Item H15BOARD OF COUNTY COMMISSIONERS
AGENDA ITEM SUMMARY
Meeting Date: September 16, 2015 Department: Building
Bulk Item: Yes X No Staff Contact Person/Phone #: Christine Hurley, 289-2517
T Ed Koconis, 453-8727
AGENDA ITEM WORDING: Approval of 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).
ITEM BACKGROUND: Chapter 122 of the Monroe County Code "Floodplain Management"
includes rules for interpreting flood hazard issues. 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 from time to time by the board of county commissioners. FEMA's Technical Bulletins
("bulletins") provide guidance concerning the building performance standards of the National Flood
Insurance Program (NFIP), which are contained in Title 44 of the U.S. Code of Federal Regulations.
The bulletins are intended for use primarily by State and local officials responsible for interpreting and
enforcing NFIP regulations and by members of the development community, such as design
professionals and builders. New bulletins, as well as updates to existing bulletins, are issued
periodically as needed. The bulletins do not create regulations; rather they provide specific guidance
for complying with the minimum requirements of existing NFIP regulations. Adopting these
documents as well as internal County policies would serve to allow the County to not only remain in
the NFIP as stated in Section 122-1(b), but also to move forward with the intent of becoming eligible
to enter FEMA's Community Rating System (CRS). The proposed resolution would adopt FEMA P-
499, "Home Builder's Guide to Coastal Construction" dated December 2010 as required pursuant to
Monroe County Code Section 122-2(c).
PREVIOUS RELEVANT BOCC ACTION:
January 18, 1994 — BOCC approved Ordinance No. 002-1994 adding the language "as adopted by
resolution from time to time by the Board of County Commissioners" to the rules for interpreting flood
hazard issues.
July 15, 2015 — BOCC rejected proposed ordinance amending Section 122-2(c) and directed staff to
continue proposing resolutions for adoption of both new and amended documents to be used by the
building official for guidance on Floodplain management.
CONTRACT/AGREEMENT CHANGES: NIA
STAFF RECOMMENDATION: Approval
TOTAL COST: NIA INDIRECT COST: NIA BUDGETED: Yes No NIA
DIFFERENTIAL OF LOCAL PREFERENCE: NIA
COST TO COUNTY: NIA SOURCE OF FUNDS: NIA
REVENUE PRODUCING: Yes _ No NIA AMOUNT PER MONTH NIA Year
APPROVED BY: County Atty X % lk OMB/Purchasing Risk Management _
DOCUMENTATION: Included X Not Required_
DISPOSITION: AGENDA ITEM #
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MONROE COUNTY, FLORIDA
MONROE COUNTY BOARD OF COUNTY COMMISSIONERS
RESOLUTION NO. - 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.
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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
Mayor pro tem Heather Carruthers
Commissioner Sylvia Murphy
Commissioner George Neugent
Commissioner David Rice
BOARD OF COUNTY COMMISSIONERS
OF MONROE COUNTY, FLORIDA
(SEAL)
ATTEST: AMY HEAVILIN, CLERK
Deputy Clerk
Mayor Danny L. Kolhage
MONROE COUNTY ATTORNEY
PROVED AS ]�Q FORM:
%.1..1511..��_
STEVEN T. WILLIAMS
ASSISTANT OUNTY ATTORNEY
Date
..
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•'-�?�:C'-.;Y?-•'(,r
Home Builder's Guide
to Coastal Construction
Technical Fact Sheet Series
FEMA P-499 / December 2010
ZA)K9 iF �
ti
Coastal Construction
Fact Sheet Series
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
sheets make extensive use of photographs and drawings to illustrate National Flood Insurance Program
(NFIP) regulatory requirements, the proper siting of coastal buildings, and recommended design and
construction practices, including structural connec-
tions, the building envelope, utilities, and accessory
structures. In addition, many of the fact sheets in-
clude lists of additional resources that provide more
information about the topics discussed.
Available Fact Sheets
The following 37 fact sheets are also available on the
FEMA website (www.fema.gov) as Adobe° Portable
Document Format (PDF) files and as plain text (.txt) files.
You must have Adobe° Reader to view the PDF files.
The latest version of Adobe Reader is recommended.
Download the free Reader from www.adobe.com.
Category 1 — General
Fact Sheet No. 1.1, Coastal
Building Successes and Fail-
ures — Explains how coastal
construction requirements
differ from those for inland
--_--- -- construction, and discusses
the characteristics that make
for a successful coastal res-
idential building. Includes
design and construction recommendations for
achieving building success.
Fact Sheet No. 1.2, Summary of
Coastal Construction Require-
ments and Recommendations
for Flood Effects — Summa-
--. --- _- = rizes recommendations for
exceeding NFIP regulatory
requirements for new con-
struction and for repairs,
remodeling, and additions.
Topics include building foundations, enclosures
below the Base Flood Elevation (BFE), use of
nonstructural fill, use of space below the BFE,
utilities, certification requirements, and repairs,
remodeling, and additions. Cross-references to
related fact sheets are provided.
FEMA
._ .a
Fact Sheet No. 1.3, Using a Dig-
ital Flood Insurance Rate Map
(DFIRM) — Explains the pur-
__ pose of Flood Insurance Rate
— -`-: Maps (FIRMs) and Digital
- Flood Insurance Rate Maps
(DFIRMs); highlights features
that are important to coastal
builders, including flood zones
and flood elevations; and ex-
plains how to obtain FIRMs, DFIRMs, and Flood
Insurance Studies (FISs).
Fact Sheet No. 1.4, Low-
est Floor Elevation — Defines
"lowest floor," discusses ben-
efits of exceeding the NFIP
— minimum building elevation
-------------- ---- -- requirements, identifies com-
mon construction practices
- that are violations of NFIP
regulations, which result in
significantly higher flood insurance premiums;
and discusses the NFIP Elevation Certificate.
Also includes a copy of the certificate.
HOME BUILDER W-DETO COASTAL CONSTRUCTION f ":;..
12/10
Fact Sheet No. 1.5, V Zone De-
"'""`' sign Certification — Explains
�_ the certification requirements
_ == = __= for structural design and
methods of construction in V
Zones. Also includes a copy
of a sample certificate and
explains how to complete it.
Fact Sheet No. 1.6, Design-
ing for Flood Levels Above the
_- . - BFE — Recommends design
00&m and construction practices
that reduce the likelihood of
- flood damage in the event
_- -. that flood levels exceed the
BFE. It includes illustrations
of appropriate construction
practices and information on the insurance ben-
efits of building above the BFE.
Fact Sheet No. 1.7, Coastal
Building Materials — Provides
__ _ guidance and best practices
on the selection of building
materials used for coastal
construction. Flood, wind, cor-
-__—_ -_ rosion, and decay resistance
...;; are discussed, including pro-
tection recommendations.
Fact Sheet No. 1.8, Non -Tradi-
tional Building Materials and
Systems — Provides guidance
on alternative building ma
terials and techniques and
_ their application in coastal
environments. It includes dis-
cussions of Engineered Wood
Products, Structural Insulated
Panels, Insulating Concrete Forms, Prefabricat-
ed Shear Walls and Moment Frames, Sprayed
Closed -Cell Foam Insulation, Advanced Wall
Framing, and Modular Houses.
Fact Sheet No. 1.9, Moisture
Barrier Systems — Describes
the moisture barrier system,
explains how typical wall mois-
t ture barrier systems work, and
discusses common problems
associated with moisture bar-
;',; rier systems.
Category 2 — Planning
Fact Sheet No. 2.1, How Do
Siting and Design Decisions
- Affect the Owner's Costs? —
Discusses effects of planning,
= siting, and design decisions
on coastal home costs. Topics
_ - include initial, operating, and
long-term costs; risk deter-
mination; and the effect on
costs of meeting and exceeding code and NFIP
design and construction requirements.
Fact Sheet No. 2.2, Selecting
a Lot and Siting the Building —
Presents guidance concerning
lot selection and building sit-
_ _ ... - .. ing considerations for coastal
residential buildings. Topics
-- -- include factors that constrain
siting decisions, coastal set-
back lines, common siting
problems, and suggestions for builders, design-
ers, and owners.
Category 3 — Foundations
Fact Sheet No. 3.1,
Foundations in Coastal Areas —
Explains foundation design
criteria and describes foun-
dation types suitable for
-_ - -- coastal environments. Also
addresses foundations for
- high -elevation coastal areas
(e.g., bluff areas).
Fact Sheet No. 3.2, Pile Design
and Installation— Presents ba-
sic information about pile
design and installation, in-
cluding pile types, sizes
_ - and lengths, layout, installa
tion methods, bracing, field
cutting, connections, and veri-
fying capacities.
:,.. FactSheetNo. 3.3,WoodPile-to-
Beam Connections — Illustrates
typical wood -pile -to -beam
connections; presents ba
- = sic construction guidance
T for various connection meth
=Y ods, including connections
for misaligned piles; and illus
trates pile bracing connection
techniques.
,
12/10
Fact Sheet No. 3.4, Reinforced
Masonry Pier 6On0zU[u0n—
Provdoa an alternative to
piles in VZonoa and AZonoa
in coastal areas vvhoro soil
properties preclude pile in'
a1aUa1ion, but the need for
an "open foundation sys-
tem" a1i|| exists. |no|udoa
recommendations for good masonry pnuo1iooa in
coastal environments.
F8C1 Sheet NO 3.5, Founda-
tion VV8N— Diaouaaoa and
illustrates the use of foun'
da1ion weUa in coastal
buildings. Topics include foot-
ing embedment, we|| height,
materials and workmanship,
lateral support, flood openings
and ventilation ro0uiromon1a,
and interior grade elevations
fororaw|apaooa.
Category 4 — Load Paths
Fact Sheet No. 4.1, Load
P81U8— |||ua1ra1oa the con-
--
oopt of load paths and
highlights important connec-
tions in a typical wind uplift
load path.
Fact Sheet No. 4.2, Masonry
D0t8|N— Illustrates important
roof -to -wall and we||-to-foun'
da1ion connection details
for masonry construction in
coastal areas. Topics include
load paths, building ma1ori'
a|a, and reinforcement.
F8C1 Sheet NO. 4.3, Use OY
COnn0C1Or8 and Br8Ck018—
|||ua1ra1oa important building
connections and the proper
use of connection hardware
throughout abuilding.
COASTALC��STRUCT|O�F'ACTSE]B|E�j
Category 5—Wall Systems
Fact Sheet No. 5.1. House
wrap— Explains the function
of houamwnuA examines its
attribu1oa, and addresses
common problems aaaooiat
odwith its use. Topics include
houamwnupva. building paper
and housewrap installation.
Fact Sheet No. ROOY-tO-VV8|
and D0Ck-t]-VV8U Flashing —
Emphasizes the importance
ofproper roof and deck flash
ing, and presents typical and
enhanced flashing techniques
for coastal homes.
Fact Sheet No.
|ng Installation in High -Wind
R0g|OO8— Provides basic de-
sign and installation tips for
various types of aiding for
high -wind regions, including
vinyl, wood, and fiber cement
and diaouaaoa sustainable
design issues.
Fact Sheet No. 5.4, Attachment
OYBrick Veneer UlHigh-Wind R0-
gK]n8—Provdoar000mmondod
pnuo1iooa for installing brick
veneer that will enhance wind
roaia1anoo in high wind re'
giona. Examples of proper
installations and brick veneer
tie spacings are provided.
Category 6-Openings
Fact Sheet No. 6.1. Window
and Door Installation— Pres-
ents flashing detail concepts
for window and door openings
that provide adequate roaia'
1anoo to water intrusion in
coastal environments, do not
dopondsolely onsealants, are
integral with secondary weath-
er barriora(o.g.,houaovvnup),andaroado0ua1o|y
attached 10the wall. Topics include the Ameri-
can Society for Testing and K4a1oria|a (ASTK4)
Standard E 2112 and specific considerations
concerning pan f|ashin8s. Exterior Insulation Fin-
ishing Systems, frame anchoring, shutters, and
weatherstripping.
HOME BUULDER"S GUIDE TOCOASTAL CONSTRUCTION
Fact Sheet No. 6.2, Protection
' " ` of Openings — Shutters and
Glazing— Presents informa-
tion about the selection and
installation of storm shutters
and impact resistant glazing
_- and other types of opening
protection in windborne de-
bris regions. Shutter types
addressed include temporary plywood panels;
temporary manufactured panels; permanent,
manual closing; and permanent, motor -driven.
Category 7 Roofing
Fact Sheet No. 7.1, Roof
Sheathing Installation— Pres-
ents information about proper
........ . roof sheathing installation
and its importance in coastal
construction; also discuss-
es fastening methods that
-------------
will enhance the durability
of a building in a high -wind
area. Topics include sheathing types and layout
methods for gable -end and hip roofs, fastener se-
lection and spacing, the treatment of ridge vents
and ladder framing, and common sheathing at-
tachment mistakes.
Fact Sheet No. 7.2, Roof Un-
derlayment for Asphalt Shingle
-, Roofs— Presents recommend-
-- — = ed practices for the use
of roofing underlayment
as an enhanced second-
-= I ary water barrier in coastal
- environments. Optional instal-
lation methods are illustrated.
Fact Sheet No. 7.3, Asphalt
Shingle Roofing for High -Wind
Regions— Recommends prac-
tices for installing asphalt roof
shingles that will enhance the
:' wind resistance of roof cov-
erings in high -wind, coastal
regions. Issues include in-
stallation at hips, eaves, and
ridges; shingle characteristics; weathering and
durability; and wind resistance.
Fact Sheet No. 7.4, Tile Roofing
for High -Wind Areas— Pres-
ents design and construction
guidance for ti le roofing attach
_ ment methods. Topics include
uplift loads, uplift resistance,
special considerations con-
3;,,;: ' cerning tile attachment at
hips and ridges, tile installation on critical and
essential buildings, and quality control.
Fact Sheet No. 7.5, Minimiz-
ing Water Intrusion through
Roof Vents in High -Wind Re-
gions— Describes practices
for minimizing water intrusion
_ - through roof vent systems,
which can lead to interior
s- =- - damage and mold growth in
high -wind regions. Topics in-
clude soffit vents, ridge vents, gable end vents,
off -ridge vents, gable rake vents, and turbines.
Fact Sheet No. 7.6, Metal Roof
Systems in High -Wind Re-
_ gions— Presents design and
_ installation guidance for met-
al roofing systems that will
enhance wind -resistance in
-: high -wind regions. Discus-
'; sions on sustainable design
options are included.
Category 8 - Attachments
Fact Sheet No. 8.1, Enclosures
and Breakaway Walls— Dis-
cusses requirements and
recommendations for enclo-
sures and breakaway walls
for their use below the BFE. It
_ includes a diagram of a compli
ant wall system and examples
of systems that have either re-
sulted in increased damages
or increased flood insurance premiums.
Fact Sheet No. 8.2, Decks,
Pools, and Accessory Struc-
tures— Summarizes NFIP
j� requirements, general guide-
-_ lines, and recommendations
concerning the construction
- and installation of decks, ac-
cess stairs and elevators,
swimming pools, and acces-
sory buildings under or near coastal residential
buildings.
Fact Sheet No. 8.3, Protecting
Utilities— Identifies the spe-
cial considerations that must
- - ---- be made when installing utility
equipment, such as fuel, sew
age, and water/sewage lines
- =-=�- in a coastal home, and pres-
ents recommendations for
utility protection.
4 ,f
12/10
CategoryRepairs
Fac1 Sheet No. 9.1 Repairs,
Remodeling, Additions, and
Retrofitting - Flood— Outlines
NFIPrequirements for repairs,
remodeling, and additions,
and diaouaaoa opportunities
for retrofitting incoastal flood
hazard areas. Also proaon1a
recommendations for exceed-
ing the minimum NF|P requirements. Definitions
of "substantial damage" and "substantial im-
provement" are included.
Fact Sheet No. 9.2, Repairs,
Remodeling, Additions, and
Retrofitting - Wind— Outlines
requirements and makes
"best practice" recommenda-
tions for repairs, remodeling,
and additions, and discusses
opportunities for retrofitting
in coastal high wind areas.
Category G - Guide
Fact Sheet No. FL2References
and Resources— Lists referenc-
es that provide information
relevant to topics covered by
the Home Builder's Guide to
Coastal Construction technical
fact sheets.
FEMAP-499 Home Builder's Guide to Coastal Construction— 2BB5tn201B Crosswalk
==121011031MEM
121:l=
G 1
Technical Fact Sheet Guide
General
1
1
Coastal Building Success and Failures
1
General
1
2
Summary of Coastal Construction Requirements
and Recommendations for Flood Effects
2
General
1
3
Using a Digital Flood Insurance Rate Map
3
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
Owner's Costs?
6
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
�OASTALC0��TRUCT|O�F�CTSH�ETS�B|E�
HOME BMDER"S GUIDE TOCOASTAL CONSTRUCTION
=1=MEEE=1=iffiffl
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 Installationin High -Wind Regions
25
Wall Systems
5
4
Attachment of Brick Veneer in High; Wind Regions
New
Openings
6
1
Window and Door Installation
22
Openings
6
2
Protection of Openings - Shutters and Glazing
26
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
High -Wind) Regions
New
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
g
1
Repairs, Remodeling, Additions and Retrofitting -
Flood
30
Repairs
9
2
Repairs, Remodeling, Additions and Retrofitting -
Wind
30
nv
6
2
References and Resources
31
t t~JAHl
'.„ RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E R
1-,1: r3 "'ASIA.. CDINIwr,F 4 1I ;:. rIN I:: I...I.:.I vI 1.1.:.
12/10
Coastal Building Successes
and Failures
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.
Is Coastal Construction That Different From
Inland Construction?
The short answer is yes, building in a coastal environ-
ment is different from building in an inland area:
Flood levels, velocities, and wave action in coast-
al areas tend to make coastal flooding more
damaging than inland flooding.
Coastal erosion can undermine buildings and de-
stroy land, roads, utilities, and infrastructure.
Wind speeds are typically higher in coastal areas
and require stronger engineered building connec-
tions and more closely spaced nailing of building
sheathing, siding, and roof shingles.
Wind -driven rain, corrosion, and decay are fre-
quent concerns in coastal areas.
In general, homes in coastal areas must be designed
and built to withstand higher loads and more extreme
conditions. Homes in coastal areas will require more
maintenance and upkeep. Because of their expo-
sure to higher loads and extreme conditions, homes
in coastal areas will cost more to design, construct,
maintain, repair, and insure.
Building Success
In order for a coastal building to be considered a
"success," four things must occur:
The building must be designed to withstand
coastal forces and conditions.
The building must be constructed as designed.
The building must be sited so that erosion
does not undermine the building or render it
uninhabitable.
The building must be maintained/repaired.
FEMA
._ .a
A well-built but poorly sited building can be under-
mined and will not be a success (see Figure 1).
Even if a building is set back or situated farther
from the coastline, it will not perform well (i.e., will
not be a success) if it is incapable of resisting high
winds and other hazards that occur at the site (see
Figure 2).
Figure 2. Well -sited building that still sustained damage.
HOME BUILDER IETO COASTAL CONSTRUCTION
12/10
Recommended Practice
0 Siting— Site buildings away from
eroding shorelines and high -haz-
ard areas.
0 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 1oover-
turning. Each of
1hoao problems
can be overcome -~�o
through the de-
sign process, but U[
each must receive
special attention. In
the design process, choose
moderate -sloped hip roofs (4/1210
0/12)ifpossible.
LOw081 F|OO[ E|0V81|OO— Elevate above the DFE
the bottom of the lowest horizontal structur-
al member supporting the lowest floor. Add
"freeboard" to reduce damage and lower flood
insurance premiums.
orfinish enclosed areas below the DFE(owners
tend to convert these areas to habitable uses,
which is prohibited under the National Flood
|naununoo Program and will lead to additional
flood damage and economic |oss).
Free OYObstructions— Use an open foundation. Foundation— Make sure the foundation is deep
Do not obstruct the area below the o|ova1od enough to roaia1 the ofh*o1a of scour and
portion of the building. Avoid or minimize the erosion; strong enough to roaia1 wave, cur -
use of breakaway walls. Do not install utilities rent, flood, and debris forces; and capable of
LBU|LD1NG AWDFA|LUBES
2ofB
HOME BU|LDEWS GU|DET000ASTAL CONSTRUCTION
transferring wind and seismic forces on upper
stories to the ground.
connections— Key connections include roof
sheathing, roof -to -wall, wall-to-wall, and walls -
to -foundation. Be sure these connections are
constructed according to the design. Bolts,
screws, and ring-shanked nails are common re-
quirements. Standard connection details and
nailing should be identified on the plans.
Exterior Walls— Use structural sheathing in high -
wind areas for increased wall strength. Use
tighter nailing schedules for attaching sheath-
ing. Care should be taken not to over -drive
pneumatically driven nails. This can result in
loss of shear capacity in shearwalls.
Windows and Glass Doors— In high -wind areas,
use windows and doors capable of withstand-
ing increased wind pressures. In windborne
debris areas, use impact -resistant glazing or
shutters.
Flashing and Weather Barriers— Use stronger
connections and improved flashing for roofs,
walls, doors, and windows and other openings.
Properly installed secondary moisture barriers,
such as housewrap or building paper, can re-
duce water intrusion from wind -driven rain.
Roof— In high -wind areas, select appropriate roof
coverings and pay close attention to detailing.
Avoid roof tiles in hurricane -prone areas.
Porch Roofs and Roof overhangs— Design and tie
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
have enhanced corrosion protection.
Mechanical and Utilities— Electrical boxes, HVAC
equipment, and other equipment should be el-
evated to avoid flood damage and strategically
located to avoid wind damage. Utility lines and
runs should be installed to minimize potential
flood damage.
Quality control— Construction inspections and
quality control are essential for building suc-
cess. Even "minor" construction errors and
defects can lead to major damage during high -
wind or flood events. Keep this in mind when
inspecting construction or assessing yearly
maintenance needs.
Recommended practice and guidance concerning the
topics listed above can be found in the documents
referenced in these fact sheets and in many trade
publications (e.g., The Journal of Light Construction,
PI- www.jlconline.com).
Will the Likelihood of Success (Building
Performance) Be Improved by Exceeding
Minimum Requirements?
States and communities enforce regulatory require-
ments that determine where and how buildings may
be sited, designed, and constructed. There are of-
ten economic benefits to exceeding the enforced
requirements (see box). Designers and home build-
ers can help owners evaluate their options and make
informed decisions about whether to exceed these
requirements.
* 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 (http:Ljwww.fema.ov nfipjmanualshtrt ).
NAHIB
€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center C E T E
12/10
Summary of Coastal
Construction Requirements
and Recommendations
Purpose: To summarize recommendations for exceeding National Flood Insurance Program (NFIP)
regulatory requirements concerning coastal construction.
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:jjwww.fema.gov/nfip/manual.shtm).
The following table summarizes NFIP regulatory requirements and recommendations for exceeding those
requirements for both (1) new construction and (2) repairs, remodeling, and additions.
FEmA HOWIE BUILD:,E-RS GUM-
12/10
1=
- I. I
V Zone
Coastal A Zone
A Zone
Additional Resources
................
.................................
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.
ASCE: ASCE 24 Sec. 2.4
Other: FEIVIATB#5
Solid Foundation
Prohibited
Requirement:
Requirement:
IBC: 1612.5,1
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
NFIP 60.3(c)(3)
8.11).
Recommendation:
flood openings (see
Sheets Nos. 3.5
Other:'FEMA TB #5, FEMAFact
An open foundation
and 8.11).
550
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
No. 3.1]
landward of the long-
are recommended in
recommended in A
term erosion setback
Coastal A Zones.
Zones.
ASCE: ASCE 7 Sec. 5.4.4.1,
NFIP 60.3(e)(5)
and landward of the
to
ASCE 24 Sec 4.5.5
area subject erosion
Other: FEIVIATB#5
and 603(c)(5)
during the 1 % coastal
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: FEIVIATB#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, 1612A, 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
No. 1.4]
Fact Sheet No. 1.5).
following V Zone
Ch. 5
recommendations for
the lowest horizontal
Other:(FEMA 55, FEMA TB
NFIP 60.3(e)(4)
structural member
#8, FEMA TB #5
elevation to further
minimize the risk of
flood damage.
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V Zone
Goastal A Zone
A Zone
Additional Resources
................
.................................
.............................
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
expected direction of
Other: IFEMATB #5
Member
waves, elevate the
bottom of the member
to or above BFE; If
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
Nos. 1.1, 1.4]
but freeboard is
recommended in
recommended in A
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 11 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: FEMAT13#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,
[see Fact Sheet
screening.
R322.3.5
No. 8.1]
ASCE: ASCE 24 Sec. 4.6,
ASCE 7 Sec. C5.3.3
NAP 60.3(c)(5)
Other: FEMA 55, FEMA T13
#5, FEIVIA TB #9
U C �4 R".:. -'J �4 S A 1 11 C' CNA E IT 'A"FIR OINJS
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I-IONIE BUILDEWS GUIDE TOTOASTAL CONSTRUCTION 3
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I. I
V Zone
Coastal A Zone
A Zone
Additional Resources
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: IFEMATB#5
flood waters and debris
beneath the building, or
cause changes in flow
direction during coastal
storms that could result
in damage to buildings.
Use of Space
Requirement:
Requirement:
Requirement:
IBC: 1107.75, G105.7 (5),
Below BFE
Allowed only for
Allowed only for
Allowed only for
801.5, G103.5, G103.8
[see Fact Sheet
parking, building
parking, building
parking, building
IRC: R309.3, R322.1,
No. 8.1]
access, and storage
access, and storage
access, and storage
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
.................
..............................................................................................................................
..................................................
...... ...............................
.................................
.................................
............................... ................. ................
Sanitary Sewer
IBC: 1403.6, App. G 4013
IRC: R322A�7, R P2602.2,
NFIP 60.3(a)(6)(i)
R P3001.3, R P3101.5
and 60.3(a)(6)(ii)
ASCE: ASCE 24 Sec. 7.3.4
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,
NFIP 60.3(a)(3)
waters from entering
and accumulating in
equipment and other
service facilities to
equipment and other
service facilities to
R P2602.2, R M1301.1.1,
IV )
components during
be designed and/or
be designed and/or
R M1401.5, R M1601.4.9,
R M1701.2, R M2001.4,
flooding. Utility lines
located as to prevent
located as to prevent
R M2201.6
must not be installed
water from entering or
water from entering or
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
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
IRC: R104.2, R105, App. E,
certificate, and
App. J
Elevation Certificate.
ASCE: ASCE 24 Sec. 4.6,
ASCE 7 Sec. C5.3.3
Other: <FEMA EMI IS-9
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4 Of 1 i) 1-10NIE BUILDEWS GI-11DIETO COASTAL CONSTRUCTION
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8. I
V Zone
Goastal A Zone
A Zone
Additional Resources
...............
.............................................................................................................................................................
........
................
...
: ...............................
................................................................
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
NAP 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,
heating, ventilation,
Top of lowest floor
Users should consider
1.5.2,4.4
plumbing, and
must be at, or above,
following V Zone
air-conditioning
BFE; electrical
recommendations for
equipment and other
htin
eag, ventilation,
the lowest horizontal
service facilities
plumbing, and
structural member
(including ductwork)
air conditioning
elevation to further
must be designed
equipment and other
minimize the risk of
and/or located so
service facilities
flood damage.
as to prevent water
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,
11.4,11.5, 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)
H
.1 1- N " ONE E BUILDEWS GUIDE TO COASTAL CONSTRUCTION
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V Zone
Coastal A Zone
A Zone
Additional Resources
.............................................................................................................................................................
................. ...............................
................. .........
...............
..............................................................................................
........
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
Below BFE)
load, (2) design seismic
load, or (3) 10 psf,
used and enclose an
area, flood openings
Other: IFEMATB #5, FEMA
acting perpendicular to
are required (see Fact
TB #9
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
[see Fact
size of the openings
size of the openings
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: FEMATB#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 603(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.
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
of Substantial
concerning new
construction in V
elevation and open
foundations.
structural member to
or above BFE.
IRC: R322.1.6, R322,11
Damage
Zones except for siting
Requirement:
Requirement:
ASCE: ASCE 24 Sec. 4.3,
landward of mean high
tide (see Fact Sheet
Must meet current
Must meet current
ASCE 7 Sec. 1.6
NFIP 60.3(e)(5)
Nos. 1.4, 1.5, 2.2, 1
NFIP requirements
NFIP requirements
Other: FEMA P-758
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)
R ' U "' I r U M M A f -Y C C "'A - �TA L, "D � \J S C T Q i, .RE E INITS A P J" (11 0 M M E I
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Requirement:
Both the addition and
the existing building
must meet current
NFIP requirements
concerning new
construction in V Zones
(see Fact Sheet Nos.
1.4, 1.5, 2.2, 3.1, 3.5,
8.1, 8.3).
Recommendation:
Make addition
compliant with current
NFIP requirements for
V Zone construction.
Requirements:
Post -FIRM existing
building — the
addition must meet
NFIP requirements
in effect at time the
building was originally
constructed. Pre -FIRM
existing building —
NFIP requirements
concerning new
construction are not
triggered (see Fact
Sheet Nos. 1 d, 1 e, 2b,
3a, 3e, 8a, 8c)
Recommendation:
Follow V Zone
requirement for
building elevation and
open foundations for
the addition and the
existing building.
Requirement:
Only additions
must meet current
NFIP requirements
concerning new
construction in A Zones
(see Fact Sheet Nos.
1.4, 1.5, 3.1, 3.5, 8.1,
8.3), provided the
existing building is not
subject to any work
other than cutting an
entrance in a common
wall and connecting
the existing building
to the addition; if any
other work is done to
the existing building it
too must meet current
NFIP requirements for
new construction in A
Zones.
Recommendation:
Follow V Zone
requirement for
building elevation and
open foundations for
the addition and the
existing building.
Requirements:
Post -FIRM existing
building — the addition
must meet NFIP
requirements in
effect at the time the
building was originally
constructed (see Fact
Sheet Nos. 1 d, 1 e, 2b,
3a, 3e, 8a, 8c). Pre -
FIRM existing building
-- NFIP requirements
concerning new
construction are not
triggered.
Recommendation:
Elevate bottom of
lowest structural
member of the addition
to or above BFE (same
for the existing building
if it is elevated).
Requirement:
Only additions
must meet current
NFIP requirements
concerning new
construction in A Zones
(see Fact Sheet Nos.
1.4, 2.2, 3.1, 3.5, 8.1,
8.3), provided the
existing building is not
subject to any work
other than cutting an
entrance in a common
wall and connecting
the existing building
to the addition; if any
other work is done to
the existing building it
too must meet current
NFIP requirements for
new construction in A
Zones.
Recommendation:
Elevate bottom of
lowest horizontal
structural member to
or above BFE (same
for existing building
if it is elevated) (see
Fact Sheet No. 1d)
Requirements:
Post -FIRM existing
building — the addition
must meet NFIP
requirements in
effect at the time the
building was originally
constructed (see Fact
Sheet Nos. 1 d, 1 e, 2b,
3a, 3e, 8a, 8c). Pre -
FIRM existing building
-- NFIP requirements
concerning new
construction are not
triggered.
HONIE BUILDEWS GUIDE O COASTAL L CONSTRUCTION
12/10
Requirement:
Entire building
must meet current
NFIP requirements
concerning new
construction in V Zones
(see Fact Sheet Nos.
1 d, 1 e, 2b, 3a, 3e, 8a,
8c).
Recommendation:
Make the addition
compliant with current
NFIP requirements for
V Zone construction.
Requirements:
Post -FIRM existing
building — the addition
must meet NFIP
requirements in
effect at the time the
building was originally
constructed. Pre -
FIRM existing building
-- NFIP requirements
concerning new
construction are not
triggered (see Fact
Sheet Nos. 1.4, 1.5,
2.2, 3.1, 3.5, 8.1, 8.3).
Recommendation:
Follow V Zone
requirements for
building elevation and
open foundations.
Requirement:
Entire building
must meet current
NFIP requirements
concerning new
construction in A Zones
(see Fact Sheet Nos.
1 d, 1 e, 2b, 3a, 3e, 8a,
8c).
Recommendation:
Follow the V Zone
requirement for
building elevation and
open foundations for
the existing building.
Requirements:
Post -FIRM existing
building — the addition
must meet NFIP
requirements in
effect at the time the
building was originally
constructed (see
Fact Sheet Nos. 1.4,
1.5, 2.2, 3.1, 3.5,
8.1, 8.3). Pre -FIRM
existing building --
NFIP requirements
concerning new
construction are not
triggered.
Recommendation:
Elevate bottom of
lowest horizontal
structural member to
or above BFE (same
for existing building if i
is elevated) (see Fact
Sheet No. 1d).
Requirements:
Post -FIRM existing
building — the addition
must meet NFIP
requirements in
effect at the time the
building was originally
constructed (see Fact
Sheet Nos. 1 d, 1 e, 2b,
3a, 3e, 8a, 8c). Pre -
FIRM existing building
-- NFIP requirements
concerning new
construction are not
triggered.
Recommendation:
Elevate bottom of
lowest horizontal
structural member
at, or above, BFE
(same for the existing
building if it is
elevated) (see Fact
Sheet No. 1.4).
Requirements:
Post -FIRM existing
building — the
addition must meet
NFIP requirements
in effect at the time
the building was
originally constructed
(see Fact Sheet Nos.
1.4, 1.5, 2.2, 3.1, 3.5,
8.1, 8.3). Pre -FIRM
existing building --
NFIP requirements
concerning new
construction are not
triggered.
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HONIE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
Requirement:
New foundation
must meet current
NFIP requirements
concerning new
construction in V
Zones; the building
must be properly
connected and
anchored to the new
foundation.
Note: Repairing
a foundation that
does not constitute
a substantial
improvement does
not require current
compliance, but
compliance to the year
of construction.
Requirement:
Both the enclosure and
the existing building
must meet current
NFIP requirements
for new construction
in V Zones (see Fact
Sheets Nos. 1.4, 1.5,
2.2, 3.1, 8.1, 8.3).
Recommendation:
Make the enclosure
compliant with current
NFIP requirements
for new V Zone
construction.
Requirement: Post -
FIRM existing building
— the enclosure
must meet NFIP
requirements in
effect at the time the
building was originally
constructed. Pre -
FIRM existing building
-- NFIP requirements
concerning new
construction are not
triggered (see Fact
Sheet No. 8.1).
Recommendation:
Follow the V Zone
requirement for building
elevation and open
foundations.
Requirement: New
foundation must
meet current NFIP
requirements
concerning new
construction in A
Zones; the building
must be properly
connected and
anchored to the new
foundation.
Recommendation:
Follow the V Zone
requirement for building
elevation and open
foundations.
Requirement: Both
the enclosure and the
existing building must
meet current NFIP
requirements for new
construction in A Zones
(see Fact Sheets Nos.
1.4, 1.5, 2.2, 3.1, 8.1,
8.3).
Recommendation:
Construct only
breakaway enclosures;
install flood openings
in the enclosure; do not
convert the enclosed
space to habitable use.
Requirement: Post -
FIRM existing building
-- the enclosure
must meet NFIP
requirements in
effect at the time the
building was originally
constructed. Pre -
FIRM existing building
-- NFIP requirements
concerning new
construction are not
triggered (see Fact
Sheet Nos. 3.5, 8.1).
Recommendation:
Elevated bottom of
lowest horizontal
structural member to or
above BFE (see Fact
Sheet No. 1d).
Requirement: New
foundation must
meet current NFIP
requirements
concerning new
construction in A
Zones; the building
must be properly
connected and
anchored to the new
foundation.
Recommendation:
Elevated bottom of
lowest horizontal
structural member at,
or above, BFE (see
Fact Sheet No. 1.4).
Requirement: Both
the enclosure and the
existing building must
meet current NFIP
requirements for new
construction in A Zones
(see Fact Sheets Nos.
1.4, 1.5, 2.2, 3.1, 8.1,
8.3).
Recommendation:
Install flood openings
in the enclosure; do not
convert the enclosed
space to habitable use.
Requirement: Post -
FIRM existing building
— the enclosure
must meet NFIP
requirements in
effect at the time the
building was originally
constructed. Pre -
FIRM existing building
-- NFIP requirements
concerning new
construction are not
triggered (see Fact
Sheet Nos. 3.5, 8.1).
HONIE BUILDEWS GUIDE O COASTAL CONSTRUCTION� w¥
12/10
Requirement:
Where the entire
building is destroyed,
damaged, or
purposefully
demolished or razed,
the replacement
building must
meet current NFIP
requirements
concerning new
construction in V
Zones, even if it is
built on the foundation
from the original
building (see Fact
Sheet Nos. 1.4, 1.5,
9.1).
Requirement:
Where the existing
building is moved to
new location or site,
the relocated building
must meet current
NFIP requirements
concerning
construction in V
Zones (see Fact
Sheet Nos. 1.4, 1.5,
9.1).
Recommendation:
Follow the V Zone
requirement for
building elevation and
open foundations.
Requirement: Where
the entire building is
destroyed, damaged,
or purposefully
demolished or razed,
the replacement
building must
meet current NFIP
requirements
concerning new
construction in A
Zones, even if it is
built on the foundation
from the original
building (see Fact
Sheet Nos. 1.4, 9.1).
Recommendation:
Follow the V Zone
requirement for
building elevation and
open foundations.
Requirement: Where
the existing building
is moved to new
location or site, the
relocated building
must meet current
NFIP requirements
concerning
construction in A
Zones (see Fact
Sheet Nos. 1.4, 9.1).
Requirement:
Where the entire
building is destroyed,
damaged, or
purposefully
demolished or razed,
the replacement
building must
meet current NFIP
requirements
concerning new
construction in A
Zones, even if it is
built on the foundation
from the original
building (see Fact
Sheet Nos. 1.4, 9.1).
Recommendation:
Elevate bottom of
lowest horizontal
structural member at,
or above, BFE (see
Fact Sheet No. 1.4).
Requirement: Where
the existing building
is moved to new
location or site, the
relocated building
must meet current
NFIP requirements
concerning
construction in A
Zones (see Fact
Sheet Nos. 1.4, 9.1).
t NAH
(„ RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E R
c
12/10
I-IONIE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
Using a Digital Flood
Insurance Rate Man (DFI1
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
that specialize in analysis of streams, rivers, tidal shorelines,
and their adjacent floodplain or coastal area. These published
studies, known as the community's FIS, provide detailed infor-
mation on the study area that facilitates the creation of flood
maps. FISs are usually produced for the highest risk streams,
most rivers, and almost all coastal reaches.
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
through the Map Modernization Program into a digital prod-
uct that depicts flood -prone areas for a community. These are
known as Digital Flood Insurance Rate Maps, or DFIRMs.
Effective October 1, 2009, FEMA discontinued the distribution
of paper maps. Paper FIRMS were replaced with DFIRMs. The FIRM for
your specific site can be viewed online and reproduced by creating a
printable FIRMettei that can be downloaded to a personal computer.
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.
1 FIRMettes are user -selected portions of flood maps available through the FEMA Map Service Center.
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12/10
Why Are FIRMs and DFIRMs Important?
FIRMs and DFIRMs show the boundaries of mod-
eled flood hazard areas in a community.
SFHAs shown on the maps are used to set flood
insurance rates and premiums.
The 1-percent-annual-chance flood elevations
and flood depths shown on FIRMs and DFIRMs
are the minimum regulatory elevations on which
community floodplain management ordinances
and building codes are based.
The information shown on these maps can af-
fect the design and construction of new build-
ings and infrastructure, the improvement and
repair of existing buildings, and additions to
existing buildings (see Fact Sheet Nos. 1.2,
Summary of Coastal Construction Requirements
and Recommendations for Flood Effects, and 8.3,
Protecting Utilities).
What Are Flood Zones and Base Flood
Elevations, and How Do They Affect Coastal
Buildings?
BFEs are typically shown on DFIRMs for riverine
flood zones (Zone A, AE, A0, and AH) and coast-
al flood zones (Zone V and VE). The BFE is the
predicted elevation of flood waters and wave ef-
fects during the 1-percent-annual-chance flood
(also known as the base flood). The BFE is ref-
erenced to the vertical datum shown on the
DFIRM. Most have been updated to the 1988
North American Vertical Datum.
The minimum lowest floor elevation and the
foundation type and design for new construc-
tion* are determined by the BFE and flood zone,
as required in the community's floodplain man-
agement ordinance and building code (see Fact
Sheet Nos. 1.4, Lowest Floor Elevation, and 3.1,
Foundations in Coastal Areas). This ordinance,
along with the most current DFIRM and FIS, are
adopted by resolution to meet NFIP participation
requirements. Use of these tools supports com-
munity planning, zoning, and building inspection
programs that require specific structure design
and new construction* in high -hazard coastal
floodplains.
Some communities have adopted higher standards
for coastal construction (e.g., lowest floor elevations
above the BFE [freeboard], restrictions on foundation
types, and enclosures in Zone A). Builders should
consult their local jurisdiction for details.
* Note that new construction may include some additions, improve-
ments, repairs, and reconstruction. Consult the community about
substantial improvement and substantial damage requirements.
HONIE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
Sample DFIRM
This map is a portion of the DFIRM for the Town of Oyster Bay
and the City of Glen Cove in Nassau County, New York. Several
important things to note are highlighted:
The effective date of the DFIRM is September 11, 2009. d
PANEL 0019G
.....
. ....... ....
..
FIRM
FLOOD INSURANCE RATE MAP
(?5
`01 NASSAU COUNTY NEW YORK
.......
... ... ... ... I
I . ... .. (A ' L ' L
CONTAINS:
COMMUNITY NUMBER
.. ..
... .. ... ... ... ... ... ... ... ...
.................................................................
GLER"M:VE, CITY 1 F F3
OYSTER I 3AY, TOWN OF 36048a
]Tr -
PANE 1,0F 366
M 3 X: G
I '�R
c
5vAP N1--X - RA PrN- L vY�UT,
Ec::
Nolc la U— r Ve Nap K—Mr slam oe r., &ho.
—d n-e —g —P cV— Co —ft Number
�'TxRrll' MAP NUMBER
36059CO019G
....... . .. . .... .......... . . .
.........
... ... ... .
... ...........
... ... ... ... SEPTEMBER 11, 2009
ZONE AE
LIMIT QF —"--1 L
-Al OTH E RWISE PROW�ED AREA
ZONE t ESTABLISHED 11-16-1991
PC S)
(SEE MRS LZGE NO)
4T dm
Area designated as
a Coastal Barrier
O. Resource System.
ZON�E,AF
-EL I re
4e. " I ZONEAE
EL 13)
ZoN.
LIMITOrMCDERATE
WAVE ACTION
.,31 G A I 'T'A I I:`I...'0%0[-' N't A P D'I"I F1 'A
HONIE BUILDERS GUIDE TO COASTAL CONSTRUCTION
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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
produced during the past few years without im-
proved analysis of flood hazards. While some cor-
rections were made, the maps may not accurate-
ly represent coastal flood hazards. Sections 7.8
and 7.9 of FEMA's Coastal Construction Manual
(FEMA-55, 2005) describe how coastal flood haz-
ards are mapped and how to determine whether
coastal FIRMs reflect present-day flood hazards.
DFIRMs do not incorporate the effects of long-
term shoreline erosion. This information should
be obtained from other sources.
Recent post -storm investigations and studies
have shown flood forces and damage in Areas
of Moderate Water Action (MOWAs) or Coastal
A Zones can be very similar to those in Zone V.
Some communities have adopted DFIRMs that
show MOWAs as a white line on the DFIRM that
depicts the LiMWA. Although DFIRMs (and mini-
mum NFIP building standards) do not differenti-
ate between Zone A in coastal areas and Zone
A in riverine areas, builders should consider us-
ing Zone V foundation and elevation standards for
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-
ed their buildings with the lowest floor several
feet above the BFE because of the potential for
flood waters to exceed the BFE and enter the
building. Flood insurance is not available in ar-
eas designated as being in the Coastal Barrier
Resource System (CBRS). Only structures con-
structed prior to the designation of the area as
being in the CBRS are allowed to purchase fed-
eral flood insurance.
Community floodplain administrator. The community's
DFIRMs and its local floodplain management regula-
tions, should be on file and available for viewing at
the office of the community floodplain administrator.
FEMA's Map Information eXchange, or FMIX. This
service center serves as a one -stop shop for a
variety of information, products, services, and
tools that support the National Flood Insurance
Program. To contact a FEMA Map Specialist, please
call 1-877-FEMAMAP (1-877-336-2627) or email
FEMAMapSpecialist@riskmapcds.com. DFIRMs and
FISs can be accessed at www.msc.fema.gov. Index
sheets and specific FIRM panels can be viewed on-
line at the FEMA Map Service Center website by
entering either a parcel address or the specific
DFIRM panel number, if known. A user -selected por-
tion of flood maps (called a FIRMette) such as the
previous sample can be created, saved, and printed.
An effective tutorial on interpretation and use of the
old FIRM product is available at www.FloodSmart.
gov. While not specific to the newer DFIRM platform,
the tutorial defines basic flood hazard map termi-
nology and will be helpful to those less experienced
with using flood hazard maps.
NAHB
€ RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E R
4 Of :+
12/10
HOVE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
Lowest Floor Elevation
Purpose: To describe the benefits of excel.eding the Nationa! Flood Insurance Program (WRpi, minhnum
elevation requirements; to identify common construction practices that violate NFIP regulations, which
resuft in significantly lsklherflood insuraimce preml I Ums; x,no dis,1-tiss th,& hIRP Dev'aliofs Centificat'-s.
Why Is the Lowest Floor Elevation Important? G
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
-V
action causes even more damage, often destroying enclosed building areas below the flood level (and any >
building areas above the flood level that depend on the lower area for structural support). Once waves rise
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.
A NO
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FEMA
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HOME BUILDERS GUM-DETO COASTAL CONSTRUCTION I of2
12/10
What Does FEMA Consider the Lowest Floor?
The lowest floor means "the lowest floor of the
lowest enclosed area, except for unfinished or
flood -resistant enclosures used solely for park-
ing of vehicles, building access, or storage."
If the lowest enclosed area is used for anything
other than vehicle parking, building access, or
storage, the floor of that area is considered the
lowest floor. Such prohibited use will violate NFIP
requirements, resulting in drastically increased
flood insurance premiums.
Note that any below-BFE finished areas, includ-
ing foyers, will violate NFIP requirements, may
sustain unreimbursable flood damage, and make
the building subject to increased flood insurance
premiums.
The floor of a basement (where "basement"
means the floor is below grade on all sides) will
always be the lowest floor, regardless of how the
space is used. Basements are prohibited from
being constructed in V Zones and A Zones un-
less the basement is elevated to or above the
flood elevation or a basement exception has
been granted.
Walls of enclosed areas below the BFE must
meet special requirements in coastal areas (see
Fact Sheet No. 8.1, Enclosures and Breakaway
Walls; TB 5, Free -of -Obstruction Requirements
(2008); and TB 9, Design and Construction Guid-
ance for Breakaway Walls Below Elevated Coastal
Buildings (2008)). However, it should be empha-
sized that in no instance are basements recom-
mended in Coastal A Zones.
Construction Practices and the Lowest Floor
Constructing the lowest floor at the correct elevation
is critical. Failure to do so can result in a building
being built below the BFE. As a result, construction
work can be stopped, certificates of occupancy can
be withheld, and correcting the problem can be ex-
pensive and time-consuming. Here are some helpful
tips to consider when constructing the lowest floor:
After the piles have been installed and the low-
est horizontal structural supporting members
have been installed, have a licensed profession-
al engineer, architect, or surveyor validate the in-
tended elevation of the lowest floor before the
piles are cut off. This should be noted on the
Elevation Certificate.
Alternatively, after the piers or columns have
been constructed, the intended elevation of the
lowest floor should be validated during an in-
spection by the licensed professional and noted
on the Elevation Certificate prior to installation
of the lowest horizontal structural supporting
members.
Do not modify building plans to create habitable
space below the intended lowest floor. Doing so will
put the building in violation of floodplain manage-
ment ordinances and building code requirements.
Also, this space cannot be converted to living space
after the certificate of occupancy is awarded.
FEMA Elevation Certificate
The NFIP requires participating communities to adopt
a floodplain management ordinance that specifies
minimum requirements for reducing flood losses.
Communities are required to obtain and maintain
a record of the lowest floor elevations for all new
and substantially improved buildings. The Elevation
Certificate (see the following pages) allows the com-
munity to comply with this requirement and provides
insurers the necessary information to determine
flood insurance premiums.
A licensed surveyor, engineer, or architect must com-
plete, seal, and submit the Elevation Certificate to
the community code official. Not placing the lowest
supporting horizontal members and the first floor
of a building at the proper elevation in a coastal
area can be extremely costly and difficult to correct.
Following the carpenter's adage to measure twice,
but cut once, the elevation of the building must be
checked at several key stages of construction. Note
that multiple Elevation Certificates may need to be
submitted for the same building: a certificate may
be required when the lowest floor level is set (and be-
fore additional vertical construction is carried out); a
final certificate must be submitted upon completion
of all construction prior to issuance of the certifi-
cate of occupancy.
The Elevation Certificate requires that the following
information be certified and signed by the licensed
professional (surveyor/engineer/architect) and
signed by the building owner:
Name and address of property owner.
NFIP flood zone and elevation from a Digital
Flood Insurance Rate Map (DFIRM) and/or Flood
Insurance Study (FIS).
GPS coordinates.
Adjacent grade elevation.
Lowest horizontal structural supporting member
elevation.
Elevation of certain floors in the building.
Lowest elevation of utility equipment/machinery.
The Elevation Certificate provided in this fact sheet
expires March 31, 2012. Updated versions can be
found at http://www.fema.gov/business/nfip/forms.
shtm. The Elevation Certificate and instructions are
available on FEMA's website: http://www.fema.gov/
pdf/ nfi p/e Ivice rt. pdf.
t ' V' [. fs.i..FIX` t I i..I
12/10
V Zone Design and
Construction Certification
Purpose: To explain the certification
for structural design and methods of construction
in V Zones.
Structural Design and Methods of
Construction Certification
As part of the agreement for making flood insurance
available in a community, the National Flood Insurance
Program (NFIP) requires the community to adopt a
floodplain management ordinance that specifies min-
imum design and construction requirements. Those
requirements include a certification of the structural
design and the proposed methods of construction
(a similar documentation requirement appears in the
2009 IRC, Section R322.3.6). It is recommended that
the design professional use ASCE 24 and ASCE 7 as
appropriate engineering standards.
Specifically, NFIP regulations and local floodplain
management ordinances require that:
1. A registered professional engineer or architect
shall develop or review the structural design,
specifications, and plans for the construction.
2. A registered professional engineer or architect
shall certify that the design and methods of
construction to be used are in accordance with
accepted standards of practice in meeting these
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).
The pile or column foundation and structure at-
tached thereto is anchored to resist flotation, col-
lapse, and lateral movement due to the effects
of wind and water loads acting simultaneously
on all building components. ASCE 7-10, Minimum
Design Loads for Buildings and Other Structures,
provides guidelines on different load combina-
tions, which include flood and wind loads.
FEMA
._ .a
Completing the V Zone Design Certificate
There is no single V Zone certificate used on a na-
tionwide basis. Instead, local communities and/or
states have developed their own certification pro-
cedures and documents. Registered engineers and
architects involved in V Zone construction projects
should check with the authority having jurisdiction
regarding the exact nature and timing of required
certifications.
Page 2 shows a sample certification form. It is intend-
ed to show one way that a jurisdiction may require
that the certification and supporting information be
provided. In this example, the certification statement
can address both design and proposed methods of
construction and breakaway wall design.
5 x xi s...wi G IN AxC x v . iU` T' IFIT'I rk
H Rh`I#..... BUILDER WED i COASTAL COl iKUC O f z
12/10
V ZONE DESIGN CERTIFICATE
Name
Building Address or Other Description
Permit No.
City
PolicyNumber(Insurance Co.
SECTION I: Flood Insurance Rate Map
Community No. Panel No. Suffix
SECTION II:
(NOTE. This section documents the elevations/depths us
and is not equivalent to the as -built elevations required t
1. FIRM Base Flood Elevation (BFE) ....................
2. Community's Design Flood Elevation (DFE) ,......
3. Elevation of the Bottom of Lowest Horizontal Sta
4. Elevation of Lowest Adjacent Grade ....................
5. Depth of Anticipated Scour/Erosion used for Fou
6. Embedment Depth of Pilings or Foundation Belo
n
■❑
State
FI
pecified in the design - it does not document surveyed elevations
omitted during or after construction.]
...... ......... ...................... ........ feet*
.....I. ......... ........................................................... _ feet*
Member................................................................... feet*
......... ..........................................................._ feet*
7 Design....'................................................................_ feet
est Adjacent Grade ....................................................... feet
LJ NAVD88 ❑ Other
Design Certification Statement
I certify that: (1) 1 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 walls are designed to have a resistance of
more than 20 psf (0.96 kN/m2) determined using allowable stress design]
I certify that: (1) 1 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
Title
Address
City
Signature
License Number
Company Name
Place Seal Here
State Zip Code
Date _Telephone
( `I.:: I .... Iw; I a [NJ E III lli0 t I:::Ir 1 9 flJ
12/10
Alit BUILDEWS GUIDE TO COASTAL CONST,RUCTION
Designing for Flood Levels
Above the BFE
Purpose: o eominr nd design and construction practices that uce thre iNeli ood Of floodam
n tile wenf that to d exceed the B-ise ROOd
mm 1 m 1 (K
Key Issues
BFEs are established at a flood level, includ-
ing wave effects, that has a 1-percent chance
of being equaled or exceeded in any given year,
also known as the 100-year flood or base flood.
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
Flood Hazard Area [SFHAj) shown on the FIRM
(see Figure 1).
Flood damage increases rapidly once the el-
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
a wave crest 3 to 4 feet above the bottom of
the floor beam (approximately 1 to 2 feet above
the walking surface of the floor) will be sufficient
to substantially damage or destroy most light -
frame residential and commercial construction
(see Figure 2).
There are design and construction practices that
can eliminate or minimize damage to buildings
when flood levels exceed the BFE. The most
common approach is to add freeboard to the
design (i.e., to elevate the building higher than
required by the FIRM). This practice is outlined
in American Society of Civil Engineers (ASCE) 24-
05, Flood Resistant Design and Construction.
There are other benefits of designing for flood
levels above the BFE: reduced building damage
and maintenance, longer building life, reduced
flood insurance premiums, reduced period of
time in which the building occupants may need
to be displaced in the event of a flood disas-
ter (and need for temporary shelter and assis-
tance), reduced job loss, and increased reten-
tion of tax base.
The cost of adding freeboard at the time of home
construction is modest, and reduced flood insur-
ance premiums will usually recover the freeboard
cost in a few years' time.
HOME BUILDER W-DETO COASTAL CONSTRUCTION
12/10
How High Above the BFE Should a Building
be Elevated?
Ultimately, the building elevation will depend on sev-
eral factors, all of which must be considered before
a final determination is made:
The accuracy of the BFE shown on the FIRM:
If the BFE is suspect, it is probably best to ele-
vate 3 or more feet above the BFE; if the BFE is
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
BFE, the historical high water levels should be
considered in building elevation decisions.
Availability of preliminary Digital Flood Insur-
ance Rate Maps (DFIRMs): As new Flood Insur-
ance Studies (FISs) are completed, preliminary
DFIRMs will be produced and available for use,
even before they are officially adopted by those
communities.
Future conditions: Since the FIRM reflects con-
ditions at the time of the FIS, some owners or
jurisdictions may wish to consider future condi-
tions (such as sea level rise, subsidence, wet-
land loss, shoreline erosion, increased storm
frequency/intensity, and levee settlement/fail-
ure) when they decide how high to elevate.
State or local requirements: The state or local
jurisdiction may require a minimum freeboard
through its floodplain management requirements
or building code.
Building code requirements: The International
Building Code (IBC) requires buildings be de-
signed and constructed in accordance with ASCE
24. ASCE 24 requires between 0 and 2 feet of
freeboard, depending on the building impor-
tance and the edition of ASCE 24 referenced.'
The 2009 International Residential Code (IRC)
requires 1 foot of freeboard in V Zones and in
Coastal A Zones.
Building owner tolerance for damage, displace-
ment, and downtime: Some building owners may
wish to avoid building damage and disruption,
and may choose to elevate far above the BFE.
In V Zones and A Zones, FEMA 499 recommends
considering elevation of residential structures to the
500-year flood elevation, or to the requirements of
ASCE 24-05, whichever is higher.
1 The 1998 edition of ASCE 24 is referenced by the 2003 edition of the
IBC, and requires between 0 and 1 foot of freeboard. The 2005 edition
of ASCE 24 is referenced by the 2006 and 2009 editions of the IBC,
and require between 0 and 2 feet of freeboard.
Flood Insurance Rate Maps and Flood Risk
Hurricanes Ivan (2004), Katrina (2005), Rita (2005),
and Ike (2008) have demonstrated that constructing
a building to the minimum National Flood Insurance
Program (NFIP) requirements —or constructing a
building outside the SFHA shown on the FIRMs—is
no guarantee that the building will not be damaged
by flooding.
This is due to two factors: 1) flooding more severe
than the base flood occurs, and 2) some FIRMs, par-
ticularly older FIRMs, may no longer depict the true
base flood level and SFHA boundary.
Even if the FIRM predicted flood levels perfect-
ly, buildings constructed to the elevations shown
on the FIRM will offer protection only against the
1-percent-annual-chance flood level (BFE). Some
coastal storms will result in flood levels that exceed
the BFE, and buildings constructed to the minimum
elevation could sustain flood damage. The black line
in Figure 3 shows the probability that the level of the
flood will exceed the 100-year flood level during time
periods between 1 year and 100 years; there is an
18 percent chance that the 100-year flood level will
be exceeded in 20 years, a 39 percent chance it will
be exceeded in 50 years, and a 51 percent chance
it will be exceeded in 70 years. As the time period
increases, the likelihood that the 100-year flood will
be exceeded also increases.
Figure 3 also shows the probabilities that floods of
other severities will be exceeded. For example, tak-
ing a 30-year time period where there is a 26 percent
chance that the 100-year flood level will be exceeded
and a 6 percent chance that a flood more severe
than the 500-year flood will occur.
12/10
0 NIE BUILDER E TO C 0 A S TA L CO N S T, RUCTION
FIRMS depict the limits of flooding, flood
elevations, and flood zones during the
base flood. As seen in Figure 3, buildings
elevated only to the BFEs shown on the
FIRMS have a significant chance of being
flooded over a period of decades. Users
should also be aware that the flood lim-
its, flood elevations, and flood zones
shown on the FIRM reflect ground eleva-
tions, development, and flood conditions
at the time of the FIS.2
Consequences of Flood Levels
Exceeding the BFE
Buildings are designed to resist most
environmental hazards (e.g., wind,
seismic, snow, etc.), but are generally
designed to avoid flooding by elevat-
ing the building above the anticipated
flood elevation. The difference in design
approach is a result of the sudden on-
set of damage when a flood exceeds
the lowest floor elevation of a build-
ing. Unlike wind —where exposure to a
wind speed slightly above the design
speed does not generally lead to se-
vere building damage —occurrence of a
flood level even a few inches above the
lowest floor elevation generally leads to
significant flood damage. Therefore, the
recommendation is to add freeboard.
Probability of a Flood Exceeding the n-Year Flood Level
During a Given Period of Time
ioo/
90 r
v
80/
70 70/
v 60%
x
w 50%
O 40%
30/
20
O
10%
0/
0 10 20 30 40 50 60 70 80 90 100
Period of Time (years)
10-yr flood -�— 100-yr flood = 200-yr flood
50-yr flood °- 150-yr flood --*— 500-yr flood
Figure 3. Probability that a flood will exceed the n-year flood level
over a given period of time.
(Note: this analysis assumes no shoreline erosion, and no increase in sea level
or storm frequency/severitylover time.)
9a
8a
70100000 V Zone
a� (No Obstruction)
so
E
CO 50
a
4
v 30 A Zone
a (Two -Story Without
20 Basement)
10-0000
a
-2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Depth in Feet Relative to
Bottom of Lowest Horizontal Structural Member"
Assumes distance between top of floor and bottom of lowest
horizontal structural member = 2' for A Zone buildings.
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.
6w �." I. S I G IN"' I G 1: � )::t f .- � . (... E..:.. wi :�, B V 1... ) , 1 & I
I-IONIE BUILDEWS GUIDE O COASTAL CONSTRUCTION1 s1
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.
_. -..
e
R
'
411,
�.
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
The goal of this fact sheet is to provide methods to
minimize damage to buildings in the event that coast-
al flood levels rise above the BFE. Achieving this goal
will require implementation of one or more of the fol-
lowing general recommendations:
In all areas where flooding is a concern, inside
and outside the SFHA, elevate the lowest floor
so that the bottom of the lowest horizontal struc-
tural member is at or above the Design Flood
Elevation (DFE). Do not place the top of the low-
est floor at the DFE, since this guarantees flood
damage to wood floor systems, floor coverings,
and lower walls during the design flood, and may
lead to mold growth and contamination damage
(see Figure 6).
In V Zones and A Zones, use a DFE that results
in freeboard (elevate the lowest floor above the
BFE) (see Figure 7).
In V Zones and A Zones, calculate design loads
and conditions (hydrostatic loads, hydrodynamic
loads, wave loads, floating debris loads, and ero-
sion and scour) under the assumption that the
flood level will exceed the BFE.
4 ,f
12/10
HOVE BUILDEWS GUIDE TO COASTAL CONST, RUCTION
In an A Zone subject to moderate waves (1.5
to 3.0 feet high) and/or erosion (i.e., Coastal A
Zone), use a pile or column foundation (see Fig-
ure 7).
Outside the SFHA (in Zone B, Zone C, and Zone
X), adopt flood -resistant design and construction
practices if historical evidence or a review of the
available flood data shows the building could be
damaged by a flood more severe than the base
flood (see Figure 8).
Design and construct buildings in accordance
with the latest model building code (e.g., IRC
or IBC), ASCE 7-10, Minimum Design Loads for
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-
ble, which are shown in FEMA 550, Recommend-
ed Residential Construction for the Gulf Coast:
Building on Strong and Safe Foundations.
Use strong connections between the foundation
and the elevated building to prevent the building
from floating or washing off the foundation, in
the event that flood levels do rise above the low-
est floor.
Where additional freeboard is prohibited or not
provided use flood damage -resistant building
materials and methods above the lowest floor.
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.
New and replacement manufactured homes
should be installed in accordance with the pro-
visions of the 2009 edition of the National Fire
Protection Association (NFPA) 225, Model Man-
ufactured Home Installation Standard. The stan-
dard provides flood, wind, and seismic -resistant
installation procedures. It also calls for elevat-
ing manufactured homes in A Zones with the
bottom of the main chassis frame beam at or
above the BFE, not with the top of the floor at the
BFE. FEMA P-85, Protecting Manufactured Homes
from Floods and Other Hazards provides addition-
al guidance on proper manufactured home siting
and installation.
Off } BUILD GU D}E O O � a � O �'R �� � s
12/10
Batt Insulation
Above Gap
— Pressure -treater
Lumber
Elevated
Outlets
Gap in Wallboar[
to Prevent Wickin
L1 09.0a' per -face
�ypsum
Wallboard
Rigid, Closed -cell
Insulation
Water-resistal I < —a y
Drained Cavity Exterior Rigid 1x4 Furing
Brick Veneer Insulation Fiber -cement
Non -paper -faced Siding
Gypsum Sheathing
Latex Paint
1 Non -paper -faced
Gypsum Wallboard
Uninsulated Steel or Pressure -treated
Wood -framed Wall
Membrane or Trowel -on
Vapor Barrier (Class 1)
rovable
iscot
Exterior Rigid
Insulation
Non -paper -faced
Gypsum Sheathing
Latex Paint
Non -paper -faced
Gypsum Wallboard
F '--Uninsulated Steel or Pressure -treated
Wood -framed Wall
Membrane or Trowel -on
Vapor Barrier (Class 1)
10NIE BUILDEWS G ID TO COASTAL COI§ISLRUCTION
12/10
Drained Cavity
Exterior Rigid
Brick
Insulation
figure 1L Recommended flood -
resistant exterior mass wall
Veneer
Concrete
Q
construction. The following
Q
Block
materials and methods will limit
flood damage to exterior mass
walls:
Painted
#) use concretemasonry with
Stucco
stucco or brick veneer (provide'
drainage cavity if brick veneer is
000
used);
2) use rigid, closed -cell insulation;
-
3) use steel framing; and 4) use
non -paper -faced gypsum wallboard
i
I
Non -paper -faced
painted with latex paint'
Gypsum Wallboard
YP
(Source: Coastal Contractor Magazine
with Latex Paint
and Building Science Corporation).
Uninsulated
Membrane or
Steel framed Wall
Non -paper -faced
Trowel -on Vapor Barrier
Gypsum Wallboard
(Classl)
with Latex Paint
Other Considerations
As previously stated, in addition to reduced building
damage, there are other reasons to design for flood
levels above the BFE:
Reduced building maintenance and longer build
ing life.
Reduced flood insurance premiums.
Reduced displacement and dislocation of build-
ing occupants after floods (and need for tempo-
rary shelter and assistance).
Until flooded, many homeowners and communities
do not think about these benefits. However, one of
the most persuasive (to homeowners) arguments for
elevating homes above the BFE is the reduction in an-
nual flood insurance premiums. In most cases, flood
premiums can be cut in half by elevating a home 2
feet above the BFE, saving several hundred dollars
per year in A Zones, and $2,000 or more per year
in V Zones. In V Zones, savings increase with added
freeboard.
A comprehensive study of freeboard (American
Institutes for Research, 2006) demonstrated that
adding freeboard at the time of house construction
is cost-effective. Reduced flood damage yields a
benefit -cost ratio greater than 1 over a wide range
of scenarios, and flood insurance premium reduc-
tions make adding freeboard even more beneficial
to the homeowner. Reduced flood insurance premi-
ums will pay for the cost of incorporating freeboard
in a house in a V Zone in 1 to 3 years; for a house
in an A Zone, the payback period is approximately
6 years.
Flood Insurance Premium Reductions Can Be Significant
* Compared to flood premium with lowest floor at BFE
6w �.'E IGIN"'I G 1"::t �. � ....�E:...wi:�,B V1... ), 1& :.
I-IONIE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
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.coastalcontractor.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
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.Isuag-
center.com/NR/rdonlyres/B2B6CDEC-2B58-472E-BBD9-OBDEBOB29C4A/26120/pub277lWet6.pdf)
NFPA. 2009. Model Manufactured Home Installation Standard. NFPA 225, (http://www.nfpa.org/about-
thecodes/AboutTheCodes.asp?DocNum=225&cookie test=1)
t..NANB
'..,h RESEARCH
Developed in association with the National Association of Home Builders Research Center C.E N T E R
10fiL BUILDEWS GUIDE TO COASTCONSTRUCTION
12/10
Coastal Building Materials
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-
siderations that must be made when
selecting building materials for a coast-
al building. The harsh environment
requires that more substantial building
materials be used and more care tak-
en when using these materials in order
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
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.
The following are some key consider-
ations when screening materials.
Materials and construction methods in a coast-
al environment should be resistant to flood and
wind damage, wind -driven rain, corrosion, mois-
ture, and decay (due to sunlight, aging, insects,
chemicals, temperature, or other factors).
Ease of installation or the ability to properly in-
stall the material should be a major consider-
ation for the selection of materials.
All coastal buildings will require maintenance
and repairs (more so than inland construction)
— use proper materials and methods for re-
pairs, additions, and other work following initial
construction (see Fact Sheets Nos. 9.1, Repairs,
Remodeling, Additions and Retrofitting - Flood
and 9.2, Repairs, Remodeling, Additions and
Retrofitting - Wind).
The durability of a coastal home relies on the types of
materials and details used to construct it. For flood -
related information, see NFIP Technical Bulletin 2,
Flood Damage -Resistant Material Requirements for
Buildings Located in the Special Flood Hazard Areas
in accordance with the National Flood Insurance
Program 8/08. For other natural hazards, see the
Institute for Business and Home Safety Fortified... for
Safer Living® Builder's Guide.
FEMA
._ .a
Flood -Resistant Materials
Flooding accounts for a large percentage of the dam-
age caused by a coastal storm, which is why building
materials must be flood damage -resistant. The NFIP
defines a flood damage -resistant material as "any
building material capable of withstanding direct and
prolonged contact (i.e., at least 72 hours) with flood-
waters without sustaining significant damage (i.e.,
requires more than cosmetic repair)." The cost of
cosmetic repair should be less than the cost of re-
placing building materials. Although flood -resistant
materials typically refer to areas below the BFE, they
may be appropriate in areas above the BFE in order
to limit the amount of damage caused by wind -driven
rain. All building materials below the BFE must be
flood damage -resistant, regardless of expected or
historic flood duration.
OWIE BUILDER WEDETO COASTAL CONSTRUCTION of y.,
12/10
The following are examples of flood -resistant
materials:
Lumber: Preservative -treated or naturally dura-
ble wood as defined in the International Building
Code. Naturally durable wood includes the heart-
wood of redwood, cedar, black locust, and black
walnut.
Concrete: A sound, durable mix, and when ex-
posed to saltwater or salt spray, made with a sul-
fate -resisting cement, with a 28-day compressive
strength of 5,000 psi minimum and a water -ce-
ment ratio not higher than 0.40—such mixes are
usually nominally more expensive and rarely add
significant cost to the project (consult ACI 318-
02, Building Code Requirements for Structural
Concrete and Commentary by the American
Concrete Institute). Reinforcing steel used in
concrete or masonry construction in coastal ar-
eas should not be left exposed to moisture and
should not be stored on bare ground. The rein-
forcing steel should be free from rust and clear-
ances should be maintained as shown on the de-
sign drawings.
Masonry: Reinforced and fully grouted. If left un-
filled, then masonry block cells can create a res-
ervoir that can hold water and can make the ma-
sonry difficult to clean following a flood.
Structural Steel: Coated to resist corrosion
Insulation: Plastics, synthetics, and closed -cell
foam, or other types approved by the local build-
ing official.
The following are examples of materials that are un-
acceptable below the BFE:
Normal, water-soluble adhesives specified for
above -grade use or adhesives that are not resis-
tant to alkali or acid in water, including groundwa-
ter seepage and vapor.
Materials that contain paper -based materials,
wood -based materials, or other organic materi-
als that dissolve or deteriorate, lose structural
integrity, or are adversely affected by water.
Sheet -type floor coverings (e.g., linoleum, vinyl)
or wall coverings (e.g., wallpaper) that restrict
drying of the materials they cover.
Materials that become dimensionally unstable
when subject to wetting and drying.
Materials that absorb water excessively or main-
tain a high moisture content after submergence.
Wiring, outlets, and electrical components not
designed to be flood resistant. It is important to
locate any materials like these above the expect-
ed floodwater elevation. When this is not possi-
ble, it is important to allow for the isolation of
these components.
Flood insurance will not pay a claim for damages to
finish materials located in basements or in enclosed
areas below the lowest floor of elevated buildings,
even if such materials are considered to be flood
damage -resistant. NFIP claims for damages below
the BFE are limited to utilities and equipment, such
as furnaces and water heaters.
This table lists examples of flood -resistant materials used in coastal homes.
i = =.gym 1 I WING ; .:R ..S
o, HOME BUILDEWS GUIDE TO COAST O T,RUCT 0
12/10
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
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
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 -
resistant materials, some sidings and wall coverings
may need to be removed from framing members fol-
lowing a flooding event in order to allow the system
to properly dry. For more information on repair tech-
niques after a flood, see FEMA 234, Repairing Your
Flooded Home (08/92).
Many jurisdictions will provide a list of approved flood -
resistant materials that can be used in their local
coastal environments. Check these lists and include
all proposed construction and materials in approved
plans.
Wind -Resistant Materials
Homes in many coastal areas are often exposed to
winds in excess of 90 mph (3-second peak gust).
Choose building materials (e.g., roof shingles, siding,
windows, doors, fasteners, and framing members)
that are designed for use in high -wind areas.
Examples:
Roof coverings rated for high winds (see Roofing
Category, Fact Sheet Nos. 7.1-7.6)
Double -hemmed vinyl siding (see Fact Sheet No.
5.3, Siding Installation in High -Wind Regions)
Deformed -shank nails for sheathing attach-
ments (see Fact Sheet No. 7.1, Roof Sheathing
Installation)
Wind-borne debris resistant glazing (see Fact
Sheet No. 6.2, Protection of Openings - Shutters
and Glazing)
Reinforced garage doors
Ell I.....'1 N G I, :I...
Tie -down connectors used throughout struc-
ture (from roof framing to foundation — see
Fact Sheet Nos. 4.1, Load Paths and 4.3, Use of
Connectors and Brackets)
Wider framing members (2x6 instead of 2x4)
As hurricanes in recent years have proven, even well -
selected materials can fail if not installed properly.
Proper installation requires attention to detail, fol-
lowing the manufacturer's recommended installation
procedures, and proper maintenance. When select-
ing a material or building component it is important
to consider the level of difficulty required to properly
install the material. Improper installation of materi-
als may expose the building's systems to wind loads
that the systems were not designed to resist. Also,
it is important to verify that any special requirements
were followed and that specialized tools or adhesives
were used. Even a building component that exceeds
the design requirements can fail if it is installed
incorrectly.
Corrosion and Decay Resistance
Buildings in coastal environments are prone to dam-
age from corrosion, moisture -related decay, and
termite damage to building materials. Metal corro-
sion is most pronounced on coastal homes (within
3,000 feet of the ocean), but moisture -related decay
and termite damage are prevalent throughout coastal
areas.
110DIE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
Corrosion -Resistant Metals
Preservative -treated wood used in a coastal environ-
ment often contains chemical preservatives such
as Alkaline Copper Quat (ACQ), Copper Azole (CA-C),
Dispersed or Micronized Copper (IuCA-C), or Copper
Naphthenate (CuN-W). The connectors and fasten-
ers used in conjunction with these pressure -treated
wood products should be properly selected and it
should be verified that the connectors are compat-
ible with the wood preservative. According to the
2009 International Residential Code (IRC) R317.3.1
and International Building Code (IBC) 2304.9.5.1 the
fasteners should be compatible with the wood pre-
servative per the manufacturer's recommendations.
The fasteners shall be hot -dip zinc -coated galvanized
steel, stainless steel, silicon bronze, or copper. If the
v manufacturer's recommendations are not available,
then corrosion protection in accordance with ASTM
A 653 type G185 for zinc -coated galvanized steel or
equivalent is required. Exceptions to this rule may be
noted in the building code.
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).
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
and the fastener are the same type of met-
al. Avoid joining dissimilar metals, especial-
ly those with high galvanic potential (e.g., cop-
per and steel) because they are more prone to
corrosion.
i = =.gym � 1 i wING ; i .:R ..wr
4 0,f
12/10
HOVE BUILDEWS GUIDE TO COASTAL CONST, RUCTION
Metal -plate -connected trusses should not be
exposed to the weather. Truss joints near vent
openings are more susceptible to corrosion
and may require increased corrosion protection.
Verify the connectors used near any roof vent
openings are stainless steel or a minimum of
ASTM A 653 type G185 zinc -coated galvanized
steel or equivalent.
Due to the potential for galvanic corrosion, stan-
dard carbon -steel, aluminum, or electroplated
fasteners and hardware are not recommended
for direct contact with preservative -treated wood.
The use of aluminum flashing with many types of
treated wood should be avoided. Aluminum will
corrode quickly when in contact with most wood
preservatives. Copper flashing in many instanc-
es is the best choice although products such as
vinyl flashing are becoming more common.
Moisture Resistance
Moisture -resistant materials can greatly reduce
maintenance and extend the life of a coastal home.
However, such materials by themselves cannot
prevent all moisture damage. Proper design and in-
stallation of moisture barriers (see Fact Sheet No.
1.9, Moisture Barrier Systems) are also required.
Recommendations
Control wood decay by separating wood from
moisture, using preservative -treated wood, using
naturally durable wood, and applying protective
wood finishes.
Use proper detailing of wood joints and con-
struction to eliminate standing water and reduce
moisture absorption by the wood (e.g., avoid
:Ell w l N Gi .. i,:...
exposure of end grain cuts, which absorb mois-
ture up to 30 times faster than the sides of a
wood member).
Do not use untreated wood in ground contact or
high -moisture situations. Do not use untreated
wood in direct contact with concrete.
Field -treat any cuts or drill holes that offer paths
for moisture to enter wood members. Field treat-
ment shall be done per M4-06 of the American
Wood -Preservers' Association.
For structural uses, employ concrete that is sound,
dense, and durable; control cracks with welded
wire fabric and/or reinforcing, as appropriate.
Use masonry, mortar, and grout that conform to
the latest building codes.
Cavity wall systems (two masonry wall systems
separated by a continuous air space) should be
avoided in flood -prone areas since they can fill
with water, retain moisture, and be difficult to re-
pair without a significant level of demolition.
Consider the interior finishes for first floors
where floodwaters exceeding the design event
could cause significant damage (See Fact Sheet
No. 1.6, Designing for Flood Levels Above the
BFE). It is also important to consider that wind -
driven rain can cause damage to interior finishes
around door and window openings.
Termite Resistance
Termite damage to wood construction occurs in many
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.
Recommendations
Incorporate termite control methods into design
in conformance with requirements of the author-
ity having jurisdiction.
Where a masonry foundation is used and anchor-
age to the foundation is required for uplift resis-
tance, the upper block cores must usually be com-
pletely filled with grout, which may eliminate the
requirement for termite shields (see Fact Sheet
No. 3.4, Reinforced Masonry Pier Construction).
Use preservative -treated wood for foundations,
sills, above -foundation elements, and floor framing.
In areas with infestations of Formosan termites,
wood products treated with insect -resistant
chemicals or cold -formed steel framing are ma-
terial options for providing protection against ter-
mite damage.
12/10
Additional Resources
FEIVIA. NFIP Technical Bulletin 2-08, Flood -Resistant Materials Requirements. (http://www.fema.gov/plan/pre-
vent/floodplain/techbul.shtm)
FEIVIA. NFIP Technical Bulletin 8-96, Corrosion Protection 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)
NAHB
RESEARCH
R�
Developed in association with the National Association of Home Builders Research Center ..
C..ENTER
K...................................
........................................
HOVE BUILDEWS GUIDE TO COASTAL CONST, RUCTION
12/10
Non -Traditional Building
Materials and Systems
Purpose: To provide guidance on non-traditional building materials and techniques and their
appropriate application in coastal environments.
Key Issues
Determination of whether a material
or system is appropriate for the site -
specific hazards.
Evaluation of whether new materials
and construction systems should be
resistant to flood and wind damage,
wind -driven rain, corrosion, mois-
ture, and decay.
All coastal buildings will require
maintenance and repairs (more so
than inland construction). When
considering using a non-traditional
material or system, it is important
to ask, "What are some consider-
ations for various new materials and
systems?"
Every year, new construction materials
are introduced into the market. These
building materials cover ever art of the
Figure 1. 'Construction of a modular home.
yp
home from the foundation system to the
roof system. New materials often offer a variety of
benefits — a cost-effective solution, energy efficien-
cy, aesthetics, ease of installation, or eco-friendly
solutions.
This fact sheet will focus on providing information
on building materials and systems that while not
being considered traditional materials are not un-
common to the industry. The sheet is not intended to
encourage any one material or system, but will pro-
vide information so that the user can make a more
informed choice about whether something is an ap-
propriate material or system for a given situation.
While the fact sheet does not cover all materials, it
provides readers with an idea of what criteria they
may need to be mindful of when selecting materials
and systems. While many are reasonable alterna-
tives to traditional materials and systems, their uses
should be carefully considered. The same factors
used to consider the applicability of traditional
building materials and systems should be used to
determine whether new materials and systems are
appropriate for use in a coastal environment. Some
FEMA
._ .a
of these factors include overall hazard resistance
for flood and wind, durability, maintenance, and re-
pair requirements. Additionally, when considering
a particular building component, it is important to
consider the installation and constructability of the
component. When selecting a material or a system
for a coastal environment it is important to consid-
er available information in addition to technical data
from the manufacturer or supplier. Some examples
of considerations are:
Contact the local building official about the ac-
ceptability of the material or system.
Review test results on the material or system's
use in coastal environments.
Review product code evaluation reports.
Review field reports or a history of these materi-
als or systems performing well in similar coast-
al environments, including experience in high
winds and flooding.
Review the manufacturer's installation and main-
tenance instructions.
HOME BUILDERUIDI , TO COASTAL CONSTRUCTION of y:;..
12/10
Not all materials and systems will be specifically ad-
dressed by local building code requirements. Some
products or systems may be absent from the code
and may require engineering calculations or studies
in order to determine that they are appropriate for
use in a particular area.
System Options
Engineered Wood Products
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
floor framing they should be either flood -resistant or
elevated to a height where they are not expected to
be wetted.
Advantages:
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
to resist greater loads than sawn lumber.
EWPs are manufactured in a dry condition and
are more dimensionally stable than sawn lumber,
which may warp and twist during drying.
Availability: Certain sizes of Glulam or SCL may
be difficult to obtain. They may require special or-
dering and fabrication, which may not meet the
project schedule for the building.
Installation: Installation issues include condi-
tions for storing materials, dimensional compat-
ibility with other materials, and requirements for
use of metal connectors and fasteners to ensure
accordance with the manufacturer's installation
instructions.
Structural Insulated Panels (SIPs)
Structural Insulated Panels (SIPs) are manufactured
panels made of a foam insulation core bonded be-
tween two structural facings. SIPs are commonly
manufactured with OSB facings as discussed in the
2009 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
(see Figure 2), floors, and roofs, and are compatible
with light -framed construction.
Figure 2. Construction of a Structural Insulated Panel
house.
Advantages:
SIPs offer an efficient construction method and
quick assembly. Insulation is built-in, and wall
openings and utility chases are precut by the
manufacturer per the building plans, reducing on -
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.
,
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-
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
be opened, allowed to dry out, and
repaired or, in some instances, even
replaced.
As with conventional construction techniques,
SIPs may sustain windborne debris damage.
This may require cutting out a section of the SIPs
and repairing it with either conventional framing
techniques or a replacement SIP
The foam core of SIPs is inert and provides no
food value to termites and other pests. However,
pests may still nest within the foam. Always in-
corporate pest control methods into the design
in conformance with local jurisdictional require-
ments. Some manufacturers sell pre-treated SIPs.
Always use approved connectors and connection
methods for panel -to -panel, panel -to -foundation,
and panel -to -roof connections. For guidance on
SIPs connections, refer to IRC R613.5. It is im-
portant to consider that not all connectors are
compatible with SIPs and in some instances
specific connectors may be required in order to
maintain the load path.
Follow manufacturer's installation instructions
and product use requirements in the manufac-
turer's code evaluation report.
Insulating Concrete Forms (ICFs)
ICFs are made of molded expanded polystyrene
(MEPS) foam and are used to form cast -in -place
concrete walls (see Figure 3). Unlike conventional
cast -in -place concrete construction, the ICFs are left
in place after the concrete cures to provide insula-
tion, an attachment surface for interior and exterior
finishes, and space to run plumbing and electrical
lines within the wall.
Advantages:
ICF provides improved energy efficiency and al-
lows the use of smaller HVAC equipment than
some other construction methods.
The concrete and insulation walls are durable
and require little maintenance.
The combination of thick concrete walls and con-
tinuous insulation provide significant noise re-
duction over other construction methods.
ICF provides good wind, windborne debris, and
flood resistance.
Things to consider if building with ICFs:
Special connectors may be required for the con-
nection of the roof system, floor system, doors,
and windows.
For material and construction requirements for
concrete walls, refer to IRC R611.
Exterior foam must be protected from sunlight
and physical damage by the application of an ap-
proved exterior wall covering. Refer to IRC 611.4
for requirements for stay -in -place concrete
forms.
ICF foam is inert and provides no food value to
termites and other pests. However, pests may
still nest within the foam. Always incorporate
pest control methods into the design in confor-
mance with requirements of the authority having
jurisdiction.
In some seismically active areas, constructing
large, heavy structures on pile foundations can
present significant design challenges. As with any
I-IONIE BUILDEWS GUIDE O COASTAL CONSTRUCTION
12/10
f
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construction system, construction in areas sub-
ject to high erosion or scour could present design
challenges due to the mass of an ICF structure.
Foundation walls built with ICF (with appropriate
openings) can be an appropriate foundation sys-
tem in an A Zone. In V Zones, open foundation
systems are required and in Coastal A Zones rec-
ommended. ICF and other solid foundation walls
are not appropriate to be used in these areas.
Follow manufacturer's installation instructions
and product use requirements in the manufac-
turer's code evaluation report.
Prefabricated Shear Walls and Moment Frames
Many companies now offer prefabricated shear wall
and moment frames that are pre -designed and avail-
able in standard sizes. The wall sections and moment
frames (see Figure 4) are connected to the rest of
the structural framing with bolted, screwed, or nailed
connections. Sections are ordered and brought to
the site on trucks as one piece or constructed with
either bolted or proprietary connectors.
Advantages:
Prefabricated shear walls are often designed to
provide for quick installation and compatibility
with other framing methods, where narrow wall
solutions may not be practical with other framing
options.
Moment frames take the place of shear walls to
allow large continuous spaces for windows and
other wall openings. Much like the prefabricated
shear walls they can be assembled quickly and
incorporated into the house framing.
Things to consider if building with prefabricated shear
walls and ordinary moment frames:
Some systems may be limited in their application
due to seismic or wind loading requirements.
Verify that the members and connections used
in the prefabricated sections are designed
for the corrosive, moist coastal environment.
Preservative -treated wood and galvanized or
stainless steel connectors may be required for a
coastal application.
Not all prefabricated shear wall or moment frame
systems will be allowed in all locations. It is im-
portant to consider that panel substitutions are
subject to requirements of the applicable build-
ing code. Refer to IRC R602.10 for more infor-
mation on wall bracing requirements.
Maintaining the load path is important with any
system. Because these systems provide later-
al support for the structure, it is important to
make sure that the load path will be transferred
through the wall system and transferred down
to the lower story of foundation and into the
ground. Follow the manufacturer's installation in-
struction and product use requirements in the
manufacturer's code evaluation report.
Sprayed Closed -Cell Foam Insulation
Sprayed closed -cell foam polyurethane insulation is
used to fill wall cavities in framed construction (see
Figure 5). When sprayed, it expands and hardens
forming a rigid air barrier and acting as a moisture
retardant.
Advantages:
Sprayed closed -cell foam insulation expands to
fill wall cavities, small holes, and gaps as it ex-
pands, producing a rigid barrier that results in re-
duced energy costs.
It is quick to apply and may require less time to
install than conventional batt insulation.
It offers acceptable flood resistance, which is
shown in NFIP Technical Bulletin 2-08, Flood -
Resistant Material Requirements for Buildings
Located in Special Flood Hazard Areas in ac-
cordance with the National Flood Insurance
Program, Table 2.
Things to consider if building with sprayed closed -cell
foam insulation:
Tests have shown that sprayed foam insulation
can improve the strength of structural framing
systems and connections. However, structural
framing systems and connections must be de-
signed and constructed in accordance with all
applicable building codes.
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-
rosion -resistant metal framing.
4 #f
12/10
Closed -cell foam should not be confused with
other types of insulation. Some varieties of in-
sulation on the market may be more cost-effec-
tive and more environmentally friendly; however,
many of these products are not considered flood -
resistant materials. Testing reports and provi-
sions of the building code should be consulted
for applicability in a coastal environment.
Sprayed foam systems (such as those used in
a wall system) create an assembly that when in-
undated by floodwaters may not be easily dried.
For this reason, they are not appropriate to use
below the BFE and are not considered flood -re-
sistant material unless the entire assembly has
been determined to be flood -resistant.
Methods
Advanced Wall Framing
Advanced wall framing refers to methods designed to
reduce the amount of lumber and construction waste
generated during home construction. These methods
include spacing wall studs up at 24 inches on center
rather than 16 inches, and using smaller structural
headers and single top plates on interior non -bearing
walls.
Advantages:
In most instances, the primary benefit of such
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
techniques:
Not all wall framing techniques are applicable
for hurricane -prone regions. The designer should
carefully consider if this is an appropriate con-
struction method for the area.
Increasing wall stud spacing, even when using
larger lumber sizes, can reduce the ability of
a wall to resist transverse loads. For more in-
formation on designing framed walls to resist
transverse loading, refer to IRC R602.10 or IBC
2305.
Construction crews may be unfamiliar with advanced
wall framing techniques, which may increase con-
struction time. Construction plans for advanced
framing should be detailed enough for construction
crews to recognize differences from conventional
techniques, and additional training for construction
crews may be required.
Modular Houses
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
Off } BU L GUIDE O O ��a LCONSTRUCTION� 6
12/10
manufactured homes, modular homes are required
to meet the same building code requirements as
houses constructed on site.
Advantages:
Sections can be assembled in a controlled envi-
ronment and construction time is less sensitive
to poor weather conditions at the house site.
Due to the sections being constructed at a
manufacturing facility, materials use is often
more efficient and fabrication is more efficient
than site -built construction, resulting in reduced
costs.
Things to consider if using modular houses
Proper installation of the house is important.
Due to the sections of the house being con-
structed in another location, tight construction
tolerances with the foundation are important in
order for the sections to fit together properly.
Modular homes are to be constructed to the
same tolerances and locally enforced building
codes as traditional site -built homes. The locally
enforced building code where the house will be
sited is the standard to which the modular house
shall be constructed.
The manufacturer needs to be aware of the loca-
tion of the house and the materials that should
be used in order to resist the site -specific haz-
ards. Building component choices for flood,
wind, and windborne debris -resistant materials
should be identified prior to ordering the house
and checked before installation begins.
Extra care should be taken to verify that modu-
lar components are properly fastened to building
foundations and load path connections are prop-
erly completed to transfer building loads from
the roof to the foundation.
NAH l
RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E R
0 NIE BUILDER E TO C 0 A S TA L SO N S T, RUCTION
12/10
IL K — * —- A — — 7% — — — 0 — — r --'A — — — --
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
A successful moisture barrier sys-
tem will limit water infiltration into
unwanted areas and allow drain-
age and drying of wetted building
materials.
Most moisture barrier systems
for walls (e.g., siding and brick ve-
neer) are "redundant" systems,
which require at least two drain-
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
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HOME BUILDERS GOUIDIETO COASTAL CONSTRUCTION 1 Of2
12/10
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...
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
tNAHB
'.„ RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E RHOME BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
Key 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.'
Coastal (especially oceanfront) homes cost more
to design, construct, maintain, repair, and insure
than inland homes.
Determining the risks associated with a particu-
lar building site or design is important.
Siting, designing, and constructing to minimum
regulatory requirements do not necessarily re-
sult in the lowest cost to the owner over a long
period of time. Exceeding minimum design re-
quirements costs slightly more initially, but can
save the owner money in the long run.
Costs
A variety of costs should be considered
when planning a coastal home, not just
the construction cost. Owners should be
aware of each of the following, and con-
sider how siting and design decisions
will affect these costs:
Long-term costs include costs for preventive mainte-
nance and for repair and replacement of deteriorated
or damaged building components.
Risk
One of the most important building costs to be con-
sidered is that resulting from storm and/or erosion
damage. But how can an owner decide what level of
risk is associated with a particular building site or
design? One way is to consider the probability of a
storm or erosion occurring and the potential building
damage that results (see matrix).
Initial costs include property evaluation
and acquisition costs and the costs of permitting, 'Note: 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://wwwJema.gov/nfip/manual,shtm).
Building sites or designs resulting in extreme or high
risk should be avoided — the likelihood of build-
ing loss is great, and the long-term costs to the
owner will be very high. Building sites or designs
resulting in medium or low risk should be given
preference.
Siting
Note that over a long period, poor siting decisions are
rarely overcome by building design.
Design
How much more expensive is it to build near the
coast as opposed to inland areas? The table be-
low suggests approximately 10 - 30 percent more.
What about exceeding minimum design require-
ments in coastal areas? The table suggests that
the added construction costs for meeting the
practices recommended in the Home Builder's
Guide to Coastal Construction (beyond typical
minimum requirements) are nominal.
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and/or local building code.)
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A Zone, pile/column foundation
1.1, 1.4, 3.1
High
High
V Zone, pile/column foundation*
1.1, 1.4, 1.5, 3.1
High
Joists sheathed on underside
Low
Low
Structurally sheathed walls*
Medium
Corrosion protection*
1.1, 1.7
Low
Decay protection*
1.1, 1.7
Medium
Hip roof shape
1.1
Low
Low
Enhanced roof sheathing connection*
1.1, 7.1
Low
Low
Enhanced roof underlayment*
7.2
Low
Low
Upgraded roofing materials*
1.1, 7.3
Medium
Enhanced flashing*
1.1, 6.1, 5.2
Low
Housewrap*
1.1, 6.1, 5.1
Low
Superior siding and connection*
5.3
Medium
Medium
Protected or impact -resistant glazing*
1.1, 6.2
High
Medium
Connection hardware*
1.1, 1.7, 4.3
Low
Flood -resistant materials*
1.1, 1.7
Low
Protected utilities and mechanicals*
1.1, s.3
Low
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,
High >2.0% 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
NAH B
RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E R
, 1,: HOW > .) S (`(G r t) .¥(... i.) `l .lEC ISl S A I E (, . 1'E' 0`,> x((:..,T v. S
HOVE BUILDEWS GUIDE TO COASTAL CONST, RUCTION
12/10
Selecting a Lotr10 "o " -I Im *-1 ,
,0
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
conditions.
Parcel characteristics, infra-
structure, regulations, envi-
ronmental factors, and own-
er desires constrain siting
options.
Conformance with local/
state shoreline setback
lines does not mean build-
ings will be "safe."
Information about site con-
ditions and history is avail-
able from several sources.
The Importance of
Property Purchase and
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.
I
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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.
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OFEMA " M BUILDER GUIDETO COASTA C N iK� " �
12/10
Coastal Setback Lines — What Protection
Do They Provide?
Many states require new buildings to be sited at or
landward of coastal construction setback lines, which
are usually based on long-term, average annual ero-
sion rates. For example, a typical minimum 50-year
setback line with an erosion rate of 2.5 feet/year
would require a setback of 125 feet, typically mea-
sured from a reference feature such as the dune
crest, vegetation line, or high-water line.
Building at the 125-foot setback (in this case) does
not mean that a building will be "safe" from erosion
for 50 years.
Storms can cause short-term erosion that far ex-
ceeds setbacks based on long-term averages.
Erosion rates vary over time, and erosion could
surpass the setback distance in just a few years'
time. The rate variability must also be known to
determine the probability of undermining over a
given time period.
x What Should Builders, Designers, and
x Owners Do?
Consult local and state agencies, universities,
and consultants for detailed, site -specific ero-
sion and hazard information.
Look for historical information on erosion and
storm effects. How have older buildings in the
area fared over time? Use the experience of oth-
ers to guide siting decisions.
Determine the owner's risk tolerance, and reject
parcels or building siting decisions that exceed
the acceptable level of risk.
Recommended building location on a coastal lot.
Siting should consider both long-term erosion
and storm impacts. Siting; should consider
LNAHB
'.„ RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E R
12/10
Foundations in Coastal Areas
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-
struction are generally not suitable
for coastal construction. Some ex-
amples of foundation systems that
have a history of poor performance
in erosion prone areas are slab -on -
ground, spread footings, and mat (or
raft) foundations.
Deeply embedded pile or column
foundations are required for V Zone
construction. In A Zones they are
recommended instead of solid wall,
crawlspace, slab, or other shallow
foundations, which are more sus-
ceptible to scour. (For the reference
of this document, the term deeply embedded
means "sufficient penetration into the ground to
accommodate storm -induced scour and erosion
and to resist all design vertical and lateral loads
without structural damage.")
Areas below elevated buildings in V Zones must
be "free of obstructions" that can transfer
flood loads to the foundation and building (see
Fact Sheet No. 8.1, Enclosures and Breakaway
Walls). Areas below elevated buildings in AZones
should follow the same recommended principles
as those areas for buildings located in V Zones.
Foundation Design Criteria
All foundations for buildings in flood hazard areas
must be constructed with flood -damage -resistant
materials (see Fact Sheet No. 1.7, Coastal Building
Materials). In addition to meeting the requirements
for conventional construction, these foundations
must: (1) elevate the building above the Base Flood
Elevation (BFE), and (2) prevent flotation, collapse,
and lateral movement of the building, resulting from
loads and conditions during the design flood event
(in coastal areas, these loads and conditions include
FEMA
._ .a
inundation by fast-moving water, breaking waves,
floating debris, erosion, and high winds).
Because the most hazardous coastal areas are sub-
ject to erosion, scour, and extreme flood loads, the
only practical way to perform these two functions
is to elevate a building on a deeply embedded and
"open" (i.e., pile or column) foundation. This ap-
proach resists storm -induced erosion and scour, and
it minimizes the foundation surface area subject to
lateral flood loads.
ASCE 24-05 is recommended as a best practice for
flood resistance design and construction, especially
in V Zones and Coastal A Zones. This standard has
specific information on foundation requirements for
Coastal High Hazard Areas and Coastal A Zones and
it has stricter requirements than the NFIP. Elevation
on open foundations is required by the National Flood
Insurance Program (NFIP) in V Zones (even when the
ground elevation lies above the BFE) and is strongly
recommended for Coastal A Zones. Some states and
communities have formally adopted open foundation
requirements for Coastal A Zone construction.
While using the approach of elevation of structures
on pile foundations improves performance and
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HOME BUILDER UIDIETO COASTAL N TRUCT O ` ,
12/10
minimizes some effects, even a deeply embedded
open pile foundation will not prevent eventual under-
mining and loss due to long-term erosion (see Fact
Sheet No. 2.2, Selecting a Lot and Siting the Building).
Performance of Various Foundation Types
in Coastal Areas
There are many ways to elevate buildings above the
BFE: fill, slab -on -grade, crawlspace, stemwall, solid
wall, pier (column), and pile. Not all of these are suit-
able for coastal areas. In fact, several of them are
prohibited in V Zones and are not recommended for
A Zone construction in coastal areas (see Fact Sheet
1.2, Summary of Coastal Construction Requirements
and Recommendations for Flood Effects).
Pile: Pile foundations are recommended for V Zones
and Coastal A Zones. These open foundations are
constructed with square or round, wood, concrete, or
steel piles, driven or jetted into the ground, or set
into augered holes. Critical aspects of a pile foun-
dation include the pile size, installation method and
embedment depth, bracing, and the connections to
the elevated structure (see Fact Sheets Nos. 3.2, Pile
Installation and 3.3, Wood -Pile -to -Beam Connections).
Pile foundations with inadequate embedment will
lead to building collapse. Inadequately sized piles
are vulnerable to breakage by waves and debris.
Fill: Using fill as a means of providing structural
support to buildings in V Zones is prohibited be-
cause it is susceptible to erosion. Also, fill must not
be used as a means of elevating buildings in any
other coastal area subject to erosion, waves, or fast-
moving water. However, minor quantities of fill are
permitted for landscaping, site grading (not related to
structural support of the building), drainage around
and under buildings, and for the support of parking
slabs, pool decks, patios and walkways (2009 IRC
Section R322.3.2). These guidelines are consistent
with NFIP Technical Bulletin 5, Free -of -Obstruction
Requirements for Buildings Located in Coastal High
Hazard Areas (08/08), which states: "Fill must not
prevent the free passage of floodwaters and waves
beneath elevated buildings. Fill must not divert flood-
waters or deflect waves such that increased damage
is sustained by adjacent or nearby buildings."
Slab -on -Grade: Slab -on -grade foundations are also
susceptible to erosion and are prohibited in V Zones
and are not recommended forAZones in coastal areas.
(Note that parking slabs are often permitted below el-
evated buildings, but are susceptible to undermining
and collapse.) It is recommended that parking slabs
be designed to be frangible (breakaway) or designed
and constructed to be self-supporting structural slabs
capable of remaining intact and functional under
base flood conditions, including expected erosion. For
more information, see NFIP Technical Bulletin 5, Free -
of -Obstruction Requirements for Buildings Located in
Coastal High Hazard Areas (08/08).
Crawlspace: Crawlspace foundations are prohibited
in V Zones and are not recommended for A Zone
construction in coastal areas. They are suscepti-
ble to erosion when the footing depth is inadequate
to prevent undermining. Crawlspace walls are also
vulnerable to wave forces. Where used, crawlspace
foundations must be equipped with flood open-
ings; grade elevations should be such that water
is not trapped in the crawlspace (see Fact Sheets
Nos. 3.5, Foundation Walls and 8.1, Enclosures and
Breakaway Walls).
Stemwall: Stemwall foundations are
similar to crawlspace foundations in
construction, but the interior space that
would otherwise form the crawlspace is
often backfilled with structural fill or sand
that supports a floor slab. Stemwall foun-
dations have been observed to perform
better during storms than many Crawl -
space and pier foundations. Although the
IRC allows for heights of up to six feet, it
is usually more economical and a better
design choice to use another foundation
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
should ensure that this does not cause
consolidation of the backfill. In addition,
in some soils such as sand, capillary
action can cause water and moisture
to affect the slab. Flood openings are
not required in a backfilled stemwall
foundation. Stemwall foundations are
12/10
prohibited in V Zones but are recommended in A
Zone areas subject to limited wave action, as long as
embedment of the wall is sufficient to resist erosion
and scour (see FEMA 549, Hurricane Katrina in the
Gulf Coast).
Solid Foundation Walls: The NFIP prohibits solid foun-
dation walls in V Zones and are not recommended
for A Zone areas subject to breaking waves or other
large flood forces —the walls act as an obstruction
to flood flow. Like crawlspace walls, they are suscep-
tible to erosion when the footing depth is inadequate
to prevent undermining. Solid walls have been used
in some regions to elevate buildings one story in
height. Where used, the walls must allow floodwaters
to pass between or through the walls (using flood
openings). (See Fact Sheets Nos. 3.5, Foundation
Walls and 8.1, Enclosures and Breakaway Walls.)
Pier (column): Pier foundations are recommended for
A Zone areas where erosion potential and flood forces
are small. This open foundation is commonly con-
structed with reinforced and grouted masonry units
atop a concrete footing. Shallow pier foundations are
extremely vulnerable to erosion and overturning if the
footing depth and size are inadequate. They are also
vulnerable to breakage. Fact Sheet No. 3.4, Reinforced
Masonry Pier Construction, provides guidance on how
to determine whether pier foundations are appropri-
ate, and how to design and construct them.
Foundations for High -Elevation Coastal Areas
Foundation design is problematic in bluff areas
that are vulnerable to coastal erosion but outside
mapped flood hazard areas. Although NFIP require-
ments may not apply, the threat of undermining is
not diminished.
Moreover, both shallow and deep foundations will fail
in such situations. Long-term solutions to the prob-
lem may involve better siting (see Fact Sheet No.
2.2, Selecting a Lot and Siting the Building), moving
the building when it is threatened, or (where permit-
ted and economically feasible) controlling erosion
through slope stabilization and structural protec-
tion. Additionally FEMA 232, Homebuilders' Guide
to Earthquake Resistant Design and Construction,
provides information on foundation anchorage for hill-
side structures.
Foundations in V Zones with Ground
Elevations Above the BFE
In some instances, coastal areas will be mapped on
an NFIP Digital Flood Insurance Rate Map (DFIRM) as
Zone V, but will have dunes or bluffs with ground el-
evations above the BFE shown on the DFIRM. During
a design flood event, erosion of the bluffs and high
dunes can be expected at these areas as well as
waves and inundation. Therefore, the ground level
can be expected to be lowered to a point that wave
forces and loss of soil are a critical factor. The foun-
dations for structures in these V Zone areas with
high ground elevation are the same as V Zone ar-
eas with lower ground elevations. Deeply embedded
pile or column foundations are still required in these
areas, and solid or shallow foundations are still pro-
hibited. The presence of a V Zone designation in
these instances indicates that the dune or bluff is
expected to erode during the base flood event and
that V Zone wave conditions are expected after the
erosion occurs. The presence of ground elevations
above the BFE in a V Zone should not be taken to
mean that the area is free from base flood and ero-
sion effects.
Additional Resources
FEMA 550, Recommended Residential Construction
for the Gulf Coast: Building on Strong and Safe
Foundations (July 2006). (http://www.fema.gov/li-
brary/viewRecord.do?id=1853)
FEMA 549, Hurricane Katrina in the Gulf Coast (July
2006). (http://www.fema.gov/library/viewRecord.
do?id=1857)
FEMA, NFIP Technical Bulletin 5, Free -of -Obstruction
Requirements for Buildings Located in Coastal High
Hazard Areas, FIA-TB-S, Washington, DC, August
2008. (http://www.fema.gov/library/viewRecord.
do?id=1718)
FEMA 232, Homebuilders' Guide to Earthquake
Resistant Design and Construction, Washington,
DC, February 2001 (http://www.fema.gov/library/
viewRecord.do?id=2103)
American Society of Civil Engineers (ASCE/SEI)
Standard 7-10: Minimum Design Loads for Buildings
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)
NAHB
€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center C E T E R
MONIE BWLDER�S GUIDE TO COASTAL CONSTRUCTION
12/10
Pile Design and Installation
Purpose: To provide basic information about pile design and installation.
Key Factors
Use a pile type that is appropriate for local
conditions.
Piles should resist coastal hazards such as high
winds and flood loads in addition to withstanding
erosion and scour. Erosion being the widespread
loss of soil and scour being a localized loss of
soil around a building or foundation element due
to turbulent water movement.
Have a registered engineer design piles for ade-
quate layout, size, and length.
Use installation methods that are appropriate
for the conditions.
Brace piles properly during construction.
Make accurate field cuts, and treat all cuts and
drilled holes to prevent decay.
Have all pile -to -beam connections engineered,
and use corrosion -resistant hardware (see Fact
Sheet No. 1.7, Coastal Building Materials).
Pile Types
The most common pile types used are preservative
treated wood, concrete, and steel. Contractors doing
construction in coastal areas typically select preser-
vative treated wood piles for pile foundations. They
can be square or round in cross section. Wood piles
sFEMA
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are easily cut and adjusted in the field. Concrete
and steel can also be used but are less common in
residential construction. Concrete piles —may be an
appropriate choice depending upon the pile capacity
requirements and elevation needed by the design —
are available in longer lengths and are usually
installed by pile driving. Concrete piles tend to have
higher strengths and are durable to many factors
that are in the coastal environment when properly
designed and detailed. Steel piles are rarely used
because of potential corrosion problems.
Pile Size and Length
The foundation engineer is the one who determines
pile size and length. Specified bearing and penetra-
tion requirements must be met. Round piles should
have no less than an 8-inch tip diameter; square
piles should have a minimum timber size of 8 by 8
inches. The total length of the pile is based on build-
ing code requirements [see the 2009 International
Building Code (IBC) Section 1810 on deep founda-
tions], calculated penetration requirements, erosion
and scour potential, Design Flood Elevation (DFE),
and allowance for cut-off and beam width (see Figure
1 and Table 1, which is an example of foundation de-
sign results). Substantial improvement in foundation
performance can be achieved by increasing the mini-
mum timber size for square piles to 12 by 12 inches
or minimum tip diameter for round piles of 12 inches.
"' I I A"T .�' m
HOWIE BUILDER W-D COASTAL NSTRUCTIO
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.
......
........
U
1 gMENEM
... ........ .........
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
The foundation engineer and designer determine the
pile layout together. Accurate placement and correc-
tion of misaligned piles is important. The use of a
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
temporary guide structure that is installed in a man-
ner to restrict the lateral movement of the piles during
driving. The pile template is reused for each row of
piles to assure consistent spacing and alignment. Pile
placement should not result in more than 50 percent
of the pile cross section being cut for girder or other
connections. Verify proper pile locations on drawings
before construction and clarify any discrepancies.
Layout can be done by a licensed design professional
or surveyor, a construction surveyor, the foundation
contractor, or the builder. The layout process must
always include establishing an elevation for the fin-
ished first floor. Construction of the first -floor platform
should not begin until this elevation is established
(see Fact Sheet No. 1.4, Lowest Floor Elevation).
Installation Methods
Piles can be driven, augered, or jetted into place.
The installation method will vary with soil conditions,
bearing requirements, equipment available, and lo-
cal practice. One common method is to initially jet
the pile to a few feet short of required penetration,
then complete the installation by driving with a drop
hammer. Driving the pile even a few feet helps assure
the pile is achieving some end -bearing capacity and
some skin friction. Full depth driving where achiev-
able provides for a pile foundation that has several
advantages that merit consideration.
Pile Bracing
The engineer determines pile bracing layout.
Common bracing methods include knee and diago-
nal bracing. Knee bracing is an effective method of
improving the performance of a pile system without
creating an obstruction to the flow of water and de-
bris from a design event. Because slender bracing is
susceptible to buckling, slender bracing should be
considered as tension only. Bracing can become an
obstruction, however, and increase a foundations ex-
posure to wave and debris impact. Bracing is often
oriented perpendicular to the shoreline so that it is
not struck broadside by waves, debris, and velocity
flow (see Figure 2). Temporary bracing or jacking to
align piles and hold true during construction is the
responsibility of the contractor.
It is recommended that pile bracing be used only
for reducing the structure's sway and vibration for
comfort. In other words, bracing should be used to
address serviceability issues and not strength is-
sues. The foundation design should consider the
piles as being un-braced as the condition that may
occur when floating debris removes or damages the
bracing. If the pile foundation is not able to provide
x; Pi D Si(`N a I D, I x` € I.....: ..iC
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12/10
H 0 NIE EE I LEER E G E I EE TO COA STA L CO N S T R U CT1 ON
the desired strength performance without bracing
then the designer should consider increasing the pile
size. Pile bracing should only be for comfort of the oc-
cupants, but not for stability of the home.
Field Cutting and Drilling
A chain saw is the common tool for making cuts and
notches in wood piles. After making cuts, exposed
areas should be field -treated with the proper wood
preservative to prevent decay. This involves apply-
ing the preservative with a brush to the cut or drilled
holes in the pile until no more fluid is drawn into the
wood.
Connections
The connection of the pile to the structural mem-
bers is one of the most critical connections in the
structure. Always follow design specifications and
use corrosion -resistant hardware. Strict attention to
jN
N v ..i x
detail and good construction practices are critical for
successful performance of the foundation (see Fact
Sheet Nos. 1.7, Coastal Building Materials, and 3.3,
Wood -Pile -to -Beam Connections).
Verification of Pile Capacity
Generally, pile capacity for residential construction is
not verified in the field. If a specified minimum pile
penetration is provided, bearing is assumed to be ac-
ceptable for the local soil conditions. Subsurface soil
conditions can vary from the typical assumed con-
ditions, so verification of pile capacity is prudent,
particularly for expensive coastal homes. Various
methods are available for predicting pile capacity.
Consult a local foundation engineer for the most ap-
propriate method for the site.
HONIE BWLDERS GUIDE TO COASTAL CONSTRUCTION
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.shtm1)
Timber Pile Council, American Wood Preservers Institute, Timber Pile Design and Construction Manual,
(http://www.wwpinstitute.org/pdtfiles/TimberPileManual.pdf)
RIAFIB
'....€'' RESEARCH
Developed in association with the National Association of Home Builders Research Center e E N T E
4 of HOVE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
Wood Pile -to -Beam
Connections
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,
before making connections.
Carefully cut piles to ensure required scarf
depths.
Limit cuts to no more than 50 percent of pile
cross section.
Use corrosion -resistant connectors and fasten-
ers such as those fabricated from stainless
steel, or connectors and fasteners with corrosion
protection such as provided by hot -dip galvanized
coating (see Fact Sheet No. 1.7, Coastal Building
Materials).
Accurately locate and drill bolt holes.
Field -treat all cuts and holes to prevent decay.
Use sufficient pile and beam sizes to allow prop-
er bolt edge distances.
Built-up beams should be designed as continuous
members and not be broken over the piles. Some
homebuilders are using engi-
neered wood products, such as
glued laminated timber and par-
allel strand lumber, which can
span longer distances without
splices. The ability to span lon-
ger distances without splices
eases installation and reduces
fabrication costs.
t,�nry
a
OFEMA t�' � ...� ...� �" TAX C0 Sv,A C' XN tK iC 0 Of `..
12/10
3,3: VNICII "DE) P I I -BEAM
H 0 NIE BUILDER TO C 0 A S TA L CO N S T, RUCTION
12/10
3, 3: VNI Cl Ca I-) P I I E.'l-'l'0-BE'.APA C' NIIINECI " S
HOME BWLDER�S GUIDE TO COASTAL CONSTRUCTION 0, U
12/10
Figure 4. Connection details for misaligned piles. I
3,3: VNIC, "DE) P I I -BEAM
4 0, f G'
12/10
HOME BUILDEWS GUIDE TO COASTAL CONST, RUCTION
3, 3: VNI Cl Ca I-) P I I E.'l-'l'0-BE'.APA C' NIIINECI " S
HOME BWLDER�S GUIDE TO COASTAL CONSTRUCTION 5 ol 6
12/10
Additional Resources
American Wood Council (AWC) (http://www.awc.org)
American Institute of Timber Construction (AITC) (http://www.aitc-glulam.org)
NAH I
RESEARCH
Developed in association with the National Association of Home Builders Research Center CENTER
TO
HOME BUILDEWS GUIDE TO COASTAL CONST, RUCTION
12/10
Purpose: To provide an alternative to piles in
V Zones and A Zones in coastal areas where soil
properties and other site conditions indicate that
piers are an acceptable alternative to the usually
recommended pile foundation. Examples of ap-
propriate conditions for the use of piers are where
rock is at or near the surface or where the potential
for erosion and scour is low.
Key Issues
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-
al areas.
The connection between the pier and its footing
must be properly designed and constructed to
resist separation of the pier from the footing and
overturning due to lateral (flood, wind, debris)
forces.
The top of the footing must be below the antici-
pated erosion and scour depth.
The piers must be reinforced with steel and fully
grouted.
The connection to the floor beam at the top of
the pier must be through use of properly sized
and detailed metal connectors.
Special attention must be given to the applica-
tion of mortar and the tooling of all the joints in
order to help resist water intrusion into the pier
core, where the steel can be corroded.
Special attention must be given to corrosion pro-
tection of joint reinforcement, accessories, an-
chors, and reinforcement bars. Joint reinforce-
ment that is exposed to weather or the earth
shall be stainless steel, hot dipped galvanized,
or epoxy coated. Wall ties, plates, bars, anchors,
and inserts exposed to earth or weather shall
also be stainless steel, hot dipped galvanized, or
epoxy coated. Reinforcement bars shall be pro-
tected by proper use of masonry cover.
Piers vs. Piles
Pier foundations are most appropriate in
areas where:
Erosion and scour potential are low.
Flood depths and lateral forces are
low.
Soil can help resist overturning of
pier.
The combination of high winds and moist
(sometimes salt -laden) air can have a
damaging effect on masonry construc-
tion by forcing moisture into even the
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-
ment bars and subsequent cracking and
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.
Good Masonry Practice
If a masonry pier is determined to be an appropriate
foundation for a building, there are some practices
that should be followed during construction of the
piers.
Masonry units and packaged mortar and grout
materials should be stored off the ground and
covered.
Masonry work in progress must be well protect-
ed from exposure to weather.
Mortar and grouts must be carefully batched and
mixed. The 2009 International Building Code
(IBC 2009) and 2009 International Residential
Code (IRC) specify grout proportions by volume
for masonry construction.
Connectors should be selected that are appro-
priate for masonry to wood connection. It is im-
portant to maintain a sufficient load path from
the building into the ground. The connectors and
fasteners should be a corrosion -resistant mate-
rial or have corrosion protection at least equiva-
lent to that provided by coatings in accordance
with the 2009 IRC. Connectors should be prop-
erly embedded or attached to the pier. Wood in
contact with masonry pier should be natural-
ly durable or preservative -treated. Figure 3 il-
lustrates the importance of maintaining a prop-
er load path between the pier and the building's
beams.
Properly sized steel reinforcing bars should be
installed throughout the masonry piers. Piers
should be fully grouted and steel reinforcing bars
should not be left exposed to weather for exces-
sive amounts of time prior to installation. Lap
splices should be properly located and of suf-
ficient length to meet the standard masonry in-
dustry details and requirements to sufficiently
carry the loads imposed on the structure.
Consider incorporating grade beams into the
foundation in order to achieve greater structural
stability in the pier system.
If the design of the pier system or any details are
unclear, contact a structural engineer or appro-
priate design professional to clarify the founda-
tion details.
Pros and Cons of Grade Beams
Grade beams are horizontal structural members cast
against the ground or "grade." Grade beams can be a
useful foundation method in areas with limited poten-
tial for erosion and scour. The type of force resisted
by grade beams varies by application, but can range
from continuous vertical and horizontal loads to axial
loads. The grade beams used in this example are
used primarily for axial loads generated by stabil-
ity demands of the piers. The grade beams should
be placed below the elevation of anticipated eroded
grade so that there is no effect on scour and erosion
of the supporting soils.
The pros of using grade beams with pier foundations
are that they:
Provide vertical and lateral support.
Are less prone to rotation and overturning.
Transfer loads imposed on the elevated home
and foundation to the ground below.
12/10
0 NIE BUILDER TO COA STA L CO N TRUCT 0
Some cons of using grade beams with pier founda-
tions are that they:
Are susceptible to erosion and scour if too
shallow
Can become obstructions during flood events
and can increase scour
Figure 3. Failure of pier -to -beam connections due to
wave and flood forces acting on the elevated building
(tong Beach, Mississippi)
..
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47
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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)
t..NANB
'..,h RESEARCH
Developed in association with the National Association of Home Builders Research Center C.E N T E R
HOME i LDER S GUIDE O COASTAL CONSTRUCTION
12/10
Foundation Walls
Purpose: To discuss the use of foundation walls in coastal buildings.
Key Issues
Foundation walls include stem -
walls, cripple walls, and other sol-
id walls.
Foundation walls are prohibited
by the National Flood Insurance
Program (NFIP) in Zone V.*
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-
tential for erosion and breaking
waves is low.
Where foundation walls are used,
flood -resistant design of founda-
tion walls must consider embed-
ment, height, materials and work-
manship, lateral support at the
top of the wall, flood openings and
ventilation openings, and interior
grade elevation.
Foundation Walls — When Are
They Appropriate?
Use of foundation walls — such as
those in crawlspace and other sol-
id -wall foundations — is potentially
troublesome in coastal areas for two
reasons: (1) they present an obstruc-
tion to breaking waves and fast-moving
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-
ject to shallow flooding, where erosion potential is
low and where breaking waves do not occur during
the Base Flood. The NFIP prohibits the use of foun-
dation walls in Zone V*. This Home Builder's Guide to
Coastal Construction recommends against their use
in Zone A in coastal areas. Deeply embedded pile or
column foundations are recommended because they
present less of an obstruction to floodwaters and are
less vulnerable to erosion.
..
FEMA
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OME BUDER�" T COASTAL A N KUP O
12/10
Design Considerations for Foundation Walls
The design of foundation walls is covered by building
codes and standards (e.g., Standard for Residential
Construction in High -Wind Regions, ICC 600-2008,
by the International Code Council). For flood design
purposes, there are six additional design consid-
erations: (1) embedment, (2) height, (3) materials
and workmanship, (4) lateral support at the top of
the wall, (5) flood openings and ventilation open-
ings, and (6) interior grade elevation.
Embedment — The top of the footing should be no
higher than the anticipated depth of erosion and
scour (this basic requirement is the same as that for
piers; see figure at right and Fact Sheet No. 3.4). If
the required embedment cannot be achieved without
extensive excavation, consid-
er a pile foundation instead.
Height — The wall should be
high enough to elevate the
bottom of the floor system to
or above the DFE (see Fact
Sheet No. 1.4).
Materials and Workman-
ship— Foundation walls can
be constructed from many ma-
terials, but masonry, concrete,
and wood are the most com-
mon. Each material can be
specified and used in a man-
ner to resist damage due to
moisture and inundation (see
Fact Sheet No. 1.7). Work-
manship for flood -resistant
foundations is crucial. Wood
should be preservative -treat-
ed for foundation or marine
use (aboveground or ground -
contact treatment will not be
sufficient). Cuts and holes
should be field -treated. Masonry should be reinforced
and fully grouted (see Fact Sheet No. 4.2 for masonry
details). Concrete should be reinforced and composed
of a high -strength, low water -to -cement ratio mix.
Lateral Support at the Top of the Wall — Foundation
walls must be designed and constructed to with-
stand all flood, wind, and seismic forces, as well as
any unbalanced soil/hydrostatic loads. The walls
will typically require lateral support from the floor
system and diaphragm, and connections to the
top of the walls must be detailed properly. Cripple
walls, where used, should be firmly attached and
braced.
Flood Openings and Ventilation Openings — Any area
below the DFE enclosed by foundation walls must
be equipped with openings capable of automati-
cally equalizing the water levels inside and outside
the enclosure. Specific flood opening requirements
are included in Fact Sheet No. 8.1. Flood openings
are not required for backfilled stemwall foundations
supporting a slab. Air ventilation openings required
by building codes do not generally satisfy the flood
opening requirement; the air vents are typically in-
stalled near the top of the wall, the flood vents must
be installed near the bottom, and opening areas for
air flow may be insufficient for flood flow.
Interior Grade Elevation — Conventional practice for
crawlspace construction calls for excavation of the
crawlspace and use of the excavated soil to promote
drainage away from the structure (see left-hand figure
on page 3). This approach may be acceptable for non-
floodplain areas, but in floodplains, this practice can
result in increased lateral loads (e.g., from saturated
soil) against the foundation walls and ponding in the
crawlspace area. If the interior grade of the crawlspace
is below the DFE, NFIP requirements can be met by en-
suring that the interior grade is at or above the lowest
exterior grade adjacent to the building (see right-hand
figure on page 3). When floodwaters recede, the flood
openings in the foundation walls allow floodwaters to
automatically exit the crawlspace. FEMA may accept
a crawlspace elevation up to 2 feet below the lowest
adjacent exterior grade; however, the community must
adopt specific requirements in order for this type of
crawlspace to be constructed in a floodplain.
12/10
HOVE BUILDEWS GUIDETO COASTAL CONSTRUCTION
If a stemwall and floor slab system is used, the
interior space beneath the slab should be back -
filled with compacted gravel (or such materials as
required by the building code). As long as the sys-
tem can act monolithically, it will resist most flood
forces. However, if the backfill settles or washes
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)
FEMA. NFIP Technical Bulletin 11-01, Crawlspace
Construction. 2001. (http://www.fema.gov/plan/pre-
vent/floodplain/techbul.shtm)
FEMA. Recommended Residential Construction for the
Gulf Coast, Building on Strong and Safe Foundations.
FEMA 550. 2010. (http://www.fema.gov/library)
Developed in association with the National Association of Home Builders Research Center
NAHB
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t....CENTER€
MOM i LDER S GUIDE TO COASTAL CONSTRUCTION
,3
12/10
Load Paths
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.
r-I
I I
I I _
I I
I I -
Vertical load path from roof to ground on a
platform -and -pile -construction building. Note: Load paths will vary
depending on construction type and design. Adjacent framing
members will receive more load if a connection fails.
I'.) `, S
FEMA HO'ME BUILDERS G"UH
12/10
Load path around a window opening.
0
0
0
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0
4, FV01 HS
H 0 NIE BUILDER TO COAST L CO N S T R U CTI 0 N
12/10
Purpose: To highlight several important details for
masonry construction in coastal areas.
Key Issues
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.
Load Paths
A properly connected load path from roof to foundation
is crucial in coastal areas (see Fact Sheets Nos. 4.1
and 4.3). The following details show important connec-
tions for a typical masonry home.
Durability — High winds and salt -laden air can damage masonry construction. The entry of moisture into large
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.
Proper batching — Mortar and grout must be properly batched to yield the required strength.
Good workmanship — Head and bed joints must be well
Vjoints provide the best moisture protection (see detail
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
for mortar -to -mortar contact as two blocks are laid to-
gether in the wall and prevents hairline cracking in the
head joint.
mortared and well tooled. Concave joints and
above). All block walls should be laid with full
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.
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
E or a cut masonry bond beam.
Standard 901 hook with lap
4" minimum
Reinforced raked cast -in -place concrete
bond beam or cut masonry bond beam
2 x 4 minimum
wood nailer with
1/4" anchor bolts
.P.
Continuous gable endwall reinforcement.'
Foundation at
one-story
building or
bond beam
at multistory
Cleanouts required for grout pour heights greater than 5' unless
footing dowel is not required
Developed in association with the National Association of Home Builders Research Center
NAHB
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t....CENTER€
HOME BWLDERS GUIDETO COASTAL CONSTRUCTION
,3
12/10
Use of Connectors and
Brackets
Purpose: To highlight important building connections and illustrate the proper
use of various types of connection hardware.
l,n r;yJ,
FEMA'i�I'OME BUILDERUIDIETO COASTAL CONSTRUCTION
12/10
Housewrap
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 housewrap
or building paper depends on
the climate and on specifier
or owner preference. Both ma-
terials can provide adequate
protection.
Housewrap must be installed
properly or it could be more det-
rimental than beneficial.
Proper installation, especially in
lapping, is the key to successful
housewrap use.
Purpose of Housewrap
Housewrap serves as a dual-purpose weather bar-
rier. It not only minimizes the flow of air in and out
of a house, but also stops liquid water and acts as
a drainage plane. Housewrap is not a vapor retarder.
The unique characteristic of housewrap is that it al-
lows water vapor to pass through it while blocking
liquid water. This permits moist humid air to escape
from the inside of the home, while preventing outside
liquid water (rain) from entering the home.
When Should Housewrap Be Used?
Almost all exterior finishes allow at least some wa-
ter penetration. If this water continually soaks the
wall sheathing and framing members, problems such
as dryrot and mold growth could occur. Housewrap
stops water that passes through the siding and al-
lows it to drain away from the structural members. In
humid climates with heavy rainfall, housewrap is rec-
ommended to prevent water damage to the framing.
Use in dryer climates may not be as critical, since
materials are allowed to adequately dry, although
housewrap also prevents air movement through the
wall cavity, which is beneficial for insulating purposes.
Housewrap or Building Paper?
To answer this question, it is important to know
what attributes are most important for a particular
climate. Five attributes associated with secondary
weather barriers are:
Air permeability — ability to allow air to pass
through
Vapor permeability — ability to allow water vapor
(gaseous water) to pass through
Water resistance — ability to prevent liquid water
from passing through
Repels moisture —ability to prevent moisture
absorption
Durability — resistance to tearing and
deterioration
'U TON
FEMA ii0tvEBUILDER�S'*'��lIE'I'Of'OJkSTAL�IONS'T— el I
._ .a
12/10
As shown in the following table, the climate where the house is located determines the importance of the
attribute.
Installing Housewrap
No matter what product is used (housewrap or
building paper), neither will work effectively if not
installed correctly. In fact, installing housewrap incor-
rectly could do more harm than not using it at all.
Housewrap is often thought of and installed as if it
were an air retarder alone. A housewrap will chan-
nel water and collect it whether the installer intends
it to or not. This can lead to serious water damage
if the housewrap is installed in a manner that does
not allow the channeled water out of the wall system.
The following are tips for successful installation of
housewrap:
Follow manufacturers' instructions.
Plan the job so that housewrap is applied before
windows and doors are installed.
Proper lapping is the key —the upper layer should
always be lapped over the lower layer.
Weatherboard -lap horizontal joints at least 6
inches.
Lap vertical joints 6 to 12 inches (depending on
potential wind -driven rain conditions).
Use 1-inch minimum staples or roofing nails
spaced 12 to 18 inches on center throughout.
Tape joints with housewrap tape.
Allow drainage at the bottom of the siding.
Avoid complicated details in the design stage to
prevent water intrusion problems.
When sealant is required:
use backing rods as needed,
use sealant that is compatible with the
climate,
use sealant that is compatible with the ma-
terials it is being applied to,
surfaces should be clean (free of dirt and
loose material), and
discuss maintenance with the homeowner.
Avoid These Common Problems
Incomplete wrapping
Gable ends are often left unwrapped, leaving a
seam at the low end of the gable. This meth-
od works to prevent air intrusion, but water that
gets past the siding will run down the unwrapped
gable end and get behind the housewrap at the
seam. Also, it is common for builders to pre -wrap
a wall before standing it. If this is done, the band
joist is left unwrapped. Wrap the band joist by in-
serting a strip 6 to 12 inches underneath the
bottom edge of the wall wrap. In addition, out-
side corners are often missed.
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 -
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.
2 o3HOME BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
U� Improper integration with flashing around doors and windows —See Fact Sheet No. Si
Relying on caulking or self -sticking tape to address improper lapping
Sealant can and will do1ohora10
overtime. Alapping 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-
ly fails. Therefore, do not rely on
sealant 0rtape to correct lapping
errors.
NAHB
RESEARCH
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5J:H")U'_E��BAP
MOME BUULDER"S GUIDE TOCOASTAL CONSTRUCTION Bof3
Roof -to -Wall and
Ir"IV& I 'A TT r 11 -r-11 1 0
Purpose: To en.whasize the iniportance of lope r roof and deck flashing, and to proiddle fivDical and en-
hanced flac-17ina lechnialies for coabla,* homi-,S.
Keyissues
Poor performance of flash-
ing and subsequent water
intrusion is a common prob-
lem for coastal homes.
Enhanced flashing tech-
niques are recommended in
areas that frequently experi-
ence high winds and driving
rain.
Water penetration at deck
ledgers can cause wood
dry rot and corrosion of
connectors leading to deck
collapse.
See Fact Sheet Nos. 7.2 and 7.3 for rake and
eave details.
1: C,
5,2: Fz,XDF-
FEMA HOME BUILDERUIDETO COASTAL CONSTRUCTION
12/10
Siding Installation in
High -Wind Regions
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
and non-residential buildings during hurricanes.
Also, wind -driven rain is frequently blown into wall
cavities (even when the siding itself is not blown
off). Guidance for achieving successful wind per-
formance is presented in the following.
To avoid wind -driven rain penetration into wall
cavities, an effective moisture barrier (house -
wrap or building paper) is needed. For further in-
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.
Always follow manufacturer's installation instruc-
tions and local building code requirements.
Use products that are suitable for a coastal en-
vironment. Many manufacturers do not rate their
products in a way that makes it easy to deter-
mine whether the product will be adequate for
the coastal environment. Use only siding prod-
ucts where the supplier can provide specific in-
formation on product performance in coastal or
high -wind environments.
For buildings located within 3,000 feet of
the ocean line, stainless steel fasteners are
recommended.
Avoid using dissimilar metals together.
The installation details for starting the first (low-
est) course of lap siding can be critical. Loss
of siding often begins at the lowest course and
proceeds up the wall (Figures 4 and 12). This
is particularly important for elevated buildings,
where the wind blows under the building as well
as against the sides.
When applying new siding over existing siding,
use shims or install a solid backing to create a
uniform, flat surface on which to apply the siding,
and avoid creating gaps or projections that could
catch the wind.
Coastal buildings require more maintenance
than inland buildings. This maintenance require-
ment needs to be considered in both the selec-
tion and installation of siding.
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.
ZsrPDR
i�IOME BUILDER�ETO COASTAL CONSTRUCTION
s
7,11
12/10
,3,3: S"I'DING, INS"I'Al ATICN HN4 Hh"JI-MH tPE."GICINIS
HOME BUILDEWS GUIDE TO COASTAL CONST, RUCTION
12/10
Use aluminum, galvanized steel, or other corro-
sion -resistant nails when installing vinyl siding.
Aluminum trim pieces require aluminum or stain-
less steel fasteners.
Nail heads should be 5/16 inch minimum in di-
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
course of siding is positively locked into the pre-
vious course (Figure 5). Push the panel up into
the lock from the bottom before nailing rather
than pulling from the top. Do not attempt to align
siding courses with adjacent walls by installing
some courses loosely.
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-
ing while nailing. Reinstall any panels that have
this problem.
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-
nyl siding be installed over approved sheath-
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
code requirements. Ensure product rating is ap-
propriate for the intended application.
It is recommended that vinyl siding installers be
certified under the VSI Certified Installer Program
sponsored by the Vinyl Siding Institute.
ter.
Figure 4. Utility trim was substituted for the starter
strip and the bottom lock was cut off the siding. Siding
was able to pull loose under wind pressure.
i
f •E �r
Figure 5. The siding panel was not properly locked into
the panel below.
HOME WLDER�S GUIDE TO COASTAL CONSTRUCTION`s
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
siding before installation.
Carefully follow manufacturer's detailing instruc-
tions to prevent excessive water intrusion behind
the siding.
For attachment recommendations, see Natural
Wood Siding. Selection, Installation and Finish-
ing, published by the Western Wood Products
Association.
This publication recommends an air gap between
the moisture barrier and the backside of the siding
to promote drainage and ventilation. Such a wall
configuration is referred to as a rain screen wall.
See the text box on page 5.
Follow the installation details shown in Figures
8a and 8b. (Note: Although these details do not
show a rain screen, inclusion of vertical furring
strips to create a rain screen is recommended.)
4 ,f
HOME BUILDEWS GUIDE TO COASTAL CONST, RUCTION
12/10
5,3: INS"I'Al Al K-� It" It"JI-M PEUCINIS
HOME BWLDER�S GUIDE TO COASTAL CONSTRUCTION
12/10
Always consult and follow the manufacturer's
installation requirements for the needed wind
speed rating or design pressure (refer to the
manufacturer's building code compliance eval-
uation report). Observe the manufacturer's fas-
tener specifications, including fastener type and
size, spacing, and penetration requirements. Do
not over drive or under drive.
At gable end walls, it is recommended that fiber
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.
Face nailing (Figure 11) instead of blind nailing
is recommended where the basic (design) wind
speed is 100 mph or greater. If the local building
code or manufacturer specifies face nailing at a
lower wind speed, install accordingly.
Do not leave the underside of the first course ex-
posed or extending beyond the underlying mate-
rial (Figure 12). Consider the use of a trim board
to close off the underside of the first course.
Sustainable Design
Material selection for sustainable sources and
durability
For wood products, it is best to select material that
has been certified by a recognized program such
as the American Tree Farm System° (ATFS), the
Forest Stewardship Council (FSC) or the Sustainable
Forestry Initiative° (SFI). Not only do these programs
verify that wood is harvested in a more responsible
fashion, but they also verify that the use of chemi-
cals and genetic engineering of these products is
avoided.
The following publications discuss sustainable as-
pects of vinyl siding:
A Dozen Things You Might Not Know That Make Vinyl
Siding Green (available online at http://vinylsiding.
org/greenpaper/090710—Latest—Revised—Green—
paper.pdf).
Sidingwiththe Environment (available online athttp://
www.vinylsiding.org/publications/final—Enviro—
single—pg.pdf).
12/10
Energy Conservation and Air Barriers
Uncontrolled air leakage through the building enve-
lope is often overlooked. The U.S. Department of
Energy estimates that 40 percent of the cost of heat-
ing or cooling the average American home is lost due
to uncontrolled air leakage. In warmer climates, it is
a lower percentage of loss. An air barrier system can
reduce the heating, ventilation, and cooling (HVAC)
system size, resulting in reduced energy use and
demand.
Uncontrolled air leakage can also contribute to pre-
mature deterioration of building materials, mold and
moisture problems, poor indoor air quality, and com-
promised occupant comfort. When uncontrolled air
flows through the building envelope, water vapor
moves with it. Controlling the movement of moisture
by air infiltration requires controlling the air pathways
and/or the driving force.
To effectively control air leakage through the build-
ing envelope, an effective air barrier is required. To
be effective, it needs to be continuous; therefore,
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
less than 0.004 cubic feet per minute (cfm)/square
foot, assemblies of materials that form the air barrier
be tested to have an air infiltration rate of less than
0.04 cfm/square foot, and the whole building exte-
rior enclosure have an air infiltration rate of less than
0.4 cfm/square foot.
Air Barrier Systems Installed Behind Siding
Housewrap is the most common air barrier material
for residential walls. To be effective, it is critical that
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
frame, use of self -adhering modified bitumen flashing
tape is recommended.
An air barrier should be installed over a rigid mate-
rial, or it will not function properly. It also needs to be
restrained from pulling off of the wall under negative
wind pressures. For walls, wood sheathing serves as
a suitable substrate, and the siding (or furring strips
in a rain screen wall system) provide sufficient re-
straint for the air barrier.
At the base of the wall, the wall air barrier should be
sealed to the foundation wall. If the house is elevat-
ed on piles, the wall barrier should be sealed to an air
barrier installed at the plane of the floor.
If the building has a ventilated attic, at the top of the
wall, the wall air barrier should be sealed to an air
barrier that is installed at the plane of the ceiling.
If the building has an unventilated attic or no attic,
at the top of the wall, the wall air barrier should be
sealed to an air barrier that is installed at the plane
of the roof (the roof air barrier may be the roof mem-
brane itself or a separate air barrier element).
Siding Maintenance
For all siding products, it is very important to peri-
odically inspect and maintain the product especially
in a coastal environment. This includes recoating
on a scheduled maintenance plan that is necessary
according to the manufacturer's instructions and a
periodic check of the sealant to ensure its durability.
Check the sealant for its proper resiliency and that it
is still in place. Sealant should be replaced before it
reaches the end of its service life.
HOME WLDER�S GUIDE TO COASTAL CONSTRUCTION -7 0� s
12/10
Additional Resources
American Tree Farm System°, ATFS (http://www.treefarmsystem.org/index.shtml).
Forest Stewardship Council, FSC (http://www.fsc-info.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)
NAHB
€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center C E T E R
8 8 tot B � W TO COAST CONSTRUCTION
12/10
Attachment of Brick Veneer
in Hi
T T T•
Purpose: To recommend practices for installing
brick veneer 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
When not adequately attached, brick veneer is
frequently blown off walls of residential and non-
residential buildings during hurricanes (Figure 1).
When brick veneer fails, wind -driven water can en-
ter and damage buildings, and building occupants
can be vulnerable to injury from windborne de-
bris (particularly if walls are sheathed with plas-
tic foam insulation or wood fiberboard instead of
wood panels). Pedestrians in the vicinity of dam-
aged walls can also be vulnerable to injury from
falling veneer (Figure 2).
Common failure modes include tie (anchor) cor-
rosion (Figure 3), tie fastener pull-out (Figure 4),
failure of masons to embed ties into the mortar
(Figure 5), and poor bonding between ties and
mortar and mortar of poor quality (Figure 6).
Ties are often installed before brick laying be-
gins. When this is done, ties are often improper-
ly placed above or below the mortar joints. When
misaligned, the ties must be angled up or down
in order for the ties to be embedded into the mor-
tar joints (Figure 7). Misalignment not only reduc-
es embedment depth, but also reduces the effec-
tiveness of the ties because wind forces do not
act parallel to the ties themselves.
Corrugated ties typically used in residential ve-
neer construction provide little resistance to
compressive loads. Use of compression struts
would likely be beneficial, but off -the -shelf devic-
es do not currently exist. Two-piece adjustable
ties (Figure 8) provide significantly greater com-
pressive strength than corrugated ties and are,
therefore, recommended. However, if corrugated
ties are used, it is recommended that they be in-
stalled as shown in Figures 9 and 10 in order to
enhance their wind performance.
1 The 90 mph speed is based on ASCE 7-05. If ASCE 7-10 is being
used, the equivalent wind speed trigger is 115 mph for Risk Category
II buildings.
FEMA
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HOME BUILDERS GOW-DE TO COASTAL CONSTRUCTION
12/10
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Figure 4. This tie remained embedded in the mortar
joint while the smooth -shank nail pulled out from the
stud.
e
t.
y., P
Figure 5. These four ties were never embedded into
the mortar joint.
Buildings that experience veneer damage typi-
cally do not comply with current building codes.
Building code requirements for brick veneer
have changed over the years. Model codes prior
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.
The Masonry Society's (TMS) 402/American Con-
crete Institute 530/American Society of Civil
Engineers (ASCE) 5 Building Code Requirements
and Specifications for Masonry Structures (TMS
402) is the current masonry standard referenced
by model building codes. The 2009 International
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-
tion follows the prescriptive approach. The first
edition of TMS 402 limited the use of prescriptive
design to areas with a basic wind speed of 110
mph or less. The 2008 edition of TMS 402 extend-
ed the prescriptive requirements to include a basic
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
regions. The 2008 edition requires rational de-
sign approaches in locations where the basic wind
speeds exceed 130 mph.
Some noteworthy distinctions exist in the require-
ments for anchored brick veneer between the 2005
and the 2008 editions of TMS 402. For lower wind
speed regions (110 mph and below), TMS 402-05
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.
In TMS's high -wind regions (over 110 mph and up
to 130 mph), both editions of the code limit verti-
cal spacing to 18 inches. TMS 402-08 also limits
the space between veneer anchored with corrugat-
ed ties and the wall sheathing to 1 inch. This is to
avoid compression failures in the corrugated ties
when they are exposed to positive pressures.
The following Brick Industry Association (BIA)
Technical Notes provide guidance on brick ve-
neer: Technical Notes 28 — Anchored Brick
Veneer, Wood Frame Construction; Technical
Notes 28B — Brick Veneer/Steel Stud Walls;
and Technical Notes 44B — Wall Ties. Although
these Technical Notes provide attachment rec-
ommendations, the recommendations are inade-
quate because they are not specific for high -wind
regions.
12/10
Construction Guidance
The brick veneer wall system is complex in its be-
havior. There are limited test data on which to draw.
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
recommended:
Tie Spacing: The ability for Brick Ties and Tie
Fasteners to function properly is highly dependent
on horizontal and vertical spacing of ties. Horizontal
spacing of ties will often coincide with stud spacing
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
will overload the tie or tie fastener based on a tribu-
tary area of wind pressure on the brick veneer, or
b) prescriptive limits on spacing of ties. More in-
formation on horizontal and vertical tie spacing is
available in Table 1.
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
ties are recommended. However, where corrugated
steel ties are used, use 22-gauge minimum, 7/8 by
6 inches, complying with American Society for Test-
ing and Materials (ASTM) A 366 with a zinc coating
complying with ASTM A 153 Class B2. For ties for
use with steel studs, see BIA Technical Notes 28B —
Brick Veneer/Steel Stud Walls. Stainless steel ties
should be used in areas within 3,000 feet of the
coast.
Note: In areas that are also susceptible to high
seismic loads, brick veneer should be evaluated by
an engineer to ensure that it can resist seismic and
wind design loads.
5. ::;i. A11", 1.... I . I:.:I... i II #r I:: :( x
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Base and Eye and
Vee Anchor Pintle Anchor
Figure 8. Examples of two-
piece adjustable ties.
MONIE BWLDERS GUIDE TO COASTAL CONSTRUCTION
12/10
Tie Installation
Install ties as the brick is laid so that the ties
are properly aligned with the brick coursing.
Alternatively, instead of installing ties as the
brick is laid, measure the locations of the brick
coursing, snap chalk lines, and install ties so
that they are properly aligned with the coursing,
and then install the brick.
Install brick ties spaced based on the appropri-
ate wind speed and stud spacing shown in Table
1. In areas where the 2006 Edition of the IBC or
IRC are adopted, install brick veneer ties as not-
ed in Table 1 but with a maximum vertical spac-
ing of no more than 18 inches to satisfy the re-
quirements of TMS 402-05.
Locate ties within 8 inches of door and window
openings and within 12 inches of the top of ve-
neer sections.
Bend the ties at a 90-degree angle at the nail
head in order to minimize tie flexing when the
ties are loaded in tension or compression (Figure
9).
Embed ties in joints so that mortar completely
encapsulates the ties. Embed a minimum of 1
1/2 inches into the bed joint, with a minimum
mortar cover of 5/8 inch to the outside face of
the wall (Figure 10).
Of zb
12/10
0 NIE BUILDER TO COA STA L CO N TRUC1 0
Table 1. Brick Veneer Tie Spacing
.......
.........
xxxxxxxxx xxxxxxxxx xxxxxxxxx xxxxxxxxx xxxxxxxxx
16" stud spacing
24" stud spacing
90
19.5 (
24a,b
16'
100
—24.1
24a,b
16a
110
—29 A
20'/2 b
13'/2
120
—34.7
17
NAc
130
—40.7
15
NAc
140
—47.2 '
13
NA'
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 (1) 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, Ct=0.8; and Cp, CM,
Ceg, and Ct,=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
NAHB
€€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center E T E R
HOME BWLDERS GUIDE TO COASTAL CONSTRUCTION
12/10
Window and Door
Installation
x s z `.�s� d ix ����
that:
give adequate resistance to water intrusion in
coastal environs,
do not depend solely on sealants,
are integral with secondary weather barriers
(i.e., housewrap or building paper — see Fact
Sheet No. 5.1), and
are adequately attached to the wall.
Key Issues
Water intrusion around window and door openings
can cause dry rot and fastener corrosion that weaken
the window or door frame or the wall itself, and lead
to water damage to interior finishes, mold growth, and
preventable building damage during coastal storms.
Proper flashing sequence must be coordinated
across responsibilities sometimes divided between
two or more trade activities (e.g., weather barrier, win-
dow, and siding installation).
To combat wind -driven rain penetration and high
wind pressures, window and door frames must be
adequately attached to walls and they must be ad-
equately integrated with the wall's moisture barrier
system (see Fact Sheet No. 1.9).
ASTM E 2112
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.
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
the standard or as modified by the designer.
FEMA
._ .a
Section 1.5 states that if the manufacturer's in-
structions conflict with E 2112, the manufacturer's
instructions shall prevail. However, because a
manufacturer's instructions may be inferior to the
guidance provided in the standard, any conflict be-
tween the manufacturer's requirements and the
standard or contract documents should be dis-
cussed among and resolved by the manufacturer,
designer, and builder.
Specific Considerations
Part flashings: Windows that do not have nailing
flanges, and doors, are typically installed over a pan
flashing (see Figure 1). Section 5.16 of ASTM E 2112
discusses pan flashings and refers to Annex 3 for
minimum heights of the end dam and rear leg. Annex
3 shows a maximum end dam height of 2 inches,
which is too low for areas prone to very high winds
(i.e., wind speed greater than 110 mph). Where the
wind speed is greater than 110 mph, the end dam
should be 3 to 4 inches high (the higher the wind
speed, the higher the dam). (Note: Annex 3 says that
"high rain and wind are usually not simultaneous."
However, this statement is untrue for coastal storms,
in which extremely high amounts of rain often accom-
pany very high winds.)
HOME BUILDERS GOUIDETO COASTAL CONSTRUCTION 1 o,
12/10
Although not discussed in ASTM E 2112, for in-
stallations that require an exposed sealant joint,
installation of a removable stop (see Figure 2) is
recommended to protect the sealant from direct ex-
posure to the weather and reduce the wind -driven
rain demand on the sealant.
Exterior Insulation Finishing Systems (EIFS): Although
not discussed in ASTM E 2112, when a window or
door assembly is installed in an EIFS wall assembly,
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
top coat is somewhat porous; if sealant is applied to
it, water can migrate between the top and base coats
and escape past the sealant.)
Frame anchoring: Window and door frames should be
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-
chored to the wall, rather than the window or door
frame (see Figure 3).
Weatherstripping: E 2112 does not address door
weatherstripping. However, weatherstripping is nec-
essary to avoid wind -driven rain penetration. A variety
of weatherstripping products are available as shown
in Figures 4 through 9.
Figure 4. Drip at door head and drip with hook at head
Protection of Openings —
Shutters and Glazing
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.
Opening Requirements in Codes and Standards
What Are "Hurricane -Prone Regions" and "Windborne Debris Regions"?
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 mph' (40 m/s).
2. Hawaii, Puerto Rico, Guam, the U.S. Virgin Is-
lands, and American Samoa.
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
greater; or portions of hurricane -prone regions where
the basic wind speed is 120 mph (53 m/s)1 or great-
er; or Hawaii.
Sections 1609.1.2 and R301.2.1.2, of the 2009 edi-
tions of the IBC and IRC, respectively, address the
Protection of Openings. These sections state that
in wind-borne debris regions, glazing in buildings
shall be impact resistant or protected with an im-
pact -resistant covering that meets the requirements
of an approved impact -resistant standard or the
American Society of Testing and Materials (ASTM)
standards ASTM E 1996 and ASTM E 1886. Wood
structural panels could be used as an alternative to
provide protection so long as they meet local build-
ing code requirements. Panel attachment should be
in accordance with Table 1609.1.2 (IBC) and Table
R301.2.1.2 (IRC) and installed using corrosion -resis-
tant attachment hardware and anchors permanently
installed on the building. Under provisions of the IBC,
wood structural panels are permitted for Group R-3
and R-4 buildings with a mean roof height of 45 feet
(13,716 mm) or less where wind speeds do not ex-
ceed 140 mph (63 m/s). Under provisions of the
IRC, wood structural panels are permitted for build-
ings with a mean roof height of 33 feet (10,058 mm)
or less where wind speeds do not exceed 130 mph'
(58 m/s). Figure 1 shows a house utilizing wood
structural panels to provide opening protection.
ASCE/SEI 7-05 also discusses the protection of
glazed openings in Section 6.5.9.3. The section
states, "Glazing in buildings located in wind-borne
debris regions shall be protected with an impact -
protective system or be impact -resistant glazing
according to the requirements specified in ASTM
E1886 and ASTM E1996 or other approved test
methods and performance criteria. The levels of im-
pact resistance shall be a function of Missile Levels
and Wind Zones specified in ASTM E 1886 and ASTM
E 1996". Exceptions to this are noted in Section
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 0.61.1
C1
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O MFEMA t BUILDER ED COASTAL CONiKUC O y
12/10
Anchorage
Window and door assemblies must be strong enough
to withstand wind pressures acting on them and be
fastened securely enough to transfer those wind
pressures to the adjacent wall. Pressure failures of
doors or windows can allow glazing to fracture or glaz-
ing frames or supports to fail. Anchorage failures can
allow entire door or window units to be ripped from
the walls. Either type of failure results in the failure
of the building envelope and allows wind and water to
enter the building.
Shutters
Why Are Storm Shutters Needed?
If glazing is not resistant to windborne debris, then
shutters are an important part of a hurricane -resis-
tant home. They provide protection for glass doors
and windows against windborne debris, which is
often present in hurricanes. Keeping the building en-
velope intact (i.e., no window or door breakage) is
vital to the integrity of a home. If the envelope is
breached, sudden pressurization of the interior may
result in major structural or non-structural damage
(e.g., roof loss) and will lead to significant interior
and contents damage from wind -driven rain. The ad-
dition of shutters will not eliminate the potential for
wind -driven rain entering the building, but will improve
the building's resistance to it.
Where Are Storm Shutters Required and
Recommended?
Model building codes, which incorporate wind provi-
sions from ASCE 7 (1998 edition and later), require
that buildings within the windborne debris region (see
Figure 5 of this fact sheet), either (1) be equipped
with shutters or impact -resistant glazing and de-
signed as enclosed structures or (2) be designed as
partially enclosed structures (as if the windows and
doors are broken out). However it should be noted
that the alternative to design a Risk Category II build-
ing (defined in ASCE 7-10) as a partially enclosed
structure was removed from ASCE 7-10 and it now
requires that all Risk Category II structures in the
wind-borne debris region be designed to be enclosed
structures with impact -resistant glazing or equipped
with a shutter system. It is also recommended to
give strong consideration to the use of
opening protection in all hurricane -prone
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.
12/10
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.
Designers can refer to Miami -Dade County, Florida,
which has established a product approval mecha-
nism for shutters and other building materials to
ensure they are rated for particular wind and wind-
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.
Bahama shutter
Colonial shutters
HONIE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
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4 0, f C-5
HOMER mLDEW S GUIDETO COASTAL CONST, RUCTION
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 window 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 sheetforthe delineation of the areas where opening protection is required.
,2: ' I ...€ : ter; ` e I P .. } :. `�— I, , 1,S € x. x
HONIE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
12/10
Windborne debris resistant glazing
Laminated glazing systems typically consist of as-
semblies fabricated with two (or more) panes of glass
and an interlayer of a polyvinyl butyral (or equivalent)
film laminated into a glazing assembly. During impact
testing, the laminated glass in the system can frac-
ture but the interlayer must remain intact to prevent
water and wind from entering the building. These sys-
tems may also increase the energy efficiency of the
building over standard glazing.
Polycarbonate systems typically consist of plastic
resins that are molded into sheets, which provide
lightweight, clear glazing panels with high impact -re-
sistance qualities. The strength of the polycarbonate
sheets is much higher than non -laminated glass (i.e.,
more than 200 times stronger) or acrylic sheets or
panels (i.e., more than 30 times stronger).
Garage Doors
Garage doors many times represent large unre-
inforced openings. They are commonly damaged
during high -wind events and could allow a building to
be pressurized if they are breached. A garage door
should meet the design wind speed requirements for
the area or be retrofitted to withstand the design wind
speed. However, the viability of a retrofit depends on
the style and age of the door, and may not provide
the same level of protection as a new door system.
The 2009 editions of IBC and IRC both comment on
the glazing in garage doors in sections 1609.1.2.2
and R301.2.1.2, respectively. Any glazed opening
protection on garage doors for wind-borne debris
shall meet the requirements of an approved impact -
resisting standard or ANSI/DASMA 115-2005.
While some manufacturers provide wind speed and
exposure ratings for their products, labels on many
garage doors do not include wind speed or wind
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.
Additional Resources
American Society of Civil Engineers. Minimum Design
Loads for Buildings and Other Structures, ASCE/SEI
7-10. (http://www.asce.org)
The Engineered Wood Association (APA). Hurricane
Shutter Designs Set 5 of 5. Hurricane shutter designs
for woodframe and masonry buildings. (http://www.
apawood.org)
International Code Council. International Building
Code. 2009. (http://www.iccsafe.org)
International Code Council. International Residential
Code. 2009. (http://www.iccsafe.org)
Information about product testing and approval pro-
cess for Miami -Dade County, Florida, available at
http://www.miamidade.gov/buildingcode/product-
control.asp
American Society for Testing and Materials:
ASTM E1886, Performance of Exterior Windows,
Curtain Walls, Doors, and Storm Shutters Impacted
by Missile(s) and Exposed to Cyclic Pressure
Differentials
ASTM E1996, Standard Specification for
Performance of Exterior Windows, Curtain Walls,
Doors and Impact Protective Systems Impacted
by Windborne Debris in Hurricane
ASTM E2112, Standard Practice for Installation of
Exterior Windows, Doors and Skylights
ASTM E330, Structural Performance of Exterior
Windows, Doors, Skylights and Curtain Walls by
Uniform Static Air Pressure Difference. (http://
www.astm.org)
Door and Access Systems Manufacturers Association:
DASMA 108, Standard Method for Testing
Sectional Garage Doors: Determination of
Structural Performance Under Uniform Static Air
Pressure Difference
RIAH B
€€ RESEARCH
Developed in association with the National Association of Home Builders Research Center c E N T E R
12/10
Roof Sheathing Installation
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
structural failures in hurricanes. ,.ON
�
Fastener spacing and size�� ..*.
requirements for coastal ` 4
X���
construction are typically
different than for non -coastal areas. \\\
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The highest uplift forces occur at roof x
corners, edges, and ridge lines.
\ Typical layout of roof
Improved fasteners such as ring shank nails x
increase the uplift resistance of the roof sheathing panels on
sheathing. gable -end roof
Most critical area for connec-
Sheathing Type tion of sheathing panels
Typically, 15 32-inch or thicker panels are required in high -
wind
' .
areas. Oriented Strand Board (OSB) or plywood can be -�
used, although plywood will provide higher nail head pull -
through resistance. Use panels rated as "Exposure
1" or better.
Sheathing Layout
Install sheathing panels according „l ',
to the recommendations of the
Engineered Wood Association (APA).
Use panels no smaller than 4 feet
long. Blocking of unsupported edges mayV\. r
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
as DETO COASTAL CONSTRUCTION 3
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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.
Additional Resources
Engineered Wood Association (APA), (www.apawood.org)
NAFIB
RESEARCH
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Developed in association with the National Association of Home Builders Research Center C ETER
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HOME LIWLDERS GUIDE TO COASTAL CONSTRUCTION
12/10
Roof Underlayment for
Asphalt Shingle Roofs
v KKf and H1- ti off` � roo uncle ` ` aKK ry ^a
urpose: �u�z oryvr�� ry x �€ z z ryv s z
secondary water barrier in coastal environments.
Key Issues
Verifying proper attachment of roof sheathing be-
fore installing underlayment.
Lapping and fastening of underlayment and roof
edge flashing.
Selecting underlayment material type.
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).'
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).'
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-
ucts. If the sheathing is OSB, check
with the OSB manufacturer to deter-
mine if a primer needs to be applied
before installing these products.
3. In Southern Climates, apply a sin-
gle layer of self -adhering modified
bitumen complying with ASTM D
1970 throughout the roof area.
4. Seal the self -adhering sheet to the
deck penetrations with roof tape or
asphalt roof cement.
1 The 110 and 120 mph speeds are based on ASCE
7-05. If ASCE 7-10 is being used, the equiva-
lent wind speeds are 139 and 152 mph for Risk
Category II buildings.
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5. Apply a single layer of ASTM D 226 Type 1 (#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
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 taping. If
the sheathing is OSB, check with the
OSB manufacturer to determine if a
primer needs to be applied before
installing self -adhering modified bi-
tumen products.
3. Install self -adhering modified bitu-
men tape (4 inches wide, minimum)
over sheathing joints; seal around
deck penetrations with roof tape.
Roll tape with roller.
4. Apply two layers of ASTM D 226
Type II (#30) or ASTM D 4869 Type
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
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 taping. If
the sheathing is OSB, check with the
HOME BUILDEWS GUIDETO 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 1 (#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. N RCA. net)
ASTM Standard D6135, 2005, "Standard Practice for Application of Self -Adhering Modified Bituminous
Waterproofing," ASTM International, West Conshohocken, PA, 2005, 1O.152O/D6135-05, www.astm.org.
Developed in association with the National Association of Home Builders Research Center
NAHB
RESEARCH
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HOME WLDERS GUIDE TO COASTAL CONSTRUCTION
12/10
Asphalt Shingle Roofing for
High Wind Regions
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.
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2. Consider shingle physical properties.
g
Z
Properties
Design Wind Speed' >90 to 120 mph
Design Wind Speed' >120 mph
Fastener Pull-Through2 Resistance
Minimum Recommended
25 lb at 73 degrees Fahrenheit (F)
Minimum Recommended
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 this product.
Because of the flexibility imparted by
It is recommended that SIBS Modified
the SBS polymers, this, type of shingle is
Bitumen Shingles meet the physical
less likely to tear if the tabs are lifted in'a
properties specified in ASTM 3462.
windstorm.
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.
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i
HOVE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
After the shingles have been exposed to sufficient
sunshine to activate the sealant, inspect roofing to
ensure that the tabs have sealed. Also, shingles
should be of "interlocking" type if seal strips are not
present.
Wind -Resistance Ratings
Wind resistance determined by test methods ASTM
D 3161 and UL 997 does not provide adequate infor-
mation regarding the wind performance of shingles,
even when shingles are tested at the highest fan
speed prescribed in the standard. Rather than rely
on D 3161 or UL 997 test data, wind resistance of
shingles should be determined in accordance with
UL 2390. Shingles that have been evaluated in ac-
cordance with UL 2390 have a Class D (90 mph), G
(120 mph), or H (150 mph) rating. Select shingles
that have a class rating equal to or greater than the
basic wind speed specified in the building code. If
the building is sited in Exposure D, or is greater than
60 feet tall, or is a Category III or IV, or is sited on
an abrupt change in topography (such as an isolated
hill, ridge, or escarpment), consult the shingle man-
ufacturer. (Note: for definitions of Exposure D and
Category III and IV, refer to ASCE 7.)
NAHB
€€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center E T E R
77, ARP1-4 .., SHINGLEP IN I ��R IG }�I. I FIEGIr I
MOME BMDER�S GUIDE TO COASTAL CONSTRUCTION
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Tile Roofing for
High Wind Regions
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
and glazing, and potentially cause injury. In hurricane -
prone regions where the basic wind speed is equal to
or greater than 110 mph (3-second peak gust), the
windborne debris issue is of greater concern than in
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
have revealed performance problems with mortar -
set, mechanical (screws or nails and supplementary
clips when necessary), and foam -adhesive (adhesive -
set) attachment methods. In many instances, the
damage was due to poor installation. Investigations
revealed that the mortar -set attachment method is
typically much more susceptible to damage than are
the other attachment methods. Therefore, in lieu of
mortar -set, the mechanical or foam -adhesive attach-
ment methods in accordance with this fact sheet are
recommended.
To ensure high -quality installation, licensed contrac-
tors should be retained. This will help ensure proper
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
the foam manufacturer.
Uplift loads and resistance: Calculate uplift loads
and resistance in accordance with the Design and
Construction Guidance section below. Load and re-
sistance calculations should be performed by a
qualified person (i.e., someone who is familiar with
the calculation procedures and code requirements).
Corner and perimeter enhancements: Uplift loads are
greatest in corners, followed by the perimeter, and
then the field of the roof (see Figure 1 on page 2).
sFEMA
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However, for simplicity of application on smaller roof
areas (e.g., most residences and smaller commercial
buildings), use the attachment designed for the cor-
ner area throughout the entire roof area.
Hips and ridges: Storm damage investigations have
revealed that hip and ridge tiles attached with mor-
tar are very susceptible to blow -off. Refer to the
attachment guidance below for improved attachment
methodology.
Quality control: During roof installation, installers
should implement a quality control program in accor-
dance with the Quality Control section on page 3 of
this fact sheet.
HOME BUILDER UIDIETO COASTAL CONSTRUCTION ` '
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Design and Construction Guidance
1. Uplift Loads
In Florida, calculate loads and pressures on tiles in
accordance with the current edition of the Florida
Building Code (Section 1606.3.3). In other states,
calculate loads in accordance with the current edi-
tion of the International Building Code (Section
1609.7.3).
As an alternative to calculating loads, design uplift
pressures for the corner zones of Category II build-
ings are provided in tabular form in the Addendum to
the Third Edition of the Concrete and Clay Roof Tile
Installation Manual (see Tables 6, 6A, 7, and 7A).1
2. Uplift Resistance
For mechanical attachment, the Concrete and Clay
Roof Tile Installation Manual provides uplift resistance
data for different types and numbers of fasteners
and different deck thicknesses. For foam -adhesive -
set systems, the Manual refers to the foam -adhesive
manufacturers for uplift resistance data. Further, to
improve performance where the basic wind speed is
equal to or greater than 110 mph, it is recommended
that a clip be installed on each tile in the first row of
tiles at the eave for both mechanically attached and
foam -adhesive systems.
For tiles mechanically attached to battens, it is rec-
ommended that the tile fasteners be of sufficient
length to penetrate the underside of the sheathing
by 1/4 inch minimum. For tiles mechanically attached
to counter battens, it is recommended that the tile
fasteners be of sufficient length to penetrate the un-
derside of the horizontal counter battens by 1/4 inch
minimum. It is recommended that the batten -to -bat-
ten connections be engineered.
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.
1. You can order the Concrete and Clay Roof Tile Installation Manual
online at the website of the Florida Roofing, Sheet Metal and Air
Conditioning Contractor's Association, Inc., (www.floridaroof.corrm) or
by calling (407) 671-3772. Holders of the Third Edition of the Manual
who do not have a copy of the Addendum can download it from the
website.
3. Hips and Ridges
The Concrete and Clay Roof Tile Installation Manual
gives guidance on two attachment methods for
hip and ridge tiles: mortar -set or attachment to a
ridge board. On the basis of post -disaster field in-
vestigations, use of a ridge board is recommended.
For attachment of the board, refer to Table 21 in
the Addendum to the Concrete and Clay Roof Tile
Installation Manual.
Fasten the tiles to the ridge board with screws (f-
inch minimum penetration into the ridge board) and
use both adhesive and clips at the overlaps.
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.
4. Critical and Essential Buildings
(Category III or IV)
Critical and essential buildings are buildings that
are expected to remain operational during a severe
wind event such as a hurricane. It is possible that
people may be arriving or departing from the critical
or essential facility during a hurricane. If a mis-
sile strikes a tile roof when people are outside the
building, those people may be struck by tile debris
dislodged by the missile strike. Tile debris may also
damage the facility. It is for these reasons that tiles
are not recommended on critical or essential build-
ings in hurricane -prone regions (see ASCE 7 for the
definition of hurricane -prone regions).
If it is decided to use tile on a critical or essential
facility and the tiles are mechanically attached, it is
recommended that clips be installed at all tiles in the
corner, ridge, perimeter, and hip zones (see ASCE 7 for
the width of these zones). (See Figure 1.)
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5. Quality Control
It is recommended that the applicator designate an
individual to perform quality control (QC) inspections.
That person should be on the roof during the tile in-
stallation process (the QC person could be a working
member of the crew). The QC person should under-
stand the attachment requirements for the system
being installed (e.g., the type and number of fas-
teners per tile for mechanically attached systems
and the size and location of the adhesive for foam -
adhesive systems) and have authority to correct
noncompliant work. The QC person should ensure
that the correct type, size, and quantity of fasteners
are being installed.
For foam -adhesive systems, the QC person should en-
sure that the foam is being applied by properly trained
applicators and that the work is in accordance with
the foam manufacturer's application instructions. At
least one tile per square (100 square feet) should be
pulled up to confirm the foam provides the minimum
required contact area and is correctly located.
If tile is installed on a critical or essential building in
a hurricane -prone region, it is recommended that the
owner retain a qualified architect, engineer, or roof
consultant to provide full-time field observations dur-
ing application.
NAH
RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E RMOME BWLDER�S GUIDE TO COASTAL CONSTRUCTION
12/10
Minimizing Water Intrusion
Through Roof Vents in
High-Wind Regions
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-
ter through attic ventilation openings. The ac-
cumulating water soaks insulation and gypsum
board, which can lead to mold growth and, in
some cases, to the collapse of ceilings.
Attic ventilation can be provided by a number of
devices, most of which have been observed to al-
low water intrusion under certain conditions and
some of which have been observed to blow off.
These devices include:
Soffit vents
Ridge vents
Gable end vents
Off -ridge vents
Gable rake vents
Turbines
Adequate ventilation of attics is generally re-
quired to promote the health of wood structural
members and sheathing in the attic.
Attic ventilation can reduce the temperatures of
roof coverings, which will typically prolong the life
of the roof covering. However, roof color can have
more of an impact on roof covering temperature
than the amount of ventilation that is or is not
provided.
An unvented attic can be an effective way to
prevent water intrusion and this type of attic is
gaining popularity for energy efficiency reasons,
provided the air conditioning system is sized ap-
propriately. However, an unvented attic is best
accomplished when it is specifically designed
into the house and all of the appropriate details
are handled properly. On an existing house, any
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
FEMA
._ .a
Air barrier: Refer to Fact Sheet 5.3, Siding Installa-
tions in High -Wind Regions for recommendations
regarding,' attic air barriers.
attempt to change to an unvented attic configu-
ration needs to be done very carefully with the
advice of knowledgeable experts. There are a
number of changes that have to be made to pro-
duce a successful transition from a ventilated to
an unvented attic. One side effect of going to an
unvented attic may be to void the warranty for
the roof covering.
The following information is intended to help minimize
water intrusion through new and existing attic ventila-
tion systems, not to change from a ventilated to an
unvented system. With the exception of the plugging
of gable rake vents, all other shuttering of openings
or plugging of vents should be done on a temporary
basis and removed once the storm threat is over so
that the attic is once again properly ventilated.
7 M i I M 17[NJ ` ii lit fitr"C,' 0:1 R0 ¥i'¥ 'six
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Mitigation Guidance
Soffit Vents
KexlssU08
n� |1iaimportant tokeep the soffit ma-
terial in place. VVhi|o some water
can be blown into the attic through
almost any type of soffit vent, the
amount of water intrusion increas-
es dramatically when the soffit ma'
terial is missing (Figure 1).
U� Plywood or wood soffits are gener-
ally adequately anchored to wood
framing attached to the roof struc-
ture and/or the we||a. However, it
has been common practice for vinyl
and aluminum soffit panels toUein-
stalled in tracks that are frequently
very poorly connected 10the walls
and fascia at the edge of the roof
overhang. When 1hoao poorly an-
chored soffits are blown off, water
intrusion increases Si8nifiC@nt|y.
Properly installed vinyl and a|umi' Figure 1. Missing soffit material.
num soffit panels are fastened to
the building structure or to nailing strips 0|aoeU 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.
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2ofG 110 NIE B U|LDE R ` S G U|D E T 0C 0 A S TA L CONS T, RUCTION
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
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
lens and light mounted at the end of a flexible tube
that can be used to observe the connections. These
devices allow inspection through a small hole that
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
where the soffit channel is attached and the channel
should be fastened to that blocking. If there is no
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,
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.
- 4i•.
Figure 3. Applying a bead of sealant. (Note: Slack
sealant was used so that it would be visible in the
photograph. Normally matching', sealantcolor
would be used.)
K
Figure 4. Applying dabs of sealant.
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Figure 5. Screws through wall channel.
HOME BUILD..:. R. S GUIDE TO COASTAL CONSTRUCTION `s
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Wind -driven rain penetration: Currently there is no ade-
quate standard test method to evaluate the potential
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-
tem filters) above the vent openings; however, such
an approach needs to be custom designed.
Fascia cover: Field investigations after Hurricane Ike
showed many cases where the aluminum fascia cov-
er (fascia cap) from the fascia board was blown off
(Figure 7). The fascia cover normally covers the ends
of vinyl and aluminum soffits. When the fascia cover
is blown off, the ends of the soffit panels are ex-
posed to wind and 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
help secure the fascia cover, but would also inhibit
normal thermal movement, which can cause un-
attractive warping and dimpling of the cover. Vinyl
fascia covers are available, which are attached to
a continuous strip of utility trim placed underneath
the drip edge. This provides a somewhat more se-
cure, continuous attachment and allows for thermal
movement. Aluminum fascia covers can also be
field notched and installed with utility trim.
Ridge Vents
Key Issues
Ridge vents are frequently fastened down us-
ing ordinary roofing nails since these are nor-
mally handy. It is fairly common to find ridge
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 -
driven rain and directs it into the attic.
Most roofing manufacturers now make ridge
vents that have passed wind -driven water tests.
They are identified as having passed Florida
Building Code's Product Approvals or Testing
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
any flow of wind and water blowing up the sur-
face of the roof and deflect it over the top of the
roof ridge.
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12/10
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
water intrusion tests.
Remedial Measures
Replace nails with gasketed stainless steel wood
screws that are slightly larger than the existing nails
and, if possible, try to add fasteners at locations
where they will be embedded in the roof structure be-
low and notjust into the roof sheathing. Close spacing
of fasteners is recommended (e.g., in the range of 3
to 6 inches on center, commensurate with the design
wind loads). If the ridge vents are damaged or are one
of the older types that are not resistant to water in-
trusion, they should be replaced with vents that have
passed the wind -driven water intrusion tests.
Gable End Vents
Key Issues
Virtually all known gable end vents (Figure 9) will
leak when the wall they are mounted on faces
into the wind -driven rain. The pressures devel-
oped between the outside surface of the wall
and the inside of the attic are sufficient to drive
water uphill for a number of inches and, if there
is much wind flow through the vent, water carried
by the wind will be blown considerable distances
into the attic.
�t
"
HOME UK DER�S GUIDE TO COASTAL CONSTRUCTION
s
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
a qualified person just before a storm approaches.
If installation of shutters from the outside is diffi-
cult because of the height or other considerations,
but there is access through the attic, the gable vent
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
house and not into the wall below.
Off -ridge Vents
Key Issues
Poorly anchored off -ridge vents can flip up and be-
come scoops that direct large amounts of wind -driven
rain into the attic (Figure 11).
Some vents are also prone to leaking when winds
blow from certain directions. This will depend on the
location of the vent on the roof surface and the ge-
ometry of the roof, as well as the geometry of the
particular vent.
Checking Off -Ridge Vent Installations
Off -ridge vents typically have a flange that lies against
the top surface of the roof sheathing and is used
to anchor the vent to the roof sheathing. Frequently,
roofing nails are used to attach the flange to the roof
sheathing. The off -ridge vents should be checked to
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
Z_�
Figure 11. Two off -ridge vents are shown in this
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.
in preventing water intrusion when a storm occurs.
Since the flange and fasteners are hidden below the
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.
Remedial Measures
If the off -ridge vent is attached to the roof sheathing
with long, thin nails, it may be possible 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 good.
Some homeowners have had covers made that can
be installed from the inside of the attic over the hole
where the off -ridge vent is installed. This will be easi-
est if the vent is larger than the hole and the cover
can be attached to the sheathing in an area where
the fasteners cannot be driven through the roof cov-
ering. Otherwise, it will be important to ensure that
the fasteners are short enough that they will not ex-
tend 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 vent, it may be possible to
install metal straps that are screwed into the walls of
the vent and attached with short screws to the bot-
tom 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 covering. The strapping should be connected to
the walls of the vent with short stainless steel sheet
metal screws.
]NINIA.r...l.IG OV , E"' ..` I> .v K� K ..i r IICK"' � ..:} T I I- JG �¥ P i. I . GI, rHONIE BUILDEWS GUIDE TO COASTAL CONST, RUCTION
12/10
Gable Rake Vents
Key Issues
Gable rake vents are formed when porous soffit
panels or screen vents are installed on the bot-
tom surface of the roof overhang at the gable
end and there is a clear path for wind to blow
into the attic. This usually happens when the
gable overhang is supported by what are called
outriggers. Outriggers are typically used when
gable overhangs exceed 12 inches. In these
cases, the last roof truss or rafter (the gable
end truss or rafter) is smaller than the trusses
or rafters at the next location inside the attic.
Outriggers (2x4s) are installed over top of the
last gable truss or rafter, one end is anchored
to the second truss or rafter back from the ga-
ble end, and the other end sticks out past the
gable end wall to support the roof sheathing on
the overhang.
Finding Out if You Have Gable Rake Vents and
Whether You Still Need Them
The easiest way to tell if the roof has gable rake
vents is to look in the attic on a cool sunny day and
see if light is visible in gaps just below the sheath-
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
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 rake
vents is not needed is to simply plug them up with
metal flashing (Figure 12) or pieces of wood that are
cut and anchored. They should be well attached and
completely seal as many of the openings as possible
and particularly those near the gable peak. Sealant
can be used to seal around the edges of the metal
or wood plugs.
Turbines
Key Issues
The rotating top portion of many turbines is not
designed to withstand high -wind conditions and
they are frequently installed with just a friction fit
to the short standpipe that provides the venting
of the attic. It is possible to find high -wind rated
turbines on store shelves in hurricane -prone re-
gions but, in hurricane winds, the turbines will be
rotating at tremendous speeds and can be easi-
ly damaged by windborne debris.
The flange on the standpipe that provides the
connection of the pipe to the roof sheathing may
also be poorly anchored to the roof sheathing.
Checking Turbines and Their Installation
Check any turbines to make sure that the stand pipes
are not loose and that the turbine head is anchored
to the stand pipe by sheet metal screws and not sim-
ply by a friction fit (Figure 13).
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
good. Some homeowners have had covers made that
can be installed from the inside of the attic over the
HOME UK DER�S GUIDE TO COASTAL CONSTRUCTION -7 0� s
12/10
hole where the standpipe is installed. This will be
easiest if the standpipe is larger than the hole and
the cover can be attached to the sheathing in an area
where the fasteners cannot be driven through the
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
connected to the walls of the standpipe with short
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
g
sheathing around the hole. The best approach is to
ZI
have a qualified person remove the top active por-
tion of the turbine vent before the storm and plug the
hole at the top of the standpipe. A wooden plug can
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.
=NAHB
RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E R
i°aCICIx# V[" .. I I- JG ?VI' i. I . GI,
12/10
Metal Roof Systems in
High -Wind Regions
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
below design wind speeds given in ASCE 7. When
metal roofing (or hip, ridge, or rake flashings) blows
off during hurricanes, water may enter the building
at displaced roofing; blown -off roofing can damage
buildings and injure people. Here is general guidance
for achieving successful wind performance:
1. Always follow the manufacturer's installation in-
structions and local building code requirements.
2. Calculate loads on the roof assembly in accor-
dance with ASCE 7 or the local building code, it
is recommended to use whichever procedure re-
sults in the highest loads.
3. Specify/purchase a metal roof system that has
sufficient uplift resistance to meet the design up-
lift loads.
For standing seam metal panel systems,
the 2009 International Building Code (IBC)
requires test methods UL 580 or ASTM E
1592. For standing seam systems, it is rec-
ommended that design professionals speci-
fy E 1592 testing, because it gives a better
representation of the system's uplift perfor-
mance capability.
For safety factor determination, refer to
Chapter F in standard NAS-01, published by
the American Iron and Steel Institute.
For through -fastened steel panel systems,
the IBC allows uplift resistance to be eval-
uated by testing or by calculations in accor-
dance with standard NAS-01.
r -
For architectural panels with concealed clips,
test method UL 580 is commonly used.
However, it is recommended that design pro-
fessionals specify ASTM E 1592 because it
gives a better representation of the system's
uplift performance capability. When testing ar-
chitectural panel systems via ASTM E 1592,
the deck joints need to be unsealed in order
to allow air flow to the underside of the met-
al panels. Therefore, underlayment should be
eliminated from the test specimen, and a 1/8
inch minimum between deck panel side and
end joints should be specified.
For safety factor determination, refer to
Chapter F of the North American Specification
for the Design of Cold -Formed Steel Structural
Members (AISI S100-07).
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.
sFEMA
..a
HOWIE BUILDERS GOUI-DE TO COASTAL CONSTRUCTION
12/10
For copper roofing testing, see "NRCA ana-
lyzes and tests metal," Professional Roofing,
May 2003.
For metal shingles, it is recommended that
uplift resistance be based on test method
UL 580 or 1897.
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-
eter. (Note: For small roof areas, the corner
load can be used throughout the entire roof
area.)
4. Suitably design the roof system components
(see the "Construction Guidance" section).
5. Obtain the services of a professional roofing con-
tractor to install the roof system.
Metal Roofing Options
A variety of metal panel systems (including compos-
ite foam panels) are available for low -slope (i.e., 3:12
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:
Standing -Seam Hydrostatic (i.e., water -barrier) Systems:
These panel systems are designed to resist water
infiltration under hydrostatic pressure. They have
standing seams that raise the joint between panels
above the water line. The seam is sealed with sealant
tape (or sealant) in case it becomes inundated with
water backed up by an ice dam or driven by high wind.
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
spaced decking is provided.
Hydrokinetic (i.e., water -shedding)
panels: These panel systems are not
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
that infiltrates past the panels. Most
hydrokinetic panels are architectur-
al systems, requiring continuous or
closely spaced decking to provide
support for gravity loads.
Some hydrokinetic panels have
standing ribs and concealed clips
(Figure 2), while others (such as
5V-crimp panels, R-panels [box -rib]
For attachment of corrugatedmetal panels, see
FEMA 55,', Coastal Construction Manual, Appendix
K, available online at: http://www.fema.gov/li-
brary/viewRecord.do?id=1671.
and corrugated panels) are through -fastened (i.e., at-
tached with exposed fasteners). Panels are available
that simulate the appearance of tile.
Metal Shingles: Metal shingles are hydrokinetic prod-
ucts and require a relatively steep -slope and the use
of an underlayment. Metal shingles are available that
simulate the appearance of wood shakes and tiles.
N4E...:.?k ... �(% ¥ S Y v E.': v i' i f: , i `VV1—N i E.G
12/10
HOVE BUILDEWS GUIDETO COASTAL CONSTRUCTION
Construction Guidance
Consult local building code requirements and
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 blown
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)
felt, use a Type II (#30) felt because the heavier
felt provides greater resistance to puncture by the
panels during application. Also, if a self -adhering
modified bitumen underlayment is used, specify/
purchase a product that is intended for use under-
neath metal (such products are more resistant to
bitumen flow under high temperature).
Where the basic (design) wind speed is 110 mph2
or greater, it is recommended that not less than
two clips be used along the eaves, ridges, and
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
speed greater than 90 mph,3 it is recommended
that Type 304 or 316 stainless steel clips and
stainless steel screws be used instead of more
malleable copper clips.
S
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).
— — — "LIP,
2 The 110 mph speed is based on ASCE 7-05. If ASCE 7-10 is being
used, the equivalent wind speed is 142 mph for Risk Category II
buildings.
3 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.
HOME BMDER S GUIDE TO COASTAL CONSTRUCTION a2
12/10
When clip or panel fasteners are loaded in with-
drawal (tension), screws are recommended in
lieu of nails.
For roofs located within 3,000 feet of the ocean
line, 300 series stainless steel clips and fasten-
ers are recommended.
For concealed clips over a solid substrate, it is
recommended that chalk lines be specified so
that the clips are correctly spaced.
Hip, ridge, and rake flashings: Because exposed
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
either side of the hip/ridge line. Close spacing of
fasteners is recommended (e.g., spacing in the
range of 3 to 6 inches on center, commensurate
with the design wind loads), as shown in Figure
O
f zb
44
1
Figure 8. The ridge flashing on these corrugated metal
panels had two rows of fasteners on each side of the
ridge line.'
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.reverecopper.com)
Copper Development Association, (http://www.copper.org/publications)
Metal Building Manufacturers Association, Metal Roofing Systems Design Manual, 2000, (http://www.mbma.
com/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/defauIt.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 S1OO-07), 2007, (http://www.steel.org)
American Iron and Steel Institute (http,//www.professionaIroofing.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).
International Organization of Standards (ISO), Document ISO 14021, (http:// www.iso.org).
Professional Roofing, "NRCA analyzes and tests metal," May 2003, (http://www.professionaIroofing.net)
Developed in association with the National Association of Home Builders Research Center
NAHB
RESEARCH
=CENTER
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HOpIE BUIILDERS GUIDE TO COASTAL CONSTRUCTION
5
12/10
Enclosures and Breakaway
Walls
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
professional.
Enclosures (breakaway and non-
i
I
-n .Pi
Figure 1 'Wood louvers installedbeneath an elevated house in a
V Zone are a goad alternative to solid breakaway walls.
breakaway) in A Zone buildings
must be built with flood -resistant materials and
equipped with flood openings that allow water
levels inside and outside to equalize.
Breakaway enclosure walls should be considered
expendable, and the building owner could incur
significant costs when the walls are replaced.
Breakaway wall replacement is not covered un-
der flood insurance policies.
For V Zones, breakaway wall enclosures below
an elevated building will result in higher flood
insurance premiums; however, surrounding be-
low-BFE space with insect screening, open lat-
tice, slats, or shutters (louvers) can result in
much lower flood insurance premiums (Figure
1) and will likely reduce damage during less -
than -base -flood events. It is also recommend-
ed that breakaway walls be designed to break
into smaller sections so that they're less likely
to damage the foundation or the upper portions
of buildings.
t,�nry
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FEMA HOME BUILDER�S '"M
12/10
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H 0 NIE BUILDER TO COAST L CO N S T R U CTI 0 N
12/10
r s
Figure 4. Building siding extended down and over the
breakaway wall. lack of a clean separation allowed
damage to spread upward as the breakaway wall failed. `
Obstruction Considerations
A V Zone building, elevated on an open foundation
without an enclosure or other obstructions below the
BFE, is said to be free of obstructions, and will re-
ceive a favorable flood insurance premium (see FEMA
(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:
Below BFE space is surrounded by insect screen-
ing and/or by wooden or plastic lattice, slats, or
shutters (louvers), if at least 40 percent of the
lattice and louver area is open. Lattice can be no
thicker than 1/4 inch; slats or louvers can be no
thicker than 1 inch.
Below BFE space is surrounded by a combina-
tion of one solid breakaway wall (or garage door),
and all other sides of the enclosure are either in-
sect screening, wooden or plastic lattice, slats,
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
away walls.
Below BFE space is enclosed by a combination
of two or more solid breakaway walls, with the re-
maining sides of the enclosure comprised of ei-
ther insect screening, or wooden or plastic lat-
tice, slats, or louvers.
Flood Openings
Foundation walls and other enclosure walls of A Zone
buildings (including Coastal A Zone buildings) must
be equipped with openings that allow the automatic
entry and exit of floodwaters (Figure 5).
3 #..::: N s" ..'0 S i...,. # 1 # '. S A I E.w ' # 11 Yl A�"d�V �, Y VNIY � t...
A Zone opening requirements are as follows:
Flood openings must be provided in at least two
of the walls forming the enclosure.
The bottom of each opening is to be located
no higher than 1 foot above the grade that is
immediately under each opening. If the interior
and exterior grades are different, the higher of
the final interior grade and the finished exterior
grade that is immediately under each opening
is used to make the determination.
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
flood.
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
engineering method (which must be certified by
a registered engineer or architect).
Details concerning flood openings can be found in
FEMA (2008c) Technical Bulletin 1-08, Openings in
Foundation Walls and Walls of Enclosures.
Other Considerations
Enclosures are strictly regulated because, if not con-
structed properly, they can transfer flood forces to
the main structure (possibly leading to structural col-
lapse). There are other considerations as well.
Owners may be tempted to convert enclosed ar-
eas below the BFE into habitable space, lead-
ing to life -safety concerns and uninsured losses.
Buildings without enclosures below the lowest
floor should be encouraged. If enclosures are
constructed, contractors should not stub out
utilities in enclosures (utility stub -outs make
it easier for owners to finish and occupy the
space).
HONIE BWLDERS GUIDE TO COASTAL CONSTRUCTION a2
12/10
Siding used on the elevated portions of a build-
ing should not extend down over breakaway
walls. Instead, a clean separation should be pro-
vided so that any siding installed on breakaway
walls is structurally independent of siding else-
where on the building. Without such a separa-
tion, the failure of breakaway walls can result in
damage to siding elsewhere on the building (see
Figure 4).
Solid breakaway wall enclosures in V Zones will
result in higher flood insurance premiums (es-
pecially where the enclosed area is 300 square
feet or greater). Insect screening, lattice, slats,
or louvers are recommended.
It is recommended to use insect screening, open
wooden or plastic lattice, slats, or louversin-
stead of solid breakaway walls beneath elevated
residential' buildings.
If enclosures are constructed in Coastal A
Zones, open foundations with breakaway enclo-
sures are recommended instead of foundation
walls or crawlspaces. If solid breakaway walls
are used, then they must be equipped with flood
openings that allow floodwaters to enter and exit
the enclosure. Use of breakaway enclosures in
Coastal A Zones (or any A Zone) will not lead to
higher flood insurance premiums.
Garage doors installed in below-BFE enclosures
of V Zone buildings —even reinforced and high -
wind -resistant doors —must meet the perfor-
mance requirement discussed in the Breakaway
Walls section of this Fact Sheet. Specifically, the
doors must be designed to break free under the
larger of the following Allowable Stress Design
loads: design wind load, the design seismic
load, or 10 psf, acting perpendicular to the plane
of the door. If the Allowable Stress Design load-
ing exceeds 20 psf for the designed door, the
door must be designed and certified to collapse
under base flood conditions. See the Breakaway
Walls section for information about certification
requirements.
There are two other enclosure scenarios that should
be mentioned, both of which have construction and
flood insurance consequences. Contractors and de-
signers should be cautious when an owner asks for
either type of enclosure, and consultation with the
community and a knowledgeable flood insurance
agent is recommended.
Below-BFE enclosures that do not extend all the
way to the ground (sometimes called "hanging"
enclosures or "elevated" enclosures, occurs
when there is an enclosure floor system tied to
the building foundation and above the ground —
see Figure 6). In V Zones, the enclosure walls
must be breakaway, and the enclosure floor sys-
tem must either break away or the building foun-
dation must be designed to accommodate flood
loads transferred from the enclosure floor sys-
tem to the foundation. In V Zones, the enclosure
walls must be breakaway, and the enclosure floor
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.
In A Zones, the enclosure walls must have prop-
er flood vents, with the bottom no higher than 1
foot above the enclosure floor. These types of
enclosures were not contemplated when flood in-
surance premium rate tables were constructed,
and can result in significantly higher flood insur-
ance premiums than had the enclosure walls ex-
tended to the ground. The NFIP is working to cor-
rect this rating issue; until then, owners will pay
a substantial premium penalty for this type of
construction.
O
f zb
12/10
HOME BUILDEWS GUIDETO COASTAL CONSTRUCTION
Two-story enclosures below ele-
vated buildings (see Figure 7). As
some BFEs are established high-
er and higher above ground, some
owners have constructed two-story
solid wall enclosures below the ele-
vated building, with the upper enclo-
sure having a floor system approxi-
mately midway between the ground
and the elevated building. These
types of enclosures present unique
problems. In A Zones both levels of
the enclosure must have flood open-
ings in the walls unless there is
some way to relieve water pressure
through the floor system between
the upper and lower enclosures; in V
Zones, the enclosure walls (and pos-
sibly enclosure floor systems) must
be breakaway; special ingress and
egress code requirements may be
a factor; these enclosures may re-
sult in substantially higher flood in-
surance premiums.
711
f�
Figure Z.'Example of two-story enclosure below the BFE.This ',type
of enclosure presents special construction and flood insurance
issues. Contractors should proceed with caution when an owner
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).
FEMA. 2008c. Openings in Foundation Walls and Walls of Enclosures. Technical Bulletin 1-08,
(http://www.fema.gov/library/viewRecord.do?id=1579).
FEMA. 2009. Hurricane Ike Recovery Advisory, Design and Construction in Coastal Zones,
(http://www.fema.gov/library/viewRecord.do?id=1569).
NAHB
€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center C E T E R
i:] N L,'0 S i 11 v: I ..w l i 1 : ,{„ t, ` VNI . I...
MOME BMDERS GUIDE TO COASTAL CONSTRUCTION 5 a2
12/10
Decks, Pools, and Accessory
Structures
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-
erwise compliant with NFIP
requirements, a higher flood in-
surance premium may be as-
sessed against the entire
building.
4
Damage from Hurricane Opal in Florida. This deck was designed to meet
State of Florida Coastal Construction Control Line (CCCL) requirements.
The house predated the CCCL and did not meet the requirements.
Swimming pools, accessory build-
ings, and other construction elements outside
the perimeter (footprint) of, and not attached
to, a coastal building may alter the characteris-
tics of flooding significantly or increase wave or
debris impact forces affecting the building and
nearby buildings. If such elements are to be con-
structed, a design professional should consider
their potential effects on the building and nearby
buildings.
This Home Builder's Guide to Coastal Construction
strongly recommends that all decks, pools, ac-
cessory structures, and other construction ele-
ments in Zone A in coastal areas be designed
and constructed to meet the NFIP V Zone re-
quirements.
Post -storm investigations frequently reveal enve-
lope and structural damage (to elevated build-
ings) initiated by failure of a deck due to flood
FEMA
._ .a
and/or wind forces. Decks should be given the
same level of design and construction attention
as the main building, and failure to do so could
lead to severe building damage.
Decks
Requirements
If a deck is structurally attached to a building in
Zone V, the bottom of the lowest horizontal mem-
ber of the deck must be elevated to or above the
elevation of the bottom of the building's lowest
horizontal member.
A deck built below the Design Flood Elevation
(DFE) must be structurally independent of the
main building and must not cause an obstruction.
If an at -grade, structurally independent deck is
to be constructed, a design professional must
HOME BUILDERW-D COASTAL CONSTRUCTION
12/10
evaluate the proposed deck to determine wheth-
er it will adversely affect the building and nearby
buildings (e.g., by diverting flood flows or creat-
ing damaging debris).
Recommendations
Decks should be built on the same type of foun-
dation as the primary building. Decks should be
structurally independent of the primary structure
and designed to resist the expected wind and
water forces.
Alternatively, decks can be cantilevered from the
primary structure; this technique can minimize
the need for additional foundation members.
A "breakaway deck" design is discouraged be-
cause of the large debris that can result.
A "breakaway deck" on the seaward side poses
a damage hazard to the primary structure.
Decks should be constructed of flood -resistant
materials, and all fasteners should be made of
corrosion -resistant materials.
Access Stairs and Elevators
Requirements
Open stairs and elevators attached to or be-
neath an elevated building in V Zone are ex-
cluded from the NFIP breakaway wall re-
quirements (see NFIP Technical Bulletin
5-08 and Fact Sheet No. 8.1), but must meet
the NFIP requirement for the use of flood -resis-
tant materials (see NFIP Technical Bulletin 2-08
and Fact Sheet No. 1.7). Large solid staircases
that block flow under a building are a violation of
NFIP free -of -obstruction requirements (see NFIP
Technical Bulletin 5-08)
Although they need not be designed to break
away under flood forces, access stairs and ele-
vators are obstructions; therefore, the loads they
may transfer to the main building must be con-
sidered by the design professional.
Yr �
MUM -
Large solid stairs such as these block flow under a
building and are a violationof NFIP free -of -obstruction
requirements.
Recommendations
Open stair handrails and risers should be used
because they allow wind and water to pass
through rather than act as a barrier to flow.
The bottom of the stair, like the foundation of the
primary structure, should be designed and con-
structed to remain in place during a windstorm
or a flood.
Stairways not considered the primary means of
egress can be constructed with hinged connec-
tions that allow them to be raised in the event of
an impending storm or flood (check code require-
ments before employing this technique).
Elevators should be installed in accordance with
the guidance in NFIP Technical Bulletin 4-93 and
the building code.
Swimming Pools
Requirements
An at -grade or elevated pool adjacent to a coast-
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
Zone V, the design professional must assure
community officials that the pool will not increase
the potential for damage to the foundation or
elevated portion of the building or any nearby
12/10
HOME BUILDEWS GUIDETO COASTAL CONSTRUCTION
buildings. Pools can be designed to
break up ("frangible pools") during a
flood event, thereby reducing the po-
tential for adverse impacts on near-
by buildings.
Any pool constructed adjacent to a
coastal building must be structurally
independent of the building and its
foundation.
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
with the existing grade and only if the
lower area (below the lowest floor)
remains unenclosed. Under the NFIP
lower -area enclosures around pools
constitute a recreational use and
are not allowed, even if constructed
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
elevated on a pile -supported structural frame.
No aboveground pools should be constructed in
V Zone unless they are above the DFE and have
an open, wind- and flood -resistant foundation.
Pool equipment should be located above the
DFE whenever practical.
Check with community officials before construct-
ing pools in Zone V.
Accessory Buildings
Requirements
Unless properly elevated (to or above the DFE)
on piles or columns, an accessory building in V
Zone is likely to be destroyed during a coastal
storm; therefore, these buildings must be lim-
ited to small, low -value structures (e.g., small
wood or metal sheds) that are disposable. See
NFIP Technical Bulletin 5-08.
If a community wishes to allow unelevated ac-
cessory buildings, it must define "small" and
"low cost." NFIP Technical Bulletin 5-08 defines
"small" as less than 100 square feet and "low
cost" as less than $500. Unelevated accessory
When an accessory building is placed in Zone V,
the design professional must determine the ef-
fect that debris from the accessory building will
have on nearby buildings. If the accessory build-
ing is large enough that its failure could create
damaging debris or divert flood flows, it must be
elevated above the DFE.
Recommendations
Whenever practical, accessory buildings should
not be constructed. Instead, the functions of an
accessory building should be incorporated into
the primary building.
All accessory buildings should be located above
the DFE whenever practical.
All accessory buildings should be designed and
constructed to resist the locally expected wind
and water forces whenever practical.
The roof, wall, and foundation connections in ac-
cessory buildings should meet the requirements
for connections in primary buildings.
Accessory buildings below the DFE should be an-
chored to resist being blown away by high winds
or carried away by floodwaters.
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.
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
Hazard Areas. (http://www.fema.gov/library/viewRecord.do?id=1718)
NAHB
RESEARCH
Developed in association with the National Association of Home Builders Research Center CENTER
4 Of :+
12/10
110NIE BUILDEWS GUIDE TO COASTAL CONSTRUCTION
Protecting Utilities
Purpose: To identify the special
considerations that must be made
when installing utility equipment
in a coastal home.
Key Issues:
Hazards, requirements, and recom-
mendations — Special considerations
must be made when installing util-
ity systems in coastal homes.
Proper placement and connection
of utilities and mechanical equip-
ment can significantly reduce the
costs of damage caused by coastal
storms and will enable homeowners
to reoccupy their homes soon after
electricity, sewer, and water are re-
stored to a neighborhood.
Coastal Hazards That Damage
Utility Equipment
Standing or moving floodwaters
Impact from floating debris in floodwaters
Erosion and scour from floodwaters
High winds
Windborne missiles
Common Utility Damage in Coastal Areas
Floodwaters cause corrosion and contamination,
short-circuiting of electronic and electrical equip-
ment, and other physical damage.
Electrical — Floodwaters can corrode and short-circuit
electrical system components, possibly leading to
electrical shock. In velocity flow areas, electrical pan-
els can be torn from their attachments by the force of
breaking waves or the impact of floating debris.
Water/Sewage — Water wells can be exposed by ero-
sion and scour caused by floodwaters with velocity
flow. A sewage backup can occur even without the
structure flooding.
Fuel — Floodwaters can float and rupture tanks, cor-
rode and short-circuit electronic components, and
sever pipe connections. In extreme cases, damage
to fuel systems can lead to fires.
FEMA
._ .a
Basic Protection Methods
The primary protection methods are elevation or
component protection.
Elevation
Elevation refers to the location of a component and/or
utility system above the Design Flood Elevation (DFE).
Component Protection
Component protection refers to the implementation
of design techniques that protect a component or
group of components from flood damage when they
are located below the DFE.
NFIP Utility Protection Requirements
The NFIP regulations [Section 60.3(a)(3)] state that:
All new construction and substantial improvements
shall be constructed with electrical, heating, ven-
tilation, plumbing, and air conditioning equipment
and other service facilities that are designed and/
or located so as to prevent water from entering or
accumulating within the components during condi-
tions of flooding.
I, UTH I
Elevation of utilities and mechanicalequipment
is the preferred method of protection.
HOME BUILDER UIDIETO COASTAL CONSTRUCTION
12/10
Utility Protection Recommendations
Electrical
Limit switches, wiring, and receptacles below
the DFE to those items required for life safety.
Substitute motion detectors above the DFE for
below-DFE switches whenever possible. Use only
ground -fault -protected electrical breakers below
the DFE.
Install service connections (e.g., electrical lines,
panels, and meters; telephone junction boxes;
cable junction boxes) above the DFE, on the land-
ward side of interior piles or other vertical sup-
port members.
Use drip loops to minimize water entry at
penetrations.
Never attach electrical components to break-
away walls.
Water/Sewage
Attach plumbing risers on the landward side of
interior piles or other vertical support members.
When possible, install plumbing runs inside
joists for protection.
Never attach plumbing runs to breakaway walls.
HVAC
Install HVAC components (e.g., condensers,
air handlers, ductwork, electrical components)
above the DFE.
Mount outdoor units on the leeward side of the
building.
Secure the unit so that it cannot move, vibrate,
or be blown off its support.
Protect the unit from damage by windborne debris.
Fuel
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-
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
method (elevation) is preferred.
Any anchoring, strapping, or other attachments
must be designed and installed to resist the ef-
fects of corrosion and decay.
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)
NAHB
€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center C E T E R
12/10
Repairs, Remodeling,
Additions, and Retrofitting
Flood
Purpose: To outline National Flood Insurance Program (NFIP) requirements for repairs, remodeling, and
eAhti n/ , anto opportundties for retrofitlil,il in coastel th-wo'dliazard areas; to� lor
exceeding those minimum requirements.
Key Issues
Existing buildings that sustain substantial dam-
age or that are substantially improved (see box
on page 3) will be treated as new construction
and must meet the community's current flood -
resistant construction requirements (e.g., low-
est floor elevation, foundation, and enclosure
requirements).
Work on post -Flood Insurance Rate Map (FIRM)'
existing buildings that are not substantially dam-
aged or substantially improved (see box on page
3) must meet the community's flood -resistant
construction requirements that were in effect
when the building was originally constructed.
Work on pre -FIRM' existing buildings that are not
substantially damaged or substantially improved
(see box on page 3) is not subject to NFIP flood -
resistant construction requirements.
With some minor exceptions (e.g., code viola-
tions and historic buildings), substantial damage
and substantial improvement requirements apply
to all buildings in the flood hazard area, whether
or not a flood insurance policy is in force.
Buildings damaged by a flood and covered by
flood insurance may be eligible for additional pay-
ments through the Increased Cost of Compliance
(ICC) policy provisions. Check with an insurance
agent and the authority having jurisdiction (AHJ)
for details.
Repairs and remodeling —either before or after
storm damage —provide many opportunities for
retrofitting homes and making them more resis-
tant to flood damage.
Factors That Determine Whether and How
Existing Buildings Must Comply With NFIP
Requirements
Rules governing the applicability of NFIP new construc-
tion requirements to existing buildings are confusing
to many people; this fact sheet and Fact Sheet No.
1.2, Summary of Coastal Construction Requirements
and Recommendations for Flood Effects provide guid-
ance on the subject.
When repairs, remodeling, additions, or improve-
ments to an existing building are undertaken, four
basic factors determine whether and how the exist-
ing building must comply with NFIP requirements for
new construction:
Value of damage/work— whether the cost of re-
pairs to the damaged building triggers substan-
tial damage or substantial improvement regula-
tions (see page 3).
Nature of work— whether the work involves an
expansion of the building, either laterally or ver-
tically (an addition), or an enclosure of space be-
low the Base Flood Elevation (BFE), or the demo-
lition and reconstruction of an existing building,
or the relocation of an existing building.
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.
wFEMA H O'M E B U I L"D- E' R''
�ZI�S GOUI-DE TO COASTAL CONSTRUCTION
..a
12/10
Pre -FIRM or post -FIRM building— different re-
quirements may apply to pre -FIRM existing
buildings.
Flood zone— different requirements may apply
in V Zones and A Zones (this includes both the
Coastal A Zone and A Zone).
Two other factors may need to be considered (con-
sult the AHJ regarding whether and how these factors
apply):
Code violations— if cited by a code official, the
NFIP regulations exempt certain work to correct
existing violations of state or local health, sani-
tary, or safety code requirements from the sub-
stantial improvement and substantial damage
calculations.
Historic structures— a building that is on the
National Register of Historic Places or that has
been designated as historic by federally certified
state or local historic preservation offices (or
that is eligible for such designation) may be ex-
empt from substantial damage and substantial
improvement requirements, provided any work
on the building does not cause the building to
lose its historic designation.
Code Compliance
Definitions from the International Code Council Model
Building Codes
ADDITION: An extension or increase in floor area or
height of a building or structure.
ALTERATION: Any construction or renovation to an
existing structure other than repair or addition that
requires a permit. Also, a change in a mechanical
system that involves an extension, addition or change
to the arrangement, type or purpose of the original in-
stallation that requires a permit.
REPAIR: The reconstruction or renewal of any
part of an existing building for the purpose of its
maintenance.
Substantial Damage and Substantial
Improvement
It is not uncommon for existing coastal buildings
to be modified or expanded over time, often in con-
junction with the repair of storm damage. All repairs,
remodeling, improvements, additions, and retrofitting
to buildings in flood hazard areas must be carried
out in conformance with floodplain management or-
dinances pertaining to substantial improvement and
substantial damage.
What Costs Are Included in Substantial
Damage and Substantial Improvement
Determinations?
All structural items and major building com-
ponents (e.g., foundations; beams; trusses;
sheathing; walls and partitions; floors; ceilings;
roof covering; windows and doors; brick, stucco,
and siding; attached decks and porches).
... i r, :.: ( v,,,:.¥., ¥ '�.�fir.: .. - .. ¥:
12/10
HOME BUILDEWS GUIDE TO COASTAL CONST, RUCTION
Interior finish elements (e.g., tile, vinyl flooring,
stone, carpet; plumbing fixtures; gypsum wall-
board and wall finishes; built-in cabinets, book-
cases and furniture; hardware).
Utility and service equipment (e.g., HVAC equip-
ment; plumbing and wiring; light fixtures and ceil-
ing fans; security systems; built-in appliances;
water filtration and conditioning systems).
Market value of all labor and materials for re-
pairs, demolition, and improvements, including
management, supervision, overhead, and profit
(do not discount volunteer or self -labor or donat-
ed/discounted materials).
What Costs Are Not Included in Substantial
Damage and Substantial Improvement
Determinations?
Design costs (e.g., plans and specifications,
surveys and permits).
Clean-up (e.g., debris removal, transportation,
and landfill costs).
Contents (e.g., furniture, rugs, appliances not
built in).
Outside improvements (e.g., landscaping, irri-
gation systems, sidewalks and patios, fences,
lighting, swimming pools and hot tubs, sheds,
gazebos, detached garages).
Additions
Additions increase the square footage or external
dimensions of a building. They can be divided into
lateral additions, vertical additions, and enclosures of
areas below existing buildings. When considering ad-
ditions, it is important to consider that changes to
the shape of the building may impact the potential
damages to the house. A lateral addition may change
the way flood waters travel around the structure and
potentially create obstructions for flood -borne debris
that may require additional foundation modifications.
Vertical additions may also impose greater loads on
the existing structure. A qualified design professional
should evaluate the loading to the entire structure to
see if additional structural modifications are required
in order to maintain the structure's ability to sustain
flood loading.
Lateral Additions
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).
HOME BWLDERS GUIDE TO COASTAL CONSTRUCTION
12/10
RE'JVURS, PE.'lMC-,E)E'::: ING� AlEll' R"ICNES, A".) H,%j, g I NG J
H 0 NIE BUILDER TO C 0 A S TA L CO N S T, RUCTION
12/10
Vertical Additions
If a vertical addition to a V Zone or A Zone build-
ing constitutes a substantial improvement, both
the addition and the existing building must com-
ply with the effective base flood elevation, foun-
dation, and other flood requirements for new
construction (see Figure 3).
If a vertical addition to a pre -FIRM V Zone or A
Zone building does not constitute a substantial
improvement, neither the addition nor the ex-
isting building must be elevated or otherwise
brought into compliance with NFIP requirements.
However, the HBGCC recommends that both the
addition and the existing building be elevated to,
or above, the current DFE in a manner consis-
tent with current NFIP requirements for new con-
struction, and using a V Zone -type foundation in
V Zones and in Coastal A Zones (see Figure 3).
The HBGCC also recommends strongly against
using any space below the current BFE for habit-
able uses (uses permitted by the NFIP are park-
ing, storage, and building access).
If a vertical addition to a post -FIRM V Zone or
A Zone building does not constitute a substan-
tial improvement, the addition must be designed
and constructed in accordance with the flood re-
quirements in effect at the time the building was
originally constructed. However, BFEs and flood
zones change over time as areas are remapped.
The HBGCC recommends that both the addi-
tion and the existing building be elevated to, or
above, the current DFE in a manner consistent
with current NFIP requirements for new construc-
tion, and using a V Zone -type foundation in V
Zones and in Coastal A Zones. The HBGCC also
recommends strongly against using any space
below the current BFE for habitable uses (uses
permitted by the NFIP are parking, storage, and
building access).
HOME BWLDERS GUIDE TO COASTAL CONSTRUCTION
12/10
Enclosures of Areas Below Existing
Buildings
Enclosures below existing buildings are treated like
vertical additions.
Existing NFIP requirements: (1) do not enclose and
convert to habitable use any space below the BFE
under any circumstances, and (2) construct only
breakaway enclosures below existing buildings in V
Zones and in Coastal A Zones. HBGCC recommen-
dation: in V Zones and Coastal A Zones the area
below the BFE should be built free of obstruction.
Use open lattice, screening, or breakaway walls. For
requirements concerning enclosures below elevated
buildings see Fact Sheet 8.1. It should be noted that
enclosures built with breakaway walls below the BFE
may result in increased insurance premiums when
compared to an open foundation.
Reconstruction of a Destroyed or Razed
Building
In all cases (pre -FIRM or post -FIRM, V Zone or A Zone)
where an entire building is destroyed or purposeful-
ly demolished or razed, the replacement building is
considered "new construction" and the replacement
building must meet the current NFIP requirements,
even if it is built on the foundation of the original
building.
Moving an Existing Building
When an existing building (pre -FIRM or post -FIRM, V
Zone or A Zone) is moved to a new location or site,
the work is considered "new construction" and if the
relocated building is in the SFHA, it must be installed
so as to comply with NFIP requirements.
Materials
When constructing in coastal environments, carefully
consider what construction materials to select. The
NFIP Technical Bulletin 2, Flood Damage -Resistant
Materials Requirements (August 2008), provides valu-
able information regarding the applicability of various
construction materials in a coastal environment. For
additional information, see Fact Sheet 1.7, Coastal
Building Materials. Following a storm event, repairs
should not be started until the problem is properly
evaluated and materials are selected that will entire-
ly remedy the damage. All costs of repairs should be
identified and quantified prior to starting repairs.
Repairs
Correction of only the apparent surface damage can
lead to unaddressed or overlooked problems be-
neath the surface that can potentially cause major
issues with the structural stability of the building.
Proper inspections of damage often not only require
demolition or removal of the physically damaged
building component, but also removal of associated
exterior cladding. Wind -driven rain for example can
lead to compromised connections and the decaying
or rotting of building materials that may not be visible
without further investigation.
Insurance Consequences
Designers and owners should know that the work
described previously may have insurance conse-
quences, especially if not completed strictly in
accordance with NFIP requirements.
In general, most changes to an existing building
that result from less -than -substantial damage, or
that do not constitute substantial improvement, will
not change the status from pre -FIRM to post -FIRM.
However, it is required that substantially improved
or substantially damaged buildings be brought into
compliance. NFIP flood insurance policies on those
buildings are written using rates based on elevation.
In most cases, the premium will decrease when a pre -
FIRM building is substantially improved and brought
into compliance. The building becomes a post -FIRM
building and premiums are calculated using elevation
rates. Failure to comply with the substantial damage
or substantial improvement requirements will result
in a building's status being changed and in higher
flood insurance premiums. For example:
If an NFIP-compliant enclosure built with break-
away walls is added below a post -FIRM V Zone
building, the building will no longer be rated as
"free of obstructions." Flood insurance premi-
ums on these buildings will be higher. If the en-
closure is not compliant with all NFIP require-
ments, higher premiums will result.
If work on an existing V Zone building constitutes
a substantial improvement, the building will be
rated on a current actuarial basis. Any pre -FIRM
designation will be lost and current post -FIRM
rates will be used.
If an NFIP-compliant lateral addition constitut-
ing a substantial improvement is made to a pre -
FIRM A Zone building and no changes were made
to the existing building, the building will retain its
pre -FIRM designation and rating. However, if the
addition does not comply with all requirements,
or if more than the minimum alteration neces-
sary was made to the existing building, the build-
ing and addition's lowest floor must be elevat-
ed to or above the BFE. The building including
the addition will be rated with post -FIRM actuari-
al rates.
Retrofit and Remodeling Opportunities
Retrofit opportunities will likely present themselves
any time repair or maintenance work is undertaken
for a major element of a building. Improvements to
the building that are made to increase resistance to
... :: r, :.: ( v,,,:.¥., ¥ '�.�fir.: .. - .. ¥:
12/10
HOVE BUILDEWS GUIDE TO COASTAL CONST, RUCTION
the effects of natural hazards should focus on those
items that will potentially return the largest benefit to
the building owner. Some examples of retrofit oppor-
tunities may include:
Improving floor -framing -to -beam connections
whenever they are accessible (see Fact Sheet
4.1, Load Paths and Fact Sheet 4.3, Use of Con-
nectors and Brackets for additional information).
Improving beam -to -pile connections whenev-
er they are accessible (see Fact Sheet 3.3,
Wood -Pile -to -Beam Connections for additional
information).
Periodically checking and inspecting flood open-
ings to make sure that they are not blocked and
functioning properly. If the house is older, checkto
make sure that flood openings are sized correct-
ly. Consult NFIP Technical Bulletin 1, Openings In
Foundation Walls and Walls of Enclosures (August
2008) for proper flood opening guidance. Also
see Fact Sheet 3.5, Foundation Walls for addi-
tional information.
At any time deficient metal connectors are found,
they should be replaced with stainless steel con-
nectors or metal connectors with proper corro-
sion protection, such as hot -dip galvanized steel
(see Fact Sheet 1.7, Coastal Building Materials
for additional information).
When HVAC equipment is replaced, the replace-
ment equipment selected should incorporate
a more corrosion -resistant design —so that it
will last longer in a coastal environment —and
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,
Protecting Utilities for additional information).
Improving utility attachments when the out-
side equipment is replaced or relocated (see
Fact Sheet 8.3, Protecting Utilities for additional
information).
To minimize the effects of corrosion, carbon steel
handrails can be replaced at any time with vinyl -
coated, plastic, stainless steel, or wood hand-
rails. Wood handrails may require frequent treat-
ment or painting and appropriate fasteners must
be used (see Fact Sheet 1.7, Coastal Building
Materials for additional information). Carbon
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.
The installation should be done by a licensed
plumber.
If the current water heater is at, or below, the DFE,
consider switching to a tankless water heater.
A tankless water heater will take up less space
and can be mounted to a wall due to its small
size. In addition to allowing the user to mount it
higher than a traditional water heater, it may also
result in reduced energy costs.
Older structures should consider elevation as a
possible retrofit or mitigation opportunity. Older
pre -FIRM structures can be at significant risk to
flooding events. In coastal environments, even a
little additional elevation can result in improved
flood resistance. Costs can vary greatly depend-
ing on the type of foundation. It is important
when considering an elevation project to consult
a design professional before considering how
much elevation and the appropriate foundation
type. A contractor experienced with the elevation
of buildings should be used for the actual lifting
of the house. It is common for the house to re-
quire other structural work to the interior and ex-
terior following the elevation. Before undertak-
ing an elevation, consider the elevation process,
which usually results in the structure being set
on top of a foundation that is more level than the
original foundation. This process can result in
cosmetic cracking as the structure's foundation
settles again and may require additional work to
get the structure's aesthetics back to a pre -ele-
vation appearance.
Additional Resources
FEMA. 2010. Substantial Improvement/Substantial
Damage Desk Reference. FEMA P-758. http://www.
fema.gov/library/viewRecord.do?id=4160
FEMA. 2005. Coastal Construction Manual, Chapter
14. FEMA 55. (http://www.fema.gov/library/viewRe-
cord.do?id=1671)
Florida Department of Community Affairs. 2000. A
Local Officials Guide to Implementing the National
Flood Insurance Program in Florida. (See Chapter
6). (http://www.floridadisaster.org/Mitigation/NFIP/
N FI PStudyCourse/Appendix%2OE%20-%2OFL%20
Handbook.pdf)
Consider sewer backflow preventer valves if they
are not currently part of the building's plumbing.
NAHB
€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center C E T E R
HOME LDERP S P TO COAST: Ct TRUCTION �
12/10
Repairs, Remodeling,
Additions, and Retrofitting
Wind
Purpose: To outline requirements and "best practice" recommendations for repairs, remodeling, and
ieAb � � , o `gyp � pporh ` i '� � �s f I�,comsted dgli- wind ateas.
Key Issue
Repairs and remodeling- either
before or after storm damage -
provide many opportunities for
retrofitting homes and making
them more resistant to storm
damage (see Figure 1).
Code Compliance
Definitions from the International
Code Council (ICC) Model Building
Codes
Addition: An extension or increase in
floor area or height of a building or
structure.
Alteration: Any construction or reno-
vation to an existing structure other
than repair or addition that requires
a permit. Also, a change in a me-
chanical system that involves an
extension, addition, or change to the
arrangement, type, or purpose of the
original installation that requires a permit.
Repair: The reconstruction or renewal of any part of an
existing building for the purpose of its maintenance.
Factors That Determine Whether and How Existing
Buildings Must Comply With Current Building Code
Requirements
When undertaking repairs, remodeling, additions, or
improvements to an existing building, there are two
basic factors that determine whether and how the
existing building must comply with building code re-
quirements for new construction.
Value of damage/work- whether the value of the
building damage and/or work qualifies as sub-
stantial damage or substantial improvement un-
der NFIP regulations (see text box).
NO
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HOME BUILDER UI-D .. TO COASTAL CONSTRUCTION
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12/10
Nature of work— whether the work involves an ex-
pansion of the building, either laterally or verti-
cally (an addition), or the demolition and recon-
struction of an existing building, or the relocation
of an existing building.
Two other factors occasionally come into play (con-
sult the authority having jurisdiction [AHJ] regarding
whether and how these factors apply):
Code violations— certain work to correct existing
violations of state or local health, sanitary, or
safety code requirements that have been cited
by a code official may be excluded from calcu-
lations of value of work used to determine sub-
stantial improvement or substantial damage.
Historic structures— work on a building that is on
the National Register of Historic Places or that
has been designated as historic by federally cer-
tified state or local historic preservation offices
(or that is eligible for such designation) may be
excluded from calculations of value of work used
to determine substantial damage and substan-
tial improvement requirements, provided such
work does not cause the building to lose its his-
toric designation.
Substantial Damage and Substantial
Improvement
It is not uncommon for existing coastal buildings
to be modified or expanded over time, often in con-
junction with the repair of storm damage. All repairs,
remodeling, improvements, additions, and retrofit-
ting to buildings must be made in conformance with
existing building code requirements pertaining to sub-
stantial improvement and substantial damage.
What Costs Are Included in Substantial Damage
and Substantial Improvement Determinations?
All structural items and major building com-
ponents (e.g., foundations; beams; trusses;
sheathing; walls and partitions; floors; ceilings;
roof covering; windows and doors; brick, stucco,
and siding; attached decks and porches).
Interior finish elements (e.g., tile, linoleum,
stone, carpet; plumbing fixtures; gypsum wall-
board and wall finishes; built-in cabinets, book-
cases and furniture; hardware).
Utility and service equipment (e.g., HVAC equip-
ment; plumbing and wiring; light fixtures and ceil-
ing fans; security systems; built-in appliances;
water filtration and conditioning systems).
Market value of all labor and materials for re-
pairs, demolition, and improvements, including
management, supervision, overhead, and profit
(do not discount volunteer or self -labor or donat-
ed/discounted materials).
What Costs Are Not Included in Substantial
Damage and Substantial Improvement
Determinations?
Design costs (e.g., plans and specifications, sur-
veys and permits).
Clean-up (e.g., debris removal, transportation,
and landfill costs).
Contents (e.g., furniture, rugs, appliances not
built in).
Outside improvements (e.g., landscaping, irriga-
tion systems, sidewalks and patios, fences, light-
ing, swimming pools and hot tubs, sheds, gaze-
bos, detached garages).
Additions
Additions increase the square footage or external
dimensions of a building. They can be divided into
lateral additions, vertical additions, and enclosures
of areas below existing buildings. When considering
additions, it is important to consider that changes
to the shape and roof line of the structure may im-
pact the potential damages to the house. A lateral
addition may change the number of openings, the
way wind travels around the structure, or create a
large open space that may require additional bracing.
,
12/10
HOME BUIL'U'EWS GUIDE TO COASTAL CONST, RUCTION
Vertical additions may also impose greater loads on
the existing structure. A qualified design professional
should evaluate the loading to the entire structure to
see if additional structural modifications are required
in order to maintain the structure's ability to sustain
high -wind loading.
Lateral Additions
If a lateral addition constitutes a substantial im-
provement to a building, both the addition and
the existing building must comply with the cur-
rent wind loading requirements. The foundation,
walls, and roof may need to be altered in order to
comply with wind loading requirements.
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-
rent wind loading requirements. The foundation,
walls, and roof may need to be altered in order to
comply with wind loading requirements. Vertical
additions may apply significantly higher loadings
to the foundation and first story, it is important
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
When constructing in coastal environments, carefully
consider what construction materials to select. For
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
consist of not only wind related damage, but also wa-
ter intrusion. Following a storm event, repairs should
not be started until the problem is properly evaluated
and materials are selected that will entirely remedy
the damage.
Repairs
Correction of the apparent surface damage can lead
to unaddressed or overlooked problems that can
cause major issues with the structural stability of the
building. Inspections often not only require demoli-
tion or removal of the physically damaged building
component, but also removal of associated exterior
cladding. Wind -driven rain can lead to compromised
connections and decaying or rotting building materi-
als that may not be visible without more investigation.
The repair of interior finishes damaged by wind -driven
rain should be carefully considered. Coastal build-
ings are often subjected to high -wind events, which
many times are accompanied by wind -driven rain. The
wind pushes water through small openings in doors
and windows. This does not suggest improper func-
tioning of the door or window, but this is more the
result of the pressures these openings are subjected
to during high -wind events. Interior surfaces such as
walls, floor, and cabinets may be subjected to wa-
ter on a regular basis. These building components
may require finishes that will resist repeated water
contact.
Repairs may present an excellent opportunity to
upgrade the house. Additional connectors for main-
taining a load path, additional moisture barriers,
and installation of wind -resistant components are
some possible options. The section on "Retrofit and
Remodeling Opportunities" will outline some options
to consider when undergoing repairs.
"PAW
Figure 2. Vertical addition to a home damaged by
Hurricane Fran. Preexisting 1-story home became the
second story of a home elevated to meet new founda-
tion and floor elevation requirements.
Retrofit and Remodeling Opportunities
Retrofit opportunities will present themselves every
time repair or maintenance work is undertaken for
a major element of the building. Improvements to
the building that are made to increase resistance to
the effects of natural hazards should focus on those
items that will potentially return the largest benefit to
the building owner. For example:
When the roof covering is replaced, the attach-
ment of the sheathing to the trusses or rafters
can be checked, and additional load path connec-
tors can be installed as necessary. The Technical
Fact Sheets located in Category 7 of this publi-
cation provide details on how to improve the roof
system's ability to resist wind and water intru-
sion. The common elements of a roof system
should be carefully evaluated in order to address
opportunities to improve the load path and wa-
ter resistance of the system. The most common
repair necessary following a storm event is the
roof covering. When reroofing, tear -off is recom-
mended instead of re-covering. Although some
12/10
jurisdictions allow for reroofing, this method may
prevent the identification of more serious inade-
quacies in the system and result in more cata-
strophic failures in the next event. A roof cover-
ing project should be viewed as an opportunity
to evaluate the strength of the roof sheathing.
With the removal of the roof covering, a careful
inspection of the sheathing should be conduct-
ed to look for darkened areas or areas subject-
ed to water damage. If detected, these areas
should be replaced. The thickness of the roof
sheathing should be inspected to verify that it
is of a sufficient thickness to resist the design
wind speeds for your area. Also, consult the in-
formation in Fact Sheet 7.1, Roof Sheathing
Installation, in order to improve roof system con-
nections. Replacement of roof coverings also
may provide opportunities to evaluate the ade-
quacy of rafter or truss to wall system connec-
tions and install hurricane/seismic connectors.
Information on these connections can be found
in Fact Sheet 4.1, Load Paths and Fact Sheet
4.3, Use of Connectors and Brackets.
If siding or roof sheathing has to be replaced,
hurricane/seismic connectors can be installed
at the rafter -to -wall or truss -to -wall connections,
the exterior wall sheathing attachment can be
checked, and structural sheathing can be added
to shearwalls. Adding wall -to -foundation ties may
also be possible. Verify that all exterior sheath-
ing (wall and roof) is approved for use on exteri-
or surfaces. Verify that fasteners are indeed con-
necting the exterior sheathing to the framing.
See Fact Sheet 4.1, Load Paths and Fact Sheet
4.3, Use of Connectors and Brackets for addition-
al information.
Gable ends can be braced in conjunction with
other retrofits or by themselves. The illustration
in Figure 3 shows a typical gable end wall brac-
ing system. These improvements are typically in-
expensive, allow the loads imposed on the gable
end walls to be distributed through multiple roof
trusses or rafters, and assist in distributing the
wind loads on the gable ends. Additional guid-
ance for gable ends can be found in the Gable
End Retrofit Guide - Florida Division of Emergency
Management.
Exterior siding attachment can be improved with
more fasteners at the time the exterior is re -
coated. See Fact Sheet 5.3, Siding Installation in
High -Wind Regions for additional information.
Window, door, and skylight reinforcement and at-
tachment can be improved whenever they are ac-
cessible. Following a high -wind event, windows
and doors should be checked for leaks. The fram-
ing should be checked for cracked paint or dis-
colored paint. If the doors and windows are not
shutting correctly, then this may indicate that the
framing around the window or door suffered wa-
ter damage. Check for worn areas where paint or
caulking is missing and investigate for water dam-
age or intrusion. Repair any water -damaged areas
immediately. Framing should be inspected to veri-
fy that it is sufficiently attached to the wall system
to provide sufficient protection. Improperly framed
windows and doors have been found forced from
their framing. See Fact Sheet 6.1, Window and
Door Installation for additional information.
When windows and doors are replaced, glaz-
ing and framing can be used that is impact -re-
sistant and provides greater UV protection.
The windows and doors must
meet wind -resistance stan-
dards and be installed in accor-
dance with the manufacturer's
installation instructions for high
wind. Fasteners should be long
enough to attach the window or
door to wall framing around the
opening. Fasteners should be
spaced no greater than 16 inch-
es unless otherwise stated by
the manufacturer's recommend-
ed installation instructions. See
Fact Sheet 6.2, Protection of
Openings -Shutters and Glazing,
for additional information on
protecting openings. Verify that
doors meet ASTM E330 and
DASMA 108 and that windows
meet ASTM E1886 and E1996
or Miami -Dade TAS 201, 202
and 203.
Soffits should be inspected following high -wind
events to determine whether structural upgrades
are necessary. Soffit failures are common dur-
ing storms and damage is often experienced in
attics due to water being blown in through open
soffits. Proper attachment is the most common
problem noted with soffit failures. Wood back-
ing or supports should be installed in order to
provide a structural member to attach the sof-
fit panels to. If it is not possible to install wood
supports, the soffit should be secured at 12-
inch intervals on each side in order to limit its
ability to flex during high -wind events. See Fact
Sheet 7.5, Minimizing Water Intrusion through
Roof Vents in High -Wind Regions for additional
information.
Hurricane shutters can be added at any time
(see Fact Sheet 6.2, Protection of Openings -
Shutters and Glazing). Shutter systems should
be purchased and installed well before a storm
event. It is important to take the time neces-
sary to verify that hangers and attachment sys-
tems are properly anchored to the structural sys-
tem of the building. Shutter systems should be
anchored to the building and maintain the load
path of the building.
Floor -framing -to -beam connections can be im-
proved whenever they are accessible. See Fact
Sheet 4.1, Load Paths and Fact Sheet 4.3,
Use of Connectors and Brackets for additional
information.
Beam -to -pile connections can be improved
whenever they are accessible. See Fact Sheet
3.3, Wood Pile -to -Beam Connections for addition-
al information.
At any time, deficient metal connectors should
be replaced with stainless steel connectors or
metal connectors with proper corrosion protec-
tion such as hot -dip galvanized steel. See Fact
Sheet 1.7, Coastal Building Materials for addi-
tional information.
When HVAC equipment is replaced, the replace-
ment equipment should be more durable so that
it will last longer in a coastal environment. It
should also be elevated at, or above, the Base
Flood Elevation (BFE) and adequately anchored
to resist wind and seismic loads. See Fact Sheet
8.3, Protecting Utilities for additional information.
Utility attachment can be improved when the
outside equipment is replaced or relocated. See
Fact Sheet 8.3, Protecting Utilities for additional
information.
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
addition, the uplift resistance of the roof sheath-
ing can be increased through the application of
APA AFG-01 or ASTM 3498 (see additional re-
sources for more information) rated structural
adhesive at the joints between the roof sheath-
ing and roof rafters or trusses. The adhesive
should be applied in a continuous bead and ex-
tended to the edges of the roof (where some of
the highest uplift pressures occur). At the last
rafter or truss at gable ends, where only one side
of the joint is accessible, wood strips made of
quarter -round molding may be embedded in the
adhesive to increase the strength of the joint.
For more information about the use of adhesive,
see the "Additional Resources" section.
The addition of air admittance valves (AAV) on
all plumbing fixtures can reduce the need for roof
penetrations required for conventional venting
systems. The reduction in roof penetrations will
reduce roof maintenance and reduce the number
of openings available for water penetration. AAVs
are not allowed in all jurisdictions, so verify with a
licensed plumber that they are allowed in the ju-
risdiction where the house is being constructed.
At any time, garage doors should be reinforced
or replaced with new wind- and debris -resis-
tant doors. There are some reinforcement kits
available to provide both vertical and horizon-
tal reinforcement of the garage door. If the ga-
rage door requires replacement, then select one
that meets the design wind -speed requirements
for your area. See Fact Sheet 6.2, Protection of
Openings- Shutters and Glazing, for addition-
al guidance on protecting openings and garage
door guidance.
To minimize the effects of corrosion, metal light
fixtures can be replaced at anytime with fixtures
that have either wood or vinyl exteriors. However,
wood may require frequent treatment or painting.
See Fact Sheet 1.7, Coastal Building Materials
for additional information.
To minimize the effects of corrosion, carbon steel
handrails can be replaced at any time with vinyl -
coated, plastic, stainless steel, or wood hand-
rails. Wood handrails may require frequent treat-
ment or painting and appropriate fasteners must
be used (see Fact Sheet 1.7, Coastal Building
Materials for additional information). Carbon
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.
12/10
Additional Resources
APA — The Engineered Wood Association, 2001, APA Specification AFG-01.
ASTM, Standard Specification forAdhesives 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%20 FL%20 Handbook. pdf)
Florida Division of Emergency Management, Gable End Retrofit Guide. (http://www.floridadisaster.org/hrg)
N AHB
€€ RESEARCH !
Developed in association with the National Association of Home Builders Research Center E T E R
IE..WO..; ..L.I, G, A...,I. S, }:, E R F ' G - lw1I El
1101VE BUILD C S GUIDE TO COASTAL CO St RUCTION
12/10
References and Resources
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
Vinyl Siding Green (http://vinylsiding.org/greenpa-
per/090710_Latest_Revised_Green_paper. pdf)
American Concrete Institute. ACI Detailing Manual.
SP-66(04). 2004. (http://www.concrete.org)
American Concrete Institute. Building Code Require-
ments for Structural Concrete and Commentary. ACI
318-02. (http://www.concrete.org)
American Concrete Institute. Design, Manufacture,
and Installation of Concrete Piles. ACI 543R-00. Re-
approved 2005. (http://www.concrete.org)
American Forest and Paper Association. National
Design Specification for Wood Construction. (http://
www.afandpa.org)
American Institute of Timber Construction. (http://
www.aitc-glulam.org)
American Institutes for Research. Evaluation of the
National Flood Insurance Program's Building Stan-
dards. 2006. (http://www.fema.gov/library)
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 National Standards Institute. National De-
sign Standard for Metal Plate Connected Wood Truss
Construction. ANSI/TPI-1 95.
American Society of Civil Engineers. Minimum Design
Loads for Buildings and Other Structures. ASCE/SEI
7-05. (http://www.asce.org)
American Society of Civil Engineers. Minimum Design
Loads for Buildings and Other Structures. ASCE/SEI
7-10. (http://www.asce.org)
American Society of Civil Engineers. Flood Resistant
Design and Construction. ASCE/SEI 24-05. (http://
www.asce.org)
American Society for Testing and Materials. Stan-
dard Practice forApplication of Self -Adhering Modified
FEMA
._ .a
Bituminous Waterproofing. ASTM D6135-05. 2005.
(http://www.sstm.org)
American Society for Testing and Materials. Standard
Practice for Installation of Exterior Windows, Doors and
Skylights. ASTM E2112-07. (http://www.sstm.org)
American Society for Testing and Materials. Standard
Specification for Round Timber Piles. ASTM D25-99.
2005. (http://www.sstm.org)
American Society for Testing and Materials. Standard
Specification forAdhesives for Field -Gluing Plywood to
Lumber Framing for Floor Systems. ASTM D3498-03.
2003. (http://www.sstm.org)
American Society for Testing and Materials. Standard
Specification for Performance of Exterior Windows,
Curtain Walls, Doors, and Impact Protective Systems
Impacted by Windborne Debris in Hurricanes. ASTM
E1996-09. (http://www.sstm.org)
American Society for Testing and Materials. Stan-
dard Test Method for Performance of Exterior Windows,
Curtain Walls, Doors, and Impact Protective Systems
Impacted by Missile(s) and Exposed to Cyclic Pressure
Differentials. ASTM E1886-05. (http://www.sstm.org)
American Society for Testing and Materials. Standard
Test Method for Structural Performance of Exterior
Windows, Doors, Skylights and Curtain Walls by Uni-
form Static Air Pressure Difference. ASTM E330-02.
2010. (http://www.sstm.org)
American Forest Foundation, Inc. American Tree Farm
System. (http://www.treefarmsystem.org/index.shtml)
American Wood Council. (http://www.awc.org)
American Wood Protection Association. All Timber
Products - Preservative Treatment by Pressure Pro-
cesses, AWPA C1-00; Lumber, Timber, Bridge Ties
and Mine Ties - Preservative Treatment by Pressure
Processes, AWPA C2-01; Piles - Preservative Treat-
ment by Pressure Process, AWPA C3-99; and others.
(http://www.awpa.com)
APA, The Engineered Wood Association. APA Specifi-
cation AFG-01. 2001. (http://www.apawood.org)
il0tVIE BUILDERS G"WEDETO COASTAL CONSTRUCTION
12/10
APA, The Engineered Wood Association. Hurricane
Shutter Designs Set 5 of 5. Hurricane Shutter Designs
for Woodframe and Masonry Buildings. (http://www.
apawood.org)
Brick Industry Association. (http://www.gobrick.com)
Clemson University, Department of Civil Engineering
and South Carolina Sea Grant Extension Program.
Not Ready to Re -Roof? Use Structural Adhesives to
Strengthen the Attachment of Roof Sheathing and
Holding onto Your Roof - A Guide to Retrofitting Your
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# :+
12/10
I10fiE BUILDEWS GUIDETO COASTAL ONSTRU TIT
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12/10
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t NAHB
'.„ RESEARCH
Developed in association with the National Association of Home Builders Research Center C E T E R
4 of :. HOVE BUILDEWS GUIDE TO COASTCONSTRUCTION
12/10
BOCC AGENDA ROUTING SLIP
BUILDING DEPARTMENT
Agenda Item Subject: Resolution adopting FEMA P-758, "Substantial Improvement
/Substantial Damage Desk Reference"
Date: August 17, 2015
Prepared By: Ed Koconis, AICP, Permit Manager
Agenda Deadline: August 20, 2015 BOCC meeting date: September 16, 2015
#
Reviewer
***Internal Deadline to Teresa:***
Notes
Initials
Date
Permit Manager
g 1' 84
174 page
document.
Senior Director of Building
County Attorney
Deadline:
Deadline:
Assistant County Administrator
Deadline:
FINAL review by legal
:::::r
_XBulk Approval
Time Approximate Requested
Type of Proceeding:
Ad (Ad neap, if applicable) Deadline
Surrounding Property Owner Notice: Deadline
Public Hearing
Yes
_Legislative
NIA
Discussion
Time
Quasi -Judicial
Publish Date
***Reminder***
Once your item is complete and includes all corrections,
email all final word documents to Teresa Smith.