriate provisions of Chapter 14 of and/ory airthe driving force. the 2009 IBC or Chapter 6 of the 2009 IRC. Also refer to the Moisture Control section of the NRCA To effectively control air leakage through the build- Roofing and Waterproofing Manual, published ing envelope, an effective air barrier is required. To by the National Roofing Contractors Association be effective, it needs to be continuous; therefore, (NRCA) (http://www.nrca.net). air barrier joints need to be sealed and the barrier needs to be sealed at penetrations through it.The Air Barrier Association of America recommends that ma- terials used as a component of a building envelope air barrier be tested to have an air infiltration rate of ASTM E 1677, Standard Specification for an Air less than 0.004 cubic feet per minute (cfm)/square Retarder (AR) Material or System for Low-Rise foot,assemblies of materials that form the air barrier Framed Building Walls: This specification covers be tested to have an air infiltration rate of less than the minimum performance and acceptance crite- 0.04 cfm/square foot, and the whole building exte- ria for an air barrier material or system for framed nor enclosure have an air infiltration rate of less than walls of low-rise buildings with the service life of 0.4 cfm/square foot. the building wall in mind. The provisions con- tained in this specification are intended to allow the user to design the wall performance criteria Air Barrier Systems Installed Behind Siding and increase air barrier specifications to accom- Housewrap is the most common air barrier material modate a particular climate location,function, or for residential walls. To be effective, it is critical that design of the intended building. the joints between sheets of housewrap be sealed as recommended by the manufacturer,and penetrations (other than fasteners) should also be sealed. At tran- sitions between the housewrap and door and window If the building has an unventilated attic or no attic, frame, use of self-adhering modified bitumen flashing at the top of the wall, the wall air barrier should be tape is recommended. sealed to an air barrier that is installed at the plane An air barrier should be installed over a rigid mate- of the roof(the roof air barrier may be the roof mem- rial, or it will not function properly. It also needs to be brane itself or a separate air barrier element). restrained from pulling off of the wall under negative wind pressures. For walls, wood sheathing serves as Siding Maintenance a suitable substrate, and the siding (or furring strips For all siding products, it is very important to peri- in a rain screen wall system) provide sufficient re- odically inspect and maintain the product especially straint for the air barrier. in a coastal environment. This includes recoating At the base of the wall, the wall air barrier should be on a scheduled maintenance plan that is necessary sealed to the foundation wall. If the house is elevat- according to the manufacturer's instructions and a r— ed on piles,the wall barrier should be sealed to an air periodic check of the sealant to ensure its durability. cn barrier installed at the plane of the floor. Check the sealant for its proper resiliency and that it is still in place. Sealant should be replaced before it m If the building has a ventilated attic, at the top of the reaches the end of its service life. wall, the wall air barrier should be sealed to an air cn barrier that is installed at the plane of the ceiling. 5.3: SIDING INSTALLATION IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 7 of 8 12,10 Additional Resources American Tree Farm System®, ATFS (http://www.trleefarmsystem.org/index.shtml). Forest Stewardship Council, FSC (http://www.fsc-nfo.org) International Code Council. International Building`Code. 2009. (http://www.iccsafe.org) International Code Council. International Residential Code. 2009. (http://www.iccsafe.org) Sustainable Forestry Initiative® Program, SFI (http://www.sfiprogram.org) Vinyl Siding Institute,VSI (http://www.vinylsiding.org) Cn 2 w I— Cn >- -J 1(1AHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 5.3: SIDING INSTALLATION IN HIGH-WIND REGIONS 8 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1210 Attachment of Brick Veneer in High -Wind Regions HOME BUILDER'S GUIDE TO COASTAL CON 3TRUCTION Technical Fact Sheet No. 5.4 Purpose: To recommend practices for installing brick veneer that will enhance wind resistance in high-wind regions (i.e., greater than 90-miles per 7N`-‘, hour[mph]basic[gust design] wind speed).1 Key Issues When not adequately attached, brick veneer is frequently blown off walls of residential and non- residential buildings during hurricanes (Figure 1). CI When brick veneer fails,wind-driven water can en- ter and damage buildings,and building occupants k -- - can be vulnerable to injury from windborne de- I _" bris (particularly if walls are sheathed with plas- tic foam insulation or wood fiberboard instead of Figure 1. Failed brick veneer over plywood.Many of wood panels). Pedestrians in the vicinity of dam- the ties are still attached to the substrate,but several of the tie fasteners pulled out of the substrate and the aged walls can also be vulnerable to injury from ties are embedded in the collapsed veneer.Estimated falling veneer(Figure 2). wind speed:107 miles per hour(peak gust,Exposure Common failure modes include tie (anchor) cor C,at 33 feet). rosion (Figure 3), tie fastener pull-out (Figure 4), failure of masons to embed ties into the mortar ow— -- '� (Figure 5), and poor bonding between ties and ., �` mortar and mortar of poor quality (Figure 6). - - sr Ties are often installed before brick laying be- I I i11 gins. When this is done, ties are often improper- ly placed above or below the mortar joints. When _ I misaligned, the ties must be angled up or down in order for the ties to be embedded into the mor- i, ,, tar joints (Figure 7). Misalignment not only reduc- - ' - es embedment depth, but also reduces the effec- r . . i ' tiveness of the ties because wind forces do not v ' '' act parallel to the ties themselves. '4.:-• — Corrugated ties typically used in residential ve- ,. neer construction provide little resistance to compressive loads. Use of compression struts I would likely be beneficial, but off-the-shelf devic- . es do not currently exist. Two-piece adjustable ./ua ; ' .. ties (Figure 8) provide significantly greater corn- , ..<. pressive strength than corrugated ties and are, - - D therefore, recommended. However, if corrugated - - 1— ties are used, it is recommended that they be In t— Figure 2. The upper portion of the brick veneer at stalled as shown in Figures 9 and 10 in order to CD this apartment building collapsed.Pedestrian and -< enhance their wind performance. vehicular traffic in the vicinity of the damaged wall are Cl) 1 The 90 mph speed is based on ASCE 7-05. If ASCE 7-10 is being vulnerable to injury and damage if remaining portions m used,the equivalent wind speed trigger is 115 mph for Risk Category of the wall were to collapse during subsequent storms. II buildings. Cl) 5.4: ACHMENT OF BRICK VENEER N HIGH WIND J ` FEIN4.A. HOMETBUILDER'S GUIDE O COASTAIL CONSTRUCTIONION 1 of 5 o�F44ND SE/� 12 10 ¢ Buildings that experience veneer damage typi- . cally do not comply with current building codes. "9 s.>,*,% , Building code requirements for brick veneer • have changed over the years. Model codes prior • r to 1995 permitted brick veneer in any location, '" with no wind speed restrictions. Also, some old- er model codes allowed brick veneers to be an- chored with fewer ties than what is required by today's standards. Figure 3.Significant tie corrosion caused the brick at a fire station to fail,even though the building is not The Masonry Society's (TMS) 402/American Con- near the coast.Note that metal is missing for half of crete Institute 530/American Society of Civil the width of the tie at two locations (red arrows). The Engineers (ASCE) 5 Building Code Requirements left end of the tie was still embedded into a concrete and Specifications for Masonry Structures (TMS masonry unit back-up wall.The right end is where the 402) is the current masonry standard referenced tie failed in tension,thus leaving a portion of the tie by model building codes. The 2009 International embedded in the collapsed brick. Residential Code (IRC) and the 2009 International Building Code (IBC) references the 2008 edition of TMS 402, which is the latest edition. TMS 402 addresses brick veneer in two manners: _ rational design and a prescriptive approach. Nearly `. all brick veneer in residential and low-rise construc- °>t.,_,� tion follows the prescriptive approach. The first • -"V , . edition of TMS 402 limited the use of prescriptive design to areas with a basic wind speed of 110 AI mph or less. The 2008 edition of TMS 402 extend- j ed the prescriptive requirements to include a basic j!► v wind speed of 130 mph, but limits the veneer wall ,. �` area per tie that can be anchored with veneer ties to 70 percent of that allowed in lower wind speed IOW �' regions. The 2008 edition requires rational de sign approaches in locations where the basic wind � speeds exceed 130 mph. a Some noteworthy distinctions exist in the require- ments for anchored brick veneer between the 2005 Figure 4.This tie remained embedded in the mortar and the 2008 editions of TMS 402. For lower wind joint while the smooth-shank nail pulled out from the speed regions (110 mph and below), TMS 402-05 stud.L limited the vertical spacing of ties to 18 inches; the 2008 edition allows vertical ties to be spaced up to 25 inches, provided the wall area of veneer an- chored per tie does not exceed 2.67 square feet. A In TMS's high-wind regions (over 110 mph and up to 130 mph), both editions of the code limit verti- ,4 cal spacing to 18 inches. TMS 402-08 also limits L LoiN v ,) the space between veneer anchored with corrugat- 0 ed ties and the wall sheathing to 1 inch. This is to N; 1 avoid compression failures in the corrugated ties when they are exposed to positive pressures. i The following Brick Industry Association (BIA) t 1 ", Technical Notes provide guidance on brick ve- C :I neer: Technical Notes 28 — Anchored Brick Veneer, Wood Frame Construction; Technical w , •' Notes 28B — Brick Veneer/Steel Stud Walls; H v, n and Technical Notes 44B — Wall Ties. Although Cl) 1 these Technical Notes provide attachment rec- cn ommendations,the recommendations are inade quate because they are not specific for high-wind Q Figure 5.These four ties were never embedded into regions. the mortar joint. 5.4:ATTACHMENT OF BRICK VENEER IN HIGH WIND REGIONS 2 of 5 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12 I Construction Guidance The brick veneer wall system is complex in its be- havior. There are limited test data on which to drew. The following guidance is based on professional judg- ment, wind loads specified in ASCE 7-10, Minimum Design Loads for Buildings and Other Structures, fastener strengths specified in the American Forest and Paper Association's (AF&PA's) National Design Specification (NDS) for Wood Construction, and brick veneer standards contained in TMS 402-08. In ad- dition to the general guidance given in BIA Technical Notes 28 and 28B, the following guidelines are 41111, recommended: L 4 Tie Spacing: The ability for Brick Ties and Tie Fasteners to function properly is highly dependent on horizontal and vertical spacing of ties. Horizontal Figure 6.This tie was embedded in the mortar,but the spacing of ties will often coincide with stud spacing bond was poor. of either 16-inch or 24-inch on center (see Table 1) because tie fasteners are required to be installed directly into framing. Spacing of ties horizontally and vertically must not exceed a) spacings which should be used in areas within 3,000 feet of the will overload the tie or tie fastener based on a tribu- coast. tary area of wind pressure on the brick veneer, or Note: In areas that are also susceptible to high b) prescriptive limits on spacing of ties. More in seismic loads, brick veneer should be evaluated by formation on horizontal and vertical tie spacing is an engineer to ensure that it can resist seismic and available in Table 1. wind design loads. Tie Fasteners: 8d (0.131" diameter) ring-shank nails are recommended instead of smooth-shank nails. A minimum embedment of 2 inches into framing is suggested. Ties: For use with wood studs, two-piece adjustable Sustainability ties are recommended. However, where corrugated Brick veneer can offer a very long service life, steel ties are used, use 22-gauge minimum, 7/8 by provided the ties are not weakened by corro- 6 inches, complying with American Society for Test- sion. To help ensure that brick veneer achieves ing and Materials (ASTM) A 366 with a zinc coating its long life potential, in addition to properly de- complying with ASTM A 153 Class 82. For ties for signing and installing the ties, stainless steel use with steel studs, see BIA Technical Notes 28B— ties are recommended. Brick Veneer/Steel Stud Walls. Stainless steel ties Housewrap or Building Paper p b . 0 0 r . 0 )i/ Wood Sheathing Air Space / Poor A Installation I preI wig _Ad, I- laBase and Eye and r Vee Anchor Pintle Anchor m Figure Z Misalignment of the tie reduces the embedment and promotes veneer Figure 8.Examples of two- failure. piece adjustable ties. (I) 5.4:ATTACHMENT OF BRICK VENEER IN HIGH WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 5 12/10 Tie Installation Install ties as the brick is laid so that the ties are properly aligned with the brick coursing. C Alternatively, instead of installing ties as the brick is laid, measure the locations of the brick • coursing, snap chalk lines, and install ties so 1" maximum for corrugated in / that they are properly aligned with the coursing, ties(per ACI 530-08) I' and then install the brick. Air Good Space Install brick ties spaced based on the appropri- Installation I� ate wind speed and stud spacing shown in Table 1. In areas where the 2006 Edition of the IBC or 90° IRC are adopted, install brick veneer ties as not- II IP, ed in Table 1 but with a maximum vertical spac- a d ing of no more than 18 inches to satisfy the re- 8d common ring-shank nail 111, quirements of TMS 402-05. (0.131"diameterx2.5"length) Locate ties within 8 inches of door and window Figure 9.Bend ties at nail heads. openings and within 12 inches of the top of ve- neer sections. C Bend the ties at a 90-degree angle at the nail o head in order to minimize tie flexing when the p' - u' ties are loaded in tension or compression (Figure 1" maximum for corrugated inI� 9). ties(per ACI 530-08) I� Embed ties in joints so that mortar completely Good Air encapsulates the ties. Embed a minimum of 1 Installation Space 1/2 inches into the bed joint, with a minimum 5/8" 11/2" Al mortar cover of 5/8 inch to the outside face of Minimum Minimum the wall (Figure 10). • !I�, o ,1 Figure 10.Tie embedment. U) 2 W >- - U) U) J J 5.4: ATTACHMENT OF BRICK VENEER IN HIGH WIND REGIONS 4 of 5 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12'10 Table 1. Brick Veneer Tie Spacing Wind Speed$rnph) Maximum Vertical Spacing for Ties(inches) 3—Second Peak Gust Wind Pressure (psf) ( ) 16" stud spacing 24" stud spacing 90 —19.5 24a� -- --- 16, -- 100 —24.1 24a,b 16a 110 —29.1 201/2 b 131/2 120 —34.7 17 NAc 130 —40.7 15 NAc 140 —47.2 13 NAc 150 —54.2 11 NAc Notes: 1. The tie spacing is based on wind loads derived from Method 1 of ASCE 7-05,for the corner area of buildings up to 30'high,located in Exposure B with an importance factor(I)of 1.0 and no topographic influence.For other heights,exposures,or importance factors,engi- neered designs are recommended. 2. Spacing is for 21/2"long 8d common(0.131"diameter)ring-shank fasteners embedded 2"into framing.Fastener strength is for wall fram- ing with a Specific Gravity G=0.55 with moisture contents less than 19 percent and the following adjustment factors,C,=0.8;and Co,CM, Ceg,and Cth=1.0. Factored withdrawal strength W'=65.6#. 3. The brick veneer tie spacing table is based on fastener loads only and does not take into account the adequacy of wall framing,sheath- ing,and other building elements to resist wind pressures and control deflections from a high-wind event.Prior to repairing damaged brick veneer,the adequacy of wall framing,wall sheathing,and connections should be verified by an engineer. a Maximum spacing allowed by ACI 530-08. b In locales that have adopted the 2006 IBC/IRC,the maximum vertical spacing allowed by ACI 530-05 is 18". c 24"stud spacing exceeds the maximum horizontal tie spacing of ACI 530-08 prescribed for wind speeds over 110 mph. Additional Resources Brick Industry Association (BIA). (http://www.gobrick.com) Technical Notes 28—Anchored Brick Veneer, Wood Frame Construction Technical Notes 28B — Brick Veneer/Steel Stud Walls Technical Notes 44B —Wall Ties cn cn r r m NAHB RESEARCH cn Developed in association with the National Association of Home Builders Research Center CENTER 5.4:ATTACHMENT OF BRICK VENEER IN HIGH WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 5 12 10 Window and Door Installation HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 6.1 Purpose: To provide flashing detail concepts for window and door openings that: give adequate resistance to water intrusion in Section 1.5 states that if the manufacturer's in- 0 coastal environs, structions conflict with E 2112, the manufacturer's -o instructions shall prevail. However, because a z_ do not depend solely on sealants, manufacturer's instructions may be inferior to the z are integral with secondary weather barriers guidance provided in the standard, any conflict be- tween the manufacturer's requirements and the (i.e., housewrap or building paper — see Fact standard or contract documents should be dis- Sheet No. 5.1), and cussed among and resolved by the manufacturer, designer, and builder. are adequately attached to the wall. Specific Considerations Pan flashings: Windows that do not have nailing Key Issues flanges, and doors, are typically installed over a pan Water intrusion around window and door openings flashing(see Figure 1). Section 5.16 of ASTM E 2112 can cause dry rot and fastener corrosion that weaken discusses pan flashings and refers to Annex 3 for the window or door frame or the wall itself, and lead minimum heights of the end dam and rear leg. Annex to water damage to interior finishes,mold growth,and 3 shows a maximum end dam height of 2 inches, preventable building damage during coastal storms. which is too low for areas prone to very high winds Proper flashing sequence must be coordinated (i.e., wind speed greater than 110 mph). Where the across responsibilities sometimes divided between wind speed is greater than 110 mph, the end dam two or more trade activities(e.g.,weather barrier,win- should be 3 to 4 inches high (the higher the wind dow, and siding installation). speed,the higher the dam). (Note: Annex 3 says that "high rain and wind are usually not simultaneous." To combat wind-driven rain penetration and high However,this statement is untrue for coastal storms, wind pressures, window and door frames must be in which extremely high amounts of rain often accom- adequately attached to walls and they must be ad- pany very high winds.) equately integrated with the wall's moisture barrier system (see Fact Sheet No. 1.9). ASTM E 2112 End dam Rear leg Detailed information about window and door instal- lation is provided in the American Society for Testing and Materials (ASTM) standard ASTM E 2112, a comprehensive installation guide intended for use in training instructors who in turn train the mechanics who actually perform window and door installation. The standard concentrates on detailing and installa- tion procedures that are aimed at minimizing water infiltration. Front End dam The standard includes a variety of window and door details. The designer should select the details deemed appropriate and modify them if necessary to meet local weather conditions, and the installer should execute the selected details as specified in Figure 1. Pan Flashing the standard or as modified by the designer. Oft��EL FEMA6.1:WINDOW AND DOOR INSTALLATION HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 44ND St 12/10 Although not discussed in ASTM E 2112, for in- Window frame stallations that require an exposed sealant joint, installation of a removable stop (see Figure 2) is recommended to protect the sealant from direcj ex- posure to the weather and reduce the wind-driven0,-Backer rod Glazing rain demand on the sealant. Sealant Exterior Insulation Finishing Systems (EIFS): Although ialli not discussed in ASTM E 2112, when a window or door assembly is installed in an EIFS wall assembly, Air space behind stop sealant between the window or door frame and the EIFS should be applied to the EIFS base coat. After sealant application,the top coat is then applied. (The Removable stop v) top coat is somewhat porous; if sealant is applied to Wall C7 it,water can migrate between the top and base coats — and escape past the sealant.) - Z Figure 2. Protection of sealant with a stop. w Frame anchoring:Window and door frames should be 0 anchored to the wall with the type and number of fas- teners specified by the designer. Shutters: If shutters are installed,they should be an- . —IIIN— chored to the wall, rather than the window or door : frame (see Figure 3). "ff.' f, Weatherstripping: E 2112 does not address door - I. weatherstripping. However, weatherstripping is nec if ;.• essary to avoid wind-driven rain penetration. A variety of weatherstripping products are available as shown ' f ;%r ------___ ' 1; in Figures 4 through 9. - Drip Figure 3. Hurricane Georges in Puerto Rico. The window lying on the ground was protected by a shutter.However,the shutter was attached to the window frame.The window frame fasteners were over-stressed and the entire assembly failed.Attach- ment of the shutter directly to the wall framing is a more reliable method of attachment. Door ----A--- Figure 5. Door shoe with drip and vinyl seal. Drip Door with Door hook MEW Figure 4. Drip at door head and drip with hook at head 6.1: WINDOW AND DOOR INSTALLATION 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Door Door O (-------.' Door/ I Adjustable m jamb Z Z weatherstrip 17 Neoprene A Neoprene Figure 6. Neoprene Figure Z Automatic Figure 8. Adjustable jamb/head weatherstripping. door bottom sweep. door bottom. Note:Set the threshold in butyl sealant.If a drain pan exists underneath the threshold,weep holes must not be blocked with sealant or debris. Door Door -s a Drip Neoprene seal 4 .. El"" --- D Sweep Etillitaill Weep Weep Pan Figure 9. Threshold Additional Resources American Society for Testing and Materials.ASTM E 2112,Standard Practice for Installation of Exterior Windows, Doors and Skylights. (www.astm.org) NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 6.1:WINDOW AND DOOR INSTALLATION HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12 10 Protection of Openings— Shutters and Glazing HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 6.2 Purpose: To provide general information about the selection and installation of storm shutters and impact-resistant glazing and other types of opening protection in windborne debris regions. 0 Opening Requirements in Codes and Standards z What Are "Hurricane-Prone Regions" and "Windborne Debris Regions"? 0 According to the 2009 International Building Code (IBC) and the 2009 International Residential Code (IRC), hurricane-prone regions are areas vulnerable to hurricanes such as: 1. The U.S. Atlantic Ocean and Gulf of Mexico coasts where the basic wind speed is greater than 90 mphl (40 m/s). • ' 2. Hawaii, Puerto Rico, Guam, the U.S. Virgin Is- ` lands, and American Samoa. 411 Wind-borne debris regions are defined as areas with- in portions of hurricane-prone regions located within 1 mile (1.61 km) of the coastal mean high water line where the basic wind speed is 110 mph (48 m/s)1 or Figure 1. Wood structural panels installed in accor- greater; or portions of hurricane-prone regions where dance with building code requirements are a cost- the basic wind speed is 120 mph (53 m/s)1 or great- effective means of protection,but they should be ad- er; or Hawaii. equately attached so they themselves do not become Sections 1609.1.2 and R301.2.1.2,of the 2009 edi windborne debris. tions of the IBC and IRC, respectively, address the Protection of Openings. These sections state that IRC, wood structural panels are permitted for build- in wind-borne debris regions, glazing in buildings ings with a mean roof height of 33 feet(10,058 mm) shall be impact resistant or protected with an im- 2 pact-resistant covering that meets the requirements or less where wind speeds do not exceed 130 mph of an approved impact-resistant standard or the (58 m/s). Figure 1 shows a house utilizing wood American Society of Testing and Materials (ASTM) structural panels to provide opening protection. standards ASTM E 1996 and ASTM E 1886. Wood ASCE/SEI 7-05 also discusses the protection of structural panels could be used as an alternative to glazed openings in Section 6.5.9.3. The section provide protection so long as they meet local build- states, "Glazing in buildings located in wind-borne ing code requirements. Panel attachment should be debris regions shall be protected with an impact- in accordance with Table 1609.1.2 (IBC) and Table protective system or be impact-resistant glazing R301.2.1.2 (IRC) and installed using corrosion-resis- according to the requirements specified in ASTM tant attachment hardware and anchors permanently E1886 and ASTM E1996 or other approved test installed on the building. Under provisions of the IBC, methods and performance criteria. The levels of im- wood structural panels are permitted for Group R-3 pact resistance shall be a function of Missile Levels and R-4 buildings with a mean roof height of 45 feet and Wind Zones specified in ASTM E 1886 and ASTM (13,716 mm) or less where wind speeds do not ex- E 1996". Exceptions to this are noted in Section ceed 140 mph (63 m/s). Under provisions of the 6.5.9.3. 1 ASCE 7-05 wind speed—in order to recalculate this for ASCE 7-10 divide the ASCE 7-05 wind speed by 0.6°5 I 6.2: PROTECTION OF OPENINGS- SHUTTERS AND GLAZING ";-. FEMA HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 6 FIND sy, 12/10 Anchorage Note: When glazing protection is provided by Window and door assemblies must be strong enough shutters, screens, or other panel systems, the to withstand wind pressures acting on them and be glazing and glazing frame should be designed fastened securely enough to transfer those wind and constructed to resist the full design loads pressures to the adjacent wall. Pressure failures of (i.e., do not assume that the shutter will be de- doors or windows can allow glazing to fracture or glaz- creasing the wind pressure on the glazing). Also ing frames or supports to fail. Anchorage failures can note that it should be assumed that the shutter allow entire door or window units to be ripped from will not significantly decrease the wind-driven rain the walls. Either type of failure results in the failure demand on the glazed assembly. of the building envelope and allows wind and water to enter the building. t" Shutters Where Are Storm Shutters Required and o z Recommended? Z Why Are Storm Shutters Needed? Model building codes, which incorporate wind provi- a if glazing is not resistant to windborne debris, then sions from ASCE 7 (1998 edition and later), require 0 shutters are an important part of a hurricane-resis- that buildings within the windborne debris region(see tant home. They provide protection for glass doors Figure 5 of this fact sheet), either (1) be equipped and windows against windborne debris, which is with shutters or impact-resistant glazing and de- often present in hurricanes. Keeping the building en- signed as enclosed structures or(2) be designed as velope intact (i.e., no window or door breakage) is partially enclosed structures (as if the windows and vital to the integrity of a home. If the envelope is doors are broken out). However it should be noted breached, sudden pressurization of the interior may that the alternative to design a Risk Category II build- result in major structural or non-structural damage ing (defined in ASCE 7-10) as a partially enclosed (e.g., roof loss) and will lead to significant interior structure was removed from ASCE 7-10 and it now and contents damage from wind-driven rain. The ad- requires that all Risk Category II structures in the dition of shutters will not eliminate the potential for wind-borne debris region be designed to be enclosed wind-driven rain entering the building,but will improve structures with impact-resistant glazing or equipped the building's resistance to it. with a shutter system. It is also recommended to give strong consideration to the use of opening protection in all hurricane-prone I areas where the basic wind speed is 100 mph (3-second gust speed)or great- er, even though the IBC and IRC building codes do not require it. Designers should check with the jurisdiction to determine whether state or local requirements for opening protection exceed those of the model code. WARNING: A shutter AImay look like it is ca- pable of withstanding windborne missiles; un- less it is tested, however, its missile resistance is unknown. Figure 2. Metal panel shutter.The shutter is installed in a track per- manently mounted above and below the window frame.The shutter is placed in the track and secured with wing nuts to studs mounted on the track.This type of shutter is effective and quickly installed. and the wing nut and stud system provides a secure anchoring method.Track designs that have permanently mounted studs for the nuts have been shown to be more reliable than track designs using studs that slide into the track. 6.2: PROTECTION OF OPENINGS- SHUTTERS AND GLAZING HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION r What Types of Shutters Are Available? A wide variety of shutter types are available, from the very expensive motor-driven, roll-up type, to the less expensive temporary wood structural panels. Note: Many coastal homes have large and un- Designers can refer to Miami-Dade County, Florida, usually shaped windows, which will require which has established a product approval mecha- expensive, custom shutters. Alternatively, such nism for shutters and other building materials to windows can be fabricated with laminated (im- ensure they are rated for particular wind and wind- pact-resistant) glass. borne debris loads (see the "Additional Resources" section). Figures 3 and 4 illustrate some of the shut- ter styles available. Shutter Styles Shutter styles include colonial, Bahama, roll-up, and accordion. z z C Bahama shutter rn -00010/1. mimmis anommi monimi == * —_ Colonial shutters • �, — I 4 0 . 1 1 .. 1 . _,Ii_i__________ ______...,....____ ..... ....:: Roll-up shutter / Accordion shutter Figure 3. Colonial shutters,Bahama style shutters.Roll-up style shutters,and Accordion style shutters. , 6.2: PROTECTION OF OPENINGS— SHUTTERS AND GLAZING HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION i I *For a latch bolt option of mpsonry walls see the APA guidance. Stud framed Masonry wall Stud framed wall system system wall system Finish wall III Finish wall Finish wall �� 2"x4" trim Aluminum 2"x4" trim channel 1"x1"x1"x 1n Attach plywood 16d-3i" ; l 16d double a sections to nails headed f;tno stiffeners with 3i" nails 1, ` 12" minimum 16d nails 6" o.c. No. 10 screw (typical) 15/32" plywood rn minimum Ledger 0 Z 2"x4"vertical 15/32" plywood 15/32" plywood z minimum minimum W stiffeners Window glazing Window glazing -� O Window glazing 2"x4"vertical iPanel 2"x4" vertical stiffeners strength stiffeners Note: adjust stiffeners axis as necessary. Use (typical) No. 2 2"x4"at 16" o.c. Caulk or No. 2 2"x6" Window sill — at 16" o.c. Window sill Window sill 111 13-" minimum 1i" minimum Mark all shutter �'�.1M 4„ I sections for 3" BM location and T No. 10 screw 4" Lag screw must be long orientation (typical) e " plywood enough to penetrate veneer trim and into window framing Siding at 6" o.c. / 4" x 1" screw in anch. Wood shim (4" x 1 1/2" for stucco) (shutter Brick veneer thickness at 6" (4")o.c. plus8") Wood Stud Wall Masonry Wall Wood Stud with Brick Veneer See APA Guidance for additional details and nail specifications. Only for use on residential structures with a mean roof height of 45 feet or less. Figure 4.Common methods for plywood shutter attachment to wood-frame and masonry walls. (For actual shutter design,refer to design drawings or see the APA,Engineered Wood Association guidelines for constructing plywood shutters.) Shutter Type Cost Advantages Shutter Type Advantages Disadvantages Wood structural Must be installed and taken down every time they are needed; Low Inexpensive must be adequately anchored to prevent blow-off;difficult to panels install on upper levels;storage space is needed. Metal or Low/ Easily installed on Must be installed and taken down every time they are needed; polycarbonate panels Medium lower levels difficult to install on upper levels;storage space is needed. Accordion,manual Medium/ Always in place; Always in place;ready to be closed. Must be closed manually closing High ready to be closed from the outside;difficult to access on upper levels. Easily opened and Expensive. Permanent,motor- High closed from the (It is important to find a motorized shutter that allows the shutter driven inside to be manually raised in order to allow the interior to vent following the storm and prior to electrical power restoration.) 6.2: PROTECTION OF OPENINGS— SHUTTERS AND GLAZING HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Are There Special Requirements for Shutters in Coastal Areas? When installing any type of shutter, follow the manufacturer's instructions and guidelines carefully. Be sure to attach the shutters to structurally adequate framing members (see shutter details in Figures 3 and 4 of this fact sheet). Avoid attaching the shutters to the wihdow frame or brick veneer face. Always use hardware that is corrosive-resistant when installing shutters. Figure 5 is the ASCE 7-05 basic wind map for the East Coast of the United States.See page 1 of this fact sheet for the delineation of the areas where opening protection is required. WARNING:According to the International Window Film Association, "It should be noted that the testing of commercial windows does not imply performance of residential windows." While post-manufacture ap- 0 plied window film may provide more protection than unprotected 90(40) windows, in residential applications it is no substitute for shut- m 100(45) Z ters or impact-resistant glass. Z0 rn ie,,, Hurricane-prone regions ' v49) " 1 '120(54) - Shutters orimpact-resistant glazing recommended - Windborne debris regionsF shutters or impact-resistant glazing required --�`. k mph (m/s) 3-second peak gust wind speed ,..Alt 1 130(58) 140(63) 1 i 90(40) 1p0(45) I law 8) { 140~ �► ` 7S0/6�/ 74% 131450( 3) ( 3) 150(67) t nLn o`o N M Figure 5. An illustration of the ASCE 7-05 wind speed contours and windborne debris region.See ASCE 7-05 Figure 6-1 for wind load design. i 6.2: PROTECTION OF OPENINGS— SHUTTERS AND GLAZING HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 6 1 12'lO Windborne debris resistant glazing Additional Resources Laminated glazing systems typically consist of as- American Society of Civil Engineers. Minimum Design semblies fabricated with two(or more)panes of glass Loads for Buildings and Other Structures, ASCE/SEI and an interlayer of a polyvinyl butyral (or equivalent) 7-10. (http://www.asce.org) film laminated into a glazing assembly. During impact The Engineered Wood Association (APA). Hurricane testing, the laminated glass in the system can frac Shutter Designs Set 5 of 5. Hurricane shutter designs ture but the interlayer must remain intact to prevent water and wind from entering the building. These sys for woodframe and masonry buildings. (http://www. tems may also increase the energy efficiency of the apawood.org) building over standard glazing. International Code Council. International Building Code. 2009. (http://www.iccsafe.org) cn Polycarbonate systems typically consist of plastic International Code Council. International Residential resins that are molded into sheets, which provide Code. 2009. (http://www.iccsafe.org) Z lightweight, clear glazing panels with high impact-re- Information about product testing and approval pro- Z sistance qualities. The strength of the polycarbonate cess for Miami-Dade County, Florida, available at d sheets is much higher than non-laminated glass (i.e., http://www.miamidade.gov/buildingcode/product- 0 more than 200 times stronger) or acrylic sheets or control.asp panels (i.e., more than 30 times stronger). American Society for Testing and Materials: Garage Doors ASTM E1886, Performance of Exterior Windows, Garage doors many times represent large unre Curtain Walls,Doors,and Storm Shutters Impacted inforced openings. They are commonly damaged by Missile(s) and Exposed to Cyclic Pressure Differentials during high-wind events and could allow a building to be pressurized if they are breached. A garage door ASTM E1996, Standard Specification for should meet the design wind speed requirements for Performance of Exterior Windows, Curtain Walls, the area or be retrofitted to withstand the design wind Doors and Impact Protective Systems Impacted speed. However, the viability of a retrofit depends on by Windborne Debris in Hurricane the style and age of the door, and may not provide ASTM E2112,Standard Practice for Installation of the same level of protection as a new door system. Exterior Windows, Doors and Skylights The 2009 editions of IBC and IRC both comment on ASTM E33O, Structural Performance of Exterior the glazing in garage doors in sections 1609.1.2.2 Windows, Doors, Skylights and Curtain Walls by and R301.2.1.2, respectively. Any glazed opening Uniform Static Air Pressure Difference. htt protection on garage doors for wind-borne debris ( p// www•astm.org) shall meet the requirements of an approved impact resisting standard or ANSI/DASMA 115-2005. Door and Access Systems Manufacturers Association: DASMA 108, Standard Method for Testing While some manufacturers provide wind speed and Sectional Garage Doors: Determination of exposure ratings for their products, labels on many Structural Performance Under Uniform Static Air garage doors do not include wind speed or wind Pressure Difference pressure ratings. While not required to be included on the product labeling, ANSI/DASMA 108 does require that the positive and negative pressure used in testing be recorded on the ANSI/DASMA 108 Test Report Form. If the label attached to the door does not indicate the positive and negative pressure rating, consult the Test Report Form to verify it is an appropriate garage door for the area. NAHBI RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 6.2: PROTECTION OF OPENINGS- SHUTTERS AND GLAZING 6 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1210 Roof Sheathing Installation HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 7.1 Purpose: To provide information about proper roof sheathing installation, emphasize its importance in coastal construction, and illustrate fastening methods that will enhance the durability of a building in a high-wind area. Key Issues �, Insufficient fastening can lead to total building failure in - !� ''' a windstorm. Sheathing loss is one of the most common � _. „�� %, , , ` `�1 structural failures in hurricanes. ,Ii1/4I ,'\1�� ,‘ i\\` Fasteners spacing and size — per "'\ 1I\ API' l014\ 4N requirements for coastal \ \�� I\'�I��CI i � �4 construction are typically 1 \�� O��C �i,�� different than for non-coastal areas. \—, � \� - The highest uplift forces occur at roof ��` ��\;11 \ corners, edges, and ridge lines. `\\`` \ Improved fasteners such as ring shank nails \`\N Typical layout of roof increase the uplift resistance of the roof sheathing panelson sheathing. gable-end roof Most critical area for connec- Sheathing Type lion of sheathing panels Typically, 15/32-inch or thicker panels are required in high- / i wind areas. Oriented Strand Board (OSB) or plywood can be . Ii�� used,although plywood will provide higher nail head pull- through resistance. Use panels rated as "Exposure " �'" 1" or better. �� I ' 4� >✓" Sheathing Layout \ �`�� , � . Install sheathingpanels according / 1. - P g `` to the recommendations of the ` \ \ Engineered Wood Association (APA). - • / , �\' , Use panels no smaller than 4 feet '� long. Blocking of unsupported edges may o be required near gables, ridges, and eaves (follow design drawings). Unless otherwise indi \\� Typical layout of roof cated by the panel manufacturer, leave a 1/8-inch gap sheathing panels on hip (about the width of a 16d common nail) between panel roof edges to allow for expansion. (Structural sheathing is typically cut slightly short of 48 inches by 96 inches to allow for this expansion gap - look for a label that says "Sized for Spacing.") This gap prevents buckling of panels due to moisture and thermal effects, a common problem. Fastener Selection An 8d nail (2.5 inches long) is the minimum size nail to use for fastening sheathing panels. Full round heads are recommended to avoid head pull-through. Deformed-shank (i.e., ring- or screw-shank) nails are required near ridges, gables, and eaves in areas with design wind speeds over 110 mph (3-second gust), but it is rec- ommended that deformed shank nails be used throughout the entire roof. If 8d "common" nails are specified, the nail diameter must be at least 0.131 inch (wider than typical 8d pneumatic nails). Screws can be used for OF'eART44 i 7.1: ROOF SHEATHING INSTALLATION %\Cr; FEMA HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 44ND SEC 12,10 1 even greater withdrawal strength, but should be sized by the building designer. Staples are not recommended for roof sheathing attachment in high-wind areas. Fastener Spacing It is extremely Important to have proper fastener spacing on all panels. Loss of just one panel in a windstorm can lead to total building failure. Drawings should be checked to verify the required spacing; closer spacing may be required at corners, edges, and ridges. Visually inspect work after installation to ensure that fasten- ers have hit the framing members. Tighter fastener spacing schedules can be expected for homes built in high-wind areas. Installing fasteners at less than 3 inches on center can split framing members and signifi- cantly reduce fastener withdrawal capacity, unless 3-inch nominal framing is used and the nailing schedule is staggered. Ridge Vents When the roof sheathing is used as a structural diaphragm, as it typically is in high-wind and seismic hazard areas,the structural integrity of the diaphragm can be compromised by a continuous vent(see figure A., below left). Maintain ridge nailing by adding additional blocking set back from the ridge, or by using vent holes (see figure B., below right). Verify construction with a design professional. Nails from sheathing "£;= Sheathing vent holes on each . O;'O" to ridge board �' side of ridge board;note—holes O O- i z ;;•;� should not remove �, =p '1-- ` more than half of the O O ' `` 0 =�,' 1 sheathing O ,; " „l� ' section „sP fZ Roof` �Z Roof sheathing sheathing \ Ridge Ridge board board Joist or truss Joist or truss NOTE:If roof sheathing is cut and removed to achieve an air slot,continuity and diaphragm action are affected. A. Method for maintaining a continuous load path at B. Holes drilled in roof sheathing for ventilation— the roof ridge by nailing roof sheathing. roof diaphragm action is maintained. (For clarity,sheathing nails are not shown.) Ladder framing Critical nailing(4" on center maximum) Ladder Framing at Gable Ends } Use extra care when attaching a ladder-framed exten- sion to a gable end. Many homes have been severely damaged by coastal storms because of inadequate I_ / connections between the roof sheathing and the Rafters gable truss. The critical fasteners occur at the ga- 8" overhang or trusses ble-framing member, not necessarily at the edge of (recommended the sheathing. Nailing accuracy is crucial along this maximum in member. Tighter nail spacing is recommended (4 high-wind inches on center maximum). areas) t --..- Ladder framing at gable ends. 7.1: ROOF SHEATHING INSTALLATION 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1210 } Common Sheathing Attachment Mistakes Common mistakes include using the wrong size fasteners, missing the framing members when installing fas- teners, overdriving nails, and using too many or too few fasteners. i ```` k • • 4 1 .` A Missing fasteners z 4411thwr . , , . 444% , Excessive number , of fasteners Wrong size Nails missing the nails framing member Overdriven nails 4Irr Excessive space between t7t7 fasteners(not enough fasteners) Additional Resources Engineered Wood Association (APA), (www.apawood.org) NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 7.1: ROOF SHEATHING INSTALLATION HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 I 12 10 Roof for Asphalt Shingle Roo s HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 7.2 Purpose: To provide recommended practices for use of roofing underlayment as an enhanced secondary water barrier in coastal environments. Note:The underlayment options illustrated here are for asphalt shingle roofs. See FEMA publication 55, Coastal Construction Manual,for guidance concerning underlayment for other types of roofs. Key Issues Note:This fact sheet provides general guidelines Verifying proper attachment of roof sheathing be- and recommended enhancements for improving fore installing underlayment. upon typical practice. It is advisable to consult Lapping and fastening of underlayment and roof local building requirements for type and instal- edge flashing. lation of underlayment, particularly if specific 70 Selecting underlayment material type. enhanced underlayment practices are required 00 locally. -n Sheathing Installation Options The following three options are listed in order of decreasing resistance to long-term weather exposure following the loss of the roof covering. Option 1 provides the greatest reliability for long-term exposure; it is advocated in heavily populated areas where the design wind speed is equal to or greater than 120 mph (3-second peak gust).1 Option 3 provides limited protection and is advocated only in areas with a modest population density and a de- sign wind speed less than or equal to 110 mph (3-second peak gust).1 Installation Sequence — Option 12 (for moderate climates) 1. Before the roof covering is installed, have the deck inspected to verify that it is nailed as specified on the drawings. 2. Broom clean deck before installing self-adhering modified bitumen prod- One layer of self- ucts. If the sheathing is OSB, check ashering modified 4'x 8'roof sheathing with the OSB manufacturer to deter- bitumen complying mine if a primer needs to be applied with ASTM D 1970 before installing these products. (see step 3) r 3. In Southern Climates, apply a sin- gle layer of self-adhering modified Metal bitumen complying with ASTM D drip 1970 throughout the roof area. edge 4. Seal the self-adhering sheet to the deck penetrations with roof tape or 440 asphalt roof cement. ,� Southern Climate Tack underlayment(not shown) 1 The 110 and 120 mph speeds are based on ASCE Fascia to hold in place before installing Metal drip 7-05. If ASCE 7-10 is being used, the equiva- shingles(see step 5) edge lent wind speeds are 139 and 152 mph for Risk Category II buildings. aF'eN��FH i 7.2: ROOF UNDERLAYMENT FOR ASPHALT SHINGLE ROOFS FEMA� HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 AND SE 12/10 5. Apply a single layer of ASTM D 226 Type I (#15) or ASTM D 4869 Type II felt. Tack underlayment to hold in place before installing shingles. 6. In northern climates, after step 2, install self-adhering modified bitumen tape (4 inches wide, minimum) over sheathing joints; seal around deck penetrations with roof tape. Roll tape with roller. 7. Apply a single layer of ASTM D 226 Type II (#30) or ASTM D 4869 Type IV felt. Attach per steps 8 and 9. Then install a single layer of self-adhering modified bitumen per steps 3 and 4,followed by installation of the shingles. 8. Secure felt with low-profile, capped-head nails or thin metal disks ("tincaps") attached with roofing nails. 9. Fasten at approximately 6 inches on center along the laps and at approximately 12 inches on center along two rows in the field of the sheet between the side laps. Installation Sequence — Option 22 Two layers of ASTM 1. Before the roof covering is installed, D 226 Type II (#30) _ have the deck inspected to verify or ASTM D 4869 4'x 8'roof sheathing that it is nailed as specified on the Type IV felt,with drawings. offset sidelaps (see step 4) Ar 2. Broom clean deck before taping. If / Low-profile,capped-head the sheathing is OSB,check with the i nails or metal disks("tinca•�' OSB manufacturer to determine if a j (see step 5) Metal /I primer needs to be applied before r �f—.� z installingself-adhering modified bi drip / 12"on center 6"on center4 , 4 z g edge 'i x.. • O tumen products. I� _ ;� O 3. Install self-adhering modified bitu �'o o = _ . 4 i men tape (4 inches wide, minimum) over sheathing joints; seal around o GINIIIMI deck penetrations with roof tape. Rolf tape with roller. 4. Apply two layers of ASTM D 226 Fascia Center row of nails Metal drip Type II (#30) or ASTM D 4869 Type equidistant from edge rows edge IV felt with offset side laps. 5. Secure felt with low-profile, capped-head nails or thin metal disks ("tincaps") attached with roofing nails. 6. Fasten at approximately 6 inches on center along the laps and at approximately 12 inches on center along a row in the field of the sheet between the side laps. Installation Sequence—Option 32,3 One layer ASTM 1. Before the roof covering is installed, D 226 Type I (#15) 4'x 8'roof sheathing have the deck inspected to verify or ASTM D 4869 that it is nailed as specified on the Type II felt drawings. (see step 4) 2 Broom clean deck before taping. If the sheathing is OSB,check with the Ai: ,:,;z Metal drip 2 If the building is within 3,000 feet of saltwater, edge stainless steel or hot-dip galvanized fasteners are recommended for the underlayment attachment. 3 (1) If the roof slope is less than 4:12, tape and / '''. ,.,. seal the deck at penetrations and follow the rec- ommendations given in The NRCA Roofing and Ali Waterproofing Manual, by the National Roofing Contractors Association.(2)With this option,the un- derlayment has limited blow-off resistance. Water infiltration resistance is provided by the taped and sealed sheathing panels.This option is intended for Tack underlayment to hold in use where temporary or permanent repairs are likely Fascia place before installing shingles Metal drip to be made within several days after the roof cover- (see step 5) edge ing is blown off. 7.2: ROOF UNDERLAYMENT FOR ASPHALT SHINGLE ROOFS 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 OSB manufacturer to determine if a primer needs to be applied before installing self-adhering modified bi- tumen products. 3. Install self-adhering modified bitumen tape (4 inches wide, minimum) over sheathing joints; seal around deck penetrations with roof tape. Roll tape with roller. 4. Apply a single layer of ASTM D 226 Type I (#15) or ASTM D 4869 Type II felt. 5. Tack underlayment to hold in place before applying shingles. General Notes Weave underlayment across valleys. Double-lap underlayment across ridges (unless there is a continuous ridge vent). Lap underlayment with minimum 6-inch leg "turned up" at wall intersections; lap wall weather barrier over turned-up roof underlayment. Additional Resources National Roofing Contractors Association (NRCA). The NRCA Roofing and Waterproofing Manual. (www.NRCA.net) ASTM Standard D6135, 2005, "Standard Practice for Application of Self-Adhering Modified Bituminous Waterproofing," ASTM International, West Conshohocken, PA, 2005, 10.1520/D6135-05,www.astm.org. NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 7.2: ROOF UNDERLAYMENT FOR ASPHALT SHINGLE ROOFS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12%10 Asphalt Roofing Shingle High Wind Regions HOME BUILDER'S GUIDE TO COASTAL COR STRUCTION Technical Fact Sheet No. 7.3 Purpose: To recommend practices for installing asphalt roof shingles that will enhance wind resistance in high-wind, coastal regions. Key Issues Special installation methods are recommended for asphalt roof shingles used in high-wind,coastal regions (i.e., greater than 90-mph gust design wind speed). Use wind-resistance ratings to choose among shingles, but do not rely on ratings for performance. Consult local building code for specific installation requirements. Requirements may vary locally. Always use underlayment. See Fact Sheet No. 7.2 for installation techniques in coastal areas. Pay close attention to roof-to-wall flashing and use enhanced flashing techniques (see Fact Sheet No. 5.2). Construction Guidance ._ 1. Follow shingle installation procedures for enhanced wind resistance. 0—..-- Shingle installation at Eaves Six nails per Starter strip-cut tabs from shingles and place starter strip with self-sealing adhesive at eave. Underlayment First course p . cr. Metal Self-sealing . ' , , I. drip edge adhesive -, '_ % adhesive 1"-2.5"(1"is • Overlying shingle Self-sealing f - preferred if framing •` �' (see step 2) Six nails per / - , , -- conditions permit) • shingle located ` ' -- • ' as shown Three 1"dabs of asphalt roof cement ` ' O per tab between starter strip and first course . Qi1 ©DO Fasteners .—(see step 2) Shingle Installation at Hips and Ridges (' Underlying shingle • (see step 1) 1.Apply four 1-inch dabs ` •9c2 Tab of roof cement to field Pre-cut �� 0 . shingle. shingle Repeat steps 2 ` - Note:Shingles (see step 2) through 4 • should overhang 2.Set pre-cut shingle In (see step 5) asphalt roof • drip edge by 1/4" place and press down In �� 1"Dabs of cement at rake and eave. dabs of roof cement (see step 1) Fasteners before installing fasteners. i Shingle Installation at Rakes ' Roof cement 3. Install fastener (see step 4) each side of ridge. 0 1.Apply two 1-inch dabs of asphalt roof on g 0 cement on underlying shingle,and two Note: Because of 0 1-inch dabs on metal drip edge as shown. extra thickness of Field shingles at hips and shingle Fastener 2.Set overlying shingle in place and install ridges,longer nails (see step 3) fasteners except for last fastener at rake. may be needed. 3.Press shingle down to set in dabs of 1"Dabs of asphalt cement before installing final 4.Apply two 1-inch asphalt fastener. dabs of roof cement to roof cement 4. Install final fastener at rake edge. shingle where shown. (see step 1) " 5. Repeat steps 2 through 4. 5. Repeat steps for each course. Enhanced shingle securement ' ` FEmA 7.3:ASPHALT SHINGLE ROOFING FOR HIGH WIND REGIONS •� _ HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 - 4ND stc7 12/10 2. Consider shingle physical properties. Properties Design Wind Speed' >90 to 120 mph Design Wind Speed' >120 mph Fastener Pull-Through2 Resistance Minimum Recommended Minimum Recommended 25 lb at 73 degrees Fahrenheit(F) 30 lb 1. Design wind speed based on 3-second peak gust. 2. ASTM D 3462 specifies a minimum fastener pull-through resistance of 20 lb at 73°F.If a higher resistance is desired,it must be specified. 3. Ensure that the fastening equipment and method results in properly driven roofing nails for maximum blow-off resistance. The minimum required bond strength must be specified (see Wind-Resistance Ratings, below). Shingle Type Standard Characteristics Organic-Reinforced ASTM D 225 Relatively high fastener pull through resistance Considerable variation in fastener pull- Fiberglass-Reinforced ASTM D 3462 through resistance offered by different product SBS Modified Bitumen A standard does not exist for thisproduct. Because of the flexibilityimparted z � P by It is recommended that SBS Modified the SBS polymers,this type of shingle is 0 Bitumen Shingles meet the physical less likely to tear if the tabs are lifted in a Q properties specified in ASTM 3462. windstorm. 0= Fastener Guidelines Use roofing nails that extend through the underside of the roof sheathing, or a minimum of 3/4 inch into planking. Use roofing nails instead of staples. Use stainless steel nails when building within 3,000 feet of saltwater. X X Top Layer of Shingles Remainaing Shingles,- - Underlayment,and Roof Deck "The Good,the bad,and the ugly"—Properly driving roofing nails. Weathering and Durability Durability ratings are relative and are not standardized among manufacturers. However, selecting a shingle with a longer warranty (e.g., 30-year instead of 20-year) should provide greater durability in coastal climates and elsewhere. Organic-reinforced shingles are generally more resistant to tab tear-off but tend to degrade faster in warm cli- mates. Use fiberglass-reinforced shingles in warm coastal climates and consider organic shingles only in cool coastal climates. Modified bitumen shingles may also be considered for improved tear-off resistance of tabs. Organic-reinforced shingles have limited fire resistance —verify compliance with code and avoid using in areas prone to wildfires. 7.3:ASPHALT SHINGLE ROOFING FOR HIGH WIND REGIONS 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 After the shingles have been exposed to sufficient on D 3161 or UL 997 test data, wind resistance of sunshine to activate the sealant, inspect roofing to shingles should be determined in accordance with ensure that the tabs have sealed. Also, shingles UL 2390. Shingles that have been evaluated in ac- should be of "interlocking" type if seal strips are not cordance with UL 2390 have a Class D (90 mph), G present. (120 mph), or H (150 mph) rating. Select shingles that have a class rating equal to or greater than the Wind-Resistance Ratings basic wind speed specified in the building code. If the building is sited in Exposure D, or is greater than Wind resistance determined by test methods ASTM 60 feet tall, or is a Category III or IV, or is sited on D 3161 and UL 997 does not provide adequate infor- an abrupt change in topography (such as an isolated mation regarding the wind performance of shingles, hill, ridge, or escarpment), consult the shingle man- even when shingles are tested at the highest fan ufacturer. (Note: for definitions of Exposure D and speed prescribed in the standard. Rather than rely Category III and IV, refer to ASCE 7.) INAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 7.3:ASPHALT SHINGLE ROOFING FOR HIGH WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12'10 Tile Roofing High Wind Regions HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 7.4 Purpose: To provide recommended practices for designing and installing extruded concrete and clay tiles that will enhance wind resistance in high-wind areas. Key Issues Missiles: Tile roofs are very vulnerable to breakage �\ from windborne debris (missiles). Even when well at- \� tached, they can be easily broken by missiles. If a tile is broken, debris from a single tile can impact other tiles on the roof, which can lead to a progres- sive cascading failure. In addition, tile missiles can _ be blown a considerable distance, and a substantial number have sufficient energy to penetrate shutters 0 and glazing,and potentially cause injury. In hurricane- 0 prone regions where the basic wind speed is equal to -n or greater than 110 mph (3-second peak gust), the r z windborne debris issue is of greater concern than in G) lower-wind-speed regions. Note: There are currently no testing standards requiring roof tile systems to be debris impact resistant. Attachment methods: Storm damage investigations However, for simplicity of application on smaller roof have revealed performance problems with mortar- areas(e. set, mechanical (screws or nails and supplementary g•,most residences and smaller commercial s when necessary), buildings), use the attachment designed for the cor- cli ps and foam-adhesive(adhesive- ner area throughout the entire roof area. set) attachment methods. In many instances, the damage was due to poor installation. Investigations Hips and ridges: Storm damage investigations have revealed that the mortar-set attachment method is revealed that hip and ridge tiles attached with mor- typically much more susceptible to damage than are tar are very susceptible to blow-off. Refer to the the other attachment methods. Therefore, in lieu of attachment guidance below for improved attachment mortar-set, the mechanical or foam-adhesive attach- methodology. ment methods in accordance with this fact sheet are Quality control: During roof installation, installers recommended. should implement a quality control program in accor- To ensure high-quality installation, licensed contrac- dance with the Quality Control section on page 3 of tors should be retained. This will help ensure proper this fact sheet. permits are filed and local building code requirements are met. For foam-adhesive systems, it is highly rec- ommended that installers be trained and certified by Classification of Buildings the foam manufacturer. Category I Buildings that represent a low haz- Uplift loads and resistance: Calculate uplift loads and to human life in the event of a and resistance in accordance with the Design and failure Construction Guidance section below. Load and re Category II All other buildings not in Categories sistance calculations should be performed by a I, Ill, and IV qualified person (i.e., someone who is familiar with the calculation procedures and code requirements). Category III Buildings that represent a substan- Corner and perimeter enhancements: Uplift loads are tial hazard to human life greatest in corners, followed by the perimeter, and Category IV Essential facilities then the field of the roof(see Figure 1 on page 2). "--\A. � FEMA 7.4:TILE ROOFING FOR HIGH WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 4'4IND SELJ 12/10 Design and Construction Guidance 1. Uplift Loads 3. Hips and Ridges In Florida, calculate loads and pressures on tiles in The Concrete and Clay Roof Tile Installation Manual accordance with the current edition of the Florida gives guidance on two attachment methods for Building Code (Section 1606.3.3). In other states, hip and ridge tiles: mortar-set or attachment to a calculate loads in accordance with the current edi- ridge board. On the basis of post-disaster field in- tion of the International Building Code (Section vestigations, use of a ridge board is recommended. 1609.7.3). For attachment of the board, refer to Table 21 in As an alternative to calculating loads, design uplift the Addendum to the Concrete and Clay Roof Tile pressures for the corner zones of Category II build Installation Manual. ings are provided in tabular form in the Addendum to Fasten the tiles to the ridge board with screws (1- the Third Edition of the Concrete and Clay Roof Tile inch minimum penetration into the ridge board) and Installation Manual(see Tables 6, 6A, 7, and 7A).1 use both adhesive and clips at the overlaps. For roofs within 3,000 feet of the ocean,straps,fas- Note: In addition to the tables referenced above, teners,and clips should be fabricated from stainless the Concrete and Clay Roof Tile Installation Manual steel to ensure durability from the corrosive effects contains other useful information pertaining to tile of salt spray. roofs. Accordingly, it is recommended that design- ers and installers of tile obtain a copy of the Manual 4. Critical and Essential Buildings and its Addendum. Hence,the tables are not incor- (Category Ill or IV) porated in this fact sheet. Critical and essential buildings are buildings that are expected to remain operational during a severe 0 wind event such as a hurricane. It is possible that p 2. Uplift Resistance people may be arriving or departing from the critical For mechanical attachment, the Concrete and Clay or essential facility during a hurricane. If a mis Roof Tile Installation Manual provides uplift resistance sile strikes a tile roof when people are outside the data for different types and numbers of fasteners building, those people may be struck by tile debris and different deck thicknesses. For foam-adhesive- dislodged by the missile strike. Tile debris may also set systems,the Manual refers to the foam-adhesive damage the facility. It is for these reasons that tiles manufacturers for uplift resistance data. Further, to are not recommended on critical or essential build- improve performance where the basic wind speed is ings in hurricane-prone regions (see ASCE 7 for the equal to or greater than 110 mph, it is recommended definition of hurricane-prone regions). that a clip be installed on each tile in the first row of If it is decided to use tile on a critical or essential tiles at the eave for both mechanically attached and facility and the tiles are mechanically attached, it is foam-adhesive systems. recommended that clips be installed at all tiles in the For tiles mechanically attached to battens, it is rec- corner, ridge, perimeter,and hip zones(see ASCE 7 for ommended that the tile fasteners be of sufficient the width of these zones). (See Figure 1.) length to penetrate the underside of the sheathing by 14 inch minimum. For tiles mechanically attached to counter battens, it is recommended that the tile Corner zone Ridge zone fasteners be of sufficient length to penetrate the un- derside of the horizontal counter battens by 1/4inch ! Perimeter zone minimum. It is recommended that the batten-to-bat- ten connections be engineered. 111111 For roofs within 3,000 feet of the ocean, straps, fas-• teners, and clips should be fabricated from stainless steel to ensure durability from the corrosive effects of salt spray. Field Hip zone NOTE:See ASCE 7 1.You can order the Concrete and Clay Roof Tile Installation Manual for zone width. online at the website of the Florida Roofing, Sheet Metal and Air Conditioning Contractor's Association, Inc.,(www.floridaroof.com)or by calling(407)671-3772.Holders of the Third Edition of the Manual Figure 1. For critical and essential facilities,clip all who do not have a copy of the Addendum can download it from the tiles in the corner,ridge,perimeter,and hip zones. website. 7.4:TILE ROOFING FOR HIGH WIND REGIONS 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12 10 5. Quality Control It is recommended that the applicator designate an For foam-adhesive systems,the QC person should en- individual to perform quality control (QC) inspections. sure that the foam is being applied by properly trained That person should be on the roof during the tile in- applicators and that the work is in accordance with stallation process (the QC person could be a working the foam manufacturer's application instructions. At member of the crew). The QC person should under- least one tile per square (100 square feet) should be stand the attachment requirements for the system pulled up to confirm the foam provides the minimum being installed (e.g., the type and number of fas- required contact area and is correctly located. teners per tile for mechanically attached systems If tile is installed on a critical or essential building in and the size and location of the adhesive for foam- a hurricane-prone region, it is recommended that the adhesive systems) and have authority to correct owner retain a qualified architect, engineer, or roof noncompliant work. The QC person should ensure consultant to provide full-time field observations dur- that the correct type, size, and quantity of fasteners ing application. are being installed. 0 0 m C) NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 7.4:TILE ROOFING FOR HIGH WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12/10 Minimizing Water Intrusion Through Roof Vents in High - Wind Regions HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. Purpose: To describe practices for minimizing water intrusion through roof vent systems that can lead to interior damage and mold growth in high-wind regions(i.e., greater than 90-miles per hour[mph] basic[gust design] wind speed).' Key Issues Hurricane winds can drive large amounts of wa The Unvented Attic ter through attic ventilation openings. The ac- The most conservative approach to prevent- cumulating water soaks insulation and gypsum ing wind-driven rain from entering the attic is board, which can lead to mold growth and, in to eliminate attic ventilation, but unvented at- O some cases, to the collapse of ceilings. tics are controversial. Although allowed by the 0 International Residential Code (IRC), provided -n Attic ventilation can be provided by a number of the Code's criteria are met, unvented attics may Z devices,most of which have been observed to al- not comply with local building codes. low water intrusion under certain conditions and some of which have been observed to blow off. However,when unvented attics are allowed by the These devices include: building code or code compliance is not an issue, Soffit vents and when climatic and interior humidity conditions Ridge (e.g., no indoor swimming pools) are conducive g to an unvented design, an unvented attic is a reli- Gable end vents able way to prevent wind-driven rain from entering Off-ridge vents the attic. Gable rake vents Turbines Air barrier: Refer to Fact Sheet 5.3,Siding Installa- Adequate ventilation of attics is generally re- tions in High-Wind Regions for recommendations quired to promote the health of wood structural regarding attic air barriers. members and sheathing in the attic. Attic ventilation can reduce the temperatures of roof coverings,which will typically prolong the life attempt to change to an unvented attic configu- of the roof covering. However, roof color can have ration needs to be done very carefully with the more of an impact on roof covering temperature advice of knowledgeable experts. There are a than the amount of ventilation that is or is not number of changes that have to be made to pro- provided. duce a successful transition from a ventilated to An unvented attic can be an effective way to an unvented attic. One side effect of going to an prevent water intrusion and this type of attic is unvented attic may be to void the warranty for gaining popularity for energy efficiency reasons, the roof covering. provided the air conditioning system is sized ap- The following information is intended to help minimize propriately. However, an unvented attic is best water intrusion through new and existing attic ventila- accomplished when it is specifically designed tion systems, not to change from a ventilated to an into the house and all of the appropriate details unvented system. With the exception of the plugging are handled properly. On an existing house, any of gable rake vents, all other shuttering of openings or plugging of vents should be done on a temporary 1 The 90 mph speed is based on ASCE 7-05.If ASCE 7-10 is being used, basis and removed once the storm threat is over so the equivalent wind speed is 116 mph for Risk Category II buildings that the attic is once again properly ventilated. OE'eA/�`H 1 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS FEMA HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 8 12/10 1 Mitigation Guidance Soffit Vents Key Issues It is important to keep the soffit ma- terial in place. While some water can be blown into the attic through almost any type of soffit vent, the 1111 amount of water intrusion increas- es dramatically when the soffit ma- terial is missing (Figure 1). Plywood or wood soffits are gener- ally adequately anchored to wood framing attached to the roof struc- ' ture and/or the walls. However, it has been common practice for vinyl and aluminum soffit panels to be in- stalled in tracks that are frequently "e very poorly connected to the walls . and fascia at the edge of the roof overhang. When these poorly an111 - chored soffits are blown off, water _ z intrusion increases significantly. O Properly installed vinyl and alumi- Figure 1. Missing soffit material. num soffit panels are fastened to 0 the building structure or to nailing strips placed at intervals specified by the manufacturer. Proper Installation The details of proper installation of vinyl and aluminum soffits depend on the type of eave to which they are at- tached. The key elements are illustrated in Figure 2. A. Roof truss or rafter framing should extend across the bottom of the eaves, or be add- ed to create a structural support for the soffit. As an alternative, soffits can be at- tached directly to the undersides of the an- gled rafters. B B. Nailing strips should be provided, if neces- sary,to allow attachment of the soffit at the k A ends. Intermediate nailing strips may be needed, depending on the maximum span permitted for the soffit. If this is not known, the span between attachment points should w =— not exceed 12" in high-wind regions. C. A J-channel (illustrated), Fchannel, or oth- er receiver as specified by the manufactur- er should cover the ends of the soffit pan- els. Fasteners should be those specified by ' D the manufacturer. Fasteners should be used through the nailing strip of each panel and Figure 2. Key soffit installation points. at any other points (such as in the "valleys" of the soffit) if specified. D. The overall span (eave depth) of the soffit should not exceed any limits specified by the manufacturer, and any required intermediate attachment points should be used. 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS 2 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1211 Checking Soffit Material Installation As previously noted, the most critical soffit installa- tions to check are those where vinyl or aluminum soffit panels are used. Soffits should be fastened to the eave structure; they should not be loose in the - - channels. Pushing up on the soffit material and the • . channels used to support the material can be reveal- ing. If it moves readily or is easy to deform,it probably is not attached very well. Similarly, if the width of the overhang is greater than 12 inches, there should be an intermediate support running along the middle of Air the soffit and the panels should be attached to this support in addition to the supports at the ends of the �' =* panels. If the reader is concerned about the installa- tion but cannot be sure, there are a couple of tools with a viewing screen connected to a small camera Figure 3. Applying a bead of sealant. (Note:Black lens and light mounted at the end of a flexible tube sealant was used so that it would be visible in the that can be used to observe the connections. These photograph.Normally a matching sealant color devices allow inspection through a small hole that would be used.) is drilled in an inconspicuous location that can be later filled with sealant. In order to ensure that there is a strong connection at the wall, there should be wood blocking running along the wall above the track . 1111 where the soffit channel is attached and the channel _ O, should be fastened to that blocking. If there is no - - z. - O wood blocking, and there is either no vertical nailing surface on the channel or occasional tabs that have been cut and bent up to allow fastening to the wall, strengthening of the anchorage of the soffit material is clearly indicated. Remedial Measures If the inspection indicates a poorly attached soffit, the best way to ensure that the soffit material is ad- equately anchored in place is to remove it and install adequate wood blocking to allow solid anchorage of the soffit material. In some cases, it may be possible to remove the soffit material and reinstall it. However, Figure 4. Applying dabs of sealant. it is also likely that some or all of the material will -- need to be replaced, so make sure that it can be matched before it is removed. Short of removing and properly reinstalling the soffit material, testing has shown that the anchorage can be greatly improved - -— by applying a bead of sealant (Figure 3) along the bottom edge of the wall channel to adhere it to the wall surface below followed by applying large dabs of sealant in indentations between the soffit panels and the wall channel at one end (Figure 4) and the fascia flashing at the other end. Surfaces receiving sealant should be cleaned in order to facilitate bonding. Extra resistance can be gained by installing screws that mechanically tie the soffit panels to both the fascia flashing and to the wall channel (Figure 5). Note that use of sealant is a remedial measure only and is not a substitute for proper installation and fastening of soffits in a new installation. Figure 5. Screws through wall channel. 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 8 12/10 Wind-driven rain penetration:Currently there is no ade- quate standard test method to evaluate the potential PPP— iillimmion for wind-driven rain to enter attics through soffit vent openings, such as those shown in Figure 6. To avoid water entry at soffit vents, options include eliminat- ing soffit vents and providing an alternate method for = -- air to enter the attic, or design for an unvented attic. Another approach is to place filter fabric (like that �._______ used for heating, ventilation, or cooling [HVAC] sys- ,_____A_ _ tern filters) above the vent openings; however, such �_ an approach needs to be custom designed. - Figure;::;; cover exposes ends of vinyl soffit to direct entry of wind-driven rain. The IRC currently has no guidelines for the instal- lation of fascia covers. Aluminum fascia covers are typically tucked under the roof drip edge and face- nailed every few feet. More frequent nailing would CO help secure the fascia cover, but would also inhibit Z normal thermal movement, which can cause un- u_ attractive warping and dimpling of the cover. Vinyl fascia covers are available, which are attached to cc ti a continuous strip of utility trim placed underneath i a i , the drip edge. This provides a somewhat more se- , i, /4 cure, continuous attachment and allows for thermal movement. Aluminum fascia covers can also be lit field notched and installed with utility trim. Ridge Vents Key Issues ad Ridge vents are frequently fastened down us- ing ordinary roofing nails since these are nor- Figure 6. Fiber cement soffit with ventilation slots mally handy. It is fairly common to find ridge (red arrow). vents dislodged or blown off during a hurricane (Figure 8). Even a partially dislodged ridge vent can begin to act like a scoop that collects wind- Fascia cover: Field investigations after Hurricane Ike driven rain and directs it into the attic. showed many cases where the aluminum fascia cov- er (fascia cap) from the fascia board was blown off Most roofing manufacturers now make ridge (Figure 7). The fascia cover normally covers the ends vents that have passed wind-driven water tests. of vinyl and aluminum soffits. When the fascia cover They are identified as having passed Florida is blown off, the ends of the soffit panels are ex- Building Code's Product Approvals or Testing posed to wind and wind-driven rain. Application Standard (TAS) 100(A). Typically, they include a baffle in front of the vent tubes that provide the passageway for hot attic gas- ses to escape. This baffle is intended to trip Rain screen wall venting: In lieu of providing soffit any flow of wind and water blowing up the sur- vents, another method to provide attic air in- face of the roof and deflect it over the top of the take is through a pressure-equalized rain screen roof ridge. wall system as discussed in Siding Installation in High-Wind Regions, Hurricane Ike Recover Advisory. This alternative approach eliminate soffit vents and their susceptibility to wind-driv- en rain entry. 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS 4 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 v 11 °K ,!•y/.� _ 't* CIF -. • ti. `. Slotting the Deck When ridge venting is being added to a roof that previously did not have it, it is necessary to cut - a slot through the decking. When doing so, it is important to set the depth of the saw blade so that it only slightly projects below the bottom of the decking. At the residence shown in Figure 8, p the saw blade cut approximately 1 1/2 inches 0 into the trusses and cut a portion of the truss = plate (red arrow). Figure 8. This metal ridge vent was attached with widely spaced roofing nails. Checking Ridge Vents and Their Installation ' When they are used, ridge vents are the last part of the roof to be installed. Consequently, the con- nection is readily accessible and frequently visible without having to pry up the edge of the vent cover top. Check the type and condition of the fasteners. If the fasteners are nails, replacement of the fasteners is in order. If the vent has clear holes or slots without any baffle or trip next to the edge of the vent chan- nels, the vent is probably not one that is resistant to water intrusion and you should consider replacing the ridge vent with one that has passed the wind-driven Figure 9. Gable end vent. water intrusion tests. Remedial Measures Gable End Vents Replace nails with gasketed stainless steel wood Key Issues screws that are slightly larger than the existing nails and, if possible, try to add fasteners at locations Virtually all known gable end vents (Figure 9)will where they will be embedded in the roof structure be- leak when the wall they are mounted on faces low and not just into the roof sheathing. Close spacing into the wind-driven rain. The pressures devel- of fasteners is recommended (e.g., in the range of 3 oped between the outside surface of the wall to 6 inches on center, commensurate with the design and the inside of the attic are sufficient to drive wind loads). If the ridge vents are damaged or are one water uphill for a number of inches and, if there of the older types that are not resistant to water in- is much wind flow through the vent,water carried trusion, they should be replaced with vents that have by the wind will be blown considerable distances passed the wind-driven water intrusion tests. into the attic. 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 8 12/10 Remedial Measures If it is practical and possible to shutter gable end - vents from the outside of the house, this is the pref erable way to minimize water intrusion through gable --- end vents (Figure 10). Install permanent anchors in -• the wood structure around the gable vent and precut, pre-drill, and label plywood or other suitable shutter ` ` ` ; - - materials so that they are ready for installation by �-� �''`440•1 i " a qualified person just before a storm approaches. _ If installation of shutters from the outside is diffi- !►� rt r�`` cult because of the height or other considerations, ;:// but there is access through the attic, the gable vent OP opening can be shuttered from the inside. However, careful attention needs to be paid to sealing around ./� ,, the shutter and making sure that any water that accu- mulates in the cavity can drain to the outside of the Figure 11. Two off-ridge vents are shown in this house and not into the wall below. photograph.The vent that is covered with roofing felt flipped up and allowed a substantial amount of water to enter the residence.Carpeting,kitchen cabinets, and a large amount of gypsum board had to be re- placed because of the water intrusion. a zt; , ••ft F in preventing water intrusion when a storm occurs. Since the flange and fasteners are hidden below the r'. roof covering, it is not possible to simply add nails or �,.'� screws to improve the anchorage as these will create ' , •- holes through the roof covering. MINSRemedial Measures If the off-ridge vent is attached to the roof sheathing with long, thin nails, it may be possible to improve Figure 10. Shuttered gable end vent, the anchorage by cinching the nails (bending them over against the underside of the roof sheathing). However, if they are short and/or thick, trying to bend them over may cause more harm than good. Off-ridge Vents Some homeowners have had covers made that can Key Issues be installed from the inside of the attic over the hole where the off-ridge vent is installed. This will be easi- Poorly anchored off-ridge vents can flip up and be- est if the vent is larger than the hole and the cover come scoops that direct large amounts of wind-driven can be attached to the sheathing in an area where rain into the attic (Figure 11). the fasteners cannot be driven through the roof cov- Some vents are also prone to leaking when winds Bring. Otherwise, it will be important to ensure that blow from certain directions. This will depend on the the fasteners are short enough that they will not ex- location of the vent on the roof surface and the ge tend through the roof sheathing and damage the roof ometry of the roof, as well as the geometry of the cover. If the edge of the hole in the roof deck is flush particular vent. with the inside edge of the vent, it may be possible to install metal straps that are screwed into the walls of Checking Off-Ridge Vent Installations the vent and attached with short screws to the bot- tom surface of the roof sheathing. Again, it is critical Off-ridge vents typically have a flange that lies against to use screws that are short enough that they will not the top surface of the roof sheathing and is used extend through the roof sheathing and damage the to anchor the vent to the roof sheathing. Frequently, roof covering. The strapping should be connected to roofing nails are used to attach the flange to the roof the walls of the vent with short stainless steel sheet sheathing. The off-ridge vents should be checked to metal screws. make sure that they are well anchored to the roof sheathing. If they seem loose, or there are not many fasteners holding them down, it could be a weak link 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS 6 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1210 Gable Rake Vents and particularly those near the gable peak. Sealant Key Issues can be used to seal around the edges of the metal or wood plugs. Gable rake vents are formed when porous soffit panels or screen vents are installed on the bot- Turbines tom surface of the roof overhang at the gable Key Issues end and there is a clear path for wind to blow into the attic. This usually happens when the The rotating top portion of many turbines is not gable overhang is supported by what are called designed to withstand high-wind conditions and outriggers. Outriggers are typically used when they are frequently installed with just a friction fit gable overhangs exceed 12 inches. In these to the short standpipe that provides the venting cases, the last roof truss or rafter (the gable of the attic. It is possible to find high-wind rated end truss or rafter) is smaller than the trusses turbines on store shelves in hurricane-prone re- or rafters at the next location inside the attic. gions but, in hurricane winds,the turbines will be Outriggers (2x4s) are installed over top of the rotating at tremendous speeds and can be easi- last gable truss or rafter, one end is anchored ly damaged by windborne debris. to the second truss or rafter back from the ga The flange on the standpipe that provides the ble end, and the other end sticks out past the connection of the pipe to the roof sheathing may gable end wall to support the roof sheathing on the overhang. also be poorly anchored to the roof sheathing. Finding Out if You Have Gable Rake Vents and Checking Turbines and Their Installation Whether You Still Need Them Check any turbines to make sure that the stand pipes are not loose and that the turbine head is anchored 0 The easiest way to tell if the roof has gable rake to the stand pipe by sheet metal screws and not sim- 0 vents is to look in the attic on a cool sunny day and ply by a friction fit (Figure 13). -n see if light is visible in gaps just below the sheath- Z ing at the gable end. The presence of the outriggers (2x4s running perpendicular to the gable truss and disappearing into the gable overhang) should also ze N. be visible. If there is also a gable end vent or a ridge vent, then the gable rake vent will probably not be needed in order to provide adequate venting ' ` for the attic. • Remedial Measures The best solution if venting provided by the gable rake14. . vents is not needed is to simply plug them up with metal flashing(Figure 12) or pieces of wood that are • a cut and anchored. They should be well attached and , completely seal as many of the openings as possible _' mimumilaremmik_ a Figure 13. This turbine head is attached to the standpipe with dimple punches.Sheet metal screws should be added to strengthen the connection. .. � { 4411k. Remedial Measures Loose standpipes should be securely anchored to the roof sheathing. If the standpipe is attached to the roof sheathing with long,thin nails, it may be pos- sible to improve the anchorage by cinching the nails (bending them over against the underside of the roof sheathing). However, if they are short and/or thick, trying to bend them over may cause more harm than Figure 12. Metal plugs(red arrows)in gable rake vents. good. Some homeowners have had covers made that can be installed from the inside of the attic over the 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 7 of 8 12/10 hole where the standpipe is installed. This will be "100.77:, ,.: `'x• easiest if the standpipelarger than the hole and is f ► a« the cover can be attached to the sheathing in an area ��''p;"`� ' • � where the fasteners cannot be driven through the 4 f a' • a ' .; roof cover. Otherwise, it will be important to ensure . `' that the fasteners are short enough that they will not • extend through the roof sheathing and damage the roof cover. If the edge of the hole in the roof deck is flush with the inside edge of the standpipe, it may be possible to install metal straps that are screwed into the walls _ of the standpipe and attached with short screws to the bottom surface of the roof sheathing. Again, it is critical to use screws that are short enough that they will not extend through the roof sheathing and damage the roof cover. The strapping should be Figure 14. Plastic wrapped connected to the walls of the standpipe with short 9 turbines. stainless steel sheet metal screws. Beyond any remedial measures taken to anchor the standpipe to the roof sheathing or to plug the hole from the attic side, it is also important to try and seal the standpipe from the outside so that water does not build up in the pipe and leak into the roof sheathing around the hole. The best approach is to have a qualified person remove the top active por- O tion of the turbine vent before the storm and plug the O hole at the top of the standpipe. A wooden plug can cC be used that covers the entire hole and has blocks that rest against the walls of the standpipe where screws can be installed to anchor the plug to the standpipe. Some homeowners have had the entire turbine wrapped in plastic to keep water out during a storm (Figure 14). This can work as long as the tur- bine or wrapping does not get dislodged. The smaller area provided by removing the turbine top and plug- ging the hole is considered preferable. INAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS 8 of 8 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Metal Roof Systems In High -Wind Regions HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 7.6 Purpose: To describe practices for designing and installing metal roof systems that will enhance wind resistance in high-wind regions(i.e.,greater than 90 miles per hour[mph]basic[gust design]wind speed).' Key Issues Damage investigations have revealed that some metal roofing systems have sufficient strength to resist extremely high winds (Figure 1), while other systems have blown off during winds that were well -_ 111" below design wind speeds given in ASCE 7. When metal roofing (or hip, ridge, or rake flashings) blows r , :41 off during hurricanes, water may enter the building at displaced roofing; blown-off roofing can damage 4 buildings and injure people. Here is general guidance 4 ' 411111 O: for achieving successful wind performance: — 1. Always follow the manufacturer's installation in- • Z structions and local building code requirements. 411,111 2. Calculate loads on the roof assembly in accor- Figure 1. This structural standing seam roof system dance with ASCE 7 or the local building code, it survived Hurricane Andrew(Florida,1992),but some hip is recommended to use whichever procedure re- flashings were blown off.The estimated wind speed was sults in the highest loads. 170 mph(peak gust,at 33 feet for Exposure C). 3. Specify/purchase a metal roof system that has sufficient uplift resistance to meet the design up- lift loads. For architectural panels with concealed clips, For standing seam metal panel systems, test method UL 580 is commonly used. pro- the 2009 International Building Code (IBC) However, it is recommended that design requires test methods UL 580 or ASTM E fessionals specify ASTM E 1592 because it 1592. For standing seam systems, it is rec- gives a better representation of the system's ommended that design professionals speci uplift performance capability.When testing ar fy E 1592 testing, because it gives a better chitectural panel systems via ASTM E 1592, the deck joints need to be unsealed in order representation of the system's uplift perfor capability. to allow air flow to the underside of the met- manceal panels. Therefore, underlayment should be For safety factor determination, refer to eliminated from the test specimen,and a 1/8 Chapter F in standard NAS-01, published by inch minimum between deck panel side and the American Iron and Steel Institute. end joints should be specified. For through-fastened steel panel systems, For safety factor determination, refer to the IBC allows uplift resistance to be eval- Chapter F of the North American Specification uated by testing or by calculations in accor- for the Design of Cold-Formed Steel Structural dance with standard NAS-01. Members (AISI S100-07). This fact sheet addresses wind and wind-driven rain issues. For general information on other aspects of metal roof system design and construction (including seam types, metal types, and finishes), see the "Additional Resources" section. 1 The 90 mph speed is based on ASCE 7-05.If ASCE 7-10 is being used,the equivalent wind speed is 116 mph for Risk Category II buildings. J o FEIN4A. 76: METAL ROOF SYSTEMS IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 5 12/10 For copper roofing testing, see "NRCA ana- lyzes and tests metal," Professional Roofing, For observations of metal roofing performance May 2003. during Hurricanes Charley (2004, Florida), Ivan (2004, Alabama and Florida), and Katrina For metal shingles, it is recommended that (Alabama, Louisiana, and Mississippi, 2005), re- uplift resistance be based on test method spectively; see Chapter 5 in FEMA MAT reports UL 580 or 1897. 488, 489, and 549. Specify the design uplift loads for field, pe- rimeter, and corners of the roof. Also spec- ify the dimension of the width of the perim- For attachment of corrugated metal panels, see eter. (Note: For small roof areas, the corner FEMA 55, Coastal Construction Manual,Appendix load can be used throughout the entire roof K, available online at: http://www.fema.gov/li- area.) brary/viewRecord.do?id=1671. 4. Suitably design the roof system components (see the "Construction Guidance" section). 5. Obtain the services of a professional roofing con- An advantage of exposed fastener panels (ver- tractor to install the roof system. sus panels with concealed clips) is that, after installation, it is easy to verify that the correct Metal Roofing Options number of fasteners was installed. If fastening A variety of metal panel systems (including compos- ite foam panels)are available for low-slope(i.e.,3:12 easy and economical. C� or less) and steep-slope (i.e., greater than 3:12) roofs. Metal shingles are also available for steep- • slope roofs. Common metal roofing options are: O Standing-Seam Hydrostatic(i.e.,water-barrier)Systems: and corrugated panels) are through-fastened (i.e., at- cC These panel systems are designed to resist water tached with exposed fasteners). Panels are available infiltration under hydrostatic pressure. They have that simulate the appearance of tile. standing seams that raise the joint between panels Metal Shingles: Metal shingles are hydrokinetic prod- above the water line. The seam is sealed with sealant ucts and require a relatively steep-slope and the use tape (or sealant) in case it becomes inundated with of an underlayment. Metal shingles are available that water backed up by an ice dam or driven by high wind. simulate the appearance of wood shakes and tiles. Most hydrostatic systems are struc- tural systems(i.e.,the roof panel has sufficient strength to span between purlins or nailers). A hydrostatic ar- chitectural panel (which cannot span between supports) may be speci- fied, however, if continuous or closely 10‘'' spaced decking is provided. Hydrokinetic (i.e., water-shedding) panels: These panel systems are not IOW s� designed to resist water infiltration • under hydrostatic pressure and there- fore require a relatively steep slope �, �� \ (typically greater than 3:12) and the ,� use of an underlayment to provide secondary protection against water , p7 that infiltrates past the panels. Most hydrokinetic panels are architectur- al systems, requiring continuous or closely spaced decking to provide support for gravity loads. dik Some hydrokinetic panels have Figure 2. This architectural panel system has concealed clips.The panels unlatched from the clips.The first row of clips(just above the standing ribs and concealed clips red line) was several inches from the end of the panels.The first row of (Figure 2), while others (such as clips should have been closer to the eave. 5V-crimp panels, R-panels [box-rib] 7.6: METAL ROOF SYSTEMS IN HIGH-WIND REGIONS 2 of 5 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Construction Guidance Consult local building code requirements and -_._w _. manufacturer's literature for specific installation .� requirements. Requirements may vary locally. Underlayment: If a robust underlayment system is installed, it can serve as a secondary water barri- er if the metal roof panels or shingles are blown110 off (Figures 2 and 3). For enhanced underlay- ment recommendations, see Fact Sheet No. 7.2, Roof Underlayment for Asphalt Shingle Roofs. Fact Sheet 7.2 pertains to underlayment options for asphalt shingle roofs. For metal panels and tiles, where Fact Sheet 7.2 recommends a Type I (#15) Figure 4. These eave clips were too far from the panel felt, use a Type II (#30) felt because the heavier ends.The clip at the left was 13"from the edge of the felt provides greater resistance to puncture by the deck.The other clip was 17"from the edge.It would panels during application. Also, if a self-adhering have been prudent to install double clips along the modified bitumen underlayment is used, specify/ eave. purchase a product that is intended for use under- neath metal (such products are more resistant to bitumen flow under high temperature). When clip or panel fasteners are attached to nailers (Figures 5-7), detail the connection of the nailer to the nailer support(including the de- tail of where nailers are spliced over a support). O 0 41111,1 14A • MIL Alik Figure 3. These architectural panel system have snap- lock seams. One side of the seam is attached with a concealed fastener.Although a large number of panels blew away,the underlayment did not. Figure 5.The panels blew off the upper roof and landed on the lower roof of this house.The upper asphalt shingle roof shown had been re-covered with 5V-Crimp Where the basic(design)wind speed is 110 mph2 panels that were screwed to nailers.The failure was caused by inadequate attachment of the nailers (which or greater, it is recommended that not less than had widely-spaced nails) to the sheathing.Note that two clips be used along the eaves, ridges, and the hip flashing on the lower roof blew off. hips. Place the first eave clip within 2 to 3 inch- es of the eave,and place the second clip approx- imately 3 to 4 inches from the first clip. Figures 2 and 4 illustrate ramifications of clips being too far from the eave. For copper panel roofs in areas with a basic wind 2 The 110 mph speed is based on ASCE 7-05. If ASCE 7-10 is being speed greater than 90 mph,3 it is recommended used, the equivalent wind speed is 142 mph for Risk Category II that Type 304 or 316 stainless steel clips and buildings. stainless steel screws be used instead of more 3 The 90 mph speed is based on ASCE 7-05. If ASCE 7-10 is being malleable copper clips. used, the equivalent wind speed is 116 mph for Risk Category II buildings. 7.6: METAL ROOF SYSTEMS IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 5 1210 I R- iIi! ' kaki{.,it tf;5 a ��wit1o1 t iiim Figure 6. Blow-off of nailers caused these panels to Figure Z This residence had metal shingles that progressively fail.The nailers were installed directly simulated the appearance of tile.The shingles typically over the trusses.In an assembly such as this where blew off the battens,but some of the battens were also there is no decking,there is no opportunity to incorpo- blown away. rate an underlayment.With loss of the panels,rainwa- ter was free to enter the building. C`� !IF-- .. . . Z • 4 IWhen clip or panel fasteners are loaded in with- - - 0 drawal (tension), screws are recommended in lieu of nails. .\--:• 1 cc ` For roofs located within 3,000 feet of the ocean line, 300 series stainless steel clips and fasten- 1 '� ers are recommended. ye a, A 1 a ''. For concealed clips over a solid substrate, it is recommended that chalk lines be specified so i that the clips are correctly spaced. ; is 4, v Hip, ridge, and rake flashings: Because exposed a fasteners are more reliable than cleat attach- --- ment, it is recommended that hip, ridge, and ..--''- rake flashings be attached with exposed fasten- -------- ers. Two rows of fasteners are recommended on Figure 8. The ridge flashing on these corrugated metal either side of the hip/ridge line. Close spacing of panels had two rows of fasteners on each side of the fasteners is recommended (e.g., spacing in the ridge line. range of 3 to 6 inches on center, commensurate with the design wind loads), as shown in Figure 8 in order to avoid flashing blow-off as shown in Figure 9. Figure 9. The ridge flashing fasteners were placed too ilill far apart.A significant amount of water leakage can oc- cur when ridge flashings are blown away. 7 * 7.6: METAL ROOF SYSTEMS IN HIGH-WIND REGIONS 4 of 5 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12 10 Additional Resources For general information on other aspects of metal roof system design and construction (including seam types, metal types, and finishes), see: Copper and Common Sense, (http://www.revereoopper.com) Copper Development Association, (http://www.copper.org/publications) Metal Building Manufacturers Association, Metal Roofing Systems Design Manual, 2000, (http://www.mbma. cam/display.cfm?p=44&pp6&i=47) Metal Construction Association, (http://www.metalconstruction.org/pubs) National Institute of Building Sciences, Whole Building Design Guide, (http://www.wbdg.org/design/env_roof- ing.php) National Roofing Contractors Association, The NRCA Roofing Manual:Metal Panel and SPF Roof Systems, 2008, (http://www.nrca.net/rp/technical/manual/default.aspx) Sheet Metal and Air Conditioning Contractors National Association, Architectural Sheet Metal Manual, 2003, (http://www.smacna.org/bookstore) American Iron and Steel Institute, North American Specification for the Design of Cold-Formed Steel Structural Members (AISI S100-07), 2007, (http://www.steel.org) American Iron and Steel Institute (http://www.professionalroofing.net/article.aspx?id=266) FEMA MAT reports 488, 489, FEMA 543 (Section 3.4.3.4), 549, FEMA 577 (Section 4.3.3.8). (http://www. fema.gov/library). 0 International Organization of Standards (ISO), Document ISO 14021, (http:// www.iso.org). -n Professional Roofing, "NRCA analyzes and tests metal," May 2003, (http://www.professionalroofing.net) NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 7.6: METAL ROOF SYSTEMS IN HIGH-WIND REGIONS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 5 12.10 • Enclosures Breakaway and Walls HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 8.1 Purpose: To discuss requirements and recommendations for enclosures and breakaway walls below the Base Flood Elevation(BFE). Key Issues Areas enclosed by solid walls be- low the BFE ("enclosures") are sub- ject to strict regulation under the National Flood Insurance Program /` (NFIP). Note that some local jurisdic- tions enforce stricter regulations for enclosures. Spaces below elevated buildings can be used only for building ac- cess, parking, and storage. Enclosures in V Zone buildings must ., be breakaway (non-breakaway enclo sures are prohibited). Breakaway en- = ' closures in V Zones must be built with flood-resistant materials, meet specific design requirements, and _,_ . be certified by a registered design D professional. Figure 1. Wood louvers installed beneath an elevated house in a n V Zone are a good alternative to solid breakaway walls. _ Enclosures (breakaway and non- breakaway) in A Zone buildings m z must be built with flood-resistant materials and WARNING —I equipped with flood openings that allow water levels inside and outside to equalize. Designers, builders, and homeown- ers should realize that:(1)enclosures Breakaway enclosure walls should be considered and items within them are likely to expendable, and the building owner could incur be destroyed even during minor flood events; (2) significant costs when the walls are replaced. enclosures, and most items within them, are not Breakaway wall replacement is not covered un- covered under flood insurance, which can result der flood insurance policies. in significant costs to the building owner; and (3) V Zones, breakaway wall enclosures below even the presence of properly constructed break- Foraway wall enclosures will increase flood insurance an elevated building will result in higher flood insurancepremiums for the entire building (the premium premiums; however, surrounding be- low-BFE space with insect screening, open lat- rate will increase as the enclosed area increas- es). Including enclosures in a building design can tice, slats, or shutters (louvers) can result in have significant cost implications. much lower flood insurance premiums (Figure 1) and will likely reduce damage during less- The Hurricane Ike Mitigation Assessment Team than-base-flood events. It is also recommend- (MAT) observed some breakaway walls in excess ed that breakaway walls be designed to break of 11 feet high. While FEMA promotes elevating into smaller sections so that they're less likely homes above the BFE (i.e., adding freeboard),one to damage the foundation or the upper portions of the unintended consequences appears to be of buildings. the increasing size of flood-borne debris elements due to taller breakaway walls. OE,EA�\E1. 7 0 8.1: ENCLOSURES AND BREAKAWAY WALLS E FEMA t HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 5 14:44 ND SEC'''. 12/10 1 Space Below the BFE —What Can It Be Used For? NFIP regulations state that the area below an ele- _____ Ilk 11..., . vated building can only be used for parking, building 1�(1 a access, and storage. These areas must not be fin- ished li ished or used for recreational or habitable purposes. 1 ,, Only minimal electrical equipment is allowed and no e mechanical or plumbing equipment is to be installed �=r i ll ! II below the BFE. _ ailii !, , iI Si► ,I ! What is an Enclosure? -- i An "enclosure" is formed when any space below the BFE is enclosed on all sides by walls or partitions. Enclosures can be divided into two types—break- Figure 2. Breakaway walls beneath this building failed away and non-breakaway. as intended under the flood forces of Hurricane Ike. Breakaway enclosures are designed _ to fail under base flood conditions Beam Permanent 2 x 4 nailer without jeopardizing the elevat- ed building (Figure 2) - any below- BFE enclosure in a V Zone must be breakaway. Breakaway enclosures iy , k 10 f 1 1 1 1 are permitted in A Zones but must be equipped with flood openings. j- 4"-wide Non-breakaway enclosures can be utility -• constructed in an A Zone. They may blockout ...- be used to provide structural sup- +- Breakaway port to the elevated building. All A .- 2 x 4 Zone enclosures must be equipped Nonstructural sheathing with flood openings to allow the au- (f) tomatic entry and exit of floodwaters. z It is recommended that they be Breakaway w used only in A Zone areas subject 2 x 4 stud to shallow, slow-moving floodwa- 1N I ters without breaking waves (i.e., — Hdo not use in Coastal A Zones). < Gap HIPL Breakaway Walls I Breakaway Breakaway walls must be designed to Built-up 2x4 break free under the larger of the follow- 2x4 framing ing Allowable Stress Design loads: 1)the design wind load, 2)the design seis- mic load, or 3) 10 pounds per square 1 i foot (psf), acting perpendicular to the 1 1 f T f .11 T - plane of the wall (see Figure 3 for an ex- ample of a compliant breakaway wall). If the Allowable Stress Design loading ex- ceeds 20 psf for the designed breakaway Permanent 2 x 4 nailer wall,the breakaway wall design must be certified. When certification is required, a registered engineer or architect must Figure 3. An example of an NFIP-compliant breakaway wall con- certify that the walls will collapse under structed of preservative treated or decay resistant lumber. a water load associated with the base flood and that the elevated portion of the building elevated building (Figure 4). Utilities should not and its foundation will not be subject to collapse, be attached to, or pass through, breakaway walls. displacement, or lateral movement under simultane- See FEMA (2008a) Technical Bulletin 9, Design and ous wind and water loads. Breakaway walls must Construction Guidance for Breakaway Walls for more break away cleanly and must not damage the information. 8.1: ENCLOSURES AND BREAKAWAY WALLS 2 of 5 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 A Zone opening requirements are as follows: '"" Flood openings must be provided in at least two 411 of the walls forming the enclosure. IP The bottom of each opening is to be located ,r no higher than 1 foot above the grade that is immediately under each opening. If the interior I 4 Iii MN and exterior grades are different, the higher of — the final interior grade and the finished exterior �i _ grade that is immediately under each opening N;Li I ! II . is used to make the determination. -4111 . Louvers, screens, or covers may be installed over flood openings as long as they do not inter- fere with the operation of the openings during a Figure 4. Building siding extended down and over the flood. breakaway wall.Lack of a clean separation allowed damage to spread upward as the breakaway wall failed. Flood openings may be sized according to either a prescriptive method (1 square inch of flood opening per square foot of enclosed area) or an Obstruction Considerations engineering method (which must be certified by A V Zone building, elevated on an open foundation a registered engineer or architect). without an enclosure or other obstructions below the Details concerning flood openings can be found in BFE, is said to be free of obstructions, and will re- FEMA (2008c) Technical Bulletin 1-08, Openings in ceive a favorable flood insurance premium(see FEMA Foundation Walls and Walls of Enclosures. (2008b) Technical Bulletin 5-08, Free-of-Obstruction Requirements for more information). The following building scenarios are also classi- fied by the NFIP Flood Insurance Manual as free of obstructions: 4lII11 R I I Below BFE space is surrounded by insect screen- ill ing and/or by wooden or plastic lattice, slats, or ,� . I > shutters (louvers), if at least 40 percent of the 1 .. ' D lattice and louver area is open. Lattice can be no o i n thicker than 1/a inch; slats or louvers can be no , , .. . - , `. I = thicker than 1 inch. l : .— ._. - _ ' m Below BFE space is surrounded by a combina- z tion of one solid breakaway wall (or garage door), - - --- .- V) and all other sides of the enclosure are either in • - sect screening, wooden or plastic lattice, slats, Figure 5. Flood opening in a below-BFE enclosure wall. or louvers. The following building scenarios are classified by the NFIP Flood Insurance Manual as with obstructions: Below BFE space is fully enclosed by solid break- Other Considerations away walls. Enclosures are strictly regulated because, if not con- Below BFE space is enclosed by a combination structed properly, they can transfer flood forces to of two or more solid breakaway walls,with the re- the main structure (possibly leading to structural col maining sides of the enclosure comprised of ei lapse). There are other considerations as well. ther insect screening, or wooden or plastic lat- Owners may be tempted to convert enclosed ar- tice, slats, or louvers. eas below the BFE into habitable space, lead- ing to life-safety concerns and uninsured losses. Flood Openings Buildings without enclosures below the lowest Foundation walls and other enclosure walls of A Zone floor should be encouraged. If enclosures are buildings (including Coastal A Zone buildings) must constructed, contractors should not stub out be equipped with openings that allow the automatic utilities in enclosures (utility stub outs make entry and exit of floodwaters (Figure 5). it easier for owners to finish and occupy the space). 8.1: ENCLOSURES AND BREAKAWAY WALLS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 5 12 111 I Siding used on the elevated portions of a build- There are two other enclosure scenarios that should ing should not extend down over breakaway be mentioned, both of which have construction and walls. Instead, a clean separation should be pro- flood insurance consequences. Contractors and de- vided so that any siding installed on breakaway signers should be cautious when an owner asks for walls is structurally independent of siding else- either type of enclosure, and consultation with the where on the building. Without such a separa- community and a knowledgeable flood insurance tion, the failure of breakaway walls can result in agent is recommended. damage to siding elsewhere on the building(see Below-BFE enclosures that do not extend all the Figure 4). way to the ground (sometimes called "hanging" Solid breakaway wall enclosures in V Zones will enclosures or "elevated" enclosures, occurs result in higher flood insurance premiums (es- when there is an enclosure floor system tied to pecially where the enclosed area is 300 square the building foundation and above the ground - feet or greater). Insect screening, lattice, slats, see Figure 6). In V Zones, the enclosure walls or louvers are recommended. must be breakaway, and the enclosure floor sys- tem must either break away or the building foun- dation must be designed to accommodate flood It is recommended to use insect screening, open loads transferred from the enclosure floor sys- wooden or plastic lattice, slats, or louvers in- tern to the foundation. In V Zones,the enclosure stead of solid breakaway walls beneath elevated walls must be breakaway,and the enclosure floor residential buildings. system must either break away or the building foundation must be designed to accommodate flood loads transferred from the enclosure floor system to the foundation. If enclosures are constructed in Coastal A Zones,open foundations with breakaway enclo- sures are recommended instead of foundation .".P- r_ walls or crawispaces. If solid breakaway walls are used, then they must be equipped with flood _a - openings that allow floodwaters to enter and exit III IIllll111111IIII IIIIiilIiiiu1 i hill' the the enclosure. Use of breakaway enclosures in if I Coastal A Zones (or any A Zone) will not lead to higher flood insurance premiums. z w I 2 It is recommended that flood openings be con- =C.) sidered for solid breakaway walls in V Zones, even though they are not required by the NFIP. - - The presence of flood openings may relieve flood forces against the solid breakaway walls, reduce w ~' - damage to the walls, and reduce flood-borne debris. Figure 6. Example of an enclosure that does not ex- tend to grade.This type of enclosure presents special construction and flood insurance issues. Contractors Garage doors installed in below-BFE enclosures should proceed with caution when an owner requests of V Zone buildings—even reinforced and high- such an enclosure. wind-resistant doors—must meet the perfor- mance requirement discussed in the Breakaway Walls section of this Fact Sheet. Specifically, the In A Zones, the enclosure walls must have prop- doors must be designed to break free under the er flood vents, with the bottom no higher than 1 larger of the following Allowable Stress Design foot above the enclosure floor. These types of loads: design wind load, the design seismic enclosures were not contemplated when flood in- load, or 10 psf,acting perpendicular to the plane surance premium rate tables were constructed, of the door. If the Allowable Stress Design load- and can result in significantly higher flood insur ing exceeds 20 psf for the designed door, the ance premiums than had the enclosure walls ex door must be designed and certified to collapse tended to the ground. The NFIP is working to cor under base flood conditions. See the Breakaway rect this rating issue; until then, owners will pay Walls section for information about certification a substantial premium penalty for this type of requirements. construction. 8.1: ENCLOSURES AND BREAKAWAY WALLS 4 of 5 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12'10 Two-storyenclosures below ele- •'••Q� a'' '' `•,• ' --.Y: PM i vated buildings (see Figure 7). As Iip ;�� >tr•-Y some BFEs are established high- � ! ' / y -. 4,..., . er and higher above ground, some o �0 • :A owners have constructed two-story sP solid wall enclosures below the ele-vated building, with the upper enclo sure having a floor system approxi- /It r, , �,mately midway between the ground �`�. , and the elevated building. These - types of enclosures present unique V =� problems. In A Zones both levels of il 1 1 the enclosure must have flood openfil- 1 e , ' ings in the walls unless there is ,;;i some way to relieve water pressure through the floor system between the upper and lower enclosures; in V0 Zones,the enclosure walls(and pos- ; �4 sibly enclosure floor systems) must ' be breakaway; special ingress and Milk egress code requirements may be Figure 7. Example of a two-story enclosure below the BFE.This type 1 a factor; these enclosures may re- of enclosure presents special construction and flood insurance suit in substantially higher flood in- issues.Contractors should proceed with caution when an owner surance premiums. requests such an enclosure. Additional Resources FEMA. 2008a. Design and Construction Requirements for Breakaway Walls. Technical Bulletin 9-08, (http://www.fema.gov/library/viewRecord.do?id=1722). FEMA. 2008b. Free-of-Obstruction Requirements. Technical Bulletin 5 08, (http://www.fema.gov/library/viewRecord.do?id=1718). n FEMA. 2008c. Openings in Foundation Walls and Walls of Enclosures.Technical Bulletin 1-08, I (http://www.fema.gov/library/viewRecord.do?id=1579). m FEMA. 2009. Hurricane Ike Recovery Advisory, Design and Construction in Coastal A Zones, z (http://www.fema.gov/library/viewRecord.do?id=1569). (n INAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 8.1: ENCLOSURES AND BREAKAWAY WALLS HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 5 12'10 i Decks, Pools, Accessory Structures HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 8.2 Purpose: To summarize National Flood Insurance Program (NFIP) requirements and general guidelines for the construction and installation of decks,access stairs and elevators,swimming pools,and accessory buildings under or near coastal buildings. Key Issues Any deck, accessory building, or other construction element that is structurally dependent on or attached to a building in V Zone is considered part of the build- ing and must meet the NFIP reg- ulatory requirements for con- struction in V Zone (see NFIP Technical Bulletin 5-08 and Fact Sheet Nos. 1.2, 1.4, 1.5, 1.7, 3.1, 8.1, 9.1). Attached con- struction elements that do not - meet these requirements are - _ prohibited. If prohibited elements are at- tached to a building that is oth- - D erwise compliant with NFIP • - n requirements, a higher flood in- Damage surance premium may be as- from Hurricane Opal in Florida.This deck was designed to meet State of Florida Coastal Construction Control Line (CCCL)requirements. z sessed against the entire The house predated the CCCL and did not meet the requirements. - building. cn Swimming pools,accessory build- ings, and other construction elements outside and/or wind forces. Decks should be given the the perimeter (footprint) of, and not attached same level of design and construction attention to, a coastal building may alter the characteris- as the main building, and failure to do so could tics of flooding significantly or increase wave or lead to severe building damage. debris impact forces affecting the building and nearby buildings. If such elements are to be con- Decks structed, a design professional should consider Requirements their potential effects on the building and nearby buildings. If a deck is structurally attached to a building in This Home Builder's Guide to Coastal Construction Zone V,the bottom of the lowest horizontal mem strongly recommends that all decks, pools, ac ber of the deck must be elevated to or above the cessory structures, and other construction ele elevation of the bottom of the building's lowest ments in Zone A in coastal areas be designed horizontal member. and constructed to meet the NFIP V Zone re- A deck built below the Design Flood Elevation quirements. (DFE) must be structurally independent of the Post-storm investigations frequently reveal enve main building and must not cause an obstruction. lope and structural damage (to elevated build- If an at-grade, structurally independent deck is ings) initiated by failure of a deck due to flood to be constructed, a design professional must J FEMA 8.2: DECKS, POOLS, AND ACCESSORY STRUCTURES HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 4 �qND SEA' 12 10 evaluate the proposed deck to determine wheth- Although they need not be designed to break er it will adversely affect the building and nearby away under flood forces, access stairs and ele- buildings (e.g., by diverting flood flows or creat- vators are obstructions;therefore,the loads they ing damaging debris). may transfer to the main building must be con- sidered by the design professional. Recommendations Decks should be built on the same type of foun- A' - dation as the primary building. Decks should be ,.r,,_ ..ter- — structurally independent of the primary structure 4,' and designed to resist the expected wind and water forces. 1 ;Alternatively, decks can be cantilevered from the L_ — F- primary structure; this technique can minimize . ili 1 y! the need for additional foundation members. ... I I■. A "breakaway deck" design is discouraged be- -1 . cause of the large debris that can result. �__ -• > - - = A "breakaway deck" on the seaward side poses m a damage hazard to the primary structure. Decks should be constructed of flood-resistant Large solid stairs such as these block flow under a materials, and all fasteners should be made of building and are a violation of NFIP free-of-obstruction corrosion-resistant materials. requirements. Access Stairs and Elevators Requirements Recommendations Open stairs and elevators attached to or be Open stair handrails and risers should be used because they allow wind and water to pass neath an elevated building in V Zone are ex- cluded from the NFIP breakaway wall re- through rather than act as a barrier to flow. z quirements (see NFIP Technical Bulletin The bottom of the stair, like the foundation of the w 5-08 and Fact Sheet No. 8.1), but must meet primary structure, should be designed and con- the NFIP requirement for the use of flood-resis- structed to remain in place during a windstorm I U tant materials (see NFIP Technical Bulletin 2-08 or a flood. Q and Fact Sheet No. 1.7). Large solid staircases t— Stairways not considered the primary means of Q that block flow under a building are a violation of egress can be constructed with hinged connec- tions free-of-obstruction requirements (see NFIP that allow them to be raised in the event of Technical Bulletin 5-08) an Eleva impending stormbe or flood (checkin code require with I ments before employing this technique). s tors installed accordance 11.111zi.!.. i- the guidance in NFIP Technical Bulletin 4-93 and the building code. 1" i Swimming Pools '; - , 4, Requirements ( , i An at grade or elevated pool adjacent to a coast ., 6. I . al building is allowed only if the pool will not act - , as an obstruction that will result in damage to the building or nearby buildings. When a pool is constructed near a building in �� ,:k ' ! Zone V, the design professional must assure The rails on these stairs were enclosed with siding, community officials that the pool will not increase presenting a greater obstacle to the flow of flood wa- the potential for damage to the foundation or ter and contributing to the flood damage shown here. elevated portion of the building or any nearby 8.2: DECKS, POOLS, AND ACCESSORY STRUCTURES ,' HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION buildings. Pools can be designed to break up ("frangible pools") during a Frangible flood event,thereby reducing the po- concrete deck ( tential for adverse impacts on near- or walkway by buildings. House Any pool constructed adjacent to a coastal building must be structurally Rounded independent of the building and its corners in foundation. pool ` J A swimming pool may be placed be- neath a coastal building only if the top of the pool and the accompany- ing pool deck or walkway are flush Narrowest dimension with the existing grade and only if the perpendicular to direction of flood flow lower area (below the lowest floor) remains unenclosed. Under the NFIF lower-area enclosures around pools constitute a recreational use and are not allowed, even if constructed Direction of Flood Flow to breakaway standards. Recommendations Siting and design recommendations for swimming pools in coastal areas. Pools should be oriented with their narrowest dimension perpendicular to the direction of flood flow. Concrete decks or walkways around pools buildings must be unfinished inside,constructed should be frangible (i.e.,they will break apart un- with flood-resistant materials, and used only for der flood forces). storage. Molded fiberglass pools should be installed and When an accessory building is placed in Zone V, elevated on a pile-supported structural frame. the design professional must determine the ef- No aboveground pools should be constructed in fect that debris from the accessory building will V Zone unless they are above the DFE and have have on nearby buildings. If the accessory build- an open, wind- and flood-resistant foundation. ing is large enough that its failure could create damaging debris or divert flood flows, it must be Pool equipment should be located above the elevated above the DFE. DFE whenever practical. Check with community officials before construct- Recommendations ing pools in Zone V. Whenever practical, accessory buildings should not be constructed. Instead, the functions of an Accessory Buildings accessory building should be incorporated into Requirements the primary building. Unless properly elevated (to or above the DFE) All accessory buildings should be located above on piles or columns, an accessory building in V the DFE whenever practical. Zone is likely to be destroyed during a coastal All accessory buildings should be designed and storm; therefore, these buildings must be lira- constructed to resist the locally expected wind ited to small, low-value structures (e.g., small wood or metal sheds) that are disposable. See and water forces whenever practical. NFIP Technical Bulletin 5-08. The roof, wall, and foundation connections in ac- If a community wishes to allow unelevated ac cessory buildings should meet the requirements cessory buildings, it must define "small" and for connections in primary buildings. "low cost." NFIP Technical Bulletin 5-08 defines Accessory buildings below the DFE should be an- "small" as less than 100 square feet and "low chored to resist being blown away by high winds cost" as less than $500. Unelevated accessory or carried away by floodwaters. 8.2: DECKS, POOLS, AND ACCESSORY STRUCTURES HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 4 { 12,10 Accessory buildings (including their foundations) must not be attached to the primary build- ing; otherwise, failure of the ac- cessory building could damage the primary building. Orienting the narrowest dimen- sion of an accessory building • perpendicular to the expected _ flow of water will create less of an obstruction to flowing water ' __ _ — or wave action, and may result in less damage. Small accessory building anchored to resist wind forces. Additional Resources FEMA. NFIP Technical Bulletin 2-08, Flood Damage-Resistant Materials Requirements for Buildings Located in Special Flood Hazard Areas. (http://www.fema.gov/library/viewRecord.do?id=1580) FEMA. NFIP Technical Bulletin 4-10, Elevator Installation for Buildings Located in Special Flood Hazard Areas. (http://www.fema.gov/library/viewRecord.do?id=1717) FEMA. NFIP Technical Bulletin 5-08, Free-of-Obstruction Requirements for Buildings Located in Coastal High co Hazard Areas. (http://www.fema.gov/library/viewRecord.do?id=1718) z w U NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 8.2: DECKS, POOLS, AND ACCESSORY STRUCTURES 4 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Protecting Utilities HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 8.3 Purpose: To identify the special ► considerations that must be made A' , - when installing utility equipment in a coastal home. pp p . ' f. Ai4 Key Issues: . • Hazards, requirements, and recom- I \ mendations— Special considerations r r, must be made when installing util- - ity systems in coastal homes. ! • rim Proper placement and connection a 2 1 p ic , of utilities and mechanical equip- ill ment can significantly reduce the costs of damage caused by coastal • _ storms and will enable homeowners to reoccupy their homes soon after , 1• (.1ti electricity, sewer, and water are re- Electrical lines and box dislocated by hurricane forces. stored to a neighborhood. Coastal Hazards That Damage Basic Protection Methods Utility Equipment The primary protection methods are elevation or Jr' Standing or moving floodwaters component protection. -1 Impact from floating debris in floodwaters Elevation : > Erosion and scour from floodwaters • Elevation refers to the location of a component and/or 0 High winds utility system above the Design Flood Elevation (DFE). ( m Windborne missiles Component Protection p (n, Common Utility Damage in Coastal Areas Component protection refers to the implementation of design techniques that protect a component or Floodwaters cause corrosion and contamination, group of components from flood damage when they short-circuiting of electronic and electrical equip- are located below the DFE. ment, and other physical damage. Electrical— Floodwaters can corrode and short-circuit NFIP Utility Protection Requirements electrical system components, possibly leading to The NFIP regulations [Section 60.3(a)(3)] state that: electrical shock. In velocity flow areas, electrical pan- els can be torn from their attachments by the force of All new construction and substantial improvements breaking waves or the impact of floating debris. shall be constructed with electrical, heating,Water/Sewage— Water wells can be exposed by ero ven- tilation, plumbing, and air conditioning equipment sion and scour caused by floodwaters with velocity and other service facilities that are designed and/ flow. A sewage backup can occur even without the or located so as to prevent water from entering or flow. urs flooding. b accumulating within the components during condi- tions of flooding. Fuel — Floodwaters can float and rupture tanks, cor- rode and short-circuit electronic components, and sever pipe connections. In extreme cases, damage Elevation of utilities and mechanical equipment to fuel systems can lead to fires. is the preferred method of protection. ( y 8.3: PROTECTING UTILITIES o ,Y j FEI\4.A. HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 3 sF\4ND SfC;)E 12/10 Utility Protection Recommendations Water/Sewage Electrical Attach plumbing risers on the landward side of interior piles or other vertical support members. Limit switches, wiring, and receptacles below the DFE to those items required for life safety. When possible, install plumbing runs inside Substitute motion detectors above the DFE for joists for protection. below-DFE switches whenever possible. Use only Never attach plumbing runs to breakaway walls. ground-fault-protected electrical breakers below the DFE. HVAC Install service connections (e.g., electrical lines, Install HVAC components e. panels, and meters; telephone junction boxes; p ( g•, condensers,r ) air handlers, ductwork, electrical components) cable junction boxes)above the DFE, on the land- above the DFE. ward side of interior piles or other vertical sup- port members. Mount outdoor units on the leeward side of the building. Use drip loops to minimize water entry at penetrations. Secure the unit so that it cannot move, vibrate, or be blown off its support. Never attach electrical components to break Protect the unit from damage by windborne debris. away walls. Lowe-t . � `. f -mber Lo _ '� y CY - _-" of elevated building of elevated building /—Install service connections 7( 1 (e.g.,electric lines and r meters,telephone junction boxes,cable junction boxes)above DFE,on Install sewer and water (/) landward side of interior risers on landward side of ~ DFE piles or other vertical interior piles or other Z _ W . support members vertical support members U +--Secure risers with Hcorrosion-resistant straps Pile Pile or anchors(2' on center, maximum) Oceanfront Oceanfront ii viii Grade Grade ii,�Nuir /74.4,ii // uir PI Recommended installation techniques for electrical and plumbing lines and other utility components. 8.3: PROTECTING UTILITIES 2 of 3 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12n o Fuel 1 Fuel tanks should be installed so as to prevent their loss or damage. This will require one of the following techniques: (1) elevation above the DFE and anchoring to prevent blowoff, (2) buri- tt4 ' al and anchoring to prevent exposure and flota- - ,`— tion during erosion and flooding, (3) anchoring at ground level to prevent flotation during flood- ing and loss during scour and erosion. The first t method (elevation) is preferred. Any anchoring, strapping, or other attachments must be designed and installed to resist the of fects of corrosion and decay. ^� . C i c a : Additional Resources Elevated air conditioning compressors. American Society of Civil Engineers. Flood Resistant Design and Construction (SEI/ASCE 24-05). (http://www.asce.org) FEMA. Free-of-Obstruction Requirements. Technical Bulletin 5-08, (http://www.fema.gov/library/viewRecord.do?id=1718). FEMA. Protecting Building Utilities From Flood Damage. FEMA 348. November 1999. (http://www.fema.gov/library/viewRecord.do?id=1750) • • z NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 8.3: PROTECTING UTILITIES HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12/10 Repairs, Remodeling, Additions, and Retrofitting Flood HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 9.1 Purpose: To outline National Flood Insurance Program (NFIP)requirements for repairs, remodeling, and additions,and opportunities for retrofitting in coastal flood hazard areas; to provide recommendations for exceeding those minimum requirements. Key Issues Factors That Determine Whether and How Existing buildings that sustain substantial dam- Existing Buildings Must Comply With NFIP age or that are substantially improved (see box Requirements on page 3) will be treated as new construction Rules governing the applicability of NFIP new construc- and must meet the community's current flood tion requirements to existing buildings are confusing resistant construction requirements (e.g., low to many people; this fact sheet and Fact Sheet No. est floor elevation, foundation, and enclosure 1.2, Summary of Coastal Construction Requirements requirements). and Recommendations for Flood Effects provide guid- Work on post-Flood Insurance Rate Map (FIRM)1 ance on the subject. existing buildings that are not substantially dam- aged or substantially improved (see box on page When repairs, remodeling, additions, or improve- 3) must meet the community's flood-resistant ments to an existing building are undertaken, four construction requirements that were in effect basic factors determine whether and how the exist- when the building was originally constructed. ing building must comply with NFIP requirements for Work on pre-FIRM1 existing buildings that are not new construction: substantially damaged or substantially improved Value of damage/work- whether the cost of re- (see box on page 3) is not subject to NFIP flood- pairs to the damaged building triggers substan- resistant construction requirements. tial damage or substantial improvement regula- With some minor exceptions (e.g., code viola- tions (see page 3). tions and historic buildings), substantial damage Nature of work- whether the work involves an and substantial improvement requirements apply expansion of the building, either laterally or ver- to all buildings in the flood hazard area, whether tically (an addition), or an enclosure of space be- or not a flood insurance policy is in force. low the Base Flood Elevation (BFE), or the demo- Buildings damaged by a flood and covered by lition and reconstruction of an existing building, flood insurance may be eligible for additional pay or the relocation of an existing building. ments through the Increased Cost of Compliance (ICC) policy provisions. Check with an insurance agent and the authority having jurisdiction (AHJ) Note: Repairs, remodeling, additions, and retro- for details. fitting may also be subject to other community and code requirements, some of which may be Repairs and remodeling—either before or after more restrictive than the NFIP requirements. storm damage—provide many opportunities for Check with the AHJ before undertaking any work. retrofitting homes and making them more resis- tant to flood damage. 1 Pre-FIRM is defined as a building for which construction or substantial improvement occurred on or before December 31,1974,or before the effec- tive date of the initial Flood Insurance Rate Map(FIRM)for the community.Post-FIRM is defined as a building for which construction or substantial improvement occurred after December 31, 1974,or on or after the effective date of the initial Flood Insurance Rate Map(FIRM)for the community. 2 This fact sheet and Fact Sheet No.2 recommend meeting current NFIP/community requirements in these instances. Z'9, 9 1: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING - FLOOD FEMA HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 7 AND0. . 12/10 1 Pre-FIRM or post-FIRM building- different re- quirements may apply to pre-FIRM existing 2009 International Residential Code buildings. Requirements for Additions,Alterations or Flood zone- different requirements may apply Repairs in V Zones and A Zones (this includes both the R1O2.7.1 Additions, alterations or repairs. Coastal A Zone and A Zone). Additions, alterations, or repairs to any struc- Two other factors may need to be considered (con- ture shall conform to the requirements for a new suit the AHJ regarding whether and how these factors structure without requiring the existing structure apply): to comply with all of the requirements of this code, unless otherwise stated. Additions, al- Code violations- if cited by a code official, the terations or repairs shall not cause an existing NFIP regulations exempt certain work to correct structure to become unsafe or adversely affect existing violations of state or local health, sani- the performance of the building. tary, or safety code requirements from the sub- stantial improvement and substantial damage calculations. Historic structures- a building that is on the What Is Substantial Damage? National Register of Historic Places or that has been designated as historic by federally certified Substantial damage is damage, of any origin, state or local historic preservation offices (or where the cost to restore the building to its pre- that is eligible for such designation) may be ex- damage condition equals or exceeds 50 percent empt from substantial damage and substantial of the building's market value before the damage improvement requirements, provided any work occurred. on the building does not cause the building to lose its historic designation. What Is Substantial Improvement? Substantial improvement is any reconstruction, rehabilitation, addition, or improvement of a A Zones Subject to Breaking Waves and Erosion building, the cost of which equals or exceeds 50 Home Builder's Guide to Coastal Construction percent of the building's pre-improvement mar- (HBGCC) Recommendations: Treat buildings and ket value. lateral additions in A Zones subject to breaking When repairs and improvements are made simul- waves and erosion like V Zone buildings. Elevate taneously, all costs are totaled and compared all A Zone lateral additions(except garages)such with the 50 percent of market value threshold. that the bottom of the lowest horizontal structur- al member is at, or above, the DFE. For garages (in A Zones subject to breaking waves and ero- sion) below the DFE, construct with breakaway Substantial Damage and Substantial walls. Improvement It is not uncommon for existing coastal buildings to be modified or expanded over time, often in con- Code Compliance junction with the repair of storm damage. All repairs, CC remodeling, improvements, additions, and retrofitting Q Definitions from the International Code Council Model to buildings in flood hazard areas must be carried 0_ Building Codes out in conformance with floodplain management or- ADDITION: An extension or increase in floor area or dinances pertaining to substantial improvement and height of a building or structure. substantial damage. ALTERATION: Any construction or renovation to an What Costs Are Included in Substantial existing structure other than repair or addition that requires a permit. Also, a change in a mechanical Damage and Substantial Improvement system that involves an extension,addition or change Determinations? to the arrangement,type or purpose of the original in- All structural items and major building com- stallation that requires a permit. ponents (e.g., foundations; beams; trusses; REPAIR: The reconstruction or renewal of any sheathing; walls and partitions; floors; ceilings; part of an existing building for the purpose of its roof covering; windows and doors; brick, stucco, maintenance. and siding; attached decks and porches). 9.1: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING - FLOOD 2 of 7 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 } Interior finish elements (e.g., tile, vinyl flooring, stone, carpet; plumbing fixtures; gypsum wall- Note: Some jurisdictions have enacted more board and wall finishes; built-in cabinets, book- restrictive requirements—some use a less-than- cases and furniture; hardware). 50-percent damage/improvement threshold. Utility and service equipment(e.g., HVAC equip- Some track the cumulative value of damage ment; plumbing and wiring; light fixtures and ceil- ing fans; security systems; built-in appliances; for local requirements. water filtration and conditioning systems). Market value of all labor and materials for re- Additions pairs, demolition, and improvements, including Additions increase the square footage or external management, supervision, overhead, and profit dimensions of a building. They can be divided into (do not discount volunteer or self labor or donat- lateral additions, vertical additions, and enclosures of ed/discounted materials). areas below existing buildings. When considering What Costs Are Not Included in Substantial ad- ditions, it is important to consider that changes to the shape of the building may impact the potential Damage and Substantial Improvement damages to the house. A lateral addition may change Determinations? the way flood waters travel around the structure and n costs (e.g., potentially create obstructions for flood-borne debris Desig n plans and specifications, that may require additional foundation modifications. surveys and permits). Vertical additions may also impose greater loads on Clean-up (e.g., debris removal, transportation, the existing structure. A qualified design professional and landfill costs). should evaluate the loading to the entire structure to see if additional structural modifications are required Contents (e.g., furniture, rugs, appliances not in order to maintain the structure's ability to sustain built in). flood loading. Outside improvements (e.g., landscaping, irri- gation systems, sidewalks and patios, fences, Lateral Additions lighting, swimming pools and hot tubs, sheds, gazebos, detached garages). If a lateral addition constitutes a substantial im- provement to a V Zone building,both the addition and the existing building must comply with the ef- fective base flood elevation,foundation,and oth- er flood requirements for new V Zone construc- tion (see Figure 1). Existing Building in V Zone Compliant Renovated/Remodeled Building Exterior renovated ♦ ♦♦ ♦♦ Interior remodeled DFE _ m ♦' DFE Bottom of lowest horizontal Existing pre-FIRM building below DFE structural member at or above DFE Requirement: Renovated/remodeled building must be elevated to or above DFE on open (pile/column)foundation with bottom of lowest horizontal structural member at or above DFE. Figure 1. Substantial improvement:Renovated/remodeled building in a V Zone. 9.1: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING — FLOOD HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 7 12,10 If a lateral addition constitutes a substantial inn- elevated. However, the HBGCC recommends that provement to an A Zone building, only the addi- both the existing building and the addition be el- tion must comply with the current floor eleva- evated to, or above,the current DFE, in a manner tion, foundation, and other flood requirements consistent with current NFIP requirements for new for new construction, as long as the alterations construction, and using a V Zone-type foundation to the existing building are the minimum nec- in V Zones and in Coastal A Zones. essary.3 Minimum alterations necessary means If a lateral addition to a post-FIRM building does the existing building is not altered, except for not constitute a substantial improvement,the ad- cutting an entrance through the existing build- dition must be elevated in accordance with the ing wall into the addition, and except for the flood requirements in effect at the time the build- minimum alterations necessary to tie the ad- ing was originally constructed,even if the BFE and dition to the building. If more extensive alter- flood hazard have changed over time. The HBGCC ations are made to the existing building, it too recommends that both the existing building and must be brought into compliance with the re- the addition be elevated to, or above, the current quirements for new construction. DFE, in a manner consistent with current NFIP re- If a lateral addition to a pre-FIRM building does quirements for new construction, and using a V not constitute a substantial improvement, nei- Zone-type foundation in V Zones and in Coastal A ther the addition nor the existing building must be Zones (see Figure 2). Existing Building Compliant Lateral Addition An attached garage does not have to be ,,41100 elevated above Existing DFE,but must be building constructed with breakaway walls. `7 i Lateraon _000 DFE ❑ ,, IJ' DFE ` Ill�:_ EL _ Cm " l Pile/column -- - - El t 1tl.1 foundation Bottom of lowest horizontal structural member at or above new DFE U) CC Existing, NFIP-compliant post-FIRM building Requirement: Both existing building and addition must be with bottom of lowest horizontal structural elevated on open (pile/column)foundation with bottom of lowest Lll member at or above old DFE(in effect at horizontal structural member at or above new DFE(in effect at CC time of original construction) time of construction of lateral addition) Figure 2. Substantial improvement:Lateral addition to a pre-FIRM building in a V Zone. 3 However,the HBGCC recommends that both the existing building and the addition be elevated to,or above,the current DFE,in a manner consis- tent with current NFIP requirements,and using a V Zone-type foundation in Coastal A Zones. 9.1: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING — FLOOD 4 of 7 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/10 Vertical Additions using any space below the current BFE for habit- If a vertical addition to a V Zone or A Zone build able uses (uses permitted by the NFIP are park- ing constitutes a substantial improvement, both ing, storage, and building access). the addition and the existing building must com- If a vertical addition to a post-FIRM V Zone or ply with the effective base flood elevation, foun- A Zone building does not constitute a substan- dation, and other flood requirements for new tial improvement,the addition must be designed construction (see Figure 3). and constructed in accordance with the flood re- quirements in effect at the time the building was If a vertical addition to a pre-FIRM V Zone or A originally constructed. However, BFEs and flood Zone building does not constitute a substantial zones change over time as areas are remapped. improvement, neither the addition nor the ex- The HBGCC recommends that both the addi- isting building must be elevated or otherwise tion and the existing building be elevated to, or brought into compliance with NFIP requirements. above, the current DFE in a manner consistent However, the HBGCC recommends that both the with current NFIP requirements for new construc- addition and the existing building be elevated to, tion, and using a V Zone-type foundation in V or above, the current DFE in a manner consis- Zones and in Coastal A Zones. The HBGCC also tent with current NFIP requirements for new con- recommends strongly against using any space struction, and using a V Zone-type foundation in below the current BFE for habitable uses (uses V Zones and in Coastal A Zones (see Figure 3). permitted by the NFIP are parking, storage, and The HBGCC also recommends strongly against building access). Compliant Vertical Addition Existing Building 41, i �/ ❑ ❑ Alirril ❑ I ❑ m i DFE �� New,extended —DFE ❑ I I I -- ��— — ;a pile/column rl foundation �� 1 11 .!r i \",; I Bottom of lowest horizontal Bottom of lowest horizontal structural member at or above DFE structural member at or above DFE , Existing, Pre-FIRM buildingbelow DFE Requirement: Both existing building and addition must be elevated to or above DFE Figure 3. Substantial improvement:Vertical addition to a pre-FIRM building in a V Zone. 9.1: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING — FLOOD HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 7 12/10 I Enclosures of Areas Below Existing building component, but also removal of associated Buildings exterior cladding. Wind-driven rain for example can lead to compromised connections and the decaying Enclosures below existing buildings are treated like or rotting of building materials that may not be visible vertical additions. without further investigation. Existing NFIP requirements: (1) do not enclose and Insurance Consequences convert to habitable use any space below the BFE under any circumstances, and (2) construct only Designers and owners should know that the work breakaway enclosures below existing buildings in V described previously may have insurance conse- Zones and in Coastal A Zones. HBGCC recommen- quences, especially if not completed strictly in dation: in V Zones and Coastal A Zones the area accordance with NFIP requirements. below the BFE should be built free of obstruction. In general, most changes to an existing building Use open lattice, screening, or breakaway walls. For that result from less-than-substantial damage, or requirements concerning enclosures below elevated that do not constitute substantial improvement, will buildings see Fact Sheet 8.1. It should be noted that not change the status from pre-FIRM to post-FIRM. enclosures built with breakaway walls below the BFE However, it is required that substantially improved may result in increased insurance premiums when or substantially damaged buildings be brought into compared to an open foundation. compliance. NFIP flood insurance policies on those buildings are written using rates based on elevation. Reconstruction of a Destroyed or Razed In most cases,the premium will decrease when a pre- Building FIRM building is substantially improved and brought In all cases(pre-FIRM or post-FIRM,V Zone or A Zone) into compliance. The building becomes a post FIRM where an entire building is destroyed or purposeful- ly demolished or razed, the replacement building is rates. Failure to comply with the substantial damage considered "new construction" and the replacement or substantial improvement requirements will result building must meet the current NFIP requirements, in a building's status being changed and in higher even if it is built on the foundation of the original flood insurance premiums. For example: building. If an NFIP-compliant enclosure built with break- away walls is added below a post-FIRM V Zone Moving an Existing Building building, the building will no longer be rated as When an existing building (pre FIRM or post FIRM, V "free of obstructions." Flood insurance premi- umsen- Zone or A Zone) is moved to a new location or site, on these buildings will be higher. If the the work is considered "new construction" and if the closure is not compliant with all NFIP require relocated building is in the SFHA, it must be installed ments, higher premiums will result. so as to comply with NFIP requirements. If work on an existing V Zone building constitutes a substantial improvement, the building will be Materials rated on a current actuarial basis. Any pre-FIRM When constructing in coastal environments, carefully designation will be lost and current post-FIRM rates will be used. consider what construction materials to select. The , .: • NFIP Technical Bulletin 2, Flood Damage-Resistant If an NFIP-compliant lateral addition constitut- Materials Requirements(August 2008),provides valu- ing a substantial improvement is made to a pre- : able information regarding the applicability of various FIRM A Zone building and no changes were made • construction materials in a coastal environment. For to the existing building,the building will retain its ffr:d. additional information, see Fact Sheet 1.7, Coastal pre-FIRM designation and rating. However, if the BuildingMaterials. Followinga storm event, repairs addition does not comply with all requirements, p P Y q should not be started until the problem is properly or if more than the minimum alteration neces- evaluated and materials are selected that will entire- sary was made to the existing building,the build- ly remedy the damage. All costs of repairs should be ing and addition's lowest floor must be elevat- identified and quantified prior to starting repairs. ed to or above the BFE. The building including the addition will be rated with post-FIRM actuari- Repairs al rates. Correction of only the apparent surface damage can and Remodeling Opportunities lead to unaddressed or overlooked problems be Retrofitemo g pp neath the surface that can potentially cause major Retrofit opportunities will likely present themselves issues with the structural stability of the building. any time repair or maintenance work is undertaken Proper inspections of damage often not only require for a major element of a building. Improvements to demolition or removal of the physically damaged the building that are made to increase resistance to 9.1: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING - FLOOD 6 of 7 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12.10 the effects of natural hazards should focus on those The installation should be done by a licensed items that will potentially return the largest benefit to plumber. the building owner. Some examples of retrofit oppor- If the current water heater is at,or below,the DFE, tunities may include: consider switching to a tankless water heater. Improving floor-framing-to-beam connections A tankless water heater will take up less space whenever they are accessible (see Fact Sheet and can be mounted to a wall due to its small 4.1, Load Paths and Fact Sheet 4.3, Use of Con- size. In addition to allowing the user to mount it nectors and Brackets for additional information). higher than a traditional water heater, it may also Improving beam-to-pile connections whenev result in reduced energy costs. er they are accessible (see Fact Sheet 3.3, Older structures should consider elevation as a Wood-Pile-to-Beam Connections for additional possible retrofit or mitigation opportunity. Older information). pre-FIRM structures can be at significant risk to Periodically checking and inspecting flood open- flooding events. In coastal environments, even a ►ngs to make sure that they are not blocked and little additional elevation can result in improved functioning properly. If the house is older,check to flood resistance. Costs can vary greatly depend make sure that flood openings are sized correct- ing on the type of foundation. It is important ly. Consult NFIP Technical Bulletin 1, Openings In when considering an elevation project to consult Foundation Walls and Walls of Enclosures (August a design professional before considering how 2008) for proper flood opening guidance. Also much elevation and the appropriate foundation see Fact Sheet 3.5, Foundation Walls for addi type. A contractor experienced with the elevation tional information. of buildings should be used for the actual lifting of the house. It is common for the house to re- At any time deficient metal connectors are found, quire other structural work to the interior and ex- they should be replaced with stainless steel con- terior following the elevation. Before undertak- nectors or metal connectors with proper corro- ing an elevation, consider the elevation process, sion protection, such as hot-dip galvanized steel which usually results in the structure being set (see Fact Sheet 1.7, Coastal Building Materials on top of a foundation that is more level than the for additional information). original foundation. This process can result in When HVAC equipment is replaced, the replace- cosmetic cracking as the structure's foundation settles again and may require additional work to ment equipment selected should incorporate structure's a more corrosion-resistant design—so that it get the will last longer in a coastal environment—and vation appearance. aesthetics back to a pre-ele- a should be elevated to, or above, the DFE. The equipment should be adequately anchored to re- sist wind and seismic loads (see Fact Sheet 8.3, Additional Resources Protecting Utilities for additional information). FEMA. 2010. Substantial Improvement/Substantial Improving utility attachments when the out- Damage Desk Reference. FEMA P-758. http://www. side equipment is replaced or relocated (see fema.gov/library/viewRecord.do?id=4160 Fact Sheet 8.3, Protecting Utilities for additional FEMA. 2005. Coastal Construction Manual, Chapter information). 14. FEMA 55. (http://www.fema.gov/library/viewRe- To minimize the effects of corrosion,carbon steel cord.do?id=1671) handrails can be replaced at any time with vinyl- Florida Department of Community Affairs. 2000. A coated, plastic, stainless steel, or wood hand- Local Official's Guide to Implementing the National rails. Wood handrails may require frequent treat- Flood Insurance Program in Florida. (See Chapter ment or painting and appropriate fasteners must 6). (http://www.floridadisaster.org/Mitigation/NFIP/ be used (see Fact Sheet 1.7, Coastal Building NFIPStudyCourse/Appendix%20E%20-%20FL%20 Materials for additional information). Carbon Handbook.pdf) steel handrails may also be painted with a zinc- rich,vinyl, or epoxy paint appropriate for exposed wet and salt-spray environments. Regardless of the product used, proper maintenance is always necessary in order to ensure a safe handrail. Consider sewer backflow preventer valves if they are not currently part of the building's plumbing. HB RNAESEARCH Developed in association with the National Association of Home Builders Research Center CENTER 9.1: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING — FLOOD HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 7 of 7 12/10 • � Remode1in ,airs Rep Additions, and Retrofitting Wind HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 9.2 Purpose: To outline requirements and"best practice"recommendations for repairs, remodeling,and additions, and propose opportunities for retrofitting in coastal high-wind areas. Key Issue i Repairs and remodeling- either before or after storm damage- provide many opportunities for 7111111 retrofitting homes and making 1 41 them more resistant to storm I. t ��` damage (see Figure 1). 'i ld i 1 O,a Code Compliance . • - '',.."'-4'., ,. .. „0 .,i,:. . , ‘ Definitions from the International ,, % , , 1,, Code Council (ICC) Model Building • , :, � Codes s., st.' ..• ....,,I � • Addition:An extension or increase in ..�- . floor area or height of a building or l 41 structure. '�a`-t' F . . Alteration: Any construction or reno- - vation to an existing structure other Figure 1. Storm-damaged homes need repairs,but also provide op- than repair or addition that requires portunities for renovation,additions,and retrofitting.Review substantial a permit. Also, a change in a me- damage and substantial improvement regulations before undertaking chanical system that involves an any work. extension,addition, or change to the arrangement,type, or purpose of the original installation that requires a permit. ii Repair:The reconstruction or renewal of any part of an m existing building for the purpose of its maintenance. International Residential Code (IRC) > Requirements for Additions,Alterations or Factors That Determine Whether and How Existing Repairs Buildings Must Comply With Current Building Code Requirements R102.7.1 Additions,alterations or repairs.Additions, When undertaking repairs, remodeling, additions, or alterations, or repairs to any structure shall con- improvements to an existing building, there are two form to the requirements for a new structure basic factors that determine whether and how the without requiring the existing structure to corn- existing building must comply with building code re- ply with all of the requirements of this code, quirements for new construction. unless otherwise stated. Additions, alterations, or repairs shall not cause an existing structure Value of damage/work-whether the value of the building damage and/or work qualifies as sub- to become unsafe or adversely affect the perfor- mance of the building. stantial damage or substantial improvement un- der NFIP regulations (see text box). _ 9.2: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING FEIIVIA. HOME BUILDER S GU DE TOCOASTAL CONSTR C ION -WIND 04 1 of 6 12/111 Nature of work—whether the work involves an ex- What Costs Are Included in Substantial Damage pansion of the building, either laterally or verti- and Substantial Improvement Determinations? cally (an addition), or the demolition and recon All structural Items and major building con- struction of an existing building,or the relocation of an existing building. ponents (e.g., foundations; beams; trusses; sheathing; walls and partitions; floors; ceilings; Two other factors occasionally come into play (con- roof covering; windows and doors; brick, stucco, suit the authority having jurisdiction [AHJ] regarding and siding; attached decks and porches). whether and how these factors apply): interior finish elements (e.g., tile, linoleum, Code violations— certain work to correct existing stone, carpet; plumbing fixtures; gypsum wall- violations of state or local health, sanitary, or board and wall finishes; built-in cabinets, book- safety code requirements that have been cited cases and furniture; hardware). by a code official may be excluded from calcu- Utility and service equipment (e.g., HVAC equip- lations of value of work used to determine sub ment; plumbing and wiring; light fixtures and ceil stantial improvement or substantial damage. ing fans; security systems; built-in appliances; Historic structures-work on a building that is on water filtration and conditioning systems). the National Register of Historic Places or that Market value of all labor and materials for re- has been designated as historic by federally cer pairs, demolition, and improvements, including tified state or local historic preservation offices management, supervision, overhead, and profit (or that is eligible for such designation) may be excluded from calculations of value of work used (do not discount volunteer or self-labor or donat- to determine substantial damage and substan— tial improvement requirements, provided such work does not cause the building to lose its his- What Costs Are Not Included in Substantial toric designation. Damage and Substantial Improvement Determinations? Substantial Damage and Substantial Design costs (e.g., plans and specifications, sur- Improvement veys and permits). It is not uncommon for existing coastal buildings Clean-up (e.g., debris removal, transportation, to be modified or expanded over time, often in con- and landfill costs). junction with the repair of storm damage.All repairs, Contents (e.g., furniture, rugs, appliances not remodeling, improvements, additions, and retrofit- built in). ting to buildings must be made in conformance with existing building code requirements pertaining to sub- Outside improvements (e.g., landscaping, irriga- stantial improvement and substantial damage. tion systems,sidewalks and patios,fences, light- ing, swimming pools and hot tubs, sheds, gaze- bos, detached garages). What Is Substantial Damage? Note: Some jurisdictions have enacted more restrictive requirements—some use a less-than- Substantial damage is damage, of any origin, 50-percent damage/improvement threshold. cc where the cost to restore the building to its pre- Some track the cumulative value of damage and Q damage condition equals or exceeds 50 percent improvements over time. Consult the AHJ for local of the building's market value before the damage requirements. occurred. What Is Substantial Improvement? Additions Substantial improvement is any reconstruction, Additions increase the square footage or external rehabilitation, addition, or improvement of a dimensions of a building. They can be divided into building,the cost of which equals or exceeds 50 lateral additions, vertical additions, and enclosures percent of the building's pre-improvement mar- of areas below existing buildings. When considering ket value. I additions, it is important to consider that changes to the shape and roof line of the structure may im- When repairs and improvements are made at the pact the potential damages to the house. A lateral same time, all costs are totaled and compared addition may change the number of openings, the with the 50 percent of market value threshold. way wind travels around the structure, or create a large open space that may require additional bracing. 9.2: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING -WIND 2 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Vertical additions may also impose greater loads on and windows. This does not suggest improper func- the existing structure. A qualified design professional tioning of the door or window, but this is more the should evaluate the loading to the entire structure to result of the pressures these openings are subjected see if additional structural modifications are required to during high-wind events. Interior surfaces such as in order to maintain the structure's ability to sustain walls, floor, and cabinets may be subjected to wa- high-wind loading. ter on a regular basis. These building components may require finishes that will resist repeated water Lateral Additions contact. If a lateral addition constitutes a substantial im- Repairs may present an excellent opportunity to provement to a building, both the addition and upgrade the house. Additional connectors for main- the existing building must comply with the cur- taining a load path, additional moisture barriers, rent wind loading requirements. The foundation, and installation of wind-resistant components are walls,and roof may need to be altered in order to some possible options. The section on "Retrofit and comply with wind loading requirements. Remodeling Opportunities" will outline some options to consider when undergoing repairs. Vertical Additions If a vertical addition to a building constitutes a substantial improvement, both the addition and the existing building must comply with the cur- r rent wind loading requirements. The foundation, 4PPI ' walls,and roof may need to be altered in order to comply with wind loading requirements. Vertical Olt 'eta ; additions may apply significantly higher loadings r I II to the foundation and first story, it is important i, _ - - to consider all of the framing and foundation modifications that need to be made (see Figure 2). Vertical additions may require the use of a geotechnical engineer and soil borings may be needed prior to design. Materials Figure 2. Vertical addition to a home damaged by Hurricane Fran.Preexisting 1-story home became the When constructing in coastal environments, carefully second story of a home elevated to meet new founda- consider what construction materials to select. For tion and floor elevation requirements. additional information, see Fact Sheet 1.7, Coastal Building Materials. Wind events can cause damage to several parts of the structure. Often the damage will Retrofit and Remodeling Opportunities consist of not only wind related damage, but also wa- ter intrusion. Following a storm event, repairs should Retrofit opportunities will present themselves every not be started until the problem is properly evaluated time repair or maintenance work is undertaken for and materials are selected that will entirely remedy a major element of the building. Improvements to the damage. the building that are made to increase resistance to the effects of natural hazards should focus on those 33 Repairs items that will potentially return the largest benefit to m the building owner. For example: D Correction of the apparent surface damage can lead to unaddressed or overlooked problems that can When the roof covering is replaced, the attach- cn cause major issues with the structural stability of the ment of the sheathing to the trusses or rafters building. Inspections often not only require demoli- can be checked,and additional load path connec- tion or removal of the physically damaged building tors can be installed as necessary. The Technical component, but also removal of associated exterior Fact Sheets located in Category 7 of this publi- cladding. Wind-driven rain can lead to compromised cation provide details on how to improve the roof connections and decaying or rotting building materi- system's ability to resist wind and water intru- als that may not be visible without more investigation. sion. The common elements of a roof system The repair of interior finishes damaged by wind driven should be carefully evaluated in order to address wa- rain should be carefully considered. Coastal build- opportunities to improve the load path and ings are often subjected to high-wind events, which ter resistance of the system. The most common many times are accompanied by wind driven rain. The repair necessary following a storm event is the wind pushes water through small openings in doors roof covering. When reroofing, tear-off is recom- mended instead of re-covering. Although some 9.2: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING -WIND HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 6 12/10 jurisdictions allow for reroofing,this method may Gable ends can be braced in conjunction with prevent the identification of more serious inade- other retrofits or by themselves. The illustration quacies in the system and result in more cata- in Figure 3 shows a typical gable end wall brac- strophic failures in the next event. A roof cover- ing system. These improvements are typically in- ing project should be viewed as an opportunity expensive, allow the loads imposed on the gable to evaluate the strength of the roof sheathing. end walls to be distributed through multiple roof With the removal of the roof covering, a careful trusses or rafters, and assist in distributing the inspection of the sheathing should be conduct- wind loads on the gable ends. Additional guid- ed to look for darkened areas or areas subject- ance for gable ends can be found in the Gable ed to water damage. If detected, these areas End Retrofit Guide- Florida Division of Emergency should be replaced. The thickness of the roof Management. sheathing should be inspected to verify that it Exterior siding attachment can be improved with is of a sufficient thickness to resist the design more fasteners at the time the exterior is re- wind speeds for your area. Also, consult the in coated. See Fact Sheet 5.3, Siding Installation in formation in Fact Sheet 7.1, Roof Sheathing High-Wind Regions for additional information. Installation, in order to improve roof system con- nections. Replacement of roof coverings also Window, door, and skylight reinforcement and at- may provide opportunities to evaluate the ade- tachment can be improved whenever they are ac- quacy of rafter or truss to wall system connec- cessible. Following a high-wind event, windows tions and install hurricane/seismic connectors. and doors should be checked for leaks. The fram- Information on these connections can be found ing should be checked for cracked paint or dis- in Fact Sheet 4.1, Load Paths and Fact Sheet colored paint. If the doors and windows are not 4.3, Use of Connectors and Brackets. shutting correctly, then this may indicate that the If siding or roof sheathing has to be replaced, framing around the window or door suffered wa- hurricane/seismic connectors can be installed ter damage. Check for worn areas where paint or at the rafter-to-wail or truss-to-wall connections, caulking is missing and investigate for water dam the exterior wall sheathing attachment can be age or intrusion. Repair any water-damaged areas checked, and structural sheathing can be added immediately. Framing should be inspected to veri- fY that it is sufficiently attached to the wall system to shearwalls. Adding wall-to-foundation ties may also be possible. Verify that all exterior sheath- to provide sufficient protection. Improperly framed ing (wall and roof) is approved for use on exteri- windows and doors have been found forced from their framing. See Fact Sheet 6.1, Window and or surfaces. Verify that fasteners are indeed con- necting the exterior sheathing to the framing. Door Installation for additional information. See Fact Sheet 4.1, Load Paths and Fact Sheet When windows and doors are replaced, glaz- 4.3, Use of Connectors and Brackets for addition- ing and framing can be used that is impact-re- al information. sistant and provides greater UV protection. The windows and doors must meet wind-resistance stan- dards and be installed in accor- Lateral dance with the manufacturer'sBracing installation instructions for high Truss , wind. Fasteners should be long enough to attach the window or Compression door to wall framing around the Blocking opening. Fasteners should be o- • Gable spaced no greater than 16 inch- Lt1 End Stud es unless otherwise stated by 4 Additional the manufacturer's recommend- '` Stud ed installation instructions. See Gable Fact Sheet 6.2, Protection of End Truss Openings-Shutters and Glazing, Bottom for additional information on \� Nord protecting openings. Verify that Truss doors meet ASTM E330 and Bottom DASMA 108 and that windows Chord Compression Double Lateral Blocking Top Plate meet ASTM E1886 and E1996 Bracing or Miami-Dade TAS 201, 202 and 203. Figure 3. Typical gable end wall bracing retrofit example. 9.2: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING -WIND 4 o' HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Soffits should be inspected following high-wind addition,the uplift resistance of the roof sheath- events to determine whether structural upgrades ing can be increased through the application of are necessary. Soffit failures are common dur- APA AFG-01 or ASTM 3498 (see additional re- ing storms and damage is often experienced in sources for more information) rated structural attics due to water being blown in through open adhesive at the joints between the roof sheath- soffits. Proper attachment is the most common ing and roof rafters or trusses. The adhesive problem noted with soffit failures. Wood back- should be applied in a continuous bead and ex- ing or supports should be installed in order to tended to the edges of the roof (where some of provide a structural member to attach the sof- the highest uplift pressures occur). At the last fit panels to. If it is not possible to install wood rafter or truss at gable ends,where only one side supports, the soffit should be secured at 12- of the joint is accessible, wood strips made of inch intervals on each side in order to limit its quarter-round molding may be embedded in the ability to flex during high-wind events. See Fact adhesive to increase the strength of the joint. Sheet 7.5, Minimizing Water Intrusion through For more information about the use of adhesive, Roof Vents in High-Wind Regions for additional see the "Additional Resources" section. information. The addition of air admittance valves (AAV) on Hurricane shutters can be added at any time all plumbing fixtures can reduce the need for roof (see Fact Sheet 6.2, Protection of Openings- penetrations required for conventional venting Shutters and Glazing). Shutter systems should systems. The reduction in roof penetrations will be purchased and installed well before a storm reduce roof maintenance and reduce the number event. It is important to take the time neces- of openings available for water penetration. AAVs sary to verify that hangers and attachment sys- are not allowed in all jurisdictions, so verify with a tems are properly anchored to the structural sys- licensed plumber that they are allowed in the ju- tem of the building. Shutter systems should be risdiction where the house is being constructed. anchored to the building and maintain the load At any time, garage doors should be reinforced path of the building. or replaced with new wind- and debris-resis- Floor-framing-to-beam connections can be im- tant doors. There are some reinforcement kits proved whenever they are accessible. See Fact available to provide both vertical and horizon- Sheet 4.1, Load Paths and Fact Sheet 4.3, tal reinforcement of the garage door. If the ga- Use of Connectors and Brackets for additional rage door requires replacement,then select one information. that meets the design wind-speed requirements for your area. See Fact Sheet 6.2, Protection of Beam-to-pile connections can be improved Openings- Shutters and Glazing, for addition- whenever they are accessible. See Fact Sheet al guidance on protecting openings and garage 3.3, Wood Pile-to-Beam Connections for addition- door guidance. al information. To minimize the effects of corrosion, metal light At any time, deficient metal connectors should fixtures can be replaced at any time with fixtures be replaced with stainless steel connectors or that have either wood or vinyl exteriors. However, metal connectors with proper corrosion protec- wood may require frequent treatment or painting. tion such as hot dip galvanized steel. See Fact See Fact Sheet 1.7, Coastal Building Materials „:40. Sheet 1.7, Coastal Building Materials for addi- for additional information. tional information. To minimize the effects of corrosion,carbon steel When HVAC equipment is replaced, the replace handrails can be replaced at any time with vinyl- oaf: E; ment equipment should be more durable so that coated, plastic, stainless steel, or wood hand- it will last longer in a coastal environment. It rails. Wood handrails may require frequent treat- should also be elevated at, or above, the Base ment or painting and appropriate fasteners must r 1i Flood Elevation (BFE) and adequately anchored be used (see Fact Sheet 1.7, Coastal Building to resist wind and seismic loads. See Fact Sheet Materials for additional information). Carbon • 8.3,Protecting Utilities for additional information. steel handrails may also be painted with a zinc- Utility attachment can be improved when the rich,vinyl, or epoxy paint appropriate for exposed outside equipment is replaced or relocated. See wet and salt-spray environments. Regardless of Fact Sheet 8.3, Protecting Utilities for additional the product used, proper maintenance is always information. necessary in order to ensure a safe handrail. In the attic space, at any time, straps should be added to rafters across the ridge beam, straps should be added from rafters to wall top plates, and gable end-wall framing should be braced. In 9.2: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING -WIND HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 5 of 6 12 10 Additional Resources APA-The Engineered Wood Association, 2001,APA Specification AFG-01. ASTM,Standard Specification for Adhesives for Field-Gluing Plywood to Lumber Framing for Floor Systems,2003, ASTM 3498-03. Clemson University, Not Ready to Re-Roof? Use Structural Adhesives to Strengthen the Attachment of Roof Sheathing and Holding on to Your Roof-A guide to retrofitting your roof sheathing using adhesives, Department of Civil Engineering and South Carolina Sea Grant Extension Program, (http://www.haznet.org/haz_outreach/ outreach_factsheets.htm) FEMA, Substantial Improvement/Substantial Damage Desk Reference FEMA P-758, 2010, (http://www.fema. gov/library/viewRecord.do?id=4160) FEMA, Coastal Construction Manual, FEMA-55, 2005, (http://www.fema.gov/library/viewRecord.do?id=1671) Florida Department of Community Affairs,A Local Official's Guide to Implementing the National Flood Insurance Program in Florida, 2000, (http://www.floridadisaster.org/Mitigation/NFIP/NFIPStudyCourse/Appendix%20 E%20%20FL%20Handbook.pdf) Florida Division of Emergency Management, Gable End Retrofit Guide. (http://www.floridadisaster.org/hrg) titfl.,,:i :::*. :;;-;_: A „ ..1 ,._: , 4 ,,, .... !:.„ HB RESEARCH Developed in association with the National Association of Home Builders Research Center ENTER 9.2: REPAIRS, REMODELING, ADDITIONS, AND RETROFITTING -WIND 6 of 6 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12'10 References and Resources HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. G.2 Purpose: To list references and resources that provide information relevant to topics covered by the Home Builder's Guide to Coastal Construction technical fact sheets. References A Dozen Things You Might Not Know That Make Bituminous Waterproofing. ASTM D6135-05. 2005. Vinyl Siding Green (http://vinylsiding.org/greenpa- (http://www.astm.org) 0 per/090710_Latest_Revised_Green_paper.pdf) C American Society for Testing and Materials. Standard D • American Concrete Institute. ACI Detailing Manual. Practice for Installation of Exterior Windows, Doors and m f SP-66(04). 2004. (http://www.concrete.org) Skylights. ASTM E2112-07. (http://www.astm.org) American Concrete Institute. Building Code Require- American Society for Testing and Materials. Standard ments for Structural Concrete and Commentary. ACI Specification for Round Timber Piles. ASTM D25-99. 318-02. (http://www.concrete.org) 2005. (http://www.astm.org) American Concrete Institute. Design, Manufacture, American Society for Testing and Materials. Standard and Installation of Concrete Piles. ACI 543R-00. Re- Specification for Adhesives for Field-Gluing Plywood to approved 2005. (http://www.concrete.org) Lumber Framing for Floor Systems. ASTM D3498-03. 2003. (http://www.astm.org) American Forest and Paper Association. National Design Specification for Wood Construction. (http:// American Society for Testing and Materials. Standard www.afandpa.org) Specification for Performance of Exterior Windows, Curtain Walls, Doors, and Impact Protective Systems American Institute of Timber Construction. (http:// Impacted by Windborne Debris in Hurricanes. ASTM www.aitc-glulam.org) E1996-09. (http://www.astm.org) American Institutes for Research. Evaluation of the American Society for Testing and Materials. Stan- National Flood Insurance Program's Building Stan- dard Test Method for Performance of Exterior Windows, dards. 2006. (http://www.fema.gov/library) Curtain Walls, Doors, and Impact Protective Systems American Iron and Steel Institute. North American Impacted by Missile(s) and Exposed to Cyclic Pressure Specification for the Design of Cold Formed Steel Differentials. ASTM E1886-05. (http://www.astm.org) Structural Members. AISI S100-07. 2007. (http:// American Society for Testing and Materials. Standard www.steel.org) Test Method for Structural Performance of Exterior American National Standards Institute. National De- Windows, Doors, Skylights and Curtain Walls by Uni- sign Standard for Metal Plate Connected Wood Truss form Static Air Pressure Difference. ASTM E330-02. Construction. ANSI/TPI-1 95. 2010. (http://www.astm.org) American Society of Civil Engineers. Minimum Design American Forest Foundation, Inc. American Tree Farm Loads for Buildings and Other Structures. ASCE/SEI System. (http://www.treefarmsystem.org/index.shtml) 7-05. (http://www.asce.org) American Wood Council. (http://www.awc.org) American Society of Civil Engineers. Minimum Design American Wood Protection Association. All Timber Loads for Buildings and Other Structures. ASCE/SEI Products - Preservative Treatment by Pressure Pro- 7-10. (http://www.asce.org) cesses, AWPA C1-00; Lumber, Timber, Bridge Ties American Society of Civil Engineers. Flood Resistant and Mine Ties - Preservative Treatment by Pressure Design and Construction. ASCE/SEI 24-05. (http:// Processes, AWPA C2-01; Piles - Preservative Treat- www.asce.org) ment by Pressure Process, AWPA C3-99; and others. (http://www.awpa.com) American Society for Testing and Materials. Stan APA, The Engineered Wood Association. APA Specifi- dard Practice for Application of Self-Adhering Modified cation AFG-0/. 2001. (http://www.apawood.org) 1 G.2: REFERENCES AND RESOURCES °s "Y'o� FEI\4.A HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 1 of 4 tiND SEA 12/10 APA, The Engineered Wood Association. Hurricane FEMA. Engineering Principles and Practices of Shutter Designs Set 5 of 5. Hurricane Shutter Designs Retrofitting Floodprone Residential Structures. FEMA for Woodframe and Masonry Buildings. (http://www. 259. January 1995. (http://www.fema.gov/library) apawood.org) FEMA. Flood Insurance Manual. October 2010, Jan- Brick Industry Association. (http://www.gobrick.com) uary 2011. (http://www.fema.gov/business/nfip/ manual.shtm) Clemson University, Department of Civil Engineering and South Carolina Sea Grant Extension Program. FEMA. FloodSmart, the Official Site of the NFIP Not Ready to Re-Roof? Use Structural Adhesives to (http://www.floodsmart.gov) Strengthen the Attachment of Roof Sheathing and Holding onto Your Roof-A Guide to Retrofitting Your FEMA. Homebuilders' Guide to Earthquake Resistant Roof Sheathing UsingAdhesives. (http://www.haznet. Design and Construction. FEMA 232. 2001. (http:// org/haz_outreach/outreach_factsheets.htm) www.fema.gov/library) GpCoastal Contractor Magazine. Low Country Rx: Wet FEMA. Homeowner's Guide to Retrofitting, Six Ways to 5 Floodproofing. Drainable, Dryable Assemblies Made Protect Your House From Flooding. FEMA 312. 1998. 0 With Water-tolerant Materials Help Speed Recovery (http://www.fema.gov/library) From Deeper Than-expected Floods, by Ted Cush- FEMA. Map Service Center.(http://www.msc.fema.gov) man. July 2006. (http://www.coastalcontractor.net/ cgi-bin/issue.pl?issue=9) FEMA. Mitigation Assessment Team Report, Hurricane Concrete Reinforcing Steel Institute. Placing Rein Charley in Florida: Building Performance Observa- forcing Bars - Recommended Practices. PRB-2-99. tions, Recommendations, and Technical Guidance. (http://www.crsi.org) FEMA 488. 2005. (http://www.fema.gov/library) Copper and Common Sense. (http://www.reverecop- FEMA. Mitigation Assessment Team Report, Hurricane Ike in Texas and Louisiana: Building Per- per.com) formance Observations, Recommendations, and Copper Development Association. (http://www.cop- Technical Guidance. FEMA P-757. 2009. (http:// per.org/publications) www.fema.gov/library) Door and Access Systems Manufacturers Associa- FEMA. Mitigation Assessment Team Report, tion. Standard Method for Testing Sectional Garage Hurricane Ivan in Alabama and Florida: Building Doors and Rolling Doors: Determination of Structural Performance Observations, Recommendations, and Performance Under Uniform Static Air Pressure Differ- Technical Guidance. FEMA 489. 2005. (http://www. ence. ANSI/DASMA 108-2005. fema.gov/library) FEMA. Above the Flood: Elevating Your Floodprone FEMA. Mitigation Assessment Team Report, Hurricane House. FEMA 347. 2000. (http://www.fema.gov/ Katrina in the Gulf Coast:Building Performance Obser- library) vations, Recommendations, and Technical Guidance. FEMA 549. 2006. (http://www.fema.gov/library) FEMA.Answers to Questions about Substantially Dam- aged Buildings. FEMA 213. 1991. (http://www.fema. FEMA. NFIP Elevation Certificate and Instructions. gov/library) (http://www.fema.gov/pdf/nfip/elvicert.pdf) FEMA. Coastal Construction Manual - Principles and FEMA. NFIP Forms. (http://www.fema.gov/busi- Practices of Planning, Siting, Designing, Construct- ness/nfip/forms.shtm) ing, and Maintaining Residential Buildings in Coastal FEMA. NFIP Technical Bulletin 1-08, Openings in Areas. FEMA 55. 2005. (Ordering information at: Foundation Walls and Walls of Enclosures. 2008. http://www.fema.gov/pdf/plan/prevent/nhp/nhp_ (http://www.fema.gov/plan/prevent/floodplain/ fema55.pdf) techbul.shtm) FEMA. Design Guide for Improving Critical Facility FEMA. NFIP Technical Bulletin 2-08, Flood Damage- Safety from Flooding and High Winds. FEMA 543. Resistant Materials Requirements. (http://www. 2007. (http://www.fema.gov/library) fema.gov/plan/prevent/floodplain/techbul.shtm) FEMA. Design Guide for Improving Hospital Safety in FEMA. NFIP Technical Bulletin 4-10, Elevator Instal- Earthquakes, Floods, and High Winds: Providing Pro- lation. 2010. (http://www.fema.gov/plan/prevent/ tection to People and Buildings. FEMA 577. 2007. floodplain/techbul.shtm) (http://www.fema.gov/library) G.2: REFERENCES AND RESOURCES 2 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12/iu t 1 FEMA. NFIP Technical Bulletin 5-08, Free-of-Obstruc- International Code Council. International Building tion Requirements. 2008. (http://www.fema.gov/ Code. 2009. (http://www.iccsafe.org) plan/prevent/floodplain/techbul.shtm) International Code Council. International Residential FEMA. NFIP Technical Bulletin 8-96, Corrosion Pro- Code. 2009. (http://www.iccsafe.org) tection for Metal Connectors in Coastal Areas. 1996. (http://www.fema.gov/plan/prevent/floodplain/ International Code Council Evaluation Service, Inc., techbul.shtm) Protocol for Testing the Flood Resistance of Materials. (http://www.icc-es.org/index.shtml) FEMA. NFIP Technical Bulletin 9-08, Design and Construction Guidance for Breakaway Walls. 2008. International Organization of Standards. Document (http://www.fema.gov/plan/prevent/floodplain/ ISO 14021. (http://www.iso.org) techbul.shtm) LSU AgCenter. Wet Floodproofing. Reducing Dam- FEMA. NFIP Technical Bulletin 10-01, Ensuring that age from Floods. Publication 2771. 1999. (http:// Structures Built on Fill In or Near Special Flood Haz- www.Isuagcenter.com/NR/rdonlyres/B2B6CDEC- _ and Areas are Reasonably Safe From Flooding. 2001. 2B58-472E-BBD9-OBDEBOB29C4A/26120/ c (http://www.fema.gov/plan/prevent/floodplain/ pub2771Wet6.pdf) techbul.shtm) Metal Building Manufacturers Association. Metal FEMA. NFIP Technical Bulletin 11-01, Crawlspace Roofing Systems Design Manual. 2000. (http://www. Construction. 2001. (http://www.fema.gov/plan/ mbma.com/display.cfm?p=44&pp6&i=47) prevent/floodplain/techbul.shtm) Metal Construction Association. (http://www.metalc- FEMA. Protecting Building Utilities From Flood Damage. onstruction.org/pubs) FEMA 348. 1999. (http://www.fema.gov/library) National Roofing Contractors Association. The NRCA FEMA. Protecting Manufactured Homes from Floods Waterproofing Manual. (http://www.nrca.net) and Other Hazards. FEMA P-85. 2009. (http://www. National Fire Protection Association. Model Man- fema.gov/library) ufactured Home Installation Standard. NFPA 225. FEMA. Recommended Residential Construction for 2009. (http://www.nfpa.org/aboutthecodes/About- the Gulf Coast, Building on Strong and Safe Foun- TheCodes.asp?DocNum=225&cookie_test=1) dations. FEMA 550. 2010. (http://www.fema.gov/ National Institute of Building Sciences. Whole Build- library) ing Design Guide. (http://www.wbdg.org/design/ FEMA. Reducing Flood Losses Through the Inter- env_roofing.php) national Code Series. 2006 I-Codes with 2007 National Roofing Contractors Association. The NRCA Supplement. (http://www.fema.gov/library) Roofing Manual: Metal Panel and SPF Roof Systems. FEMA. Substantial Improvement/Substantial Damage 2008. (http://www.nrca.net/rp/technical/manual/ Desk Reference. FEMA P-758. 2010. (http://www. default.aspx) fema.gov/library) Pile Buck, Inc. Coastal Construction. (http://www. Florida Department of Community Affairs. A Local pilebuck.com) Official's Guide to Implementing the National Flood Professional Roofing. NRCA Analyzes and Tests Insurance Program in Florida. 2000. (http://www.flor- Metal, by James R. Kirby and Bala Sockalingam. idadisaster.org/Mitigation/NFIP/NFIPStudyCourse/ 2003. (http://www.professionalroofing.net/article. Appendix%20E%20-%20FL%20Handbook.pdf) aspx?id=266) Florida Division of Emergency Management. Hurricane The Journal of Light Construction. (http://www.jlcon- Retrofit Guide. (http://www.floridadisaster.org/hrg) line.com) Florida Roofing, Sheet Metal and Air Conditioning The Masonry Society. Building Code Requirements Contractor's Association, Inc. Concrete and Clay Roof for Masonry Structures. TMS 402-08/ACI 530-08/ Tile Installation Manual. (http://www.floridaroof.com) ASCE 5-08. 2008. (http://www.masonrysociety.org) Forest Stewardship Council. (http://www.fsc-info.org) The Masonry Society. Specifications for Masonry Information about product testing and approval pro- Structures. TMS 402-08/ACI 530.1 08/ASCE 6-08. cess for Miami-Dade County, Florida. (http://www. 2008. (http://www.masonrysociety.org) miamidade.gov/BuildingCode/home.asp) G.2: REFERENCES AND RESOURCES HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 3 of 4 1210 Sheet Metal and Air Conditioning Contractors Na- Technical Notes 28B—Brick Veneer/Steel Stud Walls tional Association.Architectural Sheet Metal Manual. 2003. (http://www.smacna.org/bookstore) Technical Notes 44B—Wall Ties Siding with the Environment (http://www.vinylsiding. Timber Pile Council,American Wood Preservers Insti- org/publications/final_Enviro_single_pg.pdf).South- tute. Timber Pile Design and Construction Manual. ern Pine Council. (http://www.southernpine.com/ (http://www.wwpinstitute.org/pdffiles/TimberPile- about.shtml) Manual.pdf) SFI Inc. Sustainable Forestry Initiative.® (http://www. U.S. Department of Housing and Urban Develop- sfiprogram.org) ment. Durability by Design, A Guide for Residential Builders and Designers. 2002. (http://www.huduser. Technical Notes 28 — Anchored Brick Veneer, Wood org/publications/destech/durdesign.html) Frame Construction Vinyl Siding Institute. (http://www.vinylsiding.org) 0 5 0 NAHB RESEARCH Developed in association with the National Association of Home Builders Research Center CENTER G.2: REFERENCES AND RESOURCES 4 of 4 HOME BUILDER'S GUIDE TO COASTAL CONSTRUCTION 12,10