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Resolution 235-2015 3 of 3 COASTAL CONSTRUCTION MANUAL • ..—.. _ 0..._ ,,, � \ $ id r 401151 Al I � ip • -. - •"_ S r FE - '' 7Tr.- fi Designing tthe Buildin Envelope 4 _ This chapter provides guidance on the design of the building envelope in the coastal environment.' The building envelope CROSS REFERENCE comprises exterior doors, windows, skylights, exterior wall coverings, soffits, roof systems, and attic vents. In buildings For resources that augment the guidance and other information in elevated on open foundations, the floor is also considered a part this Manual, see the Residential of the envelope. Coastal Construction Web site (http://www.fema.gov/rebuild/ High wind is the predominant natural hazard in the coastal mat/fema55.shtm). environment that can cause damage to the building envelope. Other natural hazards also exist in some localities. These may include wind-driven rain, salt-laden air, seismic events, hail, and wildfire. The vulnerabilities of the building envelope to these hazards are discussed in this chapter, and recommendations on mitigating them are provided. Good structural system performance is critical to avoiding injury and minimizing damage to a building and its contents during natural hazard events but does not ensure occupant or building protection. Good 1 The guidance in this chapter is based on a literature review and field investigations of a large number of houses that were struck by hurricanes,tornadoes,or straight-line winds.Some of the houses were exposed to extremely high wind speeds while others experienced moderately high wind speeds.Notable investigations include Hurricane Hugo(South Carolina, 1989)(McDonald and Smith, 1990);Hurricane Andrew(Florida, 1992)(FEMA FIA 22;Smith, 1994);Hurricane Iniki(Hawaii,1992)(FEMA FIA 23); Hurricane Marilyn(U.S.Virgin Islands,1995)(FEMA unpublished);Typhoon Paka(Guam, 1997)(FEMA-1193-DR-GU);Hurricane Georges(Puerto Rico, 1998)(FEMA 339);Hurricane Charley(Florida,2004)(FEMA 488);Hurricane Ivan(Alabama and Florida,2004) (FEMA 489);Hurricane Katrina(Louisiana and Mississippi,2005)(FEMA 549);and Hurricane Ike(Texas,2008)(FEMA P-757). COASTAL CONSTRUCTION MANUAL 11-1 11 DESIGNING THE BUILDING ENVELOPE Volume II performance of the building envelope is also necesary. Good building envelope performance is critical for buildings exposed to high winds and wildfire. Good performance depends on good design, materials, installation, maintenance, and repair. A significant shortcoming in any of these five elements could jeopardize the performance of the building. Good design, however, is the key element to achieving good performance. Good design can compensate to some extent for inadequacies in the other elements, but the other elements frequently cannot compensate for inadequacies in design. The predominant cause of damage to buildings and their contents during high-wind events has been shown to be breaching of the building envelope, as shown in Figure 11-1, and subsequent water infiltration. Breaching includes catastrophic failure (e.g., loss of the roof covering or windows) and is often followed by wind-driven water infiltration through small openings at doors, windows, and walls. The loss of roof and wall coverings and soffits on the house in Figure 11-1 resulted in significant interior water damage. Recommendations for avoiding breaching are provided in this chapter. For buildings that are in a Special Wind Region (see Figure 3-7) or in an area where the basic (design) wind speed is greater than 115 mph,2 it is particularly important to consider the building envelope design and construction recommendations in this chapter it order to avoid wind and wind-driven water damage. In wind-borne debris regions (as defined in ASCE 7), building envelope elements from damaged buildings are often the predominant source of wind-borne debris. The wall shown in Figure 11-2 has numerous wind- borne debris scars.Asphalt shingles from nearby residences were the primary source of debris. Following the design and construction recommendations in this chapter will minimize the generation of wind-borne debris from residences. Figure 11-1. Good structural system —'`� performance but the loss of shingles, underlayment,siding, housewrap, and soffits - f `1. Y resulted in significant � interior water damage. 'I r L'' Estimated wind speed: 125 mph.3 Hurricane II I G • Katrina(Louisiana, 2005) r ! �,; r I L Y .• Lia IL.Lif•r r! • 0'1 k• /1•• • 2 The 115-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings.If ASCE 7-05,or an earlier version is used,the equivalent wind speed trigger is 90 mph. 3 The estimated wind speeds given in this chapter are for a 3'second gust at a 33-foot elevation for Exposure C(as defined in ASCE 7).Most of the buildings for which estimated speeds are given in this chapter are located in Exposure B,and some are in Exposure D.For buildings in Exposure B,the actual wind speed is less than the wind speed for Exposure C conditions.For example, a 130-mph Exposure C speed is equivalent to 110 mph in Exposure B. 11-2 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Building integrity in earthquakes is partly dependent on the performance of the building envelope.Residential building envelopes have historically performed well during seismic events because most envelope elements are relatively lightweight. Exceptions have been inadequately attached heavy elements such as roof tile. This chapter provides recommendations for envelope elements that are susceptible to damage in earthquakes. A building's susceptibility to wildfire depends largely on the presence of nearby vegetation and the characteristics of the building envelope, as illustrated in Figure 11-3. See FEMA P-737,Home Builder's Guide to Construction in Wildfire Zones (FEMA 2008), for guidance on materials and construction techniques to reduce risks associated with wildfire. Figure 11-2. Numerous wind-borne debris scars on the wall of this house and several missing asphalt shingles. Estimated -- wind speed: 140 to 150 mph, Hurricane Charley ti (Florida, 2004) E I II `` v Figure 11-3. House that survived a wildfire due in part to I fire-resistant walls and roof while surrounding houses were destroyed • s _alp ," SOURCE:DECRA ROOFING SYSTEMS,USED WITH AYto. PERMISSION Ilk: . ". 4, _ ' - V . , - , • t. ., Nth ,IA."' COASTAL CONSTRUCTION MANUAL 11-3 11 DESIGNING THE BUILDING ENVELOPE Volume II This chapter does not address basic design issues or the general good practices that are applicable to residential design. Rather, the chapter builds on the basics by addressing the special design and construction considerations of the building envelope for buildings that are susceptible to natural hazards in the coastal environment. Flooding effects on the building envelope are not addressed because of the assumption that the envelope will not be inundated by floodwater, but envelope resistance to wind-driven rain is addressed. The recommended measures for protection against wind-driven rain should also be adequate to protect against wave spray. 11.1 Floors in Elevated Buildings Sheathing is commonly applied to the underside of the bottom floor framing of a building that is elevated on an open foundation. The sheathing provides the following protection: (1) it protects insulation between joists or trusses from wave spray, (2) it helps minimize corrosion of framing connectors and fasteners, and (3) it protects the floor framing from being knocked out of alignment by flood-borne debris passing under the building. A variety of sheathing materials have been used to sheath the framing,including cement-fiber panels,gypsum board, metal panels, plywood, and vinyl siding. Damage investigations have revealed that plywood offers the most reliable performance in high winds. However, as shown in Figure 11-4, even though plywood has been used, a sufficient number of fasteners are needed to avoid blow-off. Since ASCE 7 does not provide guidance for load determination, professional judgment in specifying the attachment schedule is needed.As a conservative approach, loads can be calculated by using the C&C coefficients for a roof with the slope of 7 degrees or less. However, the roof corner load is likely overly conservative for the underside of elevated floors. Applying the perimeter load to the corner area is likely sufficiently conservative. To achieve good long-term performance, exterior grade plywood attached with stainless steel or hot-dip galvanized nails or screws is recommended (see the corroded nails in Figure 11-4). 11.2 Exterior Doors This section addresses exterior personnel doors and garage doors. The most common problems are entrance of wind- CROSS REFERENCE driven rain and breakage of glass vision panels and sliding glass = _ _== doors by wind-borne debris. Blow-off of personnel doors is For information regarding garage uncommon but as shown in Figure 11-5,it can occur.Personnel doors in breakaway walls, see Fact Sheet 8.1, Enclosures and door blow-off is typically caused by inadequate attachment of Breakaway Walls, in FEMA P-499, the door frame to the wall. Garage door failure'via negative Home Builder's Guide to Coastal (suction) or positive pressure was common before doors with Construction Technical Fact high-wind resistance became available (see Figure 11-6). Sheet Series (FEMA 2010b). Garage door failure is typically caused by the use of door and - - --- -, - - - track assemblies that have insufficient wind resistance or by inadequate attachment of the tracks to nailers or to the wall.Failures such as those shown in Figures 11-5 and 11-6 can result in a substantial increase in internal pressure and can allow entrance of a significant amount of wind-driven rain. 11-4 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Figure 11-4. Plywood panels on the underside of a house that - 4, , blew away because of excessive nail spacing. Note the corroded nails '' (inset). Estimated wind or speed: 105 to 115 mph. -- Hurricane Ivan (Alabama, 1 I r • 01 r r441 '� , itrat. - X Figure 11-5. Sliding glass doors pulled out of their tracks by wind suction. Estimated wind speed: 140 to 160 mph. Hurricane Charley (Florida, 2004) lisiaLt.,lid" —3 ..,.i II t111111 6,-,..., , , --—-......... ....il I I v.,.. ei 0 E___...„,...,..-,,„_. • 7 .10 • , 1 li . --.moNINIIIIIrirlit. Agilligrrt. ,. 1'! ' ' ' COASTAL CONSTRUCTION MANUAL 11 c) • 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-6. Garage door blown from it - its track as a result 4 i .. of positive pressure. ry __ Note the damage to -- — — — - the adhesive-set tiles , � ' J+ `�---� , (left arrow; see Section i - . .: " ' I I 11.5.4.1).This house (; --'' ,. - ,s, •,i , ,1 S was equipped with u /� Y <-, I' ' roll-up shutters(right I , , -, , r e L arrow; see Section ' _-.,u , ;{'',,'�- t- ,.: - - 'may 11.3.1.2). Estimated 3 ,, 'wind speed: 140 to 160 mph. Hurricane Charley •, . . , f, . . I (Florida, 2004) -- --__._ • 4 --�_-____.—_— , 11.2.1 High Winds =_ Exterior door assemblies(i.e.,door,hardware,frame,and frame = ="----j attachment to the wall) should be designed to resist high winds CROSS REFERENCE and wind-driven rain. For design guidance on the attachment of door frames, see 11.2.1.1 Loads and Resistance AAMA TIR-A-14. The IBC and IRC require door assemblies to have sufficient For a methodology to confirm an anchorage system provides load strength to resist the positive and negative design wind resistance with an appropriate • pressure. Personnel doors are normally specified to comply safety factor to meet project with AAMA/WDMA/CSA 101/I.S.2/A440, which references requirements, see AAMA 2501. ASTM E330 for wind load testing. However, where the basic Both documents are available wind speed is greater than 150 mph,4 it is recommended that for purchase from the American design professionals specify that personnel doors comply with Architectural Manufacturers , wind load testing in accordance with ASTM E1233. ASTM Association (http://aamanet.org). E1233 is the recommended test method in high-wind areas because it is a cyclic test method, whereas ASTM E330 is a `= - static test. The cyclical test method is more representative of loading conditions in high-wind areas than ASTM E330. CROSS REFERENCE Design professionals should also specify the attachment of the For design guidance on the door frame to the wall (e.g., type, size, spacing, edge distance attachment of garage door of frame fasteners). frames, see Technical Data Sheet#161, Connecting Garage It is recommended that design professionals specify that garage Door Jambs to Building Framing doors comply with wind load testing in accordance with ANSI/ (DASMA 2010).Available at DASMA 108. For garage doors attached to wood nailers, , http://www.dasma.com/ design professionals should also specify the attachment of the PubTechData.asp. nailer to the wall. -- - _ - -- - 4 The 150-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings. If ASCE 7-05 or an earlier version is used,the equivalent wind speed trigger is 120 mph. 11-6 COASTAL CONSTRUCTION MANUAL • Volume II DESIGNING THE BUILDING ENVELOPE 11 11.2.1.2 Wind-Borne Debris If a solid door is hit with wind-borne debris, the debris may penetrate the door, but in most cases, the debris opening will not be large enough to result'in significant water infiltration or in a substantial increase in internal pressure. Therefore, in wind-borne debris regions, except for glazed vision panels and glass doors, ASCE 7, IBC, and IRC do not require doors to resist wind-borne debris. However, the 2007 FBC requires all exterior doors in the High-Velocity Hurricane Zone (as defined in the FBC) to be tested for wind-borne debris resistance. _ It is possible for wind-borne debris to cause door latch or hinge j failure, resulting in the door being pushed open, an increase in -- CROSS REFERENCE internal pressure, and potentially the entrance of a significant For more information about amount of wind-driven rain.As a conservative measure in wind- wind-borne debris and glazing in borne debris regions, solid personnel door assemblies could be doors, see Section 11.3.1.2. specified that resist the test missile load specified in ASTM - . _ _ E1996. Test Missile C is applicable where the basic wind speed is less than 164 mph. Test Missile D is applicable where the basic wind speed is 164 mph or greater.5 See Section 11.3.1.2 regarding wind-borne debris testing. If wind-borne debris-resistant garage doors are desired, the designer should specify testing in accordance with ANSI/DASMA 115. 11.2.1.3 Durability For door assemblies to achieve good wind performance, it is necessary to avoid strength degradation caused by corrosion and termites. To avoid corrosion problems with metal doors or frames, anodized aluminum or galvanized doors'and frames and stainless steel frame anchors and hardware are recommended for buildings within 3,000 feet of an ocean shoreline (including sounds and back bays). Galvanized steel doors and frames should be painted for additional protection. Fiberglass doors may also be used with wood frames. In areas with severe termite problems, metal door assemblies are recommended. If concrete, masonry, or metal wall construction is used to eliminate termite problems, it is recommended that wood not be specified for blocking or nailers. If wood is specified, see "Material Durability in Coastal Environments," a resource document available on the Residential Coastal Construction Web site, for information on wood treatment methods. 11.2.1.4 Water Infiltration Heavy rain that accompanies high winds cari cause significant wind-driven water infiltration.The magnitude of the problem increases with the wind speed. Leakage can occur between the door and its frame, the frame and the wall, and the threshold and the door.When wind speeds approach 150 mph, some leakage should be anticipated because of the high-wind pressures and numerous opportunities for leakage path development. 5 The 164-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings.If ASCE 7-05 or an earlier version is used,the equivalent wind speed trigger is 130 mph. 6 The 150-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings.If ASCE 7-05 or an earlier version is used,the equivalent wind speed trigger is 120 mph. COASTAL CONSTRUCTION MANUAL 1 1-7 11 DESIGNING THE BUILDING ENVELOPE Volume II The following elements can minimize infiltration around exterior doors: Vestibule. Adding a vestibule allows both the inner and outer doors to be equipped with weatherstripping. The vestibule can be designed with water-resistant finishes (e.g., tile), and the floor can be equipped with a drain. In addition, installing exterior threshold trench drains can be helpful (openings must be small enough to avoid trapping high-heeled shoes). Trench drains do not eliminate the problem because water can penetrate at door edges. Door swing. Out-swinging doors have weatherstripping on the interior side where it is less susceptible to degradation, which is an advantage to in-swinging doors. Some interlocking weatherstripping assemblies are available for out-swinging doors. Pan flashing. Adding flashing under the door threshold helps prevent penetration of water into the subflooring, a common place for water entry and subsequent wood decay. More information is available in Fact Sheet 6.1, Window and Door Installation, in FEMA P-499, Home Builder's Guide to Coastal Construction Technical Fact Sheet Series (FEMA 2010b). Door/wall integration. Successfully integrating the door frame and wall is a special challenge when designing and installing doors to resist wind-driven rain. More information is available in Fact Sheet 6.1 in FEMA P-499. Weatherstripping. A variety of pre-manufactured weatherstripping elements are available, including drips, door shoes and bottoms, thresholds, and jamb/head weatherstripping. More information is available in Fact Sheet 6.1 in FEMA P-499. Figure 11-7 shows a pair of doors that successfully resisted winds that were estimated at between 140 and 160 mph. However, as shown in the inset, a gap of about 3/8 inch between the threshold and the bottom of the door allowed a significant amount of water to be blown into the house. The weatherstripping and thresholds shown in Fact Sheet 6.1 in FEMA P-499 can minimize water entry. 4 if • ► is 1 • Figure 11-7. A 3/8-inch gap between the threshold and door(illustrated by the spatula handle), which allowed wind-driven rain to enter the house. Estimated wind speed: 140 to 160 mph. Hurricane Charley(Florida, 2004) 11-8 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 11.3 Windows and Sklylights This section addresses exterior windows (including door vision panels) and skylights. The most common problems in the coastal environment are entrance of wind-driven rain and glazing breakage by wind-borne debris. It is uncommon for windows to be blown-in or blown-out, but it does occur (see Figure 11-8). The type of damage shown in Figure 11-8 is typically caused by inadequate attachment of the window frame to the wall, but occasionally the glazing itself is blown out of the frame. Breakage of glazing from over- pressurization sometimes occurs with windows that were manufactured before windows with high-wind resistance became available. Strong seismic events can also damage windows although it is uncommon in residential construction. Hail can cause significant damage to skylights and occasionally cause window breakage. 11.3.1 High Winds Window and skylight assemblies (i.e., glazing, hardware for operable units, frame, and frame attachment to the wall or roof curb) should be designed to resist high winds and wind-driven rain. In wind-borne debris regions, the assemblies should also be designed to resist wind-borne debris or be equipped with shutters, as discussed below. 11.3.1.1 Loads and Resistance The IBC and IRC require that window and skylight assemblies have sufficient strength to resist the positive and negative design wind pressures. Windows and skylights are normally specified to comply with AAMA/ WDMA/CSA 101/I.S.2/A44O, which references ASTM E33O for wind load testing. However, where the basic wind speed is greater than 150 mph,7 it is recommended that design professionals specify that Figure 11-8. Window frame pulled out of the wall because of inadequate window frame attachment. Hurricane Georges(Puerto Rico, 1998) f ap a may. . • B,� — `') rfre 5 t. ,„, 7 The 150-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings.If ASCE 7-05 or an earlier version is used,the equivalent wind speed trigger is 120 mph. COASTAL CONSTRUCTION MANUAL 11-9 11 DESIGNING THE BUILDING ENVELOPE Volume II windows and skylights comply with wind load testing in accordance with ASTM E1233. ASTM E1233 is the recommended test method in high-wind areas because it is a cyclic test method, whereas ASTM E330 is a static test. The cyclical test method is more representative of loading conditions in high-wind areas than ASTM E330. Design professionals should also specify the attachment of the window and skylight frames to the wall and roof curb (e.g., type, size, spacing, edge distance of frame fasteners). Curb attachment to the roof deck should also be specified. For design guidance on the attachment of frames, see AAMA TIR-A14 and AAMA 2501. 11.3.1.2 Wind-Borne Debris When wind-borne debris penetrates most materials, only a small opening results, but when debris penetrates most glazing materials, a very large opening can result. Exterior glazing that is not impact-resistant (such as annealed, heat-strengthened, or tempered glass) or not protected by shutters is extremely susceptible to breaking if struck by debris. Even small,low-momentum debris can easily break glazing that is not protected. Broken windows can allow a substantial amount of water to be blown into a building and the internal air pressure to increase greatly, both of which can damage interior partitions and ceilings. In windstorms other than hurricanes and tornadoes, the probability of a window or skylight being struck by debris is extremely low,but in hurricane-prone regions,the probability is higher.Although the debris issue was recognized decades ago,as illustrated by Figure 11-9,wind-borne debris protection was not incorporated into U.S. codes and standards until the 1990s. In order to minimize interior damage, the IBC and IRC, through ASCE 7, prescribe that exterior glazing in wind-borne debris regions be impact-resistant (i.e., laminated glass or polycarbonate) or protected with an impact-resistant covering (shutters). ASCE 7 refers to ASTM E1996 for missile (debris) loads and to ASTM E1886 for the test method to be used to demonstrate compliance with the ASTM E1996 load criteria. Regardless of whether the glazing is laminated glass, polycarbonate, or protected by shutters, glazing is required to meet the positive and negative design air pressures. Figure 11-9. Very old building with robust shutters constructed of 2x4 lumber, bolted connections, and heavy " 11,1 metal hinges. Hurricane . Marilyn (U.S.Virgin „r Islands, 1995) y'J • -4 ,„ _f, - I ar _„, 11-10 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Wind-borne debris also occurs in the portions of hurricane-prone regions that are inland of wind-borne debris regions, but the quantity and momentum of debris are typically lower outside the wind-borne debris region.As a conservative measure, impact-resistant glazing or shutters could be specified inland of the wind- borne debris region. If the building is located where the basic wind is 125 mph8 or greater and is within a few hundred feet of a building with an aggregate surface roof or other buildings that have limited wind resistance, it is prudent to consider impact-resistant glazing or shutters. With the advent of building codes requiring glazing protection in wind-borne debris regions, a variety of shutter designs have entered the market. Shutters typically have a lower initial cost than laminated glass. However, unless the shutter is permanently anchored to the building(e.g., accordion shutter, roll-up shutter), storage space is needed.Also,when a hurricane is forecast, the shutters need to be deployed.The difficulty of shutter deployment and demobilization on upper-level glazing can be avoided by using motorized shutters, although laminated glass may be a more economical solution. Because hurricane winds can approach from any direction,when debris protection is specified,it is important to specify that all exterior glazing be protected, including glazing that faces open water. At the house shown in Figure 11-10, all of the windows were protected with roll-up shutters except for those in the cupola. One of the cupola windows was broken.Although the window opening was relatively small, a substantial amount of interior water damage likely occurred. { Figure 11-10. Unprotected cupola window that was broken. Estimated wind speed: 110 mph. Hurricane Ike (Texas, 2008) 1il1lliiiil!!i liIIIIIiI: #.., V rt 17 pi p! "Mr ; , mown — e-No!, _ --- The FBC requires exterior windows and sliding glass doors to have a permanent label or marking, indicating information such as the positive and negative design pressure rating and impact-resistant rating(if applicable). Impact-resistant shutters are also required to be labeled. Figure 11-11 is an example of a permanent label on a window assembly. This label provides the positive and negative design pressure rating, test missile rating, 8 The 125-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings.If ASCE 7-05 or an earlier version is used,the equivalent wind speed trigger is 100 mph. COASTAL CONSTRUCTION MANUAL 11-11 11 DESIGNING THE BUILDING ENVELOPE Volume II and test standards that were used to evaluate the pressure and impact resistance.Without a label,ascertaining whether a window or shutter has sufficient strength to meet pressure and wind-borne debris loads is difficult (see Figure 11-12). It is therefore recommended that design professionals specify that windows and shutters have permanently mounted labels that contain the type of information shown in Figure 11-11. Figure 11-11. Design pressure and impact-resistance information in a permanent window label. Testa �<<�•��e w,« HURRICANE RESISTAN' NG AAMA 506-2000 Hurricane Ike (Texas, V PROGRA 4". AA'r'£' Sti E e 2008) AHs 4 ti. • tlO2 4e 44,0, CoQe. MWD•1 CONFORMS TO ASTM F 588 LOVLIIITIS+u ASTM E+BSE nm E+av Figure 11-12. / 4 . f,4.T Roll-up shutter slats L„ that detached from the '° . tracks. The lack of a label makes it unclear whether the shutter was • e' 34 tested in accordance with a recognized method. Estimated wind speed: • 110 mph. Hurricane Katrina(Louisiana, 2005) t tirk aL Glazing Protection from Tile Debris Residential glazing in wind-borne debris regions is required to resist the test missile C or D, depending on the basic wind speed. However, field investigations have shown that roof tile CROSS REFERENCE can penetrate shutters that comply with test missile D (see More information, including a Figure 11-13). Laboratory research conducted at the University discussion of various types of of Florida indicates that test missile D compliant shutters do shutters and recommendations not provide adequate protection against tile debris (Fernandez pertaining to them, is available et al. 2010). Accordingly, if tile roofs occur within 100 to 200 in Fact Sheet 6.2, Protection of Openings—Shutters and Glazing, feet (depending on basic wind speed), it is recommended that in FEMA P-499. shutters complying with test missile E be specified. 11-12 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Figure 11-13. Shutter punctured by I roof tile. Estimated wind speed: 140 to 160 I l mph. Hurricane Charley (Florida, 2004) { , , 'ill% Jalousie Louvers In tropical climates such as Puerto Rico, some houses have metal jalousie louvers in lieu of glazed window openings(see Figure 11-14).Metal jalousies have the appearance of a debris-resistant shutter,but they typically offer little debris resistance. Neither the UBC nor IRC require openings equipped with metal jalousie louvers to be debris resistant because glazing does not occur. However, the louvers are required to meet the design wind pressure. Because the louvers are not tightly sealed, the building should be evaluated to determine whether it is enclosed or partially enclosed (which depends on the distribution and size of the jalousie windows). Jalousie louvers are susceptible to significant water infiltration during high winds. 11.3.1.3 Durability Achieving good wind performance in window assemblies requires avoiding strength degradation caused by corrosion and termites. To avoid corrosion, wood or vinyl frames are recommended for buildings within 3,000 feet of an ocean shoreline(including sounds and back bays).Stainless steel frame anchors and hardware are also recommended in these areas. In areas with severe termite problems,wood frames should either be treated or not used. If concrete,masonry, or metal wall construction is used to eliminate termite problems, it is recommended that wood not be specified for blocking or nailers. If wood is specified, see "Material Durability in Coastal Environments," a resource document available on the Residential Coastal Construction Web site, for information on wood treatment methods. COASTAL CONSTRUCTION MANUAL 11-13 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-14. House in Puerto Rico with metal jalousie louvers 11.3.1.4 Water Infiltration Heavy rain accompanied by high winds can cause wind-driven water infiltration.The magnitude of the problem increases with NOTE wind speed. Leakage can occur at the glazing/frame interface, the frame itself,or between the frame and wall.When the basic Laboratory research at the wind speed is greater than 150 mph,9 because of the very high University of Florida indicates that windows with compression design wind pressures and numerous opportunities for leakage seals(i.e., awning and casement path development, some leakage should be anticipated when windows)are generally more the design wind speed conditions are approached. resistant to wind-driven water infiltration than windows with A design option that partially addresses this problem is to sliding seals(i.e., hung and specify a strip of water-resistant material, such as tile, along horizontal sliding windows) walls that have a large amount of glazing instead of extending (Lopez et al. 2011). the carpeting to the wall. During a storm, towels can be placed along the strip to absorb water infiltration. These actions can _ help protect carpets from water damage. It is recommended that design professionals specify that window CROSS REFERENCE and skylight assemblies comply with AAMA 520. AAMA 520 For guidance on window has 10 performance levels.The level that is commensurate with installation, see: the project location should be specified. • FMA/AAMA 100 The successful integration of windows into exterior walls to ■ FMA/AAMA 200 protect against water infiltration is a challenge. To the extent possible, when detailing the interface between the wall and 9 The 150-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings. If ASCE 7-05 or an earlier version is used,the equivalent wind speed trigger is 120 mph. 11-14 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 the window, design professionals should rely on sealants as the secondary line of defense against water infiltration rather _, CROSS REFERENCE than making the sealant the primary protection. If a sealant Dint is the first line of defense, a second line of defense should For a comparison of wind-driven rain resistance as a function of be designed to intercept and drain water that drives past the window installation in accordance sealant joint. with ASTM E2112 (as referenced in Fact Sheet 6.1 in FEMA P-499), When designing joints between walls and windows, the design FMA/AAMA 100, and FMA/AAMA professional should consider the shape of the sealant joint(i.e., , 200, see Saizano et al. (2010). hour-glass shape with a width-to-depth ratio of at least 2:1) and -_ the type of sealant to be specified. The sealant joint should be designed to enable the sealant to bond on only two opposing surfaces (i.e., a backer rod or bond-breaker tape should be specified). Butyl is recommended as a sealant for concealed joints and polyurethane for exposed joints. During installation, cleanliness of the sealant substrate is important, particularly if polyurethane or silicone sealants are specified, as is the tooling of the sealant. Sealant joints can be protected with a removable stop (as illustrated in Figure 2 of Fact Sheet 6.1 of FEMA P-499). The stop protects the sealant from direct exposure to the weather and reduces the possibility of wind-driven rain penetration. Where water infiltration protection is particularly demanding and important,onsite water infiltration testing in accordance with\AAMA 502 can be specified. AAMA 502 provides pass/fail criteria based on testing in accordance with either of two ASTM water infiltration test methods.ASTM E1105 is the recommended test method. 11.3.2 Seismic Glass breakage due to in-plane wall deflection is unlikely, but special consideration should be given to walls with a high percentage of windows and limited shear capacity. In these cases, it is important to analyze the in-plane wall deflection to verify that it does not exceed the limits prescribed in the building code. 11.3.3 Hail A test method has not been developed for testing skylights for hail resistance, but ASTM E822 for testing hail resistance of solar collectors could be used for assessing the hail resistance of skylights. 11.4 Non-Load-Bearing Walls, Wall Coverings, and Soffits This section addresses exterior non-load-bearing walls, wall coverings, and soffits. The most common problems in the coastal environment are soffit blow-off with subsequent entrance of wind-driven rain into attics and wall covering blow-off with subsequent entrance of wind-driven rain into wall cavities. Seismic events can also damage heavy wall systems including coverings.Although hail can damage walls,significant damage is not common. COASTAL CONSTRUCTION MANUAL 11-15 11 DESIGNING THE BUILDING ENVELOPE Volume II A variety of exterior wall systems can be used in the coastal environment. The following wall coverings are commonly used over wood-frame construction: aluminum siding, brick veneer, fiber cement siding, exterior insulation finish systems (EIFS), stucco, vinyl siding, and wood siding (boards, panels, or shakes). Concrete i. or concrete masonry unit (CMU) wall construction can also be used,with or without a wall covering. 11.4.1 High Winds - NOTE Exterior non-load-bearing walls, wall coverings, _ _ and soffits should be designed to resist high ASCE 7, IBC, and IRC do not require exterior winds and wind-driven rain. The IBC and IRC walls or soffits to resist wind-borne debris. require that exterior non-load-bearing walls, wall However,the FBC requires exterior wall assemblies in the High-Velocity Hurricane coverings, and soffits have sufficient strength Zone(as defined in the FBC)to be tested for to resist the positive and negative design wind wind-borne debris or to be deemed to comply pressures. with the wind-borne debris provisions that are stipulated in the FBC. 11.4.1.1 Exterior Walls It is recommended that the exterior face of studs be fully clad with plywood or oriented strand board (OSB) sheathing so the sheathing can withstand design wind pressures that produce both in-plane and out-of- plane loads because a house that is fully sheathed with plywood or OSB is more resistant to wind-borne , debris and water infiltration if the wall cladding is lost.10 The disadvantage of not fully cladding the studs with plywood or OSB is illustrated by Figure ' , 11-15. At this residence, OSB was installed at the corner areas to provide shear resistance, but foam insulation was used in lieu of OSB in the field of NOTE the wall. In some wall areas, the vinyl siding and' Almost all wall coverings permit the passage foam insulation on the exterior side of the studs' of some water past the exterior surface and the gypsum board on the interior side of the of the covering, particularly when the rain studs were blown off. Also, although required by ' is wind-driven. For this reason, most wall building codes, this wall system did not have a coverings should be considered water- moisture barrier between the siding and OSB/ shedding rather than waterproofing.A secondary line of protection with a moisture foam sheathing. In addition to the wall covering barrier is recommended to avoid moisture- damage, OSB roof sheathing was also blown off. , ' related problems.Asphalt-saturated felt is the traditional moisture barrier, but housewrap Wood siding and panels (e.g., textured plywood) is now the predominate moisture barrier. Housewrap is more resistant to air flow than and stucco over CMU or concrete typically perform well during high winds. However, blow- asphalt-saturated felt and therefore offers improved energy performance. • off of stucco applied directly to concrete walls (i.e., wire mesh is not applied over the concrete) Fact Sheet 1.9,Moisture Barrier Systems, and Fact Sheet 5.1,Housewrap, in FEMA P-499 has occurred during high winds. This problem' address key issues regarding selecting and can be avoided by leaving the concrete exposed I installing moisture barriers as secondary or by painting it. More blow-off problems have; protection in exterior walls. been experienced with vinyl siding than with _ - _ _ _ _ _ _ 10 This recommendation is based on FEMA P-757,Mitigation Assessment Team Report:Hurricane Ike in Texas and Louisiana (FEMA 2009). ,I 1 1-1 6 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 other siding or panel materials (see Figure 11-15). 1411 Problems with aluminum and fiber cement siding NOTE have also occurred (see Figure 11-16). In areas that experience frequent wind-driven rain and in areas that are susceptible to high Siding winds, a pressure-equalized rain screen design should be considered when specifying wood A key to the successful performance of siding or fiber cement siding.A rain screen design and panel systems is attachment with a sufficient is accomplished by installing suitable vertical furring strips between the moisture barrier number of proper fasteners (based on design loads and siding material.The cavity facilitates and tested resistance) that are correctly located. drainage of water from the space between the Fact Sheet 5.3, Siding Installation and Connectors, moisture barrier and backside of the siding and in FEMA P-499 provides guidance on specifying facilitates drying of the siding and moisture and installing vinyl, wood siding, and fiber barrier. For more information, see Fact Sheet 5.3, cement siding in high-wind regions. Siding Installation in High-Wind Regions, in FEMA P-499. -4.,. _ :I - _ 4..MN Figure 11-15. ■ ,�, ' 4 Blown-off vinyl siding . t _ and foam sheathing; fix= a --R some blow-off of interior ` r 'kw• gypsum board (circle). . - `' Estimated wind speed: - � - - - 130 mph. Hurricane Katrina(Mississippi, 2006) I ' r .4 f ir l !. illtos ,. i t ,..E llit �14 1 Brick Veneer Blow-off of brick veneer has occurred often during high winds. Common failure modes include tie (anchor corrosion), tie fastener pull-out, failure of masons to embed ties into the mortar, and poor bonding between ties and mortar, and poor-quality mortar. Four of these failure modes occurred at the house shown in Figure 11-17.The lower bricks were attached to CMU and the upper bricks were attached to wood studs. In addition to the wall covering damage, roof sheathing was blown off along the eave. COASTAL CONSTRUCTION MANUAL 11-17 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-16. % IIIIIII l IlIIIIIII VBlown-off fiber cement , siding; broken window I ��` I 1 i, (arrow). Estimated ��s� wind speed: 125 mph. _ --- ._-- .- .400 Hurricane Katrina ' �°' ��, (Mississippi, 2006) .1* s `-:. of Tr f I AI ,. .., YvrII _ Ise.�• ma y, or is E a - - 44--p—"Al 4- • 1 I --_,„41 ,9p . , I ' ;i %lam• I: oy,.li III IM( ►. Ill . ' Iii . ram 4 , ,,,, :,liff," ...-4 : ill' 1 f* .. ., • / . aii.Figure 11-17. Four brick veneer failure modes; five corrugated ties that were not embedded in the mortar joints (inset). Hurricane Ivan (Florida, 2004) A key to the successful performance of brick veneer is attachment with a sufficient number of properly located ties and proper tie fasteners (based on design loads and tested resistance). Fact Sheet 5.4,Attachment of Brick Veneer in High-Wind Regions, in FEMA P-499 provides guidance on specifying and installing brick veneer in high-wind regions. 11-18 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Exterior Insulating Finishing System EIFS can be applied over steel-frame,wood-frame, concrete, or CMU construction. An EIFS assembly is composed of several NOTE types of materials, as illustrated in Figure 11-18. Some of the layers are adhered to one another, and one or more of the layers When a window or door assembly is installed in an EIFS wall is typically mechanically attached to the wall. If mechanical assembly, sealant between the fasteners are used, they need to be correctly located, of the window or door frame and the proper type and size, and of sufficient number(based on design EIFS should be applied to the loads and tested resistance). Most EIFS failures are caused by EIFS base coat. After sealant application, the top coat is an inadequate number of fasteners or an inadequate amount of then applied. The top coat is adhesive. somewhat porous; if sealant is applied to it, water can migrate At the residence shown in Figure 11-19,the synthetic stucco was between the top and base coats installed over molded expanded polystyrene(MEPS) insulation and escape past the sealant. that was adhered to gypsum board that was mechanically attached to wood studs. Essentially all of the gypsum board blew off (the boards typically pulled over the fasteners). The failure was initiated by detachment of the gypsum board or by stud blow off. Some of the gypsum board on the interior side of the studs was also blown off. Also, two windows were broken by debris. Option A Option B Steel or wood framing Concrete or masonry EIFS may be attached by mechanical EIFS attached to concrete or masonry fasteners(as shown)or by adhesive using adhesive. Mechanical fasteners (as shown in Option B). may also be used. ■r Steel or wood framing p) . Concrete or Substrate masonry substrate Adhesive applied to Insulation board insulation board � Fasteners Insulation board o Reinforced mesh Reinforced mesh embedded in embedded in 0 base coat base coat "O. Finish coat Finish coat Base coat Base coat Figure 11-18. Typical EIFS assemblies COASTAL CONSTRUCTION MANUAL I I l') 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-19. Blown-off EIFS, resulting in extensive interior water damage; detachment of the gypsum board or stud blow off(circle); two windows broken by debris(arrow). Estimated wind speed: 105 to 115 mph. Hurricane Ivan (Florida, 2004) I • NOW 11P ''1 Hi 11 PIM 1\ Several of the studs shown in Figure 11-19 were severely rotted, indicating long-term moisture intrusion behind the MEPS insulation.The residence shown in Figure 11-19 had a barrier EIFS design, rather than the newer drainable EIFS design (for another example of a barrier EIFS design, see Figure 11-21). EIFS should be designed with a drainage system that allows for dissipation of water leaks. Concrete and Concrete Masonry Unit NOTE Properly designed and constructed concrete and CMU walls are capable of providing resistance to high-wind loads and wind- Insulated versions of flood- borne debris. When concrete and CMU walls are exposed to opening devices can be sustained periods of rain and high wind, it is possible for water used when enclosures are insulated. Flood openings are to be driven through these walls. While both the IBC and recommended in breakaway IRC allow concrete and CMU walls to be installed without walls in Zone V and required in water-resistive barriers, the design professional should consider foundation walls and walls of water-penetration-resistance treatments. enclosures in Zone A and Coastal A Zones. Breakaway Walls Breakaway walls (enclosures) are designed to fail under base flood conditions without jeopardizing the elevated building. CROSS REFERENCE Breakaway walls should also be designed and constructed so that when they break away, they do so without damaging the For information on breakaway walls, see Fact Sheet 8.1, wall above the line of separation. Enclosures and Breakaway Walls, in FEMA P-499. 11-20 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 At the house shown in Figure 11-20, floodwater collapsed the breakaway wall and initiated progressive peeling of the EIFS wall covering. A suitable flashing at the top of the breakaway wall would have avoided the progressive failure.When a wall covering progressively fails above the top of a breakaway wall,wave spray and/or wind-driven water may cause interior damage. . ... ... / I Figure 11-20. :.. Collapse of the • breakaway wall, resulting in EIFS peeling. A suitable transition detail at the top of breakaway walls avoids the type of peeling damage shown by the opiio arrows. Estimated wind speed: 105 to 115 mph. Hurricane Ivan (Alabama, 2004) • (in / I 1.. , _ 11.4.1.2 Flashings Water infiltration at wall openings and wall transitions due to poor flashing design and/or installation is a common problem in many coastal homes (see Figure 11-21). In areas that experience frequent wind-driven rain and areas susceptible to high winds, enhanced flashing details and attention to their execution are recommended. Enhancements include flashings that have extra-long flanges, use of sealant, and use of self- adhering modified bitumen tape. When designing flashing, the design professional should recognize that wind-driven rain can be pushed vertically. NOTE The height to which water can be pushed increases with wind speed. Water can also migrate vertically and horizontally by Some housewrap manufacturers have comprehensive, illustrated capillary action between layers of materials (e.g., between a installation guides that address flashing flange and housewrap) unless there is sealant between integrating housewrap and the layers. flashings at openings. A key to successful water diversion is installing layers of building materials correctly to avoid water getting behind any one layer and leaking into the building. General guidance is offered below, design professionals should also attempt to determine the type of flashing details that have been used successfully in the area. COASTAL CONSTRUCTION MANUAL 11-21 11 DESIGNING THE BUILDING ENVELOPE Volume II 01.11:41111 I C ii IIIk 44111. 1 el -.. r, ill 11-1 © \,, II •.tt t Mt 4 1 - . 7.--''.---. -;7 ,:. . ' - i,„ ,,, , , ._.._, ...„......_ Figure 11-21. EIFS with a barrier design: blown-off roof decking(top circle); severely rotted OSB due to leakage at windows (inset). Hurricane Ivan(2004) Door and Window Fleshings An important aspect of flashing design and application is the integration of the door and window flashings with the moisture barrier. See the recommendations in FMA/AAMA 100, FMA/AAMA 200, and Salzano et al. (2010), as described in Section 11.3.1.4, regarding installation of doors and windows, as well as the recommendations given in Fact Sheet 5.1, Housewrap, in FEMA P-499. Applying self-adhering modified bitumen flashing tape at doors and windows is also recommended. Roof-to-Wall and Deck-to-Wall Flashing Where enhanced protection at roof-to-wall intersections is desired, step flashing with a vertical leg that is 2 to 4 inches longer than normal is recommended. For a more conservative design, in addition to the long leg, the top of the vertical flashing can be taped to the wall sheathing with 4-inch-wide self-adhering modified bitumen tape (approximately 1 inch of tape on the metal flashing and 3 inches on the sheathing). The housewrap should be extended over the flashing in the normal fashion. The housewrap should not be sealed to the flashing—if water reaches the backside of the housewrap farther up the wall, it needs to be able to drain out at the bottom of the wall. This detail and a deck-to-wall flashing detail are illustrated in Fact Sheet No. 5.2, Roof-to-Wall and Deck-to-Wall Flashing, in FEMA P-499. 11.4.1.3 Soffits Depending on the wind direction,soffits can be subjected to either positive or negative pressure. Failed soffits may provide a convenient path for wind-driven rain to enter the building, as illustrated by Figure 11-22. This house had a steep-slope roof with a ventilated attic space. The exterior CMU/stucco wall stopped just above the vinyl soffit. Wind-driven rain entered the attic space where the soffit had blown away.This example and other storm-damage research have shown that water blown into attic spaces after the loss of soffits can cause significant damage and the collapse of ceilings. Even when soffits remain in place, water can penetrate through soffit vents and cause damage (see Section 11.6). 11-22 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Figure 11-22. Blown-away soffit Jr' (arrow), which allowed wind-driven rain to enter the attic. Estimated wind speed: 140 to 160 mph. Hurricane Charley (Florida, 2004) 410 1 ,:- Loading criteria for soffits were added in ASCE 7-10. At this time, the only known test standard pertaining to soffit wind and wind-driven rain resistance is the FBC Testing Application Standard(TAS)No. 100(A)-95 (ICC 2008). Wind-pressure testing is conducted to a maximum test speed of 140 mph, and wind-driven rain testing is conducted to a maximum test speed of 110 mph. Laboratory research has shown the need for an improved test method to evaluate the wind pressure and wind-driven rain resistance of soffits. Plywood or wood soffits are generally adequately anchored to wood framing attached to the roof structure or walls. However, it has been common practice for vinyl and aluminum soffit panels to be installed in tracks that are frequently poorly connected to the walls and fascia at the edge of the roof overhang. Properly installed vinyl and aluminum soffit panels should be fastened to the building structure or to nailing strips placed at intervals specified by the manufacturer. Key elements of soffit installation are illustrated in Fact Sheet 7.5,Minimizing Water Intrusion Through Roof Vents in High-Wind Regions, in FEMA P-499. 11.4.1.4 Durability For buildings within 3,000 feet of an ocean shoreline (including sounds and back bays), stainless steel fasteners are recommended for wall and soffit systems. For other components (e.g., furring, blocking, struts, hangers), nonferrous components (such as wood), stainless steel, or steel with a minimum of G-90 hot- dipped galvanized coating are recommended. Additionally, access panels are recommended so components within soffit cavities can be inspected periodically for corrosion or wood decay. COASTAL CONSTRUCTION MANUAL 11-23 11 DESIGNING THE BUILDING ENVELOPE Volume II See"Material Durability in Coastal Environments," a resource document located on the Residential Coastal Construction Web site, for information on wood treatment if wood is specified in areas with severe termite problems. 11.4.2 Seismic Concrete and CMU walls need to be designed for the seismic load.When a heavy covering such as brick veneer or stucco is specified, the seismic design should account for the added weight of the covering. Inadequate connection of veneer material to the base substrate has been a problem in earthquakes and can result in a life-safety hazard. For more information on the seismic design of brick veneer, see Fact Sheet 5.4,Attachment of Brick Veneer in High-Wind Regions, in FEMA P-499. Some non-ductile coverings such as stucco can be cracked or spalled during seismic events. If these coverings are specified in areas prone to large ground-motion accelerations, the structure should be designed with additional stiffness to minimize damage to the wall covering. 11.5 Roof Systems This section addresses roof systems.High winds,seismic events, NOTE and hail are the natural hazards that can cause the greatest When reroofing in high-wind damage to roof systems in the coastal environment.When high areas, the existing roof covering winds damage the roof covering, water infiltration commonly should be removed rather than occurs and can cause significant damage to the interior of the re-covered so that the roof deck building and its contents. Water infiltration may also occur can be checked for deterioration and adequate attachment. See after very large hail impact. During seismic events, heavy roof Figure 11-23. Also see Chapter 14 coverings such as tile or slate may be dislodged and fall from in this Manual. the roof and present a hazard. A roof system that is not highly resistant to fire exposure can result in the destruction of the building during a wildfire. Residential buildings typically have steep-slope roofs (i.e., a NOTE slope greater than 3:12), but some have low-slope roofs. Low- Historically, damage to roof slope roof systems are discussed in Section 11.5.8. systems has been the leading A variety of products can be used for coverings on steep-slope causeroblof building highwinds. performance problems during winds. roofs. The following commonly used products are discussed in this section: asphalt shingles, cement-fiber shingles, liquid- applied membranes,tiles,metal panels,metal shingles,slate,and wood shingles and shakes.The liquid-applied membrane and metal panel systems are air-impermeable, and the other systems are air-permeable." At the residence shown in Figure 11-23, new asphalt shingles had been installed on top of old shingles. Several of the newer shingles blew off. Re-covering over old shingles causes more substrate irregularity,which can interfere with the bonding of the self-seal adhesive of the new shingles. 11 Air permeability of the roof system affects the magnitude of air pressure that is applied to the system during a wind storm. 11-24 COASTAL CONSTRUCTION MANUAL DESIGNING THE BUILDING ENVELOPE 11 r - - et4 Air ...` s. 4 fir. - • �1w1 t avj i� - ,x I 1110 Figure 11-23. Blow-off of several newer shingles on a roof that had been re-covered by installing new asphalt shingles on top of old shingles(newer shingles are lighter and older shingles are darker). Hurricane Charley (Florida, 2004) 11.5.1 Asphalt Shingles NOTE The discussion of asphalt shingles relates only to shingles with self-seal tabs. Mechanically Neither ASCE 7, IBC, or IRC require roof assemblies to resist wind-borne debris. However, interlocked shingles are not addressed because the FBC requires roof assemblies located in the of their limited use. High-Velocity Hurricane Zone(as defined by the FBC)to be tested for wind-borne debris or be deemed to comply with the wind-borne debris 11.5.1.1 High Winds provisions as stipulated in the FBC. The key elements to the successful wind —---� ---�-,-4 --�-� performance of asphalt shingles are the bond strength of the self-sealing adhesive; mechanical properties of the shingle; correct installation of the shingle fasteners; and enhanced attachment along the eave, hip, NOTE ridge, and rakes. In addition to the tab lifts, the number and/or location of fasteners used Storm damage investigations have revealed that gutters are often susceptible to blow-off.ANSI/ to attach the shingles may influence whether SPRI GD-1, Structural Design Standard for Gutter shingles are blown off. Systems Used with Low-Slope Roofs(ANSI/SPRI 2010) provides information on gutter wind and water and ice loads and includes methods for Underlayment testing gutter resistance to these loads.Although the standard is intended for low-slope roofs, If shingles blow off, water infiltration it should be considered when designing and damage can be avoided if the underlayment specifying gutters used with steep-slope roofs. remains attached and is adequately sealed at ANSI/SPRI GD-1 specifies a minimum safety penetrations. Figures 11-24 and 11-25 show factor of 1.67, but a safety factor of 2 is houses with underlayment that was not recommended. effective in avoiding water leakage. Reliable COASTAL CONSTRUCTION MANUAL 11 ?5 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-24. 4.ilk\ \_ Small area of sheathing that was exposed after loss of a few �- shingles and some a , �;1` �. • underlayment. Estimated .`:' '� r•- wind speed: 140 to 160 �i ,,,. - mph. Hurricane Charley �� ---� , , - \ — (Florida 2004) _ 11 I � I 'N., - '' `" /. rr Figure 11-25. Typical underlayment attachment; underlayment blow-off is common if the shingles 4, '" ti - are blown off, as shown. / - • Estimated wind speed: - , 115 mph. Hurricane !�i - - Katrina(Louisiana, 2005) ��"�� ' Pea I I _ rir- III! secondary protection requires an enhanced underlayment design. Design enhancements include increased blow-off resistance of the underlayment, increased resistance to water infiltration (primarily at penetrations), and increased resistance to extended weather exposure. If shingles are blown off, the underlayment may be exposed for only 1 or 2 weeks before a new roof covering is installed, but many roofs damaged by hurricanes are not repaired for several weeks. If a hurricane strikes a heavily populated area, roof covering damage is typically extensive. Because of the heavy workload, large numbers of roofs may not be repaired for several months. It is not uncommon for some roofs to be left for as long as a year before they are reroofed. 11-26 COASTAL CONSTRUCTION MANUAL { Volume II DESIGNING THE BUILDING ENVELOPE 11 The longer an underlayment is exposed to weather, the more durable it must be to provide adequate water infiltration protection for the residence. Fact Sheet 7.2, Roof Underlayment for Asphalt Shingle Roofs, in FEMA P-499 provides three primary options for enhancing the performance of underlayment if shingles are blown off. The options in the fact sheet are listed in order of decreasing resistance to long-term weather exposure. The fact sheet provides guidance for option selection, based on the design wind speed and population of the area. The following is a summary of the enhanced underlayment options: Enhanced Underlayment Option 1. Option 1 provides the greatest reliability for long-term exposure. This option j NOTE includes a layer of self-adhering modified bitumen. Option - 1 has two variations. The first variation is shown in Figure Some OSB has a factory- 11-26. In this variation, the self-adhering sheet is applied applied wax that interferes with to the sheathing, and a layer of#15 felt is tacked over the bonding of self-adhering the self-adhering sheet before the shingles are installed. modified bitumen.To facilitate bonding to waxed sheathing, a The purpose of the felt is to facilitate future tear-off of field-applied primer is needed. If the shingles. This variation is recommended in southern self-adhering modified bitumen climates (e.g., south of the border between North and sheet or tape is applied to OSB, South Carolina). If a house is located in moderate or cold the OSB manufacturer should be climates or has a high interior humidity (such as from an contacted to det whether a primer needs toermine be applied to indoor swimming pool), the second variation, shown in the OSB. Figure 11-27, is recommended. In the second variation (Figure 11-27), the sheathing joints are taped with self-adhering modified bitumen. A#30 felt is then nailed to the sheathing, and a self-adhering modified bitumen sheet is applied to the felt before the shingles are installed.The second variation costs more than the first variation because the second variation requires sheathing tape,many more felt fasteners,and heavier felt.The purpose of taping the joints Figure 11-26. Metal drip a 4-foot x 8-foot roof sheathing Enhanced edge underlayment g ��- . Option 1,first One layer of- variation: self- .D 226 c adhering modified Type I(#15)or • • bitumen over the ASTM D 4869 ' - sheathing Type II fel , Metal drip e (edge 111•11111111 ,/ MIIINIMIBMIII Fascia f Tack underlayment to One layer hold in place before self-adhering modified installing shingles bitumen complying with ASTM D 1970 COASTAL CONSTRUCTION MANUAL 11-27 11 DESIGNING THE BUILDING ENVELOPE Volume II I Figure 11-27. IEnhanced t 4-inch-wide(minimum)self-adhering underlayment Option 1, modified bitumen tape at sheathing joints second variation: self- One layer of 4-foot x 8-foot roof sheathing - adhering modified ASTM D 226 -� ; bitumen over the felt Type II (#30)or y 12 inches o.c. , ASTM D 4869 it Type IV felt A�: - o � .�...,, L 6 inches o.c. Metal drip �i . edge 3t0�i,, Stagger rows - - - Fascia Metal drip edge e j: Low-profile One layer of self-adhering modified capped-head nails bitumen complying With ASTM D 1970 or metal disks over the#30 felt throughout the roof area ("tincaps") is to avoid leakage into the residence if the felt blqws off or is torn by wind-borne debris. (Taping the joints is not included in the first variation, shown in Figure 11-26, because with the self-adhering modified bitumen sheet applied directly to the sheathing,sheet blow-off is unlikely,as is water leakage caused by tearing of the sheet by debris.) The second variation is recommended in moderate and cold climates because it facilitates drying the sheathing because water vapor escaping from the sheathing can move laterally between the top of the sheathing and the nailed felt. In the first variation, because the self-adhering modified bitumen sheet is adhered to the sheathing,water vapor is prevented from lateral movement between the sheathing and the underlayment. In hot climates where the predominate direction of water vapor flow is downward, the sheathing should not be susceptible to decay unless the house has exceptionally high interior humidity. However,if the first variation is used in a moderate or cold climate or if the house has exceptionally high interior humidity,the sheathing may gain enough moisture over time to facilitate wood decay.12 E Enhanced Underlayment Option 2. Option 2 is the same as the Option 1, second variation, except that Option 2 does not include the self-adhering modified bitumen sheet over the felt and uses two layers of felt. Option 2 costs less than Option 1 but Option 2 is less conservative. Option 2 is illustrated in Fact Sheet 7.2 in FEMA P-499. 12 Where self-adhering modified bitumen is applied to the sheathing to provide water leakage protection from ice dams along the eave, long-term experience in the roofing industry has shown little potential for development of sheathing decay.However,sheathing decay has occurred when the self-adhering sheet is applied,over all of the sheathing in cold climate areas. 11-28 COASTAL CONSTRUCTION MANUAL 1 Volume II DESIGNING THE BUILDING ENVELOPE 11 Enhanced Underlayment Option 3. Option 3 is the typical underlayment scheme (i.e., a single layer of#15 felt tacked to the sheathing, as shown in Figure 11-25) with the added enhancement of self- adhering modified bitumen tape. This option provides limited protection against water infiltration if the shingles blow off. However, this option provides more protection than the typical underlayment scheme. Option 3 is illustrated in Fact Sheet 7.2 in FEMA P-499. Figure 11-28 shows a house that used Option 3. The self-adhering modified bitumen tape at the sheathing joints was intended to be a third line of defense against water leakage (with the shingles the first line and the felt the second line). However, as shown in the inset at Figure 11-28, the tape did not provide a watertight seal. A post-storm investigation revealed application problems with the tape. Staples (arrow, inset) were used to attach the tape because bonding problems were experienced during application. Apparently, the applicator did not realize the tape was intended to prevent water from leaking through the sheathing joints. With the tape in an unbonded and wrinkled condition, it was incapable of fulfilling its intended purpose. Self-adhering modified bitumen sheet and tape normally bond quite well to sheathing. Bonding problems are commonly attributed to dust on the sheathing,wet sheathing,or a surfacing(wax) on the sheathing that interfered with the bonding. In addition to taping the sheathing joints in the field of the roof, the hip and ridge lines should also be taped unless there is a continuous ridge vent, and the underlayment should be lapped over the hip and ridge. By doing so, leakage will be avoided if the hip or ridge shingles blow off(see Figure 11-29). See Section 11.6 for recommendations regarding leakage avoidance at ridge vents. 4111 4.000 :ae A Figure 11-28. House that used enhanced underlayment Option 3 with taped sheathing joints (arrow). The self-adhering modified bitumen tape(inset)was stapled because of bonding problems. Estimated wind speed: 110 mph. Hurricane Ike(Texas, 2008) SOURCE:IBHS,USED WITH PERMISSION COASTAL CONSTRUCTION MANUAL 11-29 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-29. Underlayment that was 001101 l 7'4 not lapped over the hip; water entry possible at the sheathing joint (arrow). Estimated - wind speed: 130 mph. i ti Hurricane Katrina (Mississippi, 2005) \ • + Shingle Products, Enhancement Details, and Application Shingles are available with either fiberglass or organic reinforcement. Fiberglass-reinforced shingles are commonly specified because they have greater fire resistance. Fiberglass-reinforced styrene-butadiene-styrene (SBS)-modified bitumen shingles are another option.Because of the flexibility imparted by the SBS polymers, if a tab on a modified bitumen shingle lifts, it is less likely to tear or blow off compared to traditional asphalt shingles.13 Guidance on product selection is provided in Fact Sheet 7.3, Asphalt Shingle Roofing for High- Wind Regions, in FEMA P-499. The shingle product standards referenced in Fact Sheet 7.3 specify a minimum fastener (nail) pull-through resistance. However, if the basic wind speed is greater than 115 mph,14 the Fact Sheet 7.3 recommends minimum pull-through values as a function of wind speed. If a fastener pull-through resistance is desired that is greater than the minimum value given in the product standards,the desired value needs to be specified. ASTM D7158 addresses wind resistance of asphalt shingles.15 ASTM D7158 has three classes: Class D, G, and H. Select shingles that have a class rating equal to or greater than the basic wind speed prescribed in the building code. Table 11-1 gives the allowable basic wind speed for each class, based on ASCE 7-05 and ASCE 7-10. Shingle blow-off is commonly initiated at eaves (see Figure 11-30) and rakes (see Figure 11-31). Blow-off of ridge and hip shingles, as shown in Figure 11-29, is also common. For another example of blow-off of ridge 13 Tab lifting is undesirable.However,lifting may occur for a variety of reasons.If lifting occurs,a product that is not likely to be torn or blown off is preferable to a product that is more susceptible to tearing and blowing off. 14 The 115-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings. If ASCE 7-05,or an earlier version is used,the equivalent wind speed trigger is 90 mph. 15 Fact Sheet 7.3 in FEMA P-499 references Underwriters Laboratories(UL)2390.ASTM D7158 supersedes UL 2390. 11-30 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Table 11-1.Allowable Basic Wind Speed as a Function of Class ASTM D7158 Allowable Basic Wind Speed Class(a) Based on ASCE 7-05 Based on ASCE 7-10 D 90 mph 115 mph G 120 mph 152 mph H 150 mph 190 mph (a) Classes are based on a building sited in Exposure C.They are also based on a building sited where there is no abrupt change in topography. If the residence is in Exposure D and/or where there is an abrupt change in topography(as defined in ASCE 7),the design professional should consult the shingle manufacturer. -N Figure 11-30. At : ^ Loss of shingles and ;'• ,. underlayment along the eave and loss of a few r`• 4' • = hip shingles. Estimated ,digiL ��;� wind speed: 115 mph. Hurricane Katrina - -"_._ (Louisiana, 2005) I i !, r ' l.- F .. . - I al ii 4 y ��u ,.. .. . . ,� �!� .i.: 1; Figure 11-31. Loss of shingles and underlayment along the rake. Estimated wind speed: 110 mph. =-� _ _ Hurricane Ike (Texas, 2008) I. ./y/ r--- / - l' COASTAL CONSTRUCTION MANUAL 11-31 11 DESIGNING THE BUILDING ENVELOPE Volume II and hip shingles, see Figure 11-35. Fact Sheet 7.3 in FEMA P-499 provides enhanced eave, rake, and hip/ ridge information that can be used to avoid failure in these areas. Storm damage investigations have shown that when eave damage occurs, the starter strip was typically incorrectly installed, as shown in Figure 11-32. Rather than cutting off the tabs of the starter, the starter was rotated 180 degrees (right arrow). The exposed portion of the first course of shingles (left arrow) was unbounded because the self-seal adhesive (dashed line) on the starter was not near the eave. Even when the starter is correctly installed (as shown on shingle bundle wrappers), the first course may not bond to the starter because of substrate variation. Fact Sheet 7.3 in FEMA P-499 provides information about enhanced attachment along the eave, including special recommendations regarding nailing, use of asphalt roof cement, and overhang of the shingle at the eave. Figure 11-32. Incorrect installation ,,...ram -.1.11, -- of the starter course =t (incorrectly rotated NNW starter, right arrow, — . resulted in self-seal adhesive not near the T- eave, dashed line). 41=1111111111 . Estimated wind speed: 1,0101 130 mph. Hurricane Katrina(Mississippi, — 2005) Storm damage investigations have shown that metal drip edges (edge flashings) with vertical flanges that are less than 2 inches typically do not initiate eave or rake damage. However, the longer the flange, the greater the potential for flange rotation and initiation of damage. If the vertical flange exceeds 2 inches, it is recommended that the drip edge be in compliance with ANSI/SPRI ES-1. As with eaves, lifting and peeling failure often initiates at rakes and propagates into the field of the roof, as shown in Figure 11-33. Rakes are susceptible to failure because of the additional load exerted on the overhanging shingles and the configuration of the self-sealing adhesive. Along the long dimension of the shingle (i.e.,parallel to the eave), the tab is sealed with self-sealing adhesive that is either continuous or nearly so. However, along the rake, the ends of the tab are only sealed at the self-seal lines, and the tabs are therefore typically sealed at about 5 inches on center. The result is that under high-wind loading, the adhesive at the rake end is stressed more than the adhesive farther down along the tab. With sufficient wind loading, the corner tab of the rake can begin to lift up and progressively peel, as illustrated in Figure 11-33. Fact Sheet 7.3 in FEMA P-499 provides information about enhanced attachment along the rake, including recommendations regarding the use of asphalt roof cement along the rake. Adding dabs of cement, as shown in the Fact Sheet 7.3 in FEMA P-499 and Figure 11-33, distributes the uplift load across the ends of the rake shingles to the cement and self-seal adhesive, thus minimizing the possibility of tab uplift and progressive peeling failure. 11-32 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 �' Underlayment Metal drip edge II /%��' , ' Overlying shingle Self-sealing I� -' .---- �' adhesive i -�----/ ;' 0 - i��' `'. lic .'- .- 0 Fasteners / ` ', \ \ t IIIIII �.i�' / Underly shingle ing ;' 0 �O I . .r . • P ��.. Unsealed I` _ ��•0 Tab edge \' Not : i les ♦ I should overhang dri /4" ;' at rake and eave Self-sealing adhesive Fasteners Figure 11-33. Uplift loads along the rake that are transferred (illustrated by arrows) to the ends of the rows of self-sealing adhesive. When loads exceed resistance of the adhesive, the tabs lift and peel. The dabs of cement adhere the unsealed area shown by the hatched lines in the drawing on the left Storm damage investigations have shown that on several damaged roofs, bleeder strips had been installed. Bleeder strips are shingles that are applied along the rake, similar to the starter course at the eave, as shown at Figure 11-34.A bleeder provides an extended straight edge that can be used as a guide for terminating the rake shingles. At first glance, it might be believed that a bleeder enhances wind resistance along the rake. However, a bleeder does not significantly enhance resistance because the concealed portion of the overlying rake shingle is the only portion that makes contact with the self-seal adhesive on the bleeder. As can be seen in Figure 11-34, the tab does not make contact with the bleeder. Hence, if the tab lifts, the shingle is placed in peel mode,which can easily break the bond with the bleeder.Also, if the tabs are not cut from the bleeder and the cut edge is placed along the rake edge, the bleeder's adhesive is too far inward to be of value. If bleeder strips are installed for alignment purposes, the bleeder should be placed over the drip edge and attached with six nails per strip. The nails should be located 1 inch to 2 1/2 inches from the outer edge of the bleeder (1 inch is preferred if framing conditions permit). Dabs of asphalt roof cement are applied, similar to what is shown in Fact Sheet 7.3 in FEMA P-499. Dabs of asphalt roof cement are applied between the bleeder and underlying shingle, and dabs of cement are applied between the underlying and overlying shingles. Storm damage investigations have shown that when hip and ridge shingles are blown off, there was a lack of bonding of the self-seal adhesive. Sometimes some bonding occurred, but frequently none of the adhesive had bonded. At the hip shown in Figure 11-35, the self-seal adhesive made contact only at a small area on the right side of the hip (circle). Also, at this hip, the nails were above, rather than below, the adhesive line. Lack of bonding of the hip and ridge shingles is common and is caused by substrate irregularity along the hip/ridge line. Fact Sheet 7.3 in FEMA P-499 provides recommendations regarding the use of asphalt roof cement to ensure bonding in order to enhance the attachment of hip and ridge shingles. COASTAL CONSTRUCTION MANUAL 11-33 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-34. -11101.11111111111111P --;-111F _ :. . .._.. A bleeder strip (double- arrow) that was used atlit -_ z a rake blow-off; lack of — _ � ''�z'; " �"''"�M ._ '.. 'sue contact between the tab ----_ — _ '- "" s •r -- of the overlying shingle --�� .. 1. and the bleeder's self-seal - --_. `/ — .,, ;,_ s••• adhesive (upper arrow). �� ` � �- {;; 3 • Estimated wind speed: 125 • _ �_ , mph. Hurricane Katrina _ r �` . ''''`- (Mississippi, 2005) • , " -.._ {",,.� . 7 - 1:1‘t'1,1:1,,,.44 ., 1414 � I 1 } -c.‘ . k\14-) . Figure 11-35. f Inadequate sealing of the / self-sealing adhesive at •.- ' Y a hip as a result of the �t typical hip installation .procedure. Estimated ,__ wind speed: 105 mph. •'- Hurricane Katrina (Mississippi, 2005) ti ' Four fasteners per shingle are normally used where the basic wind speed is less than 115 mph.16 Where the basic wind speed is greater than 115 mph, six fasteners per shingle are recommended. Fact Sheet 7.3 in FEMA P-499 provides additional guidance on shingle fasteners. Storm damage investigations have shown that significant fastener mislocation is common on damaged roofs. When nails are too high above the nail line, they can miss the underlying shingle headlap or have inadequate edge distance, as illustrated 16 The 115-mph basic wind speed is based on ASCE 7-10,Risk Category II buildings.If ASCE 7-05 or an earlier version is used,the equivalent wind speed trigger is 90 mph. 11-34 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 in Figure 11-36. When laminated shingles are used, high nailing may miss the overlap of the laminated shingles; if the overlap is missed, the nail pull-through resistance is reduced (see Figure 11-37). High nailing may also influence the integrity of the self-seal adhesive bond by allowing excessive deformation (ballooning) in the vicinity of the adhesive. The number of nails (i.e., four versus six) and their location likely play little role in wind performance as long at the shingles remain bonded. However, if they are unbounded prior to a storm, or debonded during a storm, the number and location of the nails and the shingles' nail pull-through resistance likely play an important role in the magnitude of progressive damage. Figure 11-36. Proper and improper lap -\ location of shingle fasteners (nails). When properly located, the nail engages the underlying Improper Locati shingle in the headlap area (center nail). When y i too high, the nail misses the underlying shingle Improper Locati (left nail) or is too close to the edge of the underlying shingle (right nail) Proper locati Improper locati Improper locati Figure 11-37. Proper and improper location of laminated shingle fasteners (nails). With laminated shingles, properly located nails engage the underlying laminated portion of the shingle, as well as the headlap of the shingle below (right nail). When too high, the nail can miss the underlying laminated portion of the shingle but engage the headlap portion of the shingle (center nail), or the nail can miss both the underlying laminated portion of the shingle and the headlap of the underlying shingle (left nail) COASTAL CONSTRUCTION MANUAL I I 11 DESIGNING THE BUILDING ENVELOPE Volume II Shingles manufactured with a wide nailing zone provide roofing mechanics with much greater opportunity to apply fasteners in the appropriate locations. Shingle damage is also sometimes caused by installing shingles via the raking method. With this method, shingles are installed from eave to ridge in bands about 6 feet wide. Where the bands join one another, at every other course, a shingle from the previous row needs to be lifted up to install the end nail of the new band shingle. Sometimes installers do not install the end nail, and when that happens, the shingles are vulnerable to unzipping at the band lines, as shown in Figure 11-38. Raking is not recommended by the National Roofing Contractors Association or the Asphalt Roofing Manufacturers Association. Figure 11-38. 74 'II i Shingles that unzipped at ,,k`; ; the band lines because • the raking method was y, ti e.,;V used to install them. 1> %' l' o ll Estimated wind speed: ,,� s~ , t � 135 mph. Hurricane 1� _ '' . r. �' Katrina(Mississippi, 2005) , - I il. ll ii,._ 11.5.1.2 Hail Underwriters Laboratories (UL) 2218 is a method of assessing simulated hail resistance of roofing systems. The test yields four ratings (Classes 1 to 4). Systems rated Class 4 have the greatest impact resistance.Asphalt shingles are available in all four classes. It is recommended that asphalt shingle systems on buildings in areas vulnerable to hail be specified to pass UL 2218 with a class rating that is commensurate with the hail load. Hail resistance of asphalt shingles depends partly on the condition of the shingles when they are exposed to hail. Shingle condition is likely to decline with roof age. 11.5.2 Fiber-Cement Shingles Fiber-cement roofing products are manufactured to simulate the appearance of slate, tile, wood shingles, or wood shakes. The properties of various fiber-cement products vary because of differences in material composition and manufacturing processes. 1 1-36 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 11.5.2.1 High Winds Because of the limited market share of fiber-cement shingles in areas where research has been conducted after high-wind events, few data are available on the wind performance of these products. Methods to calculate uplift loads and evaluate load resistance for fiber-cement products have not been incorporated into the IBC or IRC. Depending on the size and shape of the fiber-cement product, the uplift coefficient that is used for tile in the IBC may or may not be applicable to fiber-cement. If the fiber-cement manufacturer has determined that the tile coefficient is applicable to the product, Fact Sheet 7.4, Tile Roofing for High-Wind Areas, in FEMA P-499 is applicable for uplift loads and resistance. If the tile coefficient is not applicable, demonstrating compliance with ASCE 7 will be problematic with fiber-cement until suitable coefficient(s) have been developed. Stainless steel straps, fasteners, and clips are recommended for roofs located within 3,000 feet of an ocean shoreline(including sounds and back bays).For underlayment recommendations,refer to the recommendation at the end of Section 11.5.4.1. 11.5.2.2 Seismic Fiber-cement products are relatively heavy and, unless they are adequately attached, they can be dislodged during strong seismic events and fall from the roof.At press time, manufacturers had not conducted research or developed design guidance for use of these products in areas prone to large ground-motion accelerations. The guidance provided in Section 11.5.4.2 is recommended until guidance is developed for cement-fiber products. 11.5.2.3 Hail It is recommended that fiber-cement shingle systems on buildings in areas vulnerable to hail be specified to pass UL 2218 at a class rating that is commensurate with the hail load. If products with the desired class are not available, another type of product should be considered. 11.5.3 Liquid-Applied Membranes Liquid-applied membranes are not common on the U.S. mainland but are common in Guam, the U.S. Virgin Islands, Puerto Rico, and American Samoa. 11.5.3.1 High Winds Investigations following hurricanes and typhoons have revealed that liquid-applied membranes installed over concrete and plywood decks have provided excellent protection from high winds if the deck remains attached to the building.This conclusion is based on performance during Hurricanes Marilyn and Georges.This type of roof covering over these deck types has high-wind-resistance reliability. Unprotected concrete roof decks can eventually experience problems with corrosion of the slab reinforcement, based on performance observed after Hurricane Marilyn. All concrete roof decks are recommended to be covered with some type of roof covering. COASTAL CONSTRUCTION MANUAL 11-37 11 DESIGNING THE BUILDING ENVELOPE Volume II 11.5.3.2 Hail It is recommended that liquid-applied membrane systems on buildings in areas vulnerable to hail be specified to pass UL 2218 or Factory Mutual Global testing with a class rating that is commensurate with the hail load. 11.5.4 Tiles Clay and extruded concrete tiles are available in a variety of profiles and attachment methods. 11.5.4.1 High Winds During storm damage investigations, a variety of tile profiles (e.g., S-tile and flat) of both clay and concrete tile roofs have been observed. No significant wind performance differences were attributed to tile profile or material (i.e., clay or concrete). Figure 11-39 illustrates the type of damage that has often occurred during moderately high winds. Blow- off of hip, ridge, or eave tiles is caused by inadequate attachment. Damage to field tiles is typically caused by wind-borne debris (which is often tile debris from the eaves and hips/ridges). Many tile roofs occur over waterproof(rather than water-shedding) underlayment. Waterproof underlayments have typically been well- attached and therefore have not normally blown off after tile blow-off. Hence, many residences with tile roofs have experienced significant tile damage,but little,if any water infiltration from the roof. Figure 11-40 shows an atypical underlayment blow-off, which resulted in substantial water leakage into the house. The four methods of attaching tile are wire-tied, mortar-set, mechanical attachment, and foam-adhesive (adhesive-set). Wire-tied systems are not commonly used in high-wind regions of the continental United States. On the roof shown in Figure 11-41, wire-tied tiles were installed over a concrete deck. Nose hooks occurred at the nose. In addition, a bead of adhesive occurred between the tiles at the headlap. Tiles at the first three perimeter rows were also attached with wind clips. The clips prevented the perimeter tiles from lifting. However, at the field of the roof, the tiles were repeatedly lifted and slammed against deck, which caused the tiles to break and blow away. Damage investigations have revealed that mortar-set systems often provide limited wind resistance (Figure 11-42).17 As a result of widespread poor performance of mortar-set systems during Hurricane Andrew(1992), adhesive-set systems were developed. Hurricane Charley (2004) offered the first opportunity to evaluate the field performance of this new attachment method during very high winds (see Figures 11-43 and 11-44). Figure 11-43 shows a house with adhesive-set tile.There were significant installation problems with the foam paddies, including insufficient contact area between the patty and the tile. As can be seen in Figure 11-43, most of the foam failed to make contact with the'tile. Some of the foam also debonded from 'the mineral surface cap sheet underlayment (see Figure 11-44). Figure 11-45 shows tiles that were mechanically.attached with screws. At the blow-off area, some of the screws remained in the deck,while others were pulled out. The ridge tiles were set in mortar. 17 Fact Sheet 7.4,Tile Roofing for Nigh-Wind Areas, in FEMA 499 recommends that mechanical or adhesively attached methods be used in lieu of the mortar-set method. 11-38 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Figure 11-39. bill- ........„..00,10 ..... Blow-off of eave and hip tiles and some broken tiles in the field of the roof. Hurricane Ivan (Alabama, 2004) 20 raiHN 1 ri- ; Apitii a :0 • Figure 11-40. iiestar... y,, ,.� „ Large area of blown- - --- -` ..' -- - N' off underlayment on = T - a mortar-set tile roof. The atypical loss of `% ..., if ,,,, waterproofing tile �,;, _ � underlayment resulted in i x substantial water leakage 1i into the house. Estimated z r k `- it' wind speed: 140 to 160 , .. °� ` mph. Hurricane Charley .r ' ;,_s� (Florida, 2004) -- Figure 11-41. . Blow-off of wire-tied tiles , installed over a concrete a:... deck. Typhoon Paka (Guam, 1997) -ti w-I. iiiik. _ `•" ti _ -- tir--� _.`. - a .. COASTAL CONSTRUCTION MANUAL 11-39 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-42. irsie,. . Extensive blow off of mortar-set tiles. * * Hurricane Charley =...,-, : , ; (Florida, 2004) -- • .r - . ' X.s t I-jiiti- _ -- - i I 6,? # HilanhillI --..- / V ,17111111.11 ./f17111 - J di k '''. OA .._I,- —a, -..ti r--.. 2'T: ........ "Aalt 1 A 4$ _ Ilk Figure 11-43. Blown-off adhesive-set tile. Note the very small contact area of the foam at the tile heads (left side of the tiles) and very small contact at the nose (circles). Estimated wind speed: 140 to 160 mph. Hurricane Charley (Florida, 2004) Damage investigations have revealed that blow off of hip and ridge failures are common (see Figures 11-39, 11-45, and 11-46). Some of the failed hip/ridge tiles were attached with mortar (see Figure 11-45), while others were mortared and mechanically attached to a ridge board.At the roof shown in Figure 11-46, the hip tiles were set in mortar and attached to a ridge board with a single nail near the head of the hip tile. Because of the brittle nature of tile, tile is often damaged by wind-borne debris, including tile from nearby buildings or tile from the same building (see Figure 11-47). At houses on the coast, fasteners and clips that are used to attach tiles are susceptible to corrosion unless they are stainless steel. Figure 11-48 shows a 6-year-old tile roof on a house very close to the ocean that failed because the heads of the screws attaching the tile had corroded off. Stainless steel straps, fasteners, and clips are recommended for roofs within 3,000 feet of an ocean shoreline (including sounds and back bays). 11-40 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Figure 11-44. ' 4 - . Adhesive that debonded from the cap sheet ' T I ' 'i.. - r..�.. .a. a �S ..� > a. f , -. r. jf •,"`, Figure 11-45. Y s - Blow-off of mechanically _� i attached tiles. Estimated _ ► wind speed: 140 to 160 a ,, mph, Hurricane Charley ,�. .11+'." ti-_ L- ""'�- (Florida, 2004) - -- sea i - My. - nrrr "�+r.. R -^v�rrrr ` `: - - - arJ ...: COASTAL CONSTRUCTION MANUAL 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-46. ri Is- Blow-off of hip tiles that were nailed to a ridge board and set in mortar. Hurricane Ivan . 1 •�. =-.-; (Florida,'2004) .. - ^_f./u^Imo^^• ^.'"I'l.„ r,r.^;.��„r�"'�.- t•. _ ,.. `�^rr,�,^mot^r ,�„�f f r r r''. • a --1•^ a.- ...r i..... �„�,„t Via;` ! f. �. ,_ _. J+�.,0.f„r,„` .. r r", 1"'...k1.,.." >`I *_. , 'At ._1`,.."',ft�'��, -0^-.�.....-�_ ate"'` ./",/�/.,,,,, \I"�/"`+-" Yam^. -r" -Y. Zr-' .:.a V Figure 11-47. �"' � �,._�,�,. - ;�:�r ". Y: Damage to field tiles fr'- r r. r.,. ;.1 azocaused by tiles from — r` - - . ' another area of the v� - `- - -- ' JImo" �,....r„� �?'�"`-._._=-=�==_ � - roof, including a hip r -- -�__ - .. tile(circle). Estimated _ 1 - - "' N. t..- wind speed: 140 to 1603tt 1 „-- - (5' mph. Hurricane Charley - '"""'.....s..,-..- .,.,,,.. 41. , y'' I The house in Figure 11-48 had a lightning protection system (LPS), and the LPS conductors were placed under the ridge tile. Conductors are not susceptible to wind damage if they are placed under the tile and the air terminals (lightning rods) are extended through the ridge. 1 1-42 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 Figure 11-48. The fastener heads on this mechanically attached tile roof had �, •, corroded; air terminals 11111.111111141111,_____ ,.. .„-------- i ,;- .; �w'. :, (lightning rods) in a . ,. =ry '.1•.'� ! • �' �� lightning protection 0` 19 i -Ate A 0 !l system (circle). Hurricane 0. a 111 -,, 0 & # Ivan (Alabama, 2004) I 111111111160011111111 To avoid the type of problems shown in Figures 11-39 through 11-48,see the guidance and recommendations regarding attachment and quality control in Fact Sheet 7.4, Tile Roofingfor High-Wind Areas, in FEMA P-499. Fact Sheet 7.4 references the Third Edition of the Concrete and Clay Roof Tile Installation Manual(FRSA/ TRI 2001) but, as of press time, the Fourth Edition is current and therefore recommended (FRSA/TRI 2005). The Manual includes underlayment recommendations. 11.5.4.2 Seismic Tiles are relatively heavy, and unless they are adequately attached, they can be dislodged during strong seismic events and fall away from the roof. Manufacturers have conducted laboratory research on seismic resistance of tiles, but design guidance for these products in areas prone to large ground-motion accelerations has not been developed. As shown in Figures 11-49, 11-50, and 11-51, tiles can be dislodged if they are not adequately secured. In seismic areas where short period acceleration, Ss, exceeds 0.5g, the following are recommended: If tiles are laid on battens, supplemental mechanical attachment is recommended. When tiles are only loose laid on battens, they can be shaken off, as shown in Figure 11-49 where most of the tiles on the roof were nailed to batten strips. However, in one area, several tiles were not nailed. Because of the lack of nails, the tiles were shaken off the battens. Tiles nailed only at the head may or may not perform well. If they are attached with a smooth-shank nail into a thin plywood or OSB sheathing, pullout can occur. Figure 11-50 shows tiles that were nailed to thin wood sheathing. During the earthquake, the nose of the tiles bounced and pulled out the nails. Specifying ring-shank or screw-shank nails or screws is recommended, but even with these types of fasteners, the nose of the tile can bounce, causing enlargement of the nail hole by repeated pounding. To overcome this problem, wind clips near the nose of the tile or a bead of adhesive between the tiles at the headlap should be specified. COASTAL CONSTRUCTION MANUAL 11-43 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-49. - , Area of the roof where :. tiles were not nailed to s' batten strips. Northridge .; Earthquake (California, 1994) ` ., ,. 4 �.r IPIIL ...ammidiL w� Figure 11-50. Tiles that were nailed to thin wood sheathing. Northridge Earthquake -�-1, (California, 1994) �— _ �""� lsmiNIF flill . . _ Tiles that are attached by only one fastener experience eccentric loading. This problem can be overcome by specifying wind clips near the nose of the tile or a bead of adhesive between the tiles at the headlap. Two-piece barrel (i.e., mission) tiles attached with straw nails can slide downslope a few inches because of deformation of the long straw nail. This problem can be overcome by specifying a wire-tied system or proprietary fasteners that are not susceptible to downslope deformation. When tiles are cut to fit near hips and valleys, the portion of the tile with the nail hole(s) is often cut away. Figure 11-51 shows a tile that slipped out from under the hip tiles. The tile that slipped was trimmed to fit at the hip. The trimming eliminated the nail holes, and no other attachment was provided. The friction fit was inadequate to resist the seismic forces. Tiles must have supplemental securing to avoid displacement of these loose tiles. 1 1-44 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 • o Figure 11-51. 1411' Nii:rZtigell=quutEXCIaterniilaleZiles. he hip tiles.a, 1994) Securing rake, hip, and ridge tiles with mortar is ineffective. If mortar is specified, it should be augmented with mechanical attachment. Rake trim tiles fastened just near the head of the tile often slip over the fastener head because the nail hole is enlarged by repeated pounding. Additional restraint is needed for the trim pieces. Also, the design of some rake trim pieces makes them more inherently resistant to displacement than other rake trim designs. Stainless steel straps, fasteners, and clips are recommended for roofs within 3,000 feet of an ocean shoreline (including sounds and back bays). 11.5.4.3 Hail Tile manufacturers assert that UL 2218 is not a good test method to assess non-ductile products such as tiles. A proprietary alternative test method is available to assess non-ductile products, but as of press time, it had not been recognized as a consensus test method. 11.5.5 Metal Panels and Metal Shingles A variety of metal panel and shingle systems are available. Fact Sheet 7.6, Metal Roof Systems in High-Wind Regions, in FEMA P-499 discusses metal roofing options. Some of the products simulate the appearance of tiles or wood shakes. 11.5.5.1 High Winds Damage investigations have revealed that some metal roofing systems have sufficient strength to resist extremely high winds, while other systems have blown off during winds that were well below the design speeds given in ASCE 7. Design and construction guidance is given in Fact Sheet 7.6 in FEMA P-499. Figure 11-52 illustrates the importance of load path. The metal roof panels were screwed to wood nailers that were attached to the roof deck. The panels were well attached to the nailers. However, one of the nailers was inadequately attached. This nailer lifted and caused a progressive lifting and peeling of the metal panels. Note the cantilevered condenser platform (arrow), a good practice, and the broken window (circle). COASTAL CONSTRUCTION MANUAL 11-45 11 DESIGNING THE BUILDING ENVELOPE Volume II Figure 11-52. Blow-off of one of the Hailers(dashed line on imov roof)caused panels to progressively fail; _ cantilevered condenser ''`- - R platform (arrow);(circle). `- broken window circle). '. ---�------�- -, - Estimated wind speed: 130 mph. Hurricane U ' I Katrina(Louisiana, 2005) o Isawmill AIM • 11.5.5.2 Hail Several metal panel and shingle systems have passed UL 2218.Although metal systems have passed Class 4 (the class with the greatest impact resistance), they often are severely dented by the testing. Although they may still be effective in inhibiting water entry, the dents can be aesthetically objectionable. The appearance of the system is not included in the UL 2218 evaluation criteria. 11.5.6 Slate Some fiber-cement and tile products are marketed as"slate,"but slate is a natural material. Quality slate offers very long life. However, long-life fasteners and underlayment are necessary to achieve roof system longevity. 11.5.6.1 High Winds Because of limited market share of slate in areas where research has been conducted after high-wind events, few data are available on its wind performance. However, as shown in Figure 11-53,wind damage can occur. Methods to calculate uplift loads and evaluate load resistance for slate have not been incorporated into the IBC or IRC. Manufacturers have not conducted research to determine a suitable pressure coefficient. Demonstrating slate's compliance with ASCE 7 will be problematic until a coefficient has been developed.A consensus test method for uplift resistance has not been developed for slate. In extreme high-wind areas,mechanical attachment near the nose of the slate should be specified in perimeter and corner zones and perhaps in the field. Because this prescriptive attachment suggestion is based on limited information, the uplift resistance that it provides is unknown. 11-46 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 11. 4006. _ yyrrx �• 41 u- .,, , - i Figure 11-53. Damaged slate roof with nails that typically pulled out of the deck. Some of the slate broke and small portions remained nailed to the deck. Estimated wind speed: 130 mph. Hurricane Katrina(Mississippi, 2005) Stainless steel straps, fasteners, and clips are recommended for roofs within 3,000 feet of an ocean shoreline (including sounds and back bays). For underlayment recommendations, refer to the recommendation at the end of Section 11.5.4.1. 11.5.6.2 Seismic Slate is relatively heavy and unless adequately attached, it can be dislodged during strong seismic events and fall away from the roof. Manufacturers have not conducted research or developed design guidance for use of slate in areas prone to large ground-motion accelerations. The guidance provided for tiles in Section 11.5.4.2 is recommended until guidance has been developed for slate. 11.5.6.3 Hail See Section 11.5.4.3. 11.5.7 Wood Shingles and Shakes 11.5.7.1 High Winds Research conducted after high-wind events has shown that wood shingles and shakes can perform very well during high winds if they are not deteriorated and have been attached in accordance with standard attachment recommendations. Methods to calculate uplift loads and evaluate load resistance for wood shingles and shakes have not been incorporated into the IBC or IRC. Manufacturers have not conducted research to determine suitable pressure coefficients. Demonstrating compliance with ASCE 7 will be problematic with wood shingles and shakes COASTAL CONSTRUCTION MANUAL 11-47 11 DESIGNING THE BUILDING ENVELOPE Volume II until such coefficients have been developed. A consensus test method for uplift resistance has not been developed for wood shingles or shakes. For enhanced durability, preservative-treated wood is recommended for shingle or shake roofs on coastal buildings. Stainless steel fasteners are recommended for roofs within 3,000 feet of an ocean shoreline (including sounds and back bays). See Figure 11-54 for an example of shingle loss due to corrosion of the nails. Figure 11-54. 11111111•P"-- •.r.- �. -� � Loss of wood shingles >.� due to fastener corrosion. - Hurricane Bertha(North Carolina, 1996) 410414444144,450._- - 4144% 111 . • 11.5.7.2 Hail At press time, no wood-shingle assembly had passed UL 2218, but heavy shakes had passed Class 4 (the class with the greatest impact resistance) and medium shakes had passed Class 3. The hail resistance of wood shingles and shakes depends partly on their condition when affected by hail. Resistance is likely to decline with roof age. 11.5.8 Low-Slope Roof Systems Roof coverings on low-slope roofs need to be waterproof membranes rather than the water-shedding coverings that are used on steep-slope roofs. Although most of the low-slope membranes can be used on dead-level substrates, it is always preferable (and required by the IBC and IRC) to install them on substrates that have some slope (e.g., 1/4 inch in 12 inches [2 percent]). The most commonly used coverings on low-slope roofs are built-up, modified bitumen, and single-ply systems. Liquid-applied membranes (see Section 11.5.3), structural metal panels (see Section 11.5.5), and sprayed polyurethane foam may also be used on low-slope roofs. Information on low-slope roof systems is available in The NRCA Roofing Manual(NRCA 2011). Low-slope roofing makes up a very small percentage of the residential roofing market. However, when low- slope systems are used on residences, the principles that apply to commercial roofing also apply to residential 1 1-48 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 work. The natural hazards presenting the greatest challenges to low-sloped roofs in the coastal environment are high winds (see Section 11.5.8.1), earthquakes (see Section 11.5.8.2), and hail (see Section 11.5.8.3). 11.5.8.1 High Winds Roof membrane blow-off is typically caused'by lifting and peeling of metal edge flashings (gravel stops) or copings, which serve to clamp down the membrane at the roof edge. In hurricane-prone regions, roof membranes are also often punctured by wind-borne debris. Following the criteria prescribed in the IBC will typically result NOTE in roof systems that possess adequate wind uplift resistance if properly installed. IBC references ANSI/SPRI ES-1 for edge The 2009 edition of the IBC flashings and copings. ANSI/SPRI ES-1 does not specify a prohibits the use of aggregate minimum safety factor. Accordingly, a safety factor of 2.0 is roof surfacing in hurricane-prone recommended for residences. regions. A roof system that is compliant with IBC (and the FBC) is susceptible to interior leakage if the roof membrane is punctured by wind-borne debris. If a roof system is desired that will avoid interior leakage if struck by debris, refer to the recommendations in FEMA P-424, Design Guide for Improving School Safety in Earthquakes, Floods and High Winds (FEMA 2010a). Section 6.3.3.7 also provides other recommendations for enhancing wind performance. 11.5.8.2 Seismic If a ballasted roof system is specified, its weight should be considered during seismic load analysis of the structure.Also, a parapet should extend above the top of the ballast to restrain the ballast from falling over the roof edge during a seismic event. 11.5.8.3 Hail It is recommended that a system that has passed the Factory Mutual Research Corporation's severe hail test be specified. Enhanced hail protection can be provided by a heavyweight concrete-paver-ballasted roof system. If the pavers are installed over a single-ply membrane, it is recommended that a layer of extruded polystyrene intended for protected membrane roof systems be specified over the membrane to provide protection if the pavers break. Alternatively, a stone protection.mat intended for use with aggregate-ballasted systems can be specified. 11.6 Attic Vents High winds can drive large amounts of water through attic ventilation openings, which can lead to collapse of ceilings. Fact Sheet 7.5,Minimizing Water Intrusion Through Roof Vents in High-Wind Regions, in FEMA P-499 provides design and application guidance to minimize water intrusion through new and existing attic ventilation systems. Fact Sheet 7.5 also contains a discussion of unventilated attics. COASTAL CONSTRUCTION MANUAL 11-49 11 DESIGNING THE BUILDING ENVELOPE Volume II Continuous ridge vent installations, used primarily on roofs with asphalt shingles, have typically not addressed the issue of maintaining structural integrity of the roof sheathing. When the roof sheathing is used as a structural diaphragm, as it is in high-wind and seismic hazard areas, the structural integrity of the roof can be compromised by the continuous vent. I Roof sheathing is normally intended to act as a diaphragm. The purpose of the diaphragm is to resist lateral forces.To properly function,the diaphragm must have the capability of transferring the load at its boundaries from one side of the roof to the other; it normally does this through the ridge board. The continuity, or load transfer assuming a blocked roof diaphragm, is accomplished with nails. This approach is illustrated by Figure 11-55. The problem with the continuous ridge vent installation is the t_, k, need to develop openings through the diaphragm to allow air NOTE to flow from the attic space up to and through the ridge vent. - For existing buildings not equipped with ridge vents, cutting When cutting a slot in a deck for slots or holes in the sheathing is required. If a saw thee s is used to a dge vent, it is important o set depth of the saw blade so cut off 1 to 2 inches along either side of the ridge, the integrity that it only slightly projects below of the diaphragm is affected. This method of providing roof the bottom of the sheathing. ventilation should not be used without taking steps to ensure ! Otherwise, as shown in Fact proper load transfer. Sheet 7.5,the integrity of the trusses-can be affected. The two methods of providing the proper ventilation while ' maintaining the continuity of the blocked roof diaphragm are as follows: 1. Drill 2-to 3-inch-diameter holes in the sheathing between each truss or rafter approximately 1 1/2 inches down from the ridge. The holes should be equally spaced and should remove no more than one- half of the total amount of sheathing area between the rafters. For example, if the rafters are spaced 24 inches o.c. and 2-inch-diameter holes are drilled, they should be spaced at 6 inches o.c., which will allow about 12 square inches of vent area per linear foot when the holes are placed along either side of the ridge. This concept is illustrated in Figure 1'1-56. Figure 11-55. Method for maintaining a Nails from sheathing to ridge board - continuous load path at -};=� • the roof ridge by nailing NOTE:If roof sheathing is cut and removed - ---i roof sheathing to achieve an air slot,continuity and --;=•- ;?i - diaphragm action are affected. --;= - i';. d ' <Z Roof Ridge board--- ir sheathing ,, L. 11-50 COASTAL CONSTRUCTION MANUAL y i Volume II 1 DESIGNING THE BUILDING ENVELOPE 11 1 Figure 11-56. Sheathing vet holes on - - -- _- = Holes drilled in roof each side of ridge board 0 -- sheathing for ventilation ;0 Z7 and roof diaphragm 0 -:~ action is maintained " O 6 "0" (sheathing nails not 0 0 - p shown) Ridge board r. s `Z Roof � sheathing i Joist or truss 2. Install two ridge boards separated by an air space of at ` least 3 inches,with solid blocking between the ridge boards at each rafter or truss. Stop the sheathing at the NOTE ridge board and fully nail the sheathing as required. The When continuous ridge vents ridge vent must be wide enough to cover the 3-inch gap are used, it is not possible to between the ridge boards. The ridge board and blocking continue the underlayment across must be nailed to resist the calculated shear force. the ridge. Hence, if wind-driven rain is able to drive through the For new construction, the designer should detail the ridge ventthe ridge vent blows goffff,, water will leak into the vent installation with the proper consideration for the load , house. It is likely that the ridge transfer requirement. Where high-diaphragm loads may vent test standard referenced in occur, a design professional should be consulted regarding the ; Fact Sheet 7.5 in FEMA P-499 amount of sheathing that can be removed or other methods is inadequate. One option is to avoid vent water infiltration issues of providing ventilation while still transferring lateral , by designing an unventilated loads. The need to meet these requirements may become a attic(where appropriate, as significant problem in large or complex residential buildings discussed in Fact Sheet 7.5).The where numerous ventilation openings are required. In these other option is to specify a vent that has passed the referenced instances, ridge vents may need to be augmented with other test method and attach the vent ventilating devices (e.g., off-ridge vents or gable end vents). with closely spaced screws (with , spacing a function of the design Many ridge vent products are not very wide. When these wind speed). products are used, it may be difficult to provide sufficiently _ large openings through the sheathing and maintain diaphragm integrity if holes are drilled through the sheathing. Manufacturers' literature often illustrates large openings at the ridge with little or no consideration for the transfer of lateral loads. I COASTAL CONSTRUCTION MANUAL 11-51 1 11 DESIGNING THE BUILDING ENVELOPE Volume II 11.7 Additional Environmental Considerations In addition to water intrusion and possible resulting decay, sun (heat and ultraviolet [UV] radiation) and wind-driven rain must also be considered in selecting materials to be used in coastal buildings. The coastal environment is extremely harsh, and materials should be selected that not only provide protection from the harsh elements but also require minimal maintenance. 11.7.1 Sun Buildings at or near the coast are typically exposed to extremes of sun, which produces high heat and UV radiation. This exposure has the following effects: r: The sun bleaches out many colors L Heat and UV shorten the life of many organic materials 1-= Heat dries out lubricants such as those contained in door and window operating mechanisms To overcome these problems: E Use materials that are heat/UV-resistant F2 Shield heat/UV susceptible materials with other materials E Perform periodic maintenance and repair (refer,to Chapter 14) 11.7.2 Wind-Driven Rain Wind-driven rain is primarily a problem for the building envelope. High winds can carry water droplets into the smallest openings and up, into, and behind flashings, vents, and drip edges. When buildings are constructed to provide what is considered to be complete protection from the effects of natural hazards, any small "hole" in the building envelope becomes an area of weakness into which sufficiently high wind can drive a large amount of rain. 11.8 References AAMA(American Architectural Manufacturers Association). 2008. Standard/Specification for Windows, Doors, and Unit Skylights. AAMA/WDMA/CSA 101/I.S.2/A440-08. AAMA. 2008. Voluntary Specification for Field Testing of Newly Installed Fenestration Products. AAMA 502-08. AAMA. 2009. Voluntary Specification for Rating the Severe Wind-Driven Rain Resistance of Windows, Doors, and Unit Skylights.AAMA 520-09. AAMA. Fenestration Anchorage Guidelines. AAMA TIR A14. 11-52 COASTAL CONSTRUCTION MANUAL Volume II DESIGNING THE BUILDING ENVELOPE 11 AAMA. Voluntary Guideline for Engineeringj4nalysis of Window and Sliding Glass Door Anchorage Systems. AAMA 2501. ANSI/SPRI (American National Standards Institute/Single-Ply Roofing Industry). 2003. Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems.ANSI/SPRI ES-1. ANSI/SPRI. 2010. Structural Design Standard for Gutter Systems Used with Low-Slope Roofs. ANSI/SPRI GD-1. ASCE (American Society of Civil Engineers)'. 2005.Minimum Design Loads for Buildings and Other Structures.ASCE Standard ASCE 7-05. ASCE. 2010.Minimum Design Loads for Buildings and Other Structures.ASCE Standard ASCE 7-10. ASTM. Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact with Propelled Ice Balls. ASTM E822. ASTM. Standard Specification for Performance of Exterior Windows, Curtain Walls, Doors, and Impact Protective Systems Impacted by Windborne Debris in Hurricanes.ASTM E1996. ASTM. Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls, by Uniform or Cyclic Static Air Pressure Difference. ASTM E1105. ASTM. Standard 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. ASTM. Standard Test Method for Structural Performance of Exterior Windows, Doors, Skylights, and Curtain Walls by Uniform Static Air Pressure Difference.ASTM E330. ASTM. Standard Test Method for Structural Performance of Exterior Windows, Doors, Skylights, and Curtain Walls by Cyclic Air Pressure Differential.ASTM E1233. ASTM. Standard Test Method for Wind Resistance of Asphalt Shingles (Upl ft Force/Uplift Resistance Method). ASTM D7158. DASMA(Door &Access Systems Manufacturers Association International). 2005. Standard Method for Testing Sectional Garage Doors and Rolling Doors:Determination of Structural Performance Under Missile Impact and Cyclic Wind Pressure. ANSI/DASMA 115.Available at http://www.dasma.com. Accessed January 2011. DASMA. 2005. Standard Method For Testing Sectional Garage Doors and Rolling Doors:Determination of Structural Performance Under Uniform Static Air Pressure Difference. ANSI/DASMA 108.Available at http://www.dasma.com.Accessed January 2011. DASMA. 2010. Connecting Garage Door jambs to Building Framing. Technical Data Sheet#161.Available at http://www.dasma.com/PubTechData.asp. Accessed January 2011. FEMA (Federal Emergency Management Agency). 1992. Building Performance:Hurricane Andrew in Florida—Observations, Recommendations, and Technical Guidance. FEMA FIA 22. COASTAL CONSTRUCTION MANUAL 11-53 11 DESIGNING THE BUILDING ENVELOPE Volume II JqI FEMA. 1993. Building Performance:Hurricane Iniki in Hawaii- Observations, Recommendations, and Technical Guidance. FEMA FIA 23. FEMA. 1998. Typhoon Paka: Observations and Recommendations on Building Performance and Electrical Power Distribution System, Guam, U.S.A. FEMA-1193-DR GU. FEMA. 1999. Building Performance Assessment Team (BPAT)Report-Hurricane Georges in Puerto Rico, Observations, Recommendations, and Technical Guidance. FEMA 339. FEMA. 2005a. Mitigation Assessment Team Report:Hurricane Charley in Florida. FEMA 488. FEMA. 2005b. Hurricane Ivan in Alabama and Florida: Observations, Recommendations and Technical Guidance. FEMA 489. FEMA. 2006. Hurricane Katrina in the Gulf Coast. FEMA 549. FEMA. 2008. Home Builder's Guide to Construction in Wildfire Zones. FEMA P-737. FEMA. 2009. Hurricane Ike in Texas and Louisiana. FEMA P-757. FEMA. 2010a. Design Guide for Improving School Safety in Earthquakes, Floods and High Winds. FEMA P-424. FEMA. 2010b. Home Builder's Guide to Coastal Construction Technical Fact Sheet Series. FEMA P-499. Fernandez, G., F. Masters, and K. Gurley. 2010. "Performance of Hurricane Shutters under Impact by Roof Tiles,"Engineering Structures Vol. 32, Issue 10, pp. 3384-3393. FMA/AAMA (Fenestration Manufacturers Association/American Architectural Manufacturers Association). 2007. Standard Practice for the Installation of Windows with Flanges or Mounting Fins in Wood Frame Construction. FMA/AAMA 100-07. FMA/AAMA. 2009. Standard Practice for the Installation of Windows with Frontal Flanges for Surface Barrier Masonry Construction for Extreme Wind/Water Conditions. FMA/AAMA 200-09. FRSA/TRI (Florida Roofing, Sheet Metal and Air Conditioning Contractors Association, Inc./The Roofing Institute). 2001. Concrete and Clay Roof Tile Installation Manual. Third Edition. FRSA/TRI. 2005. Concrete and Clay Roof Tile Installation Manual. Fourth Edition. ICC (International Code Council). 2008. 2007Florida Building Code:Building. ICC. 2009a. International Building Code(2009 IB,C). Country Club Hills, IL: ICC. ICC. 2009b. International Residential Code(2009 IRC). Country Club Hills, IL: ICC. ICBO (International Council of Building Officials). Uniform Building Code. Lopez, C., F.J. Masters, and S. Bolton. 2011. "Water Penetration Resistance of Residential Window and Wall Systems Subjected to Steady and Unsteady Wind Loading," Building and Environment 46, Issue 7, pp. 1329-1342. 11-54 COASTAL CONSTRUCTION MANUAL 11 Volume II DESIGNING THE BUILDING ENVELOPE 11 McDonald,J.R. and T.L. Smith. 1990. Perfgrmance of Roofing Systems in Hurricane Hugo. Institute for Disaster Research,Texas Tech University. NRCA(National Roofing Contractors Association). 2011. The NRCA Roofing Manual. Salzano, C.T., F.J. Masters, and J.D. Katsaros. 2010. "Water Penetration Resistance of Residential • Window Installation Options for HUrricane-prone Areas," Building and Environment 45, Issue 6, pp. 1373-1388. Smith, T.L. 1994. "Causes of Roof Covering,Damage and Failure Modes: Insights Provided by Hurricane Andrew,"Proceedings of the Hurricanes of 1992,ASCE. 1 COASTAL CONSTRUCTION MANUAL 11-55 COASTAL CONSTRUCTION MANUAL ,-, "--,:!"..-: :. --,.. •-:,--,-.,.,:-.,',--,::-• il 4$1;0000.,. 1 ago t s - 4- -t`- 7 t .AOIIIIIMIIIIIAIII II I1I1� r ri! �� i ns a in M Equipmentand Ut _:.:____ This chapter provides guidance on design considerations for elevators,exterior-mounted and interior mechanical equipment, CROSS REFERENCE and utilities (electric, telephone, and cable TV systems and water and wastewater systems). Protecting mechanical For resources that augment the guidance and other information equipment and utilities is a key component of successful in this Manual, see the building performance during and after a disaster event. Residential Coastal Construction Web site(http://www.fema.gov/ rebuild/mat/fema55.shtm). t 12.1 Elevators --f~' J Elevators are being installed with increasing frequency in elevated, single-family homes in coastal areas. The elevators are generally smaller than elevators in non-residential buildings but are large enough to provide handicap accessibility and accommodate small household furniture and equipment. Small (low-rise) residential elevators that are added as part of a post-construction retrofit are usually installed in a shaft independent of an outside wall. Residential elevators designed as part of new construction can be installed in a shaft in the interior of the structure. In either case, the elevator shaft must have a landing, which is usually at the ground level, and a cab platform near the top. The bottom or pit of an elevator with a landing at the lower level is almost always below the BFE. COASTAL CONSTRUCTION MANUAL 12-1 12 INSTALLING MECHANICAL EQUIPMENT AND(UTILITIES Volume II N Appendix H in NFIP Technical Bulletin 4,Elevator Installation for Buildings Located in Special Flood Hazard Areas in Accordance with the National Flood Insurance Program (FEMA 2010a), discusses the installation of elevator systems and equipment in the floodplain.As explained in the bulletin, elevator shafts and enclosures that extend below the BFE in coastal areas must be designed to resist hydrostatic, hydrodynamic, and wave forces as well as erosion and scour, but are not required to include hydrostatic openings or breakaway walls. In addition, elevator accessory equipment should be installed above the BFE, replaced with flood damage- resistant elements, or treated with flood damage-resistant paint or coatings to minimize flood damage. For safety reasons, commercial and large (high-rise) elevators are designed with "fire recall" circuitry that sends the elevator to a designated floor during a fire so emergency services personnel can use the elevators. However, during flooding, this feature may expose the cab directly to floodwaters. Therefore, for elevators in coastal buildings, the elevator must be equipped with a float switch that sends the elevator cab to a level above the BFE. In addition, the design professional must ensure that the elevator stops at a level above the BFE when the power is lost. This can be accomplished by installing an emergency generator or a battery descent feature that is integrated into the float switch, as described in NFIP Technical Bulletin 4. Finally, although elevators and elevator equipment are permitted for building access and may be covered by flood insurance, their presence, location, and size can affect flood insurance premiums. For buildings in Zone V, the NFIP considers an elevator enclosure a building enclosure or an obstruction, which may be subject to an insurance rate loading depending on: D Square footage of the enclosure L Value of the elevator equipment [_' Location of the elevator equipment in relation to the BFE 12.2 Exterior-Mounted Mechanical Equipment Exterior-mounted mechanical equipment can include exhaust fans, vent hoods, air conditioning units, duct work, pool motors, and well pumps. High winds, flooding, and seismic events are the natural hazards that can cause the greatest damage to exterior-mounted mechanical equipment. 12.2.1 High Winds Equipment is typically damaged because it is not anchored or the anchorage is inadequate. Damage may also be caused by inadequate equipment strength or corrosion. Relatively light exhaust fans and vent hoods are commonly blown away during high winds. Air conditioning condensers, which are heavier than fans and vent hoods, can also be blown off of building's. Considering the small size of most exhaust fans, vent hoods, and air-conditioning units used on residential buildings, the following prescriptive attachment recommendations should be sufficient for most residences: For curb-mounted units, #14 screws with gasketed washers L For curbs with sides smaller than 12 inches, one screw at each side of the curb 12-2 COASTAL CONSTRUCTION MANUAL Volume II INSTALLING MECHANICAL EQUIPMENT AND UTILITIES 12 For curbs between 12 and 24 inches, two screws per side = For curbs between 24 and 36 inches, three screws per side r= For buildings within 3,000 feet of the ocean, stainless steel screws For units that have flanges attached directly to the roof, #14 pan-head screws, a minimum of two screws per side, and a maximum spacing of 12 inches o.c. D Air conditioning condenser units, 1/2-inch bolts at the four corners of base of each unit If the equipment is more than 30 inches above the curb,the attachment design should be based on calculated wind loads.ASCE 7-10 contains provisions for determining the horizontal and lateral force and the vertical uplift force on rooftop equipment for buildings with a mean roof height less than or equal to 60 feet. The lateral force is based on the vertical area of the equipment as projected on a vertical plane normal to the direction of the wind. The uplift force is based on the horizontal area of the equipment as projected on a horizontal plane above the equipment and parallel to the direction of the wind. Until equipment manufacturers produce more wind-resistant equipment, job-site strengthening of vent hoods is recommended. One approach is to;use 1/8-inch-diameter stainless steel cables. Two or four cables are recommended, depending on design wind conditions. Alternatively, additional heavy straps can be screwed to the hood and curb. To avoid corrosion problems in equipment within 3,000 feet of the ocean shoreline (including sounds and backbays), nonferrous metal, such as aluminum, stainless steel, or steel with minimum G-90 hot-dip galvanized coating, is recommended for the equipment, equipment stands,and equipment anchors. Stainless steel fasteners are also recommended. See Section 11.6 for guidance regarding attic vents. 12.2.2 Flooding Flood damage to mechanical equipment is typically caused by the failure to elevate equipment sufficiently, as shown in Figure 12-1. Figure 12-2 shows proper elevation of an air-conditioning condenser in a flood- prone area. Exterior-mounted mechanical equipment in one- to four-family — - buildings is normally limited to the following: -=0) CROSS REFERENCE n Air-conditioning condensersFor additional information, see r: Ductwork (air supply and return) FEMA 348, Protecting Building Utilities From Flood Damage D Exhaust fans —Principles and Practices for the Design and Construction of tU Pool filter motors Flood-Resistant Building Utility Systems(FEMA 1999), and Li Submersible well pumps Fact Sheet 8.3,Homebuilder's Guide to Coastal Construction, Floodwaters can separate mechanical equipment from the in FEMA P-499 (FEMA 2010b). supports and sever the connection to mechanical or electric COASTAL CONSTRUCTION MANUAL 12-3 12 INSTALLING MECHANICAL EQUIPMENT AND UTILITIES Volume II Figure 12-1. Condenser damaged as .• ` a result of insufficient elevation, Hurricane I Georges (U.S. Gulf Coast, il 11 1998) • - N \\1m - riow;ix ____o _i;LII aliP - .. 111 ' ile 111111 tEn Ili i II' • fi,f, . 44)._-,k.. • _ Figure 12-2. • Proper elevation of an air-conditioning rloopw condenser in a floodprone area; additional anchorage is recommended ___ 1• L * rrs . 1 • 12-4 COASTAL CONSTRUCTION MANUAL Volume II INSTALLING MECHANICAL EQUIPMENT AND UTILITIES 12 systems. Mechanical equipment can also be damaged or destroyed when inundated by floodwaters, especially saltwater. NOTE Although a short period of inundation may not destroy some Although the 2012 IBC and 2012 types of mechanical equipment, any inundation of electric IRC specify that flood damage equipment causes, at a minimum, significant damage to wiring resistant materials be used below and other elements. the BFE, in this Manual, flood damage-resistant materials are Minimizing flood damage to mechanical equipment requires recommended below the DFE. elevating it above the DFE. Because of the uncertainty of wave heights and the probability of wave run-up, the designer should consider additional elevation above the DFE for this equipment. In Zone V, mechanical equipment must be installed either on a cantilevered platform supported by the first floor framing system or on an open foundation. A cantilevered platform is recommended. However, if the platform is not cantilevered, it is strongly recommended that the size of the elements, depth, and structural integrity of the open foundation that is used to support mechanical equipment be the same as the primary building foundation. Although smaller diameter piles could be used because the platform load is minimal, the smaller piles are more susceptible to being broken by floodborne debris, as shown in Figure 12-3. In Zone A, mechanical equipment must be elevated to the DFE on open or closed foundations or otherwise protected from floodwaters entering or accumulating in the equipment elements. For buildings constructed over crawlspaces, the ductwork of some heating, ventilation, and air-conditioning systems are routed through the crawlspace. The ductwork must be installed above the DFE or be made watertight in order to minimize flood damage. Many ductwork systems today are constructed with insulated board, which is destroyed by flood inundation. Figure 12-3. Small piles supporting a platform broken by floodborne debris V 4(4 sr ■ ■ it_c t COASTAL CONSTRUCTION MANUAL 12-5 12 INSTALLING MECHANICAL EQUIPMENT AND,1 UTILITIES Volume II 12.2.3 Seismic Events Residential mechanical equipment is normally fairly light. Therefore, with some care in the design of the attachment of the equipment for resistance to shear and overturning forces, these units should perform well during seismic events. Because air-conditioning units that are mounted on elevated platforms experience higher accelerations than ground-mounted units, extra attention should be given to attaching these units in areas that are prone to large ground accelerations. 12.3 Interior Mechanical Equipment Interior mechanical equipment includes but is not limited to furnaces,boilers,water heaters, and distribution ductwork. High winds normally do not affect interior mechanical equipment. Floodwaters, however, can cause significant damage to furnaces, boilers, water heaters, and distribution ductwork. Floodwaters can extinguish gas-powered flames, short circuit the equipment's electric system, and inundate equipment and ductwork with sediment. The following methods of reducing flood damage to interior equipment are recommended: r Elevate the equipment and the ductwork above,the DFE by hanging the equipment from the existing first floor or placing it in the attic or another location above the DFE. In areas other than Zone V (where enclosure of utilities below the BFE is not recommended), build a waterproof enclosure around the equipment, allowing access for maintenance and replacement of equipment parts. 12.4 Electric Utility, Telephone, and Cable TV Systems Electric utilities serving residential buildings in coastal areas are frequently placed in harsh and corrosive environments. Such environments increase maintenance and shorten the lifespan of the equipment. Common electric elements of utilities in residential buildings that might be exposed to severe wind or flood events, which increase maintenance and shorten the lifespan further, are electric meters, electric service laterals and service drops from the utility company, electric panelboards, electric feeders, branch circuit wiring, receptacles, lights, security system wiring and equipment, and telephone and cable television wiring and equipment. The primary method of protecting elements from flooding is to elevate them above the DFE, but elevation is not always possible. Floodplain management requirements and other code requirements sometimes conflict. One conflict that is difficult to fully resolve is the location of the electric meter. Figure 12-4 shows a bank of meters and electric feeds that failed during Hurricane Opal. Utility companies typically require electric meters to be mounted where they can be easily read for billing purposes;meters are usually centered approximately 5 feet above grade.They are normally required by utility regulations to be no higher than eye level. However, this height is often below the DFE for coastal homes, and the placement therefore conflicts with floodplain management requirements that meters be installed above the DFE. Since meter sockets typically extend 12 inches below the center of the meter, design floods 12-6 COASTAL CONSTRUCTION MANUAL Volume II INSTALLING MECHANICAL EQUIPMENT AND UTILITIES 12 Figure 12-4. ,1 ✓ Electric service meters and feeders that were destroyed by floodwaters iraitij‘ -=a aye, '— during Hurricane Opal (1995) . \\\ • ...: • that produce 4 feet of flooding can cause water to enter the meter socket and disrupt the electric service. When a meter is below the flood level, electric service can be exposed to floodborne debris, wave action, and flood forces. Figure 12-5 shows an electric meter that is easily accessible by the utility company but is above the DFE. Since many utility companies no longer manually read meters, there may be flexibility in meter socket mounting, preferably above the design flood. The use of automatic meter reading("smart meters") by electric utility companies is increasing. The designer should consult the utility to determine whether smart meters can be placed higher than meters that must be read manually. Similar situations often exist with other electrical devices. For example, switches for controlling access and egress lighting and security sensors occasionally need to be placed below the DFE. The following methods are recommended when necessary to reduce the potential for damage to electric wiring and equipment and to facilitate recovery from a flood event: Wiring methods. Use conduit instead of cable. Placing insulated conductors in conduits allows flood- damaged wiring to be removed and replaced. The conduit, after being cleaned and dried, can typically be reused. In saltwater environments, non-metallic conduits should be used. Routing and installation. Install main electric feeders on piles or other vertical structural elements to help protect them from floating debris forces. Since flood damage is often more extensive on the seaward side of a building, routing feeders on the landward side of the structural elements of the building can further reduce the potential for damage. Do not install wiring or devices on breakaway walls. Figure 12-5 is an illustration of recommended installation techniques for electric lines, plumbing, and other utility elements. Design approach. Install the minimum number of electric devices below the DFE that will provide compliance with the electric code. Feed the branch circuit devices from wiring above the DFE to minimize the risk of flood inundation. COASTAL CONSTRUCTION MANUAL 12-7 12 INSTALLING MECHANICAL EQUIPMENT AND UTILITIES Volume II Lowest horizontal structural Lowest horizontal structural member of elevated building member of elleevated building Install service connectors 1 (e.g., electric lines and meters, telephone junction < Install sewer and water boxes, cable junction boxes) risers on landward side above DFE, on landward of interior piles or other side of interior piles or other vertical support DFE vertical support members members f Secure risers with corrosion-resistant Pile Pile straps or anchors(2 feet on center, Oceanfront Oceanfront maximum) Grade /—Grade I I i I i• • _I I \_I Figure 12-5. Recommended installation techniques for electric and plumbing lines and utility elements Service style. Feed the building from underground service laterals instead of overhead electric service drops. When overhead services are needed, avoid penetrating the roof with the service mast to reduce the potential for roof damage and resulting water infiltration. Figure 12-6 illustrates the vulnerability of roof damage and resulting water infiltration when an electric service mast penetrates a roof. Panel location. Install branch circuit and service panelboards above the DFE. If required to meet utility National Electrical Code requirements, provide a separate service disconnect remote to the panel. Fact Sheet 8.3, Protecting Utilities, in FEMA P-499 contains other recommendations for reducing the vulnerability of utilities that supply buildings. Direct wind damage to exterior-mounted electric utility equipment (see Figure 12-6) is infrequent in part because of the small size of most equipment (e.g., disconnect switches, conduit). Exceptions are satellite dishes, photovoltaic panels, and electric service penetrations through the roof. Satellite dish and photovoltaic panel failures are typically caused by the design professional's failure to perform wind load calculations and provide for adequate anchorage. 12-8 COASTAL CONSTRUCTION MANUAL Volume II INSTALLING MECHANICAL EQUIPMENT AND UTILITIES 12 �a - _ 105 - _ Figure 12-6. �_�_ _____ '�`'` I `—�" Damage caused by � ....1 ....0.....r__ ""''"" dropped overhead . . �/ / service, Hurricane . i �a{ Marilyn (U.S.Virgin ilk"- '' '''. --"'"" Islands, 1995) . . . • • , . . . . . • • . • • . • • • . . ,.\ _.,„,„ . . . • • . , . , . :. .. . .. .. . • . • ____..„... f• /. _______ � -- _______,________ ___ . \ . a a,, i! a 12.4.1 Emergency Power0 CROSS REFERENCE Because a severe wind event often interrupts electric service, designers and homeowners need to make a decision about the For guidance on determining need for backup power. the proper size of an emergency generator, see Emergency power can be provided by permanently installed Section VI-D of FEMA 259, onsite generators or by temporary generators brought to the site Engineering Principles and Practices for Retrofitting Flood after the event. For permanently installed units, the following is Prone Residential Buildings recommended: (FEMA 2001). Locate the generator above the DFE. """"'"" If located on the exterior of the building, place the unit to prevent engine exhaust fumes from being drawn into doors,windows, or any air intake louvers into the building. If located on the inside of the building, provide ventilation for combustion air and cooling air and provision for adequately discharging exhaust fumes. Locate the fuel source above the DFE and store an amount of fuel adequate for the length of time the generator is expected to operate. Install the generator where its noise and vibration will cause the least disruption. Determine the expected load (e.g., heat, refrigeration, lights, sump pumps, sewer ejector pumps). Non-fuel-fired heating systems and most cooling systems require large generators. Capacity considerations may limit the generator to providing only freeze protection and localized cooling. Install manual or automatic transfer switches that prevent backfeeding power from the generator into the utility's distribution system. Backfeeding power from generators into the utility's distribution system COASTAL CONSTRUCTION MANUAL 12-9 12 INSTALLING MECHANICAL EQUIPMENT ANDUTILITIES Volume II can kill or injure workers attempting to repair damaged electrical lines. ` ----4 WARNING r' Provide an "emergency load" subpanel to supply critical Do not"backfeed"emergency circuits. Do not rely on extension cords. Supply the power through the service panel. Utility workers can be emergency panel from the load side of a manual or automatic killed! transfer switch. ' Determine whether operation of the generator will be manual or automatic. Manual operation is simpler and less expensive. However, a manual transfer switch requires human intervention. Owners should not avoid or delay evacuation to tend to an emergency power source. Size the generator, transfer switches, and interconnecting wiring for the expected load. The generator should be large enough to operate all continuous loads and have ample reserve capacity to start the largest motor load while maintaining adequate frequency and voltage control and maintaining power quality. 12.5 Water and Wastewater Systems Water and wastewater systems include wells, septic systems, sanitary systems, municipal water connections, and fire sprinkler systems. 12.5.1 Wells For protection of well systems from a severe event(primarily a flood),the design must include a consideration of the following, at a minimum: LI Floodwaters that enter aquifers or saturate the soil can contaminate the water supply. FEMA P-348, Principles and Practices for Flood-Resistant Building Utilities (FEMA 1999), recommends installing a watertight encasement that extends from at least 25 feet below grade to at least 1 foot above grade. r. Non-submersible well pumps must be above the DFE. If water is to be available following a disaster, an alternative power source must be provided. The water supply line riser must be protected from hydrodynamic and floodborne debris impact damage; the supply line must be on the landward side of a pile or other vertical structural member or inside an enclosure designed to withstand the forces from the event (see Figure 12-5). Backflow valves must be installed to prevent floodwaters from flowing into the water supply when water pressure in the supply system is lost. 12-10 COASTAL CONSTRUCTION MANUAL 1 Volume II i INSTALLING MECHANICAL EQUIPMENT AND UTILITIES 12 12.5.2 Septic Systems WARNING Leach fields and septic tanks, and the pipes that connect them, are highly susceptible to erosion and scour, particularly in In some areas, high Coastal A Zone and Zone V with velocity flow risks. The best groundwater levels may preclude the installation of way to protect leach fields and other onsite sewage management septic tanks below the level of elements is to locate them outside the floodplain. expected erosion and scour. If septic systems cannot be located outside the floodplain, the design of septic systems for protection from severe events must include a consideration of the following, at a minimum: If the septic tank is dislodged from its position in the ground, the piping will be disconnected, releasing sewage into floodwaters. Also, the tank could damage the nearest structure. Therefore, bury the system below the expected depth of erosion and scour, if possible, and ensure the tank is anchored to prevent a buoyancy failure. E The sewage riser lines and septic tank risers must be protected from water and debris flow damage; risers should be on the landward side of a,pile or other vertical structural member or inside an enclosure designed to withstand the forces from the event (see Figure 12-5). If leach fields, pipes, and tanks cannot be located outside the floodplain, one possible way to protect them is to bury them below the expected scour depth. However, many local health codes or ordinances restrict or even prohibit the placement of septic elements in the floodplain.In these cases, alternate sewage management systems must be used. Because leach fields rely on soil to absorb moisture,saturated soil conditions can render leach fields inoperable. This problem and its potential mitigating measures depend on complex geotechnical considerations. Therefore, a geotechnical engineer and/or a qualified sewer designer should be consulted for the design and installation of leach fields. 12.5.3 Sanitary Systems To protect sanitary systems from a severe event, the design must include a consideration of the following, at a minimum: Sanitary riser lines must be protected from water and debris flow damage; risers should be on the landward side of a pile or other vertical structural member or inside an enclosure designed to withstand the forces from the event (see Figure 12-5). When the line breaks at the connection of the building line and main sewer line, raw sewage can flow back out of the line, contaminating the soil near the building.A check valve in the line may help prevent this problem. COASTAL CONSTRUCTION MANUAL 12-11 4 12 INSTALLING MECHANICAL EQUIPMENT AND'UTILITIES Volume II 12.5.4 Municipal Water Connections If water risers are severed during a coastal event, damage to the water supply system can include waste from flooded sewer or septic systems intruding into the water system, sediment filling some portion of the pipes, and breaks in the pipes at multiple locations. Protecting municipal water connections is accomplished primarily by protecting the water riser that enters'the building from damage by debris. See Section 12.5.1 for more information. 12.5.5 Fire Sprinkler Systems Protecting the fire sprinkler system is similar to protecting the other systems discussed in Section 12.5. The primary issue is to locate the sprinkler riser such that the location provides shielding from damage. In addition, there must be consideration to the location of shutoff valves and other elements so that if an unprotected portion of the fire water supply line is damaged, the damage is not unnecessarily added to the damage caused by the natural hazard event. 12.6 References ASCE (American Society of Civil Engineers). 2010. Minimum Design Loads for Buildings and Other Structures.ASCE Standard ASCE 7-10. FEMA (Federal Emergency Management Agency). 1999. Principles and Practices for Flood-Resistant Building Utilities. FEMA P-348. FEMA. 2001.Engineering Principles and Practices for Retrofitting Flood Prone Residential Buildings. FEMA 259. FEMA. 2010a. Elevator Installation for Buildings Located in Special Flood Hazard Areas in Accordance with the National Flood Insurance Program. FEMA NFIP Technical Bulletin 4. FEMA. 2010b. Homebuilder's Guide to Coastal Construction. FEMA P-499. FEMA. 2010c. National Flood Insurance Program Flood Insurance Manual. ICC (International Code Council). 2011a. International Building Code. 2012 IBC. Country Club Hills, IL: ICC. ICC. 2011b. International Residential Code for One-and Two-Family Dwellings. 2012 IRC. Country Club Hills, IL: ICC. 12-12 COASTAL CONSTRUCTION MANUAL COASTAL CONSTRUCTION MANUAL i i psi'I . .. .7 _ Fit _ _ , _of.... -, J. 4; [ 11, , 41 -41R= Constructing tthe Building This chapter provides guidance on constructing residential buildings in coastal areas, which presents challenges that are usually not present in more inland locations (risk of high winds and coastal flooding and a corrosive environment) and other challenges such as the need to elevate the building. Considerations related to these challenges include the need to: Perform more detailed inspections of connection details than those performed in noncoastal areas to ensure the details can withstand the CROSS additional hazards found in coastal areas REFERENCE Include with the survey staking the building within property line For resources that 1. setbacks and at or above the design flood elevation (DFE) (see augment the guidance Section 4.5 for additional coastal survey regulatory requirements) and other information in this Manual, see the Residential Coastal 1 Ensure that all elements of the building will be able to withstand the Construction Web site I forces associated with high winds, coastal flooding, or other hazards (http://www.fema.gov/ I required of the design rebuild/mat/fema55. shtm). Ensure that the building envelope is constructed to minimize and ____..,...___. withstand the intrusion of air and moisture during high-wind events (see Section 11.3.1.4) Provide durable exterior construction that can withstand a moist and sometimes salt-laden environment Protect utilities, which may include placing them at or above the DFE COASTAL CONSTRUCTION MANUAL 13-1 13 CONSTRUCTING THE BUILDING Volume II Constructing coastal residential buildings on elevated pile foundations present the following additional challenges: I The difficulty of constructing a driven pile foundation to accepted construction plan tolerances The difficulty of constructing a building on an elevated post-and-beam foundation, which is more difficult than building on a continuous wall foundation This chapter discusses the construction aspects of the above challenges and other aspects of the coastal construction process, including the construction items that are likely to require the most attention from the builder in order for the design intent to be achieved. Although much of the discussion in this chapter is related to constructing the building to meet the architect's and engineer's design intent for existing and future conditions (such as erosion and sea-level rise), durability of the building elements is also important. Wood decay, termite infestation, metal corrosion, and concrete and masonry deterioration can weaken a building significantly, making it hazardous to occupy under any conditions and more likely to fail in a severe natural hazard event. Builders may find that the permitting and inspection procedures in coastal areas are more involved than those in inland areas. Not only must all Federal, State, and local Coastal Zone Management and other regulatory requirements be met, the design plans and specifications may need to be sealed by a design professional. Building permit submittals must often include detailed drawings and other types of information for all elements of the wind-resisting load path, including sheathing material, sheathing nailing, strap and tiedown descriptions, bolted connections, and pile description and placement. The placement of utilities at or above the DFE, breakaway walls, and flood equalization openings must be clearly shown. Site inspections are likely to focus on the approved plans, and building officials may be less tolerant of deviations from these approved construction documents than those in noncoastal areas. Inspection points are also discussed. 13.1 Foundation Construction Constructing a foundation in a coastal environment includes designing the layout, selecting the foundation type, selecting the foundation material with consideration for durability, and installing the foundation. Although pile foundations are the most common foundation type in Zone V and should be used in Coastal A Zones, shallow foundations, both masonry and concrete, may be acceptable elsewhere.Whether masonry, concrete, wood, or steel, all coastal foundation materials must be designed and installed to withstand the likelihood of high winds, moisture, and salt-laden air. See Chapter 10 for guidance on the design of coastal foundations. 13.1.1 Layout Surveying and staking must be done accurately in order to establish the building setback locations, the DFE, and the house plan and support locations. Figure 13-1 is a site layout with pile locations, batter boards, and setbacks and is intended to show the constraints a builder may face when laying out a pile-supported structure on a narrow coastal lot. There may be conflicts between what the contractor would like to do to prepare the site and what the environmental controls dictate can be done on the site. For example, leveling the site, especially altering dunes, and removing existing vegetation may be restricted. Furthermore, these 13-2 COASTAL CONSTRUCTION MANUAL s Volume II CONSTRUCTING THE BUILDING 13 I Figure 13-1. Street right-of-way , Site layout Ai ----- Property line ' Front �� property line setback r I< 60 feet >I ISide 1 Side �,, o o 0 oero property Piles line setback 'liestbck1.4 �N 3 o o, • o 0 0 `V ti -I'CD Exterior wall line •j -• I 1 i ; n n n ' n o o 412 cocci Porch 10 feet —1 a' o alb n a i. _ I A 44 '16 ' " feet feet l Coastal building ' ' IOffset Batter 'setback line Building line Rear distance, boards established property established offset of by surveyor line ' by surveyor building .setback I lines I r L_ _ _ Ocean _ ' _ _ _J restrictions may limit access by pile drivers'and other heavy equipment. Similarly, masonry and concrete foundations may require concrete pumping because of limited access to the traditional concrete mix truck and chute. In an elevated building with a pile foundation, the layout of the horizontal girders and beams should anticipate the fact that the final plan locations of the tops of the piles will likely not be precise. Irregularities in the piles and soil often prevent the piles from being driven perfectly plumb. The use of thick shims or overnotching for alignment at bolted pile-girder connections may have a significant adverse effect on the connection capacity and should be avoided.; Figure 13-2 shows the typical process of pile notching; the use of a chain saw for this process can lead to inaccuracies at this early stage of construction. Figure 13-3 shows a wood pile that is overnotched. Figure 13-4 shows a pile that has been properly notched to support the floor girder and cut so plenty of wood remains at the top of the pile. COASTAL CONSTRUCTION MANUAL ' 13-3 1 13 CONSTRUCTING THE BUILDING Volume II Figure 13-2. Typical pile notching process SOURCE:PATTY MCDANIEL,USED WITH PERMISSION 4 I .+ti 1 cirk• '\\ ,••4'.' . .1 '1 , 4%. • It ' . i , . .� o A ....... • , ),,j,.. 4 �\ f i Figure 13-3. Improper overnotched - wood pile SOURCE:PATTY MCDANIEL, USED WITH PERMISSION • 4 , ,i , , . , ,,_ - , . ,,,,- - . , . k,,,j , ) , _____ _ mi, as . , • 13-4 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 Figure 13-4. Properly notched pile; outer member of this three- member beam supported by the through-bolt rather than the beam seat Notch " .44 I . Death 4 i � 1 A rule of thumb regarding notching is to notch no more than 50 percent of the pile cross section, but in no case should notching be in excess of that specified by the design professional. Section 13.2 presents information concerning the reinforcement of overnotched and misaligned piles. The primary floor girders spanning between pile or foundation supports should be oriented parallel to the primary flow of potential floodwater and wave action if possible. This orientation (normally at right angles to the shoreline) allows the lowest horizontal structural member perpendicular to flow to be the floor joists. Thus, in an extreme flood, the girders are not likely be subjected to the full force of the floodwater and debris along their more exposed surfaces. The entire structure is built on the first floor, and it is therefore imperative that the first floor be level and square. The "squaring" process normally involves taking diagonal measurements across the outer corners and shifting either or both sides until the diagonal measurements are the same, at which point the building is square. An alternative is to take the measurements of a "3-4-5" triangle and shift the floor framing until the "3-4-5" triangular measurement is achieved. 13.1.2 Pile Foundations Pile foundations are the most common foundation type in Zone V coastal buildings and should also be used in Coastal A Zones where scour and erosion conditions along with potentially destructive wave forces make it inadvisable to construct buildings on shallow foundations. In many coastal areas, the most common type of pile foundation is the elevated wood pile foundation in which the tops of the piles extend above grade to about the level of the DFE (see Figure 13-5). COASTAL CONSTRUCTION MANUAL 13-5 13 CONSTRUCTING THE BUILDING Volume II Figure 13-5. Typical wood pile foundation 1.1 -'114111hismi. v/ I I 'I I' S'I - IN I 11 '�= te - - -+ Horizontal framing girders connected to the tops of the piles form a platform on which the house is built. Appendix B of ICC 600-2008 contains some girder designs for use with foundations discussed in FEMA P-550, Recommended Residential Construction for the Gulf Coast(FEMA 2006). In addition, the 2012 IRC contains prescriptive designs of girder and header spans. Furthermore, Fact Sheet 3.2, Pile Installation, in FEMA P-499 (FEMA 2011) presents basic information about pile design and installation, including pile types, sizes and lengths, layout, installation methods, bracing, and capacities. For more information on pile- to-beam connections, see Fact Sheet 3.3, Wood Pile-to-Beam Connections, in FEMA P-499, which presents basic construction guidance for various construction methods. The discussion in this section is focused on the construction of an elevated wood pile foundation. Precautions should be taken in handling and storing pressure-preservative-treated round or square wood piles. They should not be dragged along the ground or dropped. They should be stored well-supported on skids so that there is air space beneath the piles and the piles are not in standing water. Additional direction and precautions for pile handling, storage, and construction are found in Section 10.5 of this Manual and AWPA Standard M4-91. WARNING The effectiveness of pile foundations and the pile load capacity is The amount of long-term related directly to the method of installation. The best method is and storm-induced erosion to use a pile driver, which uses leads to hold the pile in position expected to occur at the while a single- or double-acting diesel- or air-powered hammer site (see Section 3.5 in drives the pile into the ground. Pile driving is often used with Volume I of this Manual) must detd auguring to increase pile embedment. Augurs are used to drill ao nea before any ass suumm ptidons about soils are the first several feet into the soil, and the piles are then driven made or analyses of the soils to refusal. Auguring has the added benefit of improving pile are conducted. Only the soils alignment. that will remain after erosion can be relied on to support the foundation members. 13-6 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 The pile driver method is cost-effective in a development when a number of houses are constructed at one time but may be expensive for a single building. The drop hammer method is a lower cost alternative and is considered a type of pile driving, as discussed in Section 10.5.4. A drop hammer consists of a heavy weight that is raised by a cable attached to a power-driven winch and then dropped onto the end of the pile. A less desirable but frequently used method of inserting piles into sandy soil is "jetting." Jetting involves forcing a high-pressure stream of water through a pipe advanced along the side of the CROSS REFERENCE pile. The water blows a hole in the sand into which the pile is See Section 10.5.4 for a continuously pushed or dropped until the required depth is discussion of pile capacities reached. Unfortunately, jetting loosens the soil around the pile for various installation and the soil below the tip, resulting in a lower load capacity. methods. Holes for piles may be excavated by an auger if the soil is sufficiently clayey or silty. In addition, some sands may contain enough clay or silt to permit augering. This method can be used by itself or in conjunction with pile driving. If the hole is full-sized, the pile is dropped in and the void backfilled.Alternatively, an undersized hole can be excavated and a pile driven into it.When the soil conditions are appropriate, the hole stays open long enough to drop or drive in a pile. In general, piles dropped or driven into augered holes may not have as much capacity as those driven without augering. If precast concrete piles or steel piles are used, only a regular pile driver with leads and a single- or double- acting hammer should be used. For any pile driving, the building jurisdiction or the engineer-of-record will probably require that a driving log be kept for each pile.The log will show the number of inches per blow as the driving progresses—a factor used in determining the pile capacity, as shown in Equation 13-1.As noted in Section 10.3, the two primary determinants of pile capacity are the depth of embedment in the soil and the soil properties. Piles must be able to resist vertical loads (both uplift and gravity) and lateral loads. Sections 8.5 and 8.10 contain guidance on determining pile loads. It is common practice to estimate the ultimate vertical load bearing capacity of a single pile on the basis of the driving resistance. Several equations are available for making such estimates. However, the results are not always reliable and may over-predict or under-predict the capacity, so the equations should be used with caution. One method of testing the recommended capacity based on an equation is to load test at least one pile at each location of known soil variation. The designer should also keep in mind that constructing a pile foundation appropriately for the loads it must resist in the coastal environment may drastically reduce future costs by helping to avoid premature failure. Many factors in addition to vertical and lateral loads must be taken into account in the coastal environment. For example, erosion and scour can add stress on the foundation members and change the capacity to which the piles should be designed. The complex and costly repairs to the home shown in Figure 10-2 could have been avoided if all forces and the reduced pile capacity resulting from erosion and scour had been considered in the pile foundation design. Equation 13.1 can be used to determine pile capacity for drop hammer pile drivers. Equations for other pile driver configurations are provided in U.S. Department of the Navy Design Manual 7.2, Foundation and Earth Structures Design (USDN 1982). COASTAL CONSTRUCTION MANUAL 13-7 13 CONSTRUCTING THE BUILDING Volume II , EQUATION.13.1. PILE DRIVING RESISTANCE FOR DROP HAMMER PILE DRIVERS { 2WH i Qdir— (S+1)-.. . where:'. QQl = allowable pile capacity (in 1b) W = weight of the striking parts of the hammer (in lb) H = effective height of the fall (in ft)' S = average net penetration,given as in. per blow for the last 6 in. of driving Lateral and uplift load capacity of piles varies greatly with the soils present at the site. Pile foundation designs should be based on actual soil borings at the site (see Section 10.3.3.2). Variation in the final locations of the pile tops can complicate subsequent construction of floor beams and bracing. The problem is worsened by piles with considerable warp, non-uniform soil conditions, and material buried below the surface of the ground such as logs, gravel bars, and abandoned foundations. Builders should inquire about subsurface conditions at the site of a proposed building before,committing to the type of pile or the installation method (see Section 10.3.3). A thorough investigation of site conditions can help prevent costly installation errors. The soils investigation should determine the following: t: Type of foundations that have been installed in the area in the past u Type of soil that might be expected (based on past soil borings and soil surveys) G Whether the proposed site has been used for any other purpose and if so, the likelihood of buried materials present on the site Scour and erosion both reduce pile capacities and erosion can increase flood loads on a pile. Scour and erosion must be considered in a properly designed pile foundation. Additional guidance on the effects of scour and erosion on piles is provided in Section 8.5.11 and Section 10.5.5. 13.1.3 Masonry Foundation Construction; , N _ _ _ The combination of high winds and moist and sometimes salt- _ WARNING laden air can have a damaging effect on masonry construction by forcing moisture into the smallest cracks or openings in the Open masonry foundations masonry joints. The entry of moisture into reinforced masonry in earthquake hazard areas require special reinforcement construction can lead to corrosion of the reinforcement and detailing and pier proportions subsequent cracking and spalling if proper protection of the to meet the requirement for reinforcement is not provided, as required by TMS 402/ACI 530/ increased ductility. ASCE 5 and TMS 602/ACI 530.1/ASCE 6. Moisture resistance 13-8 COASTAL CONSTRUCTION MANUAL 4 Volume II CONSTRUCTING THE BUILDING 13 is highly influenced by the quality of the materials and the quality of the masonry construction at the site. Masonry material selection is discussed in Section 9.4 of this Manual. The quality of masonry construction depends on many considerations. Masonry units and packaged mortar and grout materials should be stored off the ground and covered. Mortar and grouts must be carefully batched and mixed.As the masonry units are placed, head and bed joints must be well mortared and tooled. The 2012 IRC provides grouting requirements. Masonry work in progress must be well protected. Moisture penetration or retention must be carefully controlled where masonry construction adjoins other materials. As in any construction of the building envelope in the coastal environment, flashing at masonry must be continuous,durable, and of sufficient height and extent to impede the penetration of expected wind- driven precipitation. For more information on moisture barrier systems, see Fact Sheet 1.9,Moisture Barrier Systems, in FEMA P-499. Because most residential buildings with masonry foundations have other materials (e.g., wood, concrete, - steel, vinyl) attached to the foundation, allowance must be made for NOTE shrinkage of materials as they dry out and for differential movement -- - between the materials. Expansion and contraction joints must be Tooled concave joints and placed so that the materials can move easily against each other. V-joints provide the best moisture resistance. Masonry is used for piers, columns, and foundation walls. As explained in Section 10.2.1, the National Flood Insurance Program (NFIP) regulations require open foundations (e.g., piles, piers, posts, columns) for buildings constructed in Zone V. Buildings in Zone A may be constructed on any foundation system. However, because of the history of observed damage in Coastal A Zone and the magnitude of the flood and wind forces that can occur in these areas, this Manual recommends that only open foundation systems be constructed in Coastal A Zones. Figure 13-6 shows an open masonry foundation with only two rows of piers. It is unlikely that this foundation system could resist the overturning caused by the forces described in Chapter 8 and shown in Example 8-10. Fact Sheet 3.4, Reinforced Masonry Pier Construction, in FEMA P-499 provides recommendations on pier construction best practices. Fact Sheet 4.2, Masonry Details, in FEMA P-499 provides details on masonry wall-to-foundation connections. Reinforced masonry has much more strength and ductility than unreinforced masonry for resisting large wind, water, and earthquake forces. This Manual recommends that permanent masonry foundation construction in and near coastal flood hazard areas (both Zone A and Zone V) be fully or partially reinforced and grouted solid regardless of the purpose of the construction and the design loads. Grout should be in conformance with the requirements of the 2012 IBC. Knockouts should be placed at the bottom of fully grouted cells to ensure that the grout completely fills - the cells from top to bottom. Knockouts are required only for walls (or piers) exceeding 5 feet in height. NOTE For CMUs, shrinkage cracking can be minimized by using Type I In areas not subject to moisture-controlled units and keeping them dry in transit and on earthquake hazards, the job. Usually, for optimum crack control, Type S mortar should breakaway walls below be used for below-grade applications and Type N mortar for above- elevated buildings may be constructed using grade applications. The 2012 IBC specifies grout proportions by unreinforced and ungrouted volume for masonry construction. masonry. COASTAL CONSTRUCTION MANUAL 13-9 13 CONSTRUCTING THE BUILDING Volume II Figure 13-6. Open masonry foundation it N s :ill . . %., le ,,..., 7 r=�' l 13.1.4 Concrete Foundation Construction Concrete foundation or superstructure elements in coastal construction almost always require steel reinforcement. Figure 13-7 shows a concrete foundation, and Figure 13-8 shows a house being constructed with concrete. Completed cast-in-place exterior concrete elements should generally provide 1-1/2 inches or more of concrete cover over the reinforcing bars. Minimum cover values vary according to bar size and exposure to earth or weather per ACI 318-08.This thickness of concrete cover serves to protect the reinforcing bars from corrosion, as does an epoxy coating. The bars are also protected by the natural alkalinity of the concrete. However, if saltwater penetrates the concrete cover and reaches the reinforcing steel, the concrete alkalinity will be reduced by the salt chloride and the steel can corrode if it is not otherwise protected. As the corrosion forms, it expands and cracks the concrete, allowing the additional entry of water and further corrosion. Eventually, the corrosion of the reinforcement and the cracking of the concrete weaken the concrete structural element, making it less able to resist loads caused by natural hazards. During placement, concrete normally requires vibration to eliminate air pockets and voids in the finished surface. The vibration must be sufficient to eliminate the air without separating the concrete or water from the mix. 13-10 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 %1 ►.: I Figure 13-7. • ' -' . ! Concrete foundation ♦t ` 400 1 t i 1 . 41 1111:' T. t. - _ - k - Figure 13-8. Concrete house Il9 1 40 . , 1 a j le } l i 9 41 P ' 1 raa _ liek ! IA mAt _ WV . j To ensure durability and long life in coastal, saltwater-affected locations, it is especially important to carefully carry out concrete construction in a fashion that promotes durability. "Material Durability in Coastal Environments," available on the Residential Coastal Construction Web site (http://www.fema.gov/ rebuild/mat/fema55.html) describes the 2012 IBC requirements for more durable concrete mixes with lower water-cement ratios and higher compressive strengths (5,000 pounds/square inch) to be used in a saltwater environment. The 2012 IBC also requires that additional cover thickness be provided. Proper placement, consolidation, and curing are also essential for durable concrete. The concrete mix water-cement ratio required by 2012 IBC or by the design should not be exceeded by the addition of water at the site. It is likely that concrete will have to be pumped at many sites because of access limitations or elevation differences between the top of the forms and the concrete mix truck chute. Pumping concrete requires some COASTAL CONSTRUCTION MANUAL 13-11 13 CONSTRUCTING THE BUILDING Volume II N ' minor changes in the mix so that the concrete flows f smoothly through the pump and hoses. Plasticizers --' NOTE should be used to make the mix pumpable; water should not be used to improve the flow of the mix. ACI 318-08 specifies minimum amounts of concrete cover for various construction Concrete suitable for pumping must generally have a applications. Per the Exception to 1904.3 slump of at least 2 inches and a maximum aggregate in the 2012 IBC, concrete mixtures for any size of 33 to 40 percent of the pump pipeline R occupancies need only comply with the diameter. Pumping also increases the temperature freeze/thaw requirements (as traditionally of the concrete, thus changing the curing time and tabulated in the 2012 IBC and 2012 IRC), not the permeability and corrosion characteristics of the concrete depending on the requirements of ACI 318-08. outdoor temperature. Freeze protection may be needed, particularly .for columns and slabs, if pouring is done in cold temperatures. Concrete placed in cold weather takes longer to cure, and the uncured concrete may freeze, which adversely affects its final strength. Methods of preventing concrete from freezing during curing include: r Heating adjacent soil before pouring on-grade concrete r Warming the mix ingredients before batching C. Warming the concrete with heaters after pouring (avoid overheating) Placing insulating blankets over and around the forms after pouring L- Selecting a cement mix that will shorten curing time Like masonry, concrete is used for piers, columns, and walls; the recommendation in Section 13.1.3 regarding open foundations in Coastal A Zones also applies to concrete foundations. In addition, because the environmental impact of salt-laden air and moisture make the damage potential significant for concrete, this Manual recommends that all concrete construction in and near coastal flood hazard areas (both Zone V and Zone A) be constructed with the more durable 5,000-pounds/square inch minimum compressive strength concrete regardless of the purpose of the construction and the design loads. 13.1.5 Wood Foundation Construction All of the wood used in the foundation piles, girders, beams, and braces must be preservative-treated wood or, when allowed, naturally decay-resistant wood. Section 9.4 discusses materials selection for these wood elements. Piles must be treated with waterborne arsenicals, creosote, or both. Girders and braces may be treated with waterborne arsenicals, pentachlorophenol, or creosote. Certain precautions apply to working with any of these treated wood products, and additional precautions apply for pentachlorophenol- and creosote-treated wood (see Section 13.1.5.1). Additional information is available in Consumer Information Sheets where the products are sold. Wood foundations are being constructed in some parts of the country as part of a basement or crawlspace. These foundation elements have walls constructed with pressure-preservative-treated plywood and footings constructed with wide pressure-preservative-treated wood boards such as 2x10s or 2x12s. Because the NFIP regulations allow continuous foundation walls (with the required openings) in Coastal A Zones, continuous 13-12 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 wood foundations might seem to be acceptable in these areas. However, because of the potential forces from waves less than 2 feet high (as discussed in Section 10.8), a wood foundation supported on a wood footing is not recommended in Coastal A Zones. When working with treated wood, the following health and safety precautions should be taken: L1 Avoid frequent or prolonged inhalation of the sawdust. When sawing and boring, wear goggles and a dust mask. Use only treated wood that is visibly clean and free of surface residue should be used for patios, decks, and walkways. Before eating or drinking, wash all exposed skin areas thoroughly. Li If preservatives or sawdust accumulate on clothes, wash the clothes (separately from other household clothing) before wearing them again. Dispose of the cuttings by ordinary trash'collection or burial. The cuttings should not be burned in open fires or in stoves, fireplaces, or residential boilers because toxic chemicals may be produced as part of the smoke and ashes. The cuttings may be burned only in commercial or industrial incinerators or boilers in accordance with Federal and State regulations. r? Avoid frequent or prolonged skin contact with pentachlorophenol or creosote-treated wood;when handling it,wear long-sleeved shirts and long pants and use gloves impervious to the chemicals (e.g., vinyl-coated gloves). Do not use pentachlorophenol-pressure-treated wood in residential interiors except for laminated beams or for building elements that are in ground contact and are subject to decay or insect infestation and where two coats of an appropriate sealer are applied. Sealers may be applied at the installation site. Urethane, shellac, latex epoxy enamel, and varnish are acceptable sealers. P. Do not use creosote-treated wood in residential interiors. Coal tar pitch and coal tar pitch emulsion are effective sealers for outdoor creosote-treated wood-block flooring. Urethane, epoxy, and shellac are acceptable sealers for all creosote-treated wood. 13.1.6 Foundation Material Durability Ideally, all of the pile-and-beam foundation framing of a coastal building is protected from rain by the overhead structure, even though all of the exposed materials should be resistant to decay and corrosion. In practice, the overhead structure includes both enclosed spaces (such as the main house) and outside decks. The spaces between the floor boards on an outside deck allow water to pass through and fall on the framing below. A worst case for potential rain and moisture penetration exists when less permeable decks collect water and channel it to fall as a stream onto the framing below. In addition, wind-driven rain and ocean spray penetrates into many small spaces, and protection of the wood in these spaces is therefore important to long-term durability of the structure. The durability of the exposed wood frame can be improved by detailing it to shed water during wetting and to dry readily afterward. Decay occurs in wetted locations where the moisture content of the exposed, COASTAL CONSTRUCTION MANUAL 13-13 13 CONSTRUCTING THE BUILDING Volume II untreated interior core of treated wood elements remains above the fiber saturation point—about 30 percent. The moisture content of seasoned, surface-dry 2x lumber (S-DRY) is less than or equal to 19 percent content when it arrives at the job site, but the moisture content is quickly reduced as the wood dries in the finished building. The moisture content of the large members (i.e., greater than 3 times) is much higher than 19 percent when they arrive at the job site, and the moisture content takes months to drop below 19 percent. The potential for deterioration is greatest at end grain surfaces. Water is most easily absorbed along the grain, allowing it to penetrate deep into the member where it does not readily dry. Figure 13-9 illustrates deterioration in the end of a post installed on a concrete base. This is a typical place for wood deterioration to occur. Even when the end grain is more exposed to drying, the absorptive nature of the end grain creates an exaggerated shrink/swell cycling, resulting in checks and splits, which in turn allow increased water penetration. Exposed pile tops present the vulnerable horizontal end grain cut to the weather. Cutting the exposed top of a pile at a slant does not prevent decay and may even channel water into checks. Water enters checks and splits in the top and side surfaces of beams and girders. It can then penetrate into the untreated core and cause decay. These checks and splits occur naturally in large sawn timbers as the wood dries and shrinks over time. They are less common in glue-laminated timbers and built-up sections. It is generally, but not universally, agreed that caulking the checks and splits is unwise because caulking is likely to promote water retention more than keep water out. The best deterrent is to try to keep the water from reaching the checks and splits. Framing construction that readily collects and retains moisture, such as pile tops, pile-beam connections, and horizontal girder and beam top surfaces, can be covered with flashing or plywood. However, there should always be an air gap between the protected wood and the flashing so that water vapor passing out of the wood is not condensed at the wood surface. For example, a close-fitting cap of sheet metal on a pile top can cause water vapor coming out of the pile top to condense and cause decay.The cap can also funnel water into the end grain penetrations of the vertical fasteners. Figure 13-9. I err Wood decay at the base {'. . .7, . h , - of a post supported by I t •�., .: concrete t 0 F• kr 1 v l y-) 11 1ear .LLi� t •. Y F a u' `c am r� r.•• :� s r g fi :'! t",.�:.►a .. a Ir*fie r`14- ti l r1 � •,�: Sw` tr4�r ; 4z,1 2:141 Fp� t .V t-tt,L," 13-14 COASTAL CONSTRUCTION MANUAL Volume II i CONSTRUCTING THE BUILDING 13 When two flat wood surfaces are in contact in a connection, the contact surface tends to retain any water directed to it. The wider the connection's least dimension, the longer the water is retained and the higher the likelihood of decay. Treated wood in this contact surface is more resistant to decay but only at an uncut surface. The least dimension of the contact surface should be as small as possible.When the contact surfaces are for structural bearing, only as much bearing surface as needed should be provided, considering both perpendicular-to-grain and parallel-to-grain',bearing design stresses. For example, deck boards on 2x joists have a smaller contact surface least dimension than deck boards on 4x joists. A beam bolted alongside an unnotched round wood pile has a small least dimension of the contact surface. Figure 13-10 illustrates the least-dimension concept. Poor durability performance has been observed in exposed sistered members. When sistered members must be used in exposed conditions, they should be of ground-contact-rated treated wood, and the top surface should be covered with a self-adhering modified bitumen ("peel and stick") flashing membrane.This material is available in rolls as narrow as 3 inches. The membranes seal around nail penetrations to keep water out. In contrast, sheet-metal flashings over sistered members, when penetrated by nails, can channel water into the space between the members. Other methods of improving exposed structural frame durability include: Using drip cuts to avoid horizontal water movement along the bottom surface of a member. Figure 13-11 shows this type of cut. Figure 13-10. Examples of minimizing Contact Contact the least dimension of surfaces surfaces • wood contact surfaces Connectors Connectors Contact surfaces Contact — surfaces ' Connectors Connectors Figure 13-11. • Drip cut to minimize 1,,: horizontal water movement along the bottom surface of a wood • member Drip cut ,_______) COASTAL CONSTRUCTION MANUAL ' 13-15 i 1 13 CONSTRUCTING THE BUILDING Volume II Avoiding assemblies that form "buckets" and retain water adjacent to wood. Avoiding designs that result in ledges below a vertical or sloped surface. Ledges collect water quite readily, and the resulting ponding from rain or condensation alternating with solar radiation causes shrink-swell cycling, resulting in checks that allow increased water penetration. To the extent possible, minimizing the number of vertical holes in exposed horizontal surfaces from nails, lags, and bolts. When possible, avoiding the use of stair stringers that are notched for each stair. Notching exposes the end grain, which is then covered by the stair.As a result, the stair tends to retain moisture at the notch where the bending stress is greatest at the minimum depth section. Figure 13-12 illustrates stair stringer exposure, and Figure 13-13 shows the type of deterioration that can result. Figure 13-12. Exposure of end grain in stair stringer cuts Exposed end grains 14,--7-- Minimum depth of p stair stringer F Figure 13-13. — Deterioration in a notched j 4 ; - - stair stringer ° ' w -, Irk,,, mit ! - : •,- - . 6.101 fir' . i F fI ;� !a I 13-16 COASTAL CONSTRUCTION MANUAL i Volume II CONSTRUCTING THE BUILDING 13 C: Using the alternative stair stringer installation shown in Figure 13-14 when the stair treads are either nailed onto a cleat or the stringer is routed out so the tread fits into the routed-out area. Even these alternatives allow water retention at end grain surfaces, and these surfaces should therefore be field- treated with wood preservative. f Caulking joints at wood connections to keep water out. Caulk only the top joints in the connection. Recaulk after the wood has shrunk, which can take up to a year for larger members. When structurally possible, considering using spacers or shims to separate contact surfaces.A space of about 1/16-inch discourages water retention by capillary action but can easily fill with dirt and debris.A 1/4- to 1/2-inch space is sufficient to allow water and debris to clear from the interface. This spacing has structural limitations; a bolted connection with an unsupported shim has much less shear capacity than an unspaced connection because of increased bolt bending and unfavorable bearing stress distribution in the wood. Figure 13-14. Alternative method of installing stair treads Wood stair treads ttia Stair 4 Y stringer _ -Stair tread — Stair tread Stair tread Stair support routed Stair 2x cleat stringer out of stringer stringer 13.1.7 Field Preservative Treatment, Field cuts and bores of pressure-preservative-treated piles, timbers, and lumber are inevitable in coastal construction. Unfortunately, these cuts expose the inner untreated part of the wood member to possible decay and infestation. Although field preservative treatments are much less effective than pressure- preservative treatment, the decay and infestation potential can be minimized by treating the cuts and bolt holes with field-applied preservative. COASTAL CONSTRUCTION MANUAL 13-17 13 CONSTRUCTING THE BUILDING Volume II 13.1.8 Substitutions WARNING During construction, a builder may find that materials called for in the construction plans or specifications are not available When substitutions are proposed, the design or that the delivery time for those materials is too long and will professional's approval delay the completion of the building. These conflicts require should be obtained before decisions about substituting one type of construction material for the substitution is made.The another. Because of the high natural hazard forces imposed on ramifications of the change must be evaluated, including buildings near the coast and the effects of the severe year-round the effects on the building environment in coastal areas, substitutions should be made only elements, constructability, and after approval by a design professional and, if necessary, the local long-term durability. Code and building official. regulatory ramifications should also be considered. 13.1.9 Foundation Inspection Points If the foundation is not constructed properly, many construction details in the foundation can cause failure during a severe natural hazard event or premature failure because of deterioration caused by the harsh coastal environment. Improperly constructed foundations are frequently covered up, so any deficiency in the load- carrying or distributing capacity of one member is not easily detected until failure occurs. It is therefore very important to inspect the foundation while construction is in progress to ensure that the design is completed as intended. Table 13-1 is a list of suggested critical inspection points for the foundation. Table 13-1. Foundation and Floor Framing Inspection Points Inspection Point Reason 1. Pile-to-girder connection Ensures that pile is not overnotched, that it is field-treated, and that bolts are properly installed with washers and proper end and edge distance 2.Joist-to-girder connection Verifies presence of positive connection with properly nailed, corrosion- resistant connector 3.Joist blocking Ensures that the bottom of the joist is prevented from bending/buckling ! 4.Sheathing nailing- • Ensures that sheathing,acts as a shear diaphragm number, spacing, depth 5. Material storage- Ensures that the wood does not absorb too much moisture prior to protection from elements installation—exposure promotes checks and splits in wood, warp, and prior to installation separation in plywood 6.Joist and beam material- Ensures that new floors are installed level and eliminates need to repair excessive crown or lateral warping, large splits large splits innew'material 13.1.10 Top Foundation Issues for Builders The top foundation-related issues for builders are as follows: E. Piles, piers, or columns must be properly aligned. Piles, piers, or columns must be driven or placed at the proper elevation to resist failure and must extend below the expected depth of scour and erosion. 13-18 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 Foundation materials must be damage-resistant to flooding (pressure-treated wood, masonry, or concrete). The support at the top of the foundation element must be adequate to properly attach the floor framing system. Notching of a wood foundation element should not exceed the specifications in the construction documents. Breakaway walls should not be overnailed to the foundation. They are intended to fail. Utilities and other obstructions should not be installed behind these walls, and the interior faces should not be finished. For masonry or concrete foundation elements (except slabs-on-grade), the proper size of reinforcing, proper number of steel bars, and proper concrete cover over the steel should be used. = Concrete must have the proper mix to meet the specialized demands of the coastal environment. r: Exposed steel in the foundation corrodes; corrosion should be planned for by installing hot-dipped galvanized or stainless steel. Areas of pressure-treated wood that have been cut or drilled retain water and decay; these cut areas should be treated in the field. 13.2 Structural Frame Structural framing includes framing the floors, walls, and roof 7/1)\, and installing critical connections between each element. WARNING The connections described 13.2.1 Structural Connections in this Manual are designed to hold the building One of the most critical aspects of building in a coastal area together in a design event. is the method that is used to connect the structural members. Builders should never A substantial difference usually exists between connections underestimate the importance of installing connectors acceptable in inland construction and those required to withstand according to manufacturers' the natural hazard forces and environmental conditions in , recommendations. Installing coastal areas. Construction in noncoastal, nonseismic areas must connectors properly is normally support only vertical dead and live loads and modest extremely important. wind loads. In most coastal areas, large forces are applied by - wind, velocity flooding, wave impact, and floating debris. The calculated forces along the complete load path usually require that the builder provide considerable lateral and uplift capacity in and between the roof, walls, floors, girders, and piles. Consequently, builders should be sure to use the specified connectors or approved substitutes. Connectors that look alike may not have the same capacity, and a connector designed for gravity loads may have little uplift resistance. Fact Sheet 4.1, Load Path, in FEMA P-499 describes load paths and highlights important connections in a typical wind load path. The nails required for the connection hardware may not be regularly found on the job site. For example,full- diameter 8d to 20d short nails are commonly specified for specific hurricane/seismic connection hardware. COASTAL CONSTRUCTION MANUAL 13-19 qR 13 CONSTRUCTING THE BUILDING Volume II Figure 13-15. I 7 1 �;; Connector failure caused v � ►. . by insufficient nailing , . • -_ 11.010.1.1111.11111.61.141.1t1 a. • a 4. • •� _ r- .. to i irk AIr A r - r , h• WARNING .V `6': jr ...' • — � . Proper nail selection and ~ • ,. installation are critical. Builders a. _ should not substitute different i • nails or nailing patterns without . 1,07• approval from the designer. - � For full strength, these connections require that all of the holes in the hardware be nailed with the proper nails. In the aftermath of investigated hurricanes, failed connector straps and other hardware have often been found to have been attached with too few nails, nails of insufficient diameter, or the wrong type of nail. Figure 13-15 shows a connector that failed because of insufficient nailing. As mentioned previously, connection hardware must be corrosion-resistant. If galvanized connectors are used, additional care must be taken during nailing. When a hammer strikes the connector and nail during installation, some of the galvanizing protection is knocked off. One way to avoid this problem is to use corrosion-resistant connectors that do not NOTE depend on a galvanized coating, such as stainless steel or wood (see Section 9.2.3). Only stainless Additional information about pneumatic nail steel nails should be used with stainless steel guns can be obtained from the International connectors. An alternative to hand-nailing is to Staple, Nail and Tool Association, 512 West use a pneumatic hammer that "shoots" nails into Burlington Ave., Suite 203, LaGrange, IL 60525-2245. A report prepared by National connector holes. Evaluation Service, Inc., NER-272, Power- Driven Staples and Nails for Use in All Types All connections between members in a wood- of Building Construction (NES 1997), presents frame building are made with nails, bolts, screws, information about the performance of or a similar fastener. Each fastener is installed by pneumatic nail guns and includes prescriptive hand. The predominant method of installing nails nailing schedules. 13-20 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 is by pneumatic nail gun. Many nail guns use nails commonly referred to as "sinkers." Sinkers are slightly smaller in diameter and thus have lower withdrawal and shear capacities than common nails of the same size. Nail penetration is governed by air pressure for pneumatic nailers, and nail penetration is an important quality control issue for builders. Many prescriptive codes have nailing schedules for various building elements such as shearwalls and diaphragms. Another critical connection is the connection of the floor to the piles. Pile alignment and notching are critical not only to successful floor construction but also to the structural adequacy during a natural hazard event (see Section 13.1.1). Construction problems related to these issues are also inevitable, so solutions to pile misalignment and overnotching must be developed. Figure 13-16 illustrates a method of reinforcing an overnotched pile,including one that is placed on a corner.The most appropriate solution to pile misalignment is to re-drive a pile in the correct location.An alternative is illustrated in Figure 13-17,which shows a method of supporting a beam at a pile that has been driven "outside the layout" of the pile foundation. Figure 13-18 Figure 13-16. Beam Reinforcement of overnotched piles ft1/4-inch x 6-inch wide galvanzied steel plate or 1/4 inch x 3-inch x III II 3-inch angle support Bolts A Equal distance 2211 ' K II Pile Notch depth • Angle support Plate or . Solid blocking angle Beam 11 Pile Bolts Pile Bolts Beam In-line pile Corner pile COASTAL CONSTRUCTION MANUAL 13-21 13 CONSTRUCTING THE BUILDING Volume II Figure 13-17. Beam support at misaligned piles D-4\Pile Floor support beam Install solid spacer Misaligned pile Bolts Support angle- _ _41id A A Twice horizontal Support depth (d) of angle ang eort �------Floor support beam Misaligned pile D-4 -Pile Section A-A Figure 13-18. Proper pile notching for ir Beam Beam two-member and four- member beams Bolts11111 Pile Pile Two-member beam Four-member beam 13-22 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 illustrates the proper pile notching for both two-member and four-member beams. See Section 13.1.1 for more information on pile notching. After the "square" foundation has been built, the primary layout concerns about how the building will perform under loads are confined to other building elements being properly located so that load transfer paths are complete. 13.2.2 Floor Framing The connection between wood floor joists and the supporting w beams and girders is usually a bearing connection for gravity CROSS REFERENCE forces with a twist strap tie for uplift forces. Figure 13-19 shows a twist tie connection. This connection is subjected to large uplift See NFIP Technical Bulletin forces from high winds. In addition, the undersides of elevated 8-96, Corrosion Protection for Metal Connectors in Coastal structures, where these connectors are located, are particularly Areas (FEMA 1996). vulnerable to salt spray; the exposed surfaces are not washed by rain, and they stay damp longer because of their sheltered location. Consequently, the twist straps and the nails used to secure them must be hot-dipped galvanized or stainless steel. One way to reduce the corrosion potential for metal connectors located under the building is to cover the connectors with a plywood bottom attached to the undersides of the floor joists. (The bottom half of the joist-to-girder twist straps will still be exposed, however.) This covering will help keep insulation in the floor joist space as well as protect the metal connectors. Because the undersides of Zone V buildings are exposed, the first floor is more vulnerable to uplift wind and wave forces, as well as to the lateral forces of moving water, wave impact, and floating debris. These loads cause compressive and lateral forces in the normally unbraced lower flange of the joist. Solid blocking or lx3 cross-bridging at 8-foot centers is recommended for at least the first floor joists unless substantial sheathing (at least 1/2-inch thick) has been nailed well to the bottom of these joists. Figure 13-19 also shows solid blocking between floor joists. __ Figure 13-19. Proper use of metal twist strap ties (circled); solid - blocking between floor joists - ' . 1 AVW - ___________ if . ., __ . ....„• . . ..:.. 0, . _ . ..._ . ......, _ _ 1 i miiimii_ ' . __ vY COASTAL CONSTRUCTION MANUAL 13-23 13 CONSTRUCTING THE BUILDING Volume II Floor framing materials other than 2x sawn lumber are becoming popular in many parts of the country. These materials include wood floor trusses and wood I-joists. Depending on the shape of the joist and the manufacturer, the proper installation of these materials may require some additional steps. For instance, some wood I-joists require solid blocking at the end of the joist where it is supported so that the plywood web is not crushed or does not buckle. Figure 13-20 illustrates the use of plywood web I-joists. As shown in the figure, the bottom flanges of the joists are braced with a small metal strip that helps keep the flange from twisting. Solid wood blocking is a corrosion-resistant alternative to the metal braces. Floor surfaces in high-wind, flood, or seismic hazard areas are required to act as a diaphragm. For the builder, this means that the floor joists and sheathing are an important structural element. Therefore, the following installation features may require added attention: Joints in the sheathing should fully bear on top of a joist, not a scabbed-on board used as floor support Nailing must be done in accordance with a shear diaphragm plan Construction adhesive is important for preventing"squeaky" floors, but the adhesive must not be relied on for shear resistance in the floor Joints in the sheathing across the joists must be fully blocked with a full-joist-height block. Horizontal floor diaphragms with lower shear capacities can be unblocked if tongue-and-groove sheathing is used. 13.2.2.1 Horizontal Beams and Girders Girders and beams can be solid sawn timbers, glue-laminated timbers (see Figure 13-20), or built-up sections (see "Material Durability in Coastal Environments" on the Residential Coastal Construction Web site at http://www.fema.gov/rebuild/mat/fema55.html). The girders span between the piles and support the beams and joists. The piles are usually notched to receive the girders. To meet the design intent, girders, beams, and joists must be square and level, girders must be secured to the piles, and beams and joists must be secured to the girders. Figure 13-20. Engineered joists used as floor joists with proper metal brace to keep the ` s bottoms of the joists from twisting; engineered wood beam4.41411441 ;r. v mak , �" � -11111111 - � . avommeommi 13-24 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 The layout process involves careful surveying, notching, sawing, and boring.The bottom of the notch provides the bearing surface for downward vertical loads. The bolted connection between the girder and the vertical notch surface provides capacity for uplift loads and stability. Girder splices are made as required at these connections. Splices in multiple-member girders may be made away from the pile but should be engineered so that the splices occur at points of zero bending moment. This concept is illustrated in Figure 13-21. Figure 13-21. Acceptable locations A A A for splices in multiple- member girders A A o- 0 A A =girder A.support 0 =splice 13.2.2.2 Substitution of Floor Framing Materials The considerations discussed in Section 13.1.8 for substitution of foundation materials also apply to substitutions of floor framing materials. 13.2.2.3 Floor Framing Inspection Points Proper connections between elements of the floor framing help to guarantee that the load path is continuous and the diaphragm action of the floor is intact. If floor framing is not constructed properly, many construction details in the floor framing can become structural inadequacies during a severe natural hazard event or cause premature failure because of deterioration caused by the harsh coastal environment. Table 13-1 is a list of suggested critical inspection points in foundations and a guide for floor framing inspections. 13.2.3 Wall Framing Exterior walls and designated interior shear walls are an important part of the building's vertical and lateral force-resisting system.All exterior walls must be able to withstand in-plane (i.e., parallel to the wall surface), gravity, and wind uplift tensile forces, and out-of-plane (i.e., normal or perpendicular to the wall surface) wind forces. Exterior and designated interior shear walls must be able to withstand shear and overturning forces transferred through the walls to and from the adjacent roof and floor diaphragms and framing. The framing of the walls should be of the specified material and fastened in accordance with the design drawings and standard code practice. Exterior wall and designated shear wall sheathing panels must be of the specified material and fastened with accurately placed nails whose size, spacing, and durability are in accordance with the design. Horizontal sheathing joints in shear walls must be solidly blocked in accordance with shear wall capacity tables. Shear transfer can be better accomplished if the sheathing extends the full height from the bottom of the floor joist to the wall top plate (see Figure 13-22), but sheathing this long is often unavailable. COASTAL CONSTRUCTION MANUAL 13-25 13 CONSTRUCTING THE BUILDING I Volume II Figure 13-22. Full-height sheathing to improve transfer of shear • y;' it . . Full structural sheathing The design drawings may show tiedown connections between large shearwall vertical posts and main girders. Especially in larger, taller buildings, these connections must resist thousands of pounds of overturning forces during high winds. See Section 8.7 for information regarding the magnitude of these forces. The connections must be accomplished with careful layout, boring, and assembly. Shear transfer nailing at the top plates and sills must be in accordance with the design. Proper nailing and attachment of the framing material around openings is very important;see Section 9.2.1 for a discussion of the difficulty of transferring large shear loads when there are large openings in the shearwall. It is very important that shearwall sheathing (e.g., plywood, oriented strand board [OSB]) with an exterior exposure be finished appropriately with pigmented finishes such as paint, which last longer than unpigmented finishes, or semitransparent penetrating stains. It is also important that these finishes be properly maintained. Salt crystal buildup in surface checks in siding can damage the siding. Damage is typically worse in siding that is sheltered from precipitation because the salt crystals are never washed off with fresh rainwater. To meet the design intent, walls must: Be plumb and square to each other and to the floor r! Be lined up over solid support such as a beam, floor joists, or a perimeter band joist n, Not have any more openings than designated by the plans Not have openings located in places other than designated on the plans n Consist of material expected to resist corrosion and deterioration 11 Be properly attached to the floors above and below the wall, including the holddown brackets required to transfer overturning forces 13-26 COASTAL CONSTRUCTION MANUAL 1 Volume II CONSTRUCTING THE BUILDING 13 - i In addition, all portions of walls designed as shearwalls must be covered with sheathing nailed in accordance with either the plans or a specified prescriptive standard. 13.2.3.1 Substitution of Wall Framing Materials The considerations discussed in Section 13.1.8 for substitution of foundation materials also apply to substitutions of wall framing materials. 13.2.3.2 Wall Framing Inspection Points Proper connections between elements of the wall framing help to guarantee a continuous load path and the diaphragm action of the walls is intact. If not completed properly, there are many construction details in the floor framing that can become structural inadequacies and fail during a severe natural hazard event or cause premature failure because of deterioration caused by the harsh coastal environment. Table 13-2 is a list of suggested critical inspection points that can be used as a guide for wall framing inspections. Table 13-2.Wall Inspection Points Inspection Point Reason 1. Wall framing attachment to floors Ensures that nails are of sufficient size, type, and number 2.Size and location of openings Ensures performance of shear wall 3.Wall stud blocking Ensures that there is support for edges of sheathing material 4.Sheathing nailing-number, Ensures that sheathing acts as a shear diaphragm spacing, depth of nails 5. Material storage-protection from Ensures that the wood does not absorb too much moisture prior to elements prior to installation installation—exposure promotes checks and splits in wood,warp, and separation in plywood 6.Stud material-excessive crown Maintains plumb walls and eliminates eccentricities in vertical (crook)or lateral warping (bow) loading 7. Header support over openings Ensures that vertical and lateral loads will be transferred along the continuous load path 13.2.4 Roof Framing Proper roof construction is very important in high- - WARNING wind and earthquake hazard areas. Reviews of The most common roof structure failure is wind damage to coastal buildings reveal that most the uplift failure of porch, eave, and gable damage starts with the failure of roof elements. end overhangs.The next most common The structural integrity of the roof depends on is roof sheathing peeling away from the framing. Nailing the sheathing at the leading a complete load path, including the resistance edge of the roof,the gable edge, and to uplift of porch and roof overhangs, gable end the joints at the hip rafter or ridge is very overhangs, roof sheathing nailing, roof framing important, as is securing the roof framing to prevent uplift.This failure point(leading edge nailing and strapping, roof member-to-wall strapping, and gable end-wall bracing. of sheathing at gable edge, ridge, and hip) is also the most likely place for progressive failure of the entire structure to begin. COASTAL CONSTRUCTION MANUAL 13-27 13 CONSTRUCTING THE BUILDING Volume II 1 ti All of this construction must use the specified wood materials, straps, and nails. The appropriate nails must be used in all of the holes in the straps so that the istraps develop their full strength. Sheathing nails must be of the specified length, diameter, and head, and the sheathing must be nailed at the correct spacing. In addition, sheathing nails must penetrate the underlying roof framing members and must not be overdriven, which frequently occurs when pneumatic nail guns are used. When prefabricated roof trusses are used, handling precautions must be observed, and the trusses must be laterally braced as specified by the design professional or manufacturer. Fact Sheets 7.1 through 7.4 in FEMA P-499 discuss roof construction, including sheathing installation, asphalt shingle roofing, and tile roofing. To meet the design intent, roofs must meet the following requirements: L: Roof trusses and rafters must be properly attached to the walls F. Roof sheathing must be nailed according to either the construction plans or a specified prescriptive standard r Roofs must consist of materials expected to resist corrosion and deterioration, particularly the connectors 13.2.4.1 Substitution of Roof Framing Materials The considerations discussed in Section 13.1.8 for substitution of foundation materials also apply to substitutions of roof framing materials. 13.2.4.2 Roof Frame Inspection Points Proper connections between elements of the roof frame help to guarantee a WARNING continuous load path and the diaphragm action of the walls is intact. If not completed properly, there are many construction details in the roof framing Do not substitute nails, fasteners, or that can become structural inadequacies and fail during a severe natural connectors without hazard event or cause premature failure because of deterioration caused by approval of the the harsh coastal environment. Table 13-3 contains suggestions of critical ; designer. inspection points as a guide for roof framing inspections. _ 13.2.5 Top Structural Frame Issues for Builders The top structural frame issues for builders are as follows: n Connections between structural elements (e.g., roofs to walls) must be made so that the full natural hazard forces are transferred along a continuous load path. Care must be taken to nail elements so that the nails are fully embedded. r Compliance with manufacturers' recommendations on hardware use and load ratings is critically important. 13-28 COASTAL CONSTRUCTION MANUAL ti Volume II CONSTRUCTING THE BUILDING 13 Table 13-3. Roof Frame Inspection Points Inspection Point Reason 1. Roof framing attachment to Ensures that the sufficient number, size, and type of nails are used in walls the proper connector 2.Size and location of openings Ensures performance of roof as a diaphragm 3."H" clips or roof frame Ensures that there is support for edges of the sheathing material blocking 4.Sheathing nailing number, Ensures that sheathing acts as a shear diaphragm and is able to resist spacing, depth of nails uplift 5. Material storage-protection Ensures that the wood does not absorb too much moisture prior to from elements prior to installation—exposure promotes checks and splits in wood,warp, and installation separation in plywood , 6. Rafter or ceiling joist material excessive crown or lateral Maintains level ceilings warping 7. Gable-end bracing Ensures that bracing conforms to design requirements and specifications El Only material that is rated and specified for the expected use and environmental conditions should be used. Builders should understand that the weakest connections fail first and that it is therefore critical to pay attention to every connection. The concept of continuous load path must be considered for every connection in the structure. Exposed steel in the structural frame corrodes even in places such as the attic space. The builder should plan for it by installing hot-dipped galvanized or stainless steel hardware and nails. C Compliance with suggested nailing schedules for roof, wall, and floor sheathing is very important. 13.3 Building Envelope The building envelope comprises the exterior doors, windows, skylights, non-load-bearing walls, wall coverings,soffits,roof systems, and attic vents.The floor is also considered a part of the envelope in buildings elevated on open foundations. Building envelope design is discussed in detail in Chapter 11. The key to successful building envelope construction is having a detailed plan that is followed carefully by the builder, as described below. A suitable design must be provided that is sufficiently specified and detailed to allow the builder to understand the design intent and to give the contractor adequate and clear guidance. Lack of sufficient and clear design guidance regarding the building envelope is common. If necessary, the contractor should seek additional guidance from the design professional or be responsible for providing design services in addition to constructing the building. COASTAL CONSTRUCTION MANUAL 13-29 9 • 13 CONSTRUCTING THE BUILDING Volume II The building must be constructed as intended by die design professional (i.e., the builder must follow the drawings and specifications). Examples are: Installing flashings, building paper, or air infiltration barriers so that water is shed at laps Using the specified type and size of fasteners and spacing them as specified Eliminating dissimilar metal contact Using materials that are compatible with one another Installing elements in a manner that accommodates thermal movements so that buckling or jacking out of fasteners is avoided ! Applying finishes to adequately cleaned, dried, and prepared substrates i• Installing backer rods or bond breaker tape at sealant joints Tooling sealant joints For products or systems specified by performance criteria, the contractor must exercise care in selecting those products or systems and in integrating them into the building envelope. For example, if the design professional specifies a window by requiring that it be capable of resisting a specified wind pressure, the contractor should ensure that the type of window that is being considered can resist the pressure when tested in accordance with the specified test (or a suitable test if a test method is not specified). Furthermore, the contractor needs to ensure that the manufacturer, design professional, or other qualified entity provides guidance on how to attach the window frame to the wall so that the frame can resist the design pressures. When the selection of accessory items is left to the discretion of the contractor, without prescriptive or performance guidance, the contractor must be aware of and consider special conditions at the site (e.g., termites, unusually severe corrosion, and high earthquake or wind loads) that should influence the selection of the accessory items. For example, instead of using screws in plastic sleeves to anchor elements to a concrete or masonry wall, a contractor can use metal expansion sleeves or steel spikes intended for anchoring to concrete, which should provide a stronger and more reliable connection, or the use of plastic shims at metal doors may be appropriate to avoid termite attack. Adequate quality control (i.e., inspection by the contractor's personnel) and adequate quality assurance (i.e., inspection by third parties such as the building official, the design professional, or a test lab) must be provided. The amount of quality control/quality assurance depends on the magnitude of the natural hazards being designed for, complexities of the building design, and the type of products or systems being used. For example, installing windows that are very tall and wide and make up the majority of a wall should receive more inspection than isolated, relatively small windows. Inspecting roof coverings and windows is generally more critical than inspecting most wall coverings because of the general susceptibility of roofing and glazing to wind and the resulting damage from water infiltration that commonly occurs when these elements fail. 13.3.1 Substitution of Building Envelope Materials The considerations discussed in Section 13.1.8 for substitution of foundation materials also apply to substitutions of envelope materials. Proposed substitutions of materials must be thoroughly evaluated and 13-30 COASTAL CONSTRUCTION MANUAL Volume II CONSTRUCTING THE BUILDING 13 must be approved by the design professional1(see Section 13.1.8). The building envelope must be installed in a manner that will not compromise the building's structural integrity. For example, during construction, if a window larger than originally intended is to be installed because of delivery problems or other reasons, the contractor should obtain the design professional's approval prior to installation. The larger window may unacceptably reduce the shear capacity of the wall, or different header or framing connection details may be necessary. Likewise, if a door is to be located in a different position, the design professional should evaluate the change to determine whether it adversely affects the structure. 13.3.2 Building Envelope Inspection Points Table 13-4 is a list of suggested critical inspection points that can be used as a guide for building envelope inspections. Fact Sheet 6.1, Window and Door Installation, in FEMA P-499 discusses proper window and door installation and inspection points. Table 13-4. Building Envelope Inspection Points Inspection Point Reason 1. Siding attachment to wall framing Ensures there are sufficient number, type, and spacing of nails 2.Attachment of windows and doors . Ensures there are sufficient number,type, and spacing of either to the wall framing nails or screws 3. Flashings around wall and roof openings, roof perimeters, and at Prevents water penetration into building envelope changes in building shape 4. Roof covering attachment to Minimizes potential for wind blowoff. In high-seismic-load areas, sheathing, including special attention to attachment of heavy roof coverings, such as tile, is connection details . needed to avoid displacement of the covering. 5.Attachments of vents and fans at Reduces chance that vents or fans will blow off and allow wind- roofs and walls driven rain into the building 13.3.3 Top Building Envelope Issues for Builders The top building envelope issues for builders are as follows: r' Many manufacturers do not rate their products in a way that it is easy to determine whether the product will really be adequate for the coastal environment and the expected loads. Suppliers should be required to provide information about product reliability in the coastal environment. e Wind-driven rain finds a way into a building if there is an open path. Sealing openings and shedding water play significant parts in building a successful coastal home. D Window and door products are particularly vulnerable to wind-driven rain leakage and air infiltration. These products should be tested and rated for the expected coastal conditions. • The current high-wind techniques of adding extra roof surface sealing or attachments at the eaves and gable end edges should be used. 1-L Coastal buildings require more maintenance than inland structures. The maintenance requirement needs to be considered in the selection of materials and the care with which they are installed. COASTAL CONSTRUCTION MANUAL 13-31 7 13 CONSTRUCTING THE BUILDING Volume II 13.4 References ACI (American Concrete Institute). 2008. Building Code Requirements for Structural Concrete.ACI 318-08. AWPA (American Wood Protection Association). 1991. Care of Pressure-Treated Wood Products. AWPA Standard M4-91. Woodstock, MD. AWPA. 1994. Standards. Woodstock, MD. FEMA(Federal Emergency Management Agency). 1996. Corrosion Protection for Metal Connectors in Coastal Areas. NFIP Technical Bulletin 8-96. FEMA. 2006. Recommended Residential Construction for the Gulf Coast. FEMA P-550. FEMA. 2011. Home Builder's Guide to Coastal Construction Technical Fact Sheets. FEMA P-499. ICC (International Code Council). 2008. Standard for Residential Construction in High-Wind Regions, ICC 600-2008. ICC: Country Club Hills, IL. ICC. 2011a. International Building Code. 2012 IBC. Country Club Hills, IL: ICC. ICC. 2011b. International Residential Code for One-and Two-Family Dwellings. 2012 IRC. Country Club Hills, IL: ICC. NES (National Evaluation Service, Inc.). 1997. Power-Driven Staples and Nails for Use in All Types of Building Construction. National Evaluation Report NER-272. TMS (The Masonry Society). 2008. Building Code Requirements and Specification for Masonry Structures and Commentaries. TMS 402-08/ACI 530-08/ASCE 5-08 and TMS 602-08/ACI 530.1-08/ ASCE 6-08. USDN (U.S. Department of the Navy). 1982. Foundation and Earth Structures Design. Design Manual 7.2. 13-32 COASTAL CONSTRUCTION lMANUAL COASTAL CONSTRUCTION MANUAL 0 ' _ ,!,', '1 ,ILII' --: , �� ..• .. AN ' - , 1 i I -if- L. Maintaining tthe Building 7). This chapter provides guidance on maintaining the building structure and envelope. CROSS REFERENCE For maximum performance of a building in a coastal area, the or resources that augment building structure and envelope (i.e., exterior doors, windows, the guidance and other skylights, exterior wall coverings, soffits, roof systems, and attic information in this Manual, see the Residential Coastal vents) must not be allowed to deteriorate. Significant degradation Construction Web site(http:// by corrosion, wood decay, termite attack, or weathering increases www.fema.gov/rebuild/mat/ the building's vulnerability to damage from natural hazards. fema55.shtm). Figure 14-1 shows a post that appears on the exterior to be in ' -yriwiAlitaPIW Figure 14-1. Pile that appears immit. . . ... 1106‘, -Py ',, ' acceptable from the exterior but has interior t decay _ ,- i • COASTAL CONSTRUCTION MANUAL 14-1 14 MAINTAINING THE BUILDING Volume II acceptable condition but is weakened by interior decay,which can 0 be determined only through a detailed inspection.This post failed COST under the loads imposed by a natural hazard event. CONSIDERATION Long-term maintenance and repair demands are influenced Maintenance and repair costs are related directly to original directly by decisions about design, materials, and construction design decisions, materials methods during building design and construction. Using less selection, and construction durable materials will increase the frequency and cost of required methods. maintenance and repair. The design and detailing of various building systems (e.g., exposed structural, window, or roof systems) also significantly influence maintenance and repair demands. 14.1 Effects of Coastal Environment The coastal environment can cause severe damage to the building structure and envelope.The damage arises primarily from salt-laden moisture, termites, and weathering. • 14.1.1 Corrosion The corrosive effect of salt-laden, wind-driven moisture in coastal areas cannot be overstated. Salt-laden, moist air can corrode exposed metal surfaces and penetrate any opening in the building.The need to protect metal surfaces through effective design and maintenance (see Section 14.2.6 for maintenance of metal connectors) is very important for the long-term life of building elements and the entire building. Stainless steel is recommended because many galvanized (non-heavy-gauge) products and unprotected steel products do not last in the harsh coastal environment. Corrosion is most likely to attack metal connectors (see Section 14.2.6) that are used to attach the parts of the structure to one CROSS REFERENCE another,such as floor joists to beams and connectors used in cross- For additional information on bracing below the finished lowest floor. Galvanized connectors corrosion, see Section 9.4.5 coated with zinc at the rate of 0.9 ounce per square foot of surface in this Manual and FEMA area (designated G-90) can corrode in coastal environments at a Technical Bulletin 8-96, rate of 0.1 to 0.3 millimeter/year.At this rate, the zinc protection Corrosion Protection of Metal will be gone in 7 years.A G-185 coated connector,which provides f Connectors in Coastal Areas for Structures Located in twice as much protection as G-90, can corrode in less than 20 Special Flood Hazard Areas years.More galvanized protection(more ounces of zinc per square (FEMA 1996). foot of surface area to be protected) increases service life. ...�..-. Corrosion can also affect fasteners for siding and connectors for attaching exterior-mounted heating, ventilation, and air-conditioning units, electrical boxes, lighting fixtures, and any other item mounted on the exterior of the building.These connectors (nails,bolts, and screws) should be stainless steel or when they must be replaced, replaced with stainless steel. These connectors are small items, and the increased cost of stainless steel is small. 14-2 COASTAL CONSTRUCTION MANUAL Volume II MAINTAINING THE BUILDING 14 14.1.2 Moisture • There are many sources of exterior moisture from outside the home in the coastal environment.Whenever an object absorbs and retains moisture, the object may decay, mildew, or deteriorate in other ways. Figure 14-2 shows decay behind the connection plate on a beam. Significant sources of interior moisture, such as kitchens, baths, and clothes dryers, should be vented to the outside in such a way that condensation does not occur on interior or exterior surfaces. < ;n,; Figure 14-2. P' 1161.. Wood decay behind a metal beam connector P 1 i 4 14,-., Connectors should be designed to shed water to prevent water from accumulating between the connector and the material the connector is attached to.Trapped moisture increases the moisture content of the material and potentially leads to decay. Moisture is most likely to enter at intersections of materials where there is a hole in the building envelope (e.g.,window, door) of where two surfaces are joined (e.g., roof to wall intersection). If properly installed, the flashings for the openings and intersections should not require maintenance for many years. However, flashings are frequently not properly installed or installed at all, creating an ongoing moisture intrusion problem. The potential for wood framing in crawlspaces in low-lying coastal areas to decay is high. Moisture migration into the floor system can be reduced if the floor of the crawlspace is covered with a vapor barrier of at least 6-millimeter polyethylene.Where required by the local building code,wood framing in the crawlspace should be preservative-treated or naturally decay-resistant. The building code may have ventilation requirements. COASTAL CONSTRUCTION MANUAL 14-3 14 MAINTAINING THE BUILDING Volume II Many existing crawlspaces are being converted to "conditioned crawlspaces."A moisture barrier is placed on the floor and walls of the crawlspace interior, insulation is added to the floor system (commonly sprayed-on polyurethane foam),and conditioned air is introduced into the space. In order for a conditioned crawlspace to be successful in low-lying coastal areas, moisture control must be nearly perfect so that the moisture content of the floor system does not exceed 20 percent (the minimum water content in wood that promotes mold growth). Conditioned crawlspaces are typically not practical in a floodplain where flood vents are required. Sprinkler systems used for landscaping and other exterior water distribution systems (e.g., fountains) must be carefully tested so they do not create or increase water collection where metal connectors are fastened. Water collection can be prevented easily during installation of the exterior water distribution system by making sure the water distribution pattern does not increase the moisture that is present in the building materials. 14.1.3 Weathering The combined effects of sun and water on many building materials, particularly several types of roof and wall coverings, cause weathering damage, including: Fading of finishes Accelerated checking and splitting of wood Gradual loss of thickness of wood Degradation of physical properties (e.g., embrittlement of asphalt shingles) In combination, the effects of weathering reduce the life of building materials unless they are naturally resistant to weathering or are protected from it, either naturally or by maintenance. Even finishes intended to protect exterior materials fade in the sun, sometimes in only a few years. 14.1.4 Termites The likelihood of termite infestation in coastal buildings can be reduced by maintenance that makes the building site drier and otherwise less hospitable to termites, specifically: Storing firewood and other wood items that are stored on the ground, including wood mulch, well away from the building Keeping gutters and downspouts free of debris and positioned to direct water away from the building Keeping water pipes, water fixtures, and drainpipes in good repair Avoiding dampness in crawlspaces by providing adequate ventilation or installing impervious ground cover membranes Avoiding frequent plant watering adjacent to the house and trimming plants away from the walls If any wood must be replaced under the house in or near contact with the ground, the new wood should be treated. Removing moisture and treating the cellulose in wood, which is the termite's food source, are the most frequently used remedies to combat termites. 14-4 COASTAL CONSTRUCTION MANUAL Volume II MAINTAINING THE BUILDING 14 14.2 Building Elements That Require Frequent Maintenance To help ensure that a coastal building is properly maintained, this Manual recommends that buildings be inspected annually by professionals with the appropriate expertise. The following building elements should be inspected annually: Building envelope—wall coverings, doors, windows, shutters, skylights, roof coverings, soffits, and attic vents Foundation, attic, and the exposed structural frame Exterior-mounted mechanical and electrical equipment Table 14-1 provides a maintenance inspection checklist. Items requiring repair or replacement should be documented and the required work scheduled. Table 14-1. Maintenance Inspection Checklist Condition Repair/Replace Item Element Good Fair Poor Yes No Wood pile-decay, termite infestation, severe splits, connection to framing Sill plates-deterioration, splits, lack of attachment to foundation Masonry-deteriorated mortar joints, Foundation cracked block, step cracks indicating foundation settlement Concrete-spalling, exposed or corroding reinforcing steel, >_ 1/4-inch vertical cracks or horizontal cracks with lateral shift in the concrete across the crack Siding-deterioration, nail withdrawal, discoloration, buckling, attachment to studs (nails missing, withdrawn, or not Exterior attached to studs), sealant cracked/dried Walls out Trim-deterioration, discoloration, separation at joints, sealant cracked/ dried out Top and bottom connections to Porches/ framing-corrosion in connectors Columns Base of wood columns-deterioration Joists or beams-decay, termite infestation, corrosion at tiedown connectors, splits, excessive holes or Floors notching, excessive sagging Sheathing-deterioration, "squeaky" floors, excessive sagging, attachment to framing (nails missing, withdrawn, or not attached to framing) COASTAL CONSTRUCTION MANUAL 14-5 14 MAINTAINING THE BUILDING Volume II Table 14-1. Maintenance Inspection Checklist(concluded) Condition Repair/Replace Item Element Good Fair Poor Yes No Sheathing under floors-attachment Floors to framing, nail corrosion fastening sheathing to floor joists, buckling/warping caused by excessive moisture Glazing-cracked panes, condensation between panes of insulated glass, nicks in glass surface, sealant cracked/dried out Windows/ Trim-deterioration, discoloration, Doors separation at joints, caulking dried out or separated Shutters-permanent shutters should be operated at least twice/year and temporary panels should be checked once/year for condition Asphalt shingles-granule loss, shingles curled, nails withdrawing from sheathing, de-bonding of tabs along eaves and corners Wood shakes-splits, discoloration, deterioration, moss growth, attachment Roof to framing (nails missing, withdrawn, or not attached to framing) Metal-corrosion, discoloration, connection of fasteners or fastening system adequacy Fleshings-corrosion,joints separated, nails withdrawing Framing-condition of truss plates sagging or bowed rafters or truss Attic chords, deterioration of underside of roof sheathing, evidence of water leaks, adequate ventilation Other items that should be inspected include cavities through which air can freely circulate(e.g., above soffits and behind brick or masonry veneers) and, depending on structural system characteristics and access, the structural system. For example, painted, light-gauge, cold-formed steel framing is vulnerable to corrosion, and the untreated cores of treated timber framing are vulnerable to decay and termite damage. Depending on visual findings, it may be prudent to determine the condition of concealed items through nondestructive or destructive tests (e.g., test cuts). The following sections provide information on the building elements that require frequent maintenance in coastal environments: glazing, siding, roofs, outdoor mechanical and electrical equipment, decks and exterior wood, and metal connectors. 14-6 COASTAL CONSTRUCTION MANUAL Volume II MAINTAINING THE BUILDING 14 14.2.1 Glazing Glazing includes glass or a transparent or translucent plastic sheet in windows, doors, skylights,and shutters. Glazing is particularly vulnerable to damage in hurricane-susceptible coastal areas because high winds create wind-borne debris that can strike the glazing. Maintenance suggestions for glazing include the following: Checking glazing gaskets/sealants for deterioration and repairing or replacing as needed. Broken seals in insulated glass are not uncommon in coastal areas. Checking wood frames for decay and termite attack, and checking metal frames for corrosion. Frames should be repainted periodically (where appropriate), and damaged wood should be replaced. Maintaining the putty in older wood windows minimizes sash decay. Metal frames should be cleaned of corrosion or pitting and the operation of the windows tested on some frequency. Checking vinyl frames for cracks especially in the corners and sealing any cracks with a sealant to prevent water entry into the window frame. Vinyl may become discolored from the ultraviolet (UV) rays of the sun. Checking for signs of water damage (e.g., water stains, rust streaks from joints) and checking sealants for substrate bond and general condition. Repair or replace as needed. Checking glazing for stress cracks in corners. Stress cracks might be an indication of either settlement of the house or of lateral movement that is causing excessive stress in the lateral load system. Checking shutters for general integrity and attachment and repainting periodically where appropriate. Replacing or strengthening the attachment of the shutter system to the building as appropriate. Checking the shutters for ease of operation. Sand can easily get into the hinges and operators and render shutters inoperable. Checking locks and latches frequently for corrosion and proper operation. Lock mechanisms are vulnerable to attack by salt-laden air. Applying a lubricant or rust inhibitor improves the operation of these mechanisms over the short term. Installing double hung and awning windows, which generally perform better than sliding or jalousie windows in the coastal environment, primarily because the sliding and jalousie windows allow more water, sand, and air infiltration because of the way the windows open and close. Replacing sliding and jalousie windows to reduce infiltration. 14.2.2 Siding Solar UV degradation occurs at a rate of about 1/16 inch over 10 years on exposed wood. This rate of degradation is not significant for dimension lumber, but it is significant for plywood with 1/8-inch veneers. If the exterior plywood is the shearwall sheathing, the loss will be significant over time. Maintenance suggestions for siding materials include the following: COASTAL CONSTRUCTION MANUAL 14-7 14 MAINTAINING THE BUILDING Volume II Protecting plywood from UV degradation with pigmented finishes rather than clear finishes. Pigmented finishes are also especially recommended for exposed shearwall sheathing. Protecting wood siding with a protective sealant—usually a semi-transparent stain or paint. The coating should be re-applied regularly because the degradation will occur nearly linearly if re-application is done but will progress faster if allowed to weather with no regular sealing. Keeping siding surfaces free of salt and mildew and washing salt from siding surfaces not washed by rain, taking care to direct the water stream downward. Mildew should be washed as needed from siding using commercially available products or the homemade solution of bleach and detergent described in Finishes for Exterior Wood: Section, Application and Maintenance (Williams et al. 1996). Power washing is another technique to keep the siding clean as long as the siding sealant is not removed. Mildew grows on almost any surface facing north, no matter how small the surface. Caulking seams,joints, and building material discontinuities with a sealant intended for severe exterior exposures and renew the sealant every 5 years at a minimum or when staining or painting the siding and trim. Sealant applied at large wood members should be renewed about 1 year after the wood has shrunk away from the caulked joint. Caulking carefully to avoid closing off weep or water drainage holes below windows or in veneers that are intended to drain will prevent sealing the moisture inside the wall cavity, which can lead to significant, long-term deterioration. Renailing siding when nails withdraw (pop out) and renailing at a new location so the new nail does not go into the old nail hole. Ensuring vinyl siding has the ability to expand and contract with temperature changes. Buckling in the siding is an indication that the siding was installed too tightly to the wall sheathing with an insufficient amount of room under the siding nails to allow for the normal horizontal movement of the siding. 14.2.3 Roofs Roof coverings are typically the building envelope material most susceptible to deterioration from weathering. Also, depending on roof system design, minor punctures or tears in the roof covering can allow water infiltration, which can lead to serious damage to the roof system and other building elements. Maintenance suggestions for roof materials include the following: Checking the general condition of the roof covering. Granule loss from asphalt shingles is always a sign of some deterioration, as is curling and clawing (reverse curling) although some minor loss is expected even from new shingles. Dabbing roofing cement under the tabs of the first layer of shingles, including the base course, to help ensure that this layer stays down in high winds. Dabbing roofing cement under any shingle tabs that have lifted up from the existing tack strip. Checking the nails that attach the shingles to the roof for corrosion or pullout. Checking metal flashings and replacing or repairing as necessary. Cleaning dirt, moss, leaves, vegetative matter, and mildew from wood shakes. 14-8 COASTAL CONSTRUCTION MANUAL Volume II MAINTAINING THE BUILDING 14 Cleaning corroded surfaces of ferrous metal roofs and applying an appropriate paint or sealer. Checking the attachment of the roof surface to the deck. Screws and nails can become loose and may require tightening. Gasketed screws should be added to tighten the metal deck to the underlayment. Some roofing systems are attached to the underlayment with clips that can corrode—these clips should be inspected and any corroded clips replaced, but in many cases, the clips will be concealed and will require some destructive inspection to discover the corroded clips. Removing debris from the roof and ensuring that drains, scuppers, gutters, and downspouts are not clogged. Removing old asphalt shingles before recovering. This is recommended because installing an additional layer of shingles requires longer nails, and it is difficult to install the new asphalt shingles so that they lay flat over the old. New layers installed over old layers can therefore be susceptible to wind uplift and damage, even in relatively low wind speeds. New layers installed over old shingles could void the warranty for the new shingles. Checking attachments of eave and fascia boards. Deterioration in these boards will likely allow flashings attached to them to fail at lower than design wind speeds. 14.2.4 Exterior-Mounted Mechanical and Electrical Equipment Most outdoor mechanical and electrical equipment includes metal parts that corrode in the coastal environment. Life expectancy improves if the salt is washed off the outside of the equipment frequently. This occurs naturally if the equipment is fully exposed to rainwater, but partially protected equipment is subject to greater corrosion because of the lack of the natural rinsing action. Using alternative materials that do not include metal parts can also help reduce the problems caused by corrosion. In all cases, electrical switches should be the totally enclosed type to help prevent moisture intrusion into the switch, even if the switch is located on a screened porch away from the direct effects of the weather. Building owners should expect the following problems in the coastal environment: Electrical contacts can malfunction and either short out or cause intermittent operation Housings for electrical equipment; heating, ventilation, and air-conditioning condensers; ductwork; and other elements deteriorate more rapidly Fan coils for outside condensers can deteriorate more rapidly unless a coastal environment is specified Typical metal fasteners and clips used to secure equipment can deteriorate more rapidly in a coastal environment than a non-coastal environment 14.2.5 Decks and Exterior Wood The approach to maintaining exterior wood 2x members is different from the approach for thicker members. The formation of small checks and splits in 2x wood members from cyclical wetting and drying can be reduced by using water-repellent finishes. The formation of larger checks and splits in thicker wood members is caused more by long-term drying and shrinking and is not as significantly reduced by the COASTAL CONSTRUCTION MANUAL 14-9 14 MAINTAINING THE BUILDING Volume II use of water-repellent finishes. Installation of horizontal 2x members with the cup (concave surface) down minimizes water retention and wood deterioration. Cyclical wetting and drying, such as from dew or precipitation, causes the exterior of a wood member to swell and shrink more quickly than the interior. This causes stress in the surface, which leads to the formation of checks and splits. This shrink-swell cycling is worst on southern and western exposures. Checks and splits, especially on horizontal surfaces, provide paths for water to reach the interior of a wood member and remain, where they eventually cause decay. Maintaining a water-repellent finish, such as a pigmented paint, semi-transparent stain, or clear finish, on the wood surface can reduce the formation of checks and splits. These finishes are not completely water- or vapor- repellent, but they significantly slow cyclical wetting and drying. Of the available finishes, pigmented paints and semi- transparent stains have the longest lifetime; clear finishes must be reapplied frequently to remain effective. Matte clear finishes are available that are almost unnoticeable on bare wood. These finishes are therefore attractive for decking and other "natural"wood, but they must be renewed when water no longer beads on the finished surface. Wood deck surfaces can be replaced with synthetic materials, which are sold under a variety of trade names. Many of these products should be attached with stainless screws or hidden clips to preservative- treated framing. Moisture-retaining debris can collect between deck boards and in the gaps in connections. Periodic cleaning of this debris from between wood members, especially at end grains, allows drying to proceed and inhibits decay. Larger timbers can also be vulnerable to checks, splits, and other weather-related problems. The best way to maintain larger timbers is to keep water away from joints, end grain surfaces, checks, and splits. Much can be learned by standing under the house (given sufficient headroom) during a rain with the prevailing wind blowing to see where the water goes. Measures, such as preservative treatments, can then be taken or renewed to minimize the effect of this water on the larger timbers. Connections of deck band boards to the structure should be inspected periodically for moisture intrusion. These connections frequently leak from wind-driven rain and moisture accumulation. Leakage can occur at the flashing to structure interface or at the bolts connecting the band board to the structure. 14.2.6 Metal Connectors Most sheet-metal connectors,such as tiedown straps,joist hangers, and truss plates used in structural applications in the building, CROSS REFERENCE should be specified to last the lifetime of the building without the need for maintenance. However, the use of corrosion-prone The selection of metal connectors is a common problem in existing coastal houses. connectors for use within the building envelope and Galvanized connectors may have corrosion issues. If in exposed locations is addressed in Section 9.4 of galvanized connectors remain gray, the original strength is this Manual. generally unaffected by corrosion. When most of the surface of the connector turns rust red, the sacrificial galvanizing has T 14-10 COASTAL CONSTRUCTION MANUAL Volume II MAINTAINING THE BUILDING 14 been consumed and the corrosion rate of the unprotected steel can be expected to accelerate by up to a factor of 50 times. Figure 14-3 illustrates severe corrosion under an exterior deck. Sheet-metal connectors can be susceptible to rapid corrosion and are frequently without reserve strength. During routine inspections, any sheet-metal connectors found to have turned rust red or to show severe, localized rusting sufficient to compromise their structural capacity should be replaced immediately. However, the replacement of sheet metal connectors is usually difficult for a number of reasons: the connection may be under load, the nails or bolts used WARNING to secure connectors are usually hard to remove, and the location of a connector often makes removal awkward. Using corrosion-prone sheet metal connectors increases Salt-laden air can increase corrosion rates in building maintenance requirements materials. Covering exposed connectors with a sheathing and potentially compromises material reduces their exposure and therefore increases their structural integrity. life expectancy. Figure 14-3. Severely corroded deck • connectors • • 14.3 Hazard-Specific Maintenance Techniques The maintenance practices described above for minimizing corrosion, wood decay, termite infestation, and UV degradation will improve the resistance of a coastal building to flood, wind, and seismic damage by maintaining the strength of the structural elements. The additional measures described in the following sections will further maintain the building's resistance to natural hazards. COASTAL CONSTRUCTION MANUAL 14-11 14 MAINTAINING THE BUILDING Volume II 14.3.1 Flooding When designing for the lateral force capacity of an unbraced or braced pile foundation, the designer should allow for a certain amount of scour. Scour in excess of the amount allowed for reduces the embedment of the piles and causes them to be overstressed in bending during the maximum design flood,wind,or earthquake. As allowed by local regulations and practicality, the grade level should be maintained at the original design elevation. Scour and long-term beach erosion may affect pile maintenance requirements. If tidal wetting was not anticipated in the original design, the piles may have received the level of preservative treatment required only for ground contact and not the much higher marine treatment level that provides borer resistance. If the pile foundation is wetted by high tides or runup, borer infestation is possible. Wrapping treatments that minimize borer infestation are available for the portions of the piles above grade that are subject to wetting. 14.3.2 Seismic and Wind Many seismic and wind tiedowns at shearwall vertical chords use a vertical threaded rod as the tension member. Each end of the threaded rod engages the tiedown hardware or a structural member. Over time, cross-grain shrinkage in the horizontal wood members between the threaded rod connections loosens the threaded rod, allowing more rocking movement and possible damage to the structure. Whenever there is an opportunity to access the tiedowns, the nuts on the rods should be tightened firmly. New proprietary tiedown systems that do this automatically are available. Shearwall sill plates bearing directly on continuous footings or concrete slabs-on-grade, if used in coastal construction, are particularly susceptible to decay in moist conditions. Figure 14-4 shows a deteriorated sill plate. Even if the decay of the preservative-treated sill plate is retarded, the attached untreated plywood can easily decay and the shearwall will lose strength. Conditions that promote sill and plywood decay include an outside soil grade above the sill,stucco without a weep screed at the sill plate, and sources of excessive interior water vapor. Correcting these conditions helps maintain the strength of the shearwalls. Figure 14-4. t # r Deteriorated wood sill 4 , ` I ? ,;/ plate ';< ,a 111 t Nt �r 4014. • 14-12 COASTAL CONSTRUCTION MANUAL Volume II MAINTAINING THE BUILDING 14 14.4 References FEMA (Federal Emergency Management Agency). 1996. Corrosion Protection of Metal Connectors in Coastal Areas for Structures Located in Special Flood Hazard Areas. NFIP Technical Bulletin 8-96. Shifler, D.A. 2000. Corrosion and Corrosion Control in Saltwater Environments. Pennington, NJ: Electrochemical Society. Williams, R., M. Knaebe, and W. Feist. 1996. Finishes for Exterior Wood:Section, Application and Maintenance. Forest Products Society. COASTAL CONSTRUCTION MANUAL 14-13 COASTAL CONSTRUCTION MANUAL ' a ;— .r 41 3F41111.f L • R •t • e ro i in u � in s or Natural ___.-_____- , __ ___ This chapter provides guidance on retrofitting existing residential structures to resist or mitigate the consequences CROSS REFERENCE of natural hazards in the coastal environment.The natural For resources that augment the hazards that are addressed are wildfires, seismic events, guidance and other information in this floods, and high winds. Specific retrofitting methods Manual, see the Residential Coastal and implementation are discussed briefly, and resources Construction Web site(http://www. with more in-depth information are provided. Some fema.gov/rebuild/mat/fema55.shtm). retrofitting methods are presented together with broader, non-retrofitting mitigation methods when retrofitting _ and non-retrofitting methods are presented together in the referenced guidance. For retrofitting to mitigate NOTE high winds, the new three-tiered wind retrofit program that is provided in FEMA P-804, Wind Retrofit Guide for FEMA's Hazard Mitigation Assistance Residential Buildings (FEMA 2010c), is discussed. The (HMA) grant programs provide funding for eligible mitigation activities that program includes systematic and programmatic guidance. reduce disaster losses and protect life and property from future disaster Retrofitting opportunities present themselves every damage. Currently, FEMA administers time maintenance is performed on a major element of a the following HMA grant programs: building. Retrofitting that increases resistance to natural Hazard Mitigation Grant Program. Pre- hazards should focus on improvements that provide the Disaster Mitigation, Flood Mitigation largest benefit to the owner. Assistance, Repetitive Flood Claims, and Severe Repetitive Loss. COASTAL CONSTRUCTION MANUAL I I 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II If an existing building is inadequate to resist natural hazard loads, retrofitting should be considered. 15.1 Wildfire Mitigation Thousands of residential and non-residential buildings are damaged or destroyed every year by wildfires,resulting in more TERMINOLOGY: than $200 million in property damage annually. More than RETROFITTING $100 million is spent every year on fire suppression and even more on recovering from catastrophic natural and manmade Retrofitting is a combination hazards.Studies cited by IBHS in Mega Fires(IBHS 2008)have of adjustments or additions to existing building features that are shown that financial losses can be prevented if simple measures intended to eliminate or reduce are implemented to protect existing buildings. the potential for damage from natural hazards. Retrofitting is a If FEMA offers funding through the HMGP and the PDM specific type of hazard mitigation. Program for wildfire mitigation projects. Projects funded through these programs involve retrofits to buildings that help minimize the loss of life and damage to the buildings from wildfire. Eligible activities for wildfire mitigation per FEMA's Hazard Mitigation Assistance Unified Guidance(FEMA 2010a) may include: Provision of defensible space through the creation of perimeters around residential and non-residential buildings and structures by removing or reducing flammable vegetation. The three concentric zones of defensible space are shown in Figure 15-1. Zone 2: Prune and remove dead and Zone 1: Remove combustible litter on Zone 3: Reduce fuels by dying branches from individual and roofs and gutters and trim tree branches thinning and pruning well-spaced clumps of trees and shrubs that overhang the roof and chimney vegetation horizontally and vertically Zone 2:Place woodpiles at least Zone 1: Eliminate all 30 feet from the building and store combustible materials the wood in a vegetation-free zone within 30 feet of the home such as a graveled area '4411.44) Z4 Figure 15-1. The three concentric zones of defensible space SOURCE:ADAPTED FROM FEMA P-737 15-2 COASTAL CONSTRUCTION MANUAL Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 Application of non-combustible building envelope assemblies that can minimize the impact of wildfires through the use of ignition-resistant materials and proper retrofitting techniques. The components of the building envelope are shown in Figure 15-2. Reduction of hazardous fuels through vegetation management, vegetation thinning, or reduction of flammable materials. These actions protect life and property that are outside the defensible space perimeter but close to at-risk structures. Figure 15-3 shows a fire that is spreading vertically through vegetation. Building envelope Roof 7 ,444101,‘---- Vent Gutter r r= __ Siding ,.4" � Deck __, -_—. Eaves ' -- -1 i Exterior / tj, II door _ ` ,. Garage door —Fence / Foundation Windows Figure 15-2. The building envelope SOURCE:ADAPTED FROM FEMA P-737 , Figure 15-3. Fire spreads vertically through vegetation .a A COASTAL CONSTRUCTION MANUAL 15-_i 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II FEMA may fund above-code projects in communities with applicable fire-related codes. For homes and structures constructed or activities completed prior to the adoption of local building codes, FEMA may fund mitigation that meets or exceeds the codes currently in effect. For communities without fire codes, FEMA may fund mitigation when the materials and technologies are in accordance with the ICC, FEMA, U.S. Fire Administration, and the National Fire Protection Association (NFPA). Firewise recommendations, as appropriate. The Firewise program provides resources for communities and property owners to use in the creation of defensible space. Additional fire-related information and tools can be found at http://www. firewise.org and http://www.nfpa.org. Wildfire mitigation is required to be in accordance with the applicable fire-related codes and standards, including but not limited to the following: IWUIC, International Wildland-Urban Interface Code (ICC) NFPA 1144, Standard for Reducing Structure Ignition Hazards from Wildland Fire NFPA 1141, Standard for Fire Protection Infrastructure for Land Development in Suburban and Rural Areas NFPA 703, Standard for Fire-Retardant Treated Wood and Fire-Retardant Coatings for Building Materials Code for Fire Protection of Historical Structures (NFPA) FEMA P-737, Home Builder's Guide to Construction in Wildfire Zones (FEMA 2008a), is a Technical Fact Sheet Series (see Figure 15-4) that provides information about wildfire behavior and recommendations for building design and construction methods in the wildland/urban interface. The fact sheets cover mitigation topics for existing buildings including defensible space, roof assemblies, eaves, overhangs, soffits, exterior walls, vents, gutters, downspouts, • windows, skylights, exterior doors, foundations, - decks and other attached structures, landscape fencing and walls, fire sprinklers, and utilities and exterior equipment. Implementation of the recommended design and construction methods in FEMA P-737 can greatly increase the probability that a building will survive a wildfire. Home Builder's Guide to Construction in Wildfire Zones Technical Fact Sheet Series FEMA P 737/September 2008 Figure 15-4. Mot,*rat yw-•�-t•� FEMA Us +dNol.0 ap dM . FEMA P-737, Home Builder's Guide to Construction 10 """�u in Wildlife Zones: Technical Fact Sheet Series 15-4 COASTAL CONSTRUCTION MANUAL Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 Since it may not be financially possible for the homeowner to implement all of the measures that are recommended in FEMA P-737,homeowners should consult with local fire and building code officials or their fire management specialists to perform a vulnerability assessment and develop a customized, prioritized list of recommendations for remedial work on defensible space and the building envelope. Helpful information about the vulnerabilities of the building envelope is available at http://firecenter.berkeley.edu/building_in_ wildfire_prone_areas. The homeowner can use the Homeowner's Wildfire Assessment survey on this Web site to learn about the risks a particular building has and the measures that can be taken to address them. 15.2 Seismic Mitigation Seismic hazard, which is well documented and defined in the United States, is mitigated in existing residential buildings primarily through retrofitting.Although modifications to existing residential structures have the potential to reduce earthquake resistance, it is possible to take advantage of these modifications to increase resistance through earthquake retrofits (upgrades). FEMA has produced documents, including those referenced below, that address the evaluation and retrofit of buildings to improve performance during seismic events. For nationally applicable provisions governing seismic evaluation and rehabilitation, the design professional should reference ASCE 31 and ASCE 41. In addition, FEMA offers funding for seismic retrofits through the HMGP and the PDM Program to reduce the risk of loss of life, injury, and damage to buildings. Seismic retrofits, which are classified as structural and non-structural, are subject to the same HMGP and PDM funding processes as wind retrofits (see Section 15.4.3). FEMA 232, Homebuilders' Guide to Earthquake Resistant Design and Construction (FEMA 2006) (see Figure 15-5), contains descriptions of eight • earthquake upgrades that address common seismic weaknesses in existing residential construction. The upgrades are foundation bolting, cripple wall r I I 1 bracing, weak- and soft-story bracing, open-front .r bracing, hillside house bracing, split-level floor ( I I I interconnection, anchorage of masonry chimneys, and anchorage of concrete and masonry walls. The upgrades are summarized below. For in-depth information on these upgrades, see FEMA 232. Homebuilders' Guide to Earthquake Resistant Design and Construction FEMA 232-June 2006 Figure 15-5. ' FEMA ® rp FEMA 232, Homebuilders Guide to Earthquake Resistant Design and Construction COASTAL CONSTRUCTION MANUAL 15-5 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II Foundation bolting. Inadequate attachment of the sill plate to the foundation can allow the framed structure to separate and shift off the foundation. Sill plate anchor bolts (either adhesive or expansion type depending on the foundation material) can be added provided there is sufficient access to the top surface of the sill plate. Alternately, proprietary anchoring hardware is available that is typically attached to the face of the foundation wall for greater ease of installation when access is limited. Reinforcing sill plate anchorage offers a generally high benefit in return for low cost. Cripple wall bracing. Another relatively inexpensive foundation-level retrofit is bracing the cripple walls. Cripple walls are framed walls occasionally installed between the top of the foundation and first- floor framing in the above-grade wall sections of basements and crawl spaces. Because of their location, cripple walls are particularly vulnerable to seismic loading, as shown in Figure 15-6. These walls can be braced through the prescribed installation of wood structural panel sheathing to the interior and/or exterior wall surface. Weak-and soft-story bracing. Although first-story framed walls must bear greater seismic loads than the roof and walls above, they frequently have more openings and therefore less bracing. As a result, first-story framed walls, and any other level with underbraced wall sections, may be referred to as weak or soft stories. These walls can be retrofit by removing the interior finishes at wall corners and installing hold-down anchors between the corner studs and continuous reinforced foundation below. If renovations or repairs require removing larger areas of interior wall sheathing, additional hold- down anchors can be installed to tie in the floor or roof framing above.Additional wall bracing can be achieved by adding blocking for additional nailing and wood structural panel sheathing. Open-front bracing. An open-front configuration is one in which braced exterior walls are absent or grossly inadequate. Frequently, open-front configurations are found in garage entry walls where overhead garage doors consume most of the available wall area, as shown in Figure 15-7. Possible retrofits include reinforcing the existing framed end walls and replacing the framed wall ends with steel moment frames; common heights and lengths of steel moment frames are available commercially. Figure 15-6. A house with severe .� damage due to cripple , 't!-" wall failure letz gee IFH , 4 ILE n4 air tv+ p.-. r., 15-6 COASTAL CONSTRUCTION MANUAL Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 Figure 15-7. Set-back Common open-front configurations in one- and two-family detached opi Braced wall houses panel above 4It �F . r '*****, ' -- r - - i Illikiki- r 4, . •i 2,1 - ...,_ _ .. . ,_ ' Garage front wall is too Second story walls are too _J narrow for bracing, so an narrow for bracing due to open-front configuration windows, so an open-front at the first story exists configuration at the second story exists Hillside house bracing. Houses built on steep hillsides are vulnerable to damage when the floor system separates from the uphill foundation or foundation wall. Retrofitting to mitigate this type of seismic damage requires an engineered design that should include anchoring each floor system to the uphill foundation and the supplemental anchorage, strapping, and bracing of cripple walls. Split-level floor interconnection. Houses with vertical offsets between floor elevations on a common wall or support are exposed to seismic damage that is similar to hillside houses. The potential for separation of the floor system from the common wall may be reduced by adequately anchoring floor framing on either side of the common wall. Prescriptive solutions may apply where a direct tension tie can be provided between both floors, but an engineered design may be necessary where greater floor offsets exist. Anchorage of masonry chimneys. Unreinforced masonry chimneys can be anchored to the roof and adjacent or surrounding floor systems with metal straps but will still be subject to brittle failure. The benefit of this type of anchoring may be limited to collapse prevention. A chimney collapse reportedly caused one fatality in the 1992 earthquake in Landers, CA, but other mitigation measures may be more cost-effective. These measures include the practical approaches provided on the Association of Bay Area Governments Web site (http://quake.abag.ca.gov/residents/chimney). Anchorage of concrete and masonry walls. Floor systems in houses with full-height concrete or masonry walls may be supported by a weight-bearing ledger strip only. With this type of existing construction, a tension connection can be installed between the walls and floor system to provide the necessary direct anchorage. An engineering evaluation and design are recommended for this type of seismic retrofit. FEMA 530, Earthquake Safety Guide for Homeowners(FEMA 2005) (Figure 15-8) includes guidance similar to FEMA 232 on seismic structural retrofits along with tips on strengthening a variety of existing foundation types. One non-structural retrofit in FEMA 530 is to brace water heaters,which can cause gas leaks, fires, or flooding if toppled during an earthquake. Written for the homeowner, FEMA 530 provides information on the relative cost of prevention versus the cost of post-disaster repair or replacement and on plans, permitting, and selecting contractors. COASTAL CONSTRUCTION MANUAL 15-7 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II Figure 15-8. °�,.NIt a 9. i ;.;FEMA 530, Earthquake Safety Guide for Homeowners :;MP- : f "Niolo•••,.. .„ 0'111`klioi%‘ * tir4iN* , fat 7--41 LI ih,- .,i. . . , l a/ i�� - _ ,.. _. 15.3 Flood Mitigation Earthquake Safety Guide FEMA 259, Engineering Principles and Practices of for Homeowners Retrofitting Floodprone Structures (FEMA 2011), addresses retrofitting flood-prone residential pFMA 530/September'OM structures. The objective of the document is to provide engineering design and economic guidance to engineers, architects, and local code officials about what constitutes technically feasible and . FEMA cost-effective retrofitting measures for flood-prone nehrp residential structures. The focus in this chapter in regard to retrofitting for the flood hazard is retrofitting one- to four-family residences that are subject to flooding without wave action. The retrofitting measures that are described in this section include both active and passive efforts and wet and dry floodproofing. Active efforts require human intervention preceding the flood event and may include activities such as engaging protective shields at openings. Passive efforts do not require human intervention. The flood retrofitting measures are elevating the building in place,relocating the building,constructing barriers(levees and floodwalls),dry floodproofing (sealants, closures, sump pumps, and backflow valves), and wet floodproofing (using flood damage-resistant materials and protecting utilities and contents). Flood retrofitting projects may be eligible for funding through the following FEMA Hazard Mitigation Programs: HMGP, PDM, Flood Mitigation Assistance, Repetitive Flood Claims,and Severe Repetitive Loss. More information on obtaining funding for flood retrofitting is available in Hazard Mitigation Assistance Unified Guidance (FEMA 2010a). 15.3.1 Elevation Elevating a building to prevent floodwaters from reaching damageable portions of the building is an effective retrofitting CROSS REFERENCE technique.The building is raised so that the lowest floor is at or above the DFE to avoid damage from the design flood. Heavy- For definitions of DFE and BFE, see Section 8.5.1 of this Manual. duty jacks are used to lift the building. Cribbing is used to support the building while a new or extended foundation is """""..."" constructed. In lieu of constructing new support walls, open 15-8 COASTAL CONSTRUCTION MANUAL Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 litrFigure 15-9. 4,, j ill Home elevated on piles , I. ir to ii---- ' ii a i,...,NNW.. IPO 41 I f. "MU 1161.1"111.1 Irr. i.1I - e • Itx -- id sue. foundations such as piers, columns, posts, and piles are often used (see Figure 15-9). Elevating the building on fill may be an option. Closed foundations are not permitted in Zone V and are not recommended in Coastal A Zones. See Table 10-1 for the types of foundations that are acceptable in each flood zone. The advantages and disadvantages of elevation are listed in Table 15-1. Table 15-1.Advantages and Disadvantages of Elevation Advantages Disadvantages • Brings a substantially damaged or improved building • May be cost-prohibitive into compliance with the NFIP if the lowest horizontal • May adversely affect the building's appearance member is elevated to the BFE • Prohibits the building from being occupying during • Reduces flood risk to the structure and its contents a flood • Eliminates the need to relocate vulnerable items • May adversely affect access to the building above the flood level during flooding •Cannot be used in areas with high-velocity water • Often reduces flood insurance premiums flow, fast-moving ice or debris flow, or erosion • Uses established techniques unless special measures are taken • Requires qualified contractors who are often readily • May require additional costs to bring the building available up to current building codes for plumbing, • Reduces the physical, financial, and emotional strain electrical, and energy systems that accompanies flood events • Requires a consideration of forces from wind and • Does not require the additional land that may be seismic hazards needed for floodwalls or levees SOURCE:FEMA 259 BFE=base flood elevation NFIP=National Flood Insurance Program COASTAL CONSTRUCTION MANUAL 15-9 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II 15.3.2 Relocation Relocation involves moving a structure to a location that is less prone to flooding or flood-related hazards such as erosion.The structure may be relocated to another portion of the current site or to a different site.The surest way to eliminate the risk of flood damage is to relocate the structure out of the floodplain. Relocation normally involves preparing the structure for the move (see Figure 15-10), placing it on a wheeled vehicle, transporting it to the new location, and setting it on a new foundation. Relocation is an appropriate measure in high hazard areas where continued occupancy is unsafe and/or owners want to be free of the risk of flooding. Relocation is also a viable option in communities that are considering using the resulting open space for more appropriate floodplain activities. Relocation may offer an alternative to elevation for substantially damaged structures that are required under local regulations to meet NFIP requirements. Table 15-2 lists the advantages and disadvantages of relocation. Figure 15-10. Preparing a building for relocation Brick fireplaces are braced or taken down _ ® Main structure Li i I-+--I ; :J� disconnected from foundation Larger additions or wings may Old foundation demolished have to be moved separately and backfilled Some contractors remove brick facing for the move 4- Table 15-2.Advantages and Disadvantages of Relocation Advantages Disadvantages •Allows for substantially damaged or improved structure to be • May be cost-prohibitive brought into compliance with the NFIP • Requires locating a new site •Significantly reduces flood risk to the structure and its contents • Requires addressing disposition of the • Uses established techniques flood-prone site • Requires qualified contractors who are often readily available • May require additional costs to bring •Can eliminate the need to purchase flood insurance or reduce the structure up to current building the premium because the house is no longer in the floodplain codes for plumbing, electrical, and • Reduces the physical,financial, and emotional strain that energy systems accompanies flood events SOURCE:FEMA 259 NFIP=National Flood Insurance Program 15-10 COASTAL CONSTRUCTION MANUAL Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 15.3.3 Dry Floodproofing r In dry floodproofing, the portion of a structure that is below 2N r the chosen flood protection level (walls and other exterior _-=..-) WARNING components) is sealed to make it watertight and impermeable Dry floodproofing is not allowed to floodwaters. The objective is to make the walls and other under the NFIP for new and exterior components impermeable to floodwaters. Watertight, substantially damaged or impervious membrane sealant systems include wall coatings, improved residential structures waterproofing compounds, impermeable sheeting, and in an SFHA. For additional supplemental impermeable wall systems, such as cast-in-place information on dry floodproofing, see FEMA FIA TB-3, Non- concrete. Doors, windows, sewer and water lines, and vents Residential Floodproofing are closed with permanent or removable shields or valves. —Requirements and Certification Figure 15-11 is a schematic of a dry floodproofed home. for Buildings Located in Non-residential techniques are also applicable in residential ' Special Flood Hazard Areas situations.See Table 15-3 for the advantages and disadvantages in Accordance with the NFIP of dry floodproofing. (FEMA 1993a)and the Substantial Improvement/Substantial Damage Desk Reference (FEMA 2010b). The expected duration of flooding is critical when,deciding which sealant system to use because seepage can increase over time, rendering the floodproofing ineffective. Waterproofing compounds, sheeting, and sheathing may deteriorate or fail if exposed to floodwaters for extended periods. Sealant systems are also subject to damage (puncture) in areas that experience water flow of significant velocity, ice, or debris flow. Figure 15-11. Maximum protection level is 3 feet(including freeboard) Dry floodproofed _ structure_ FIL-1_, ' --_, gm i I,__,__,,_,,,_,,_,__‘__.._ , . ,,,._,_._._:,..2'ill ,_1"' -•Z=' ''' ;.--:.' 4rf --------- • j Shields for opening *'---- Backflow valve prevents sewer! External coating or covering and drain backup impervious to floodwater i COASTAL CONSTRUCTION MANUAL ; 15-11 P 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II Table 15-3.Advantages and Disadvantages of Dry Floodproofing Advantages Disadvantages • Reduces the flood risk to the.. , • Does not satisfy the NFIP requirement for bringing substantially , structure and contents even damaged or improved residential structures into compliance when the DFE is not exceeded • Requires ongoing maintenance • May be less costly than other • Does not reduce flood insurance premiums for residential structures retrofitting measures - ' unless community-wide basement exception is granted • Does not require the extra : • Usually requires human intervention and adequate warning time for land that may be needed for ' installation of protective measures floodwalls or reduced levees • May provide.no protection if measures fail or are exceeded during large • Reduces the physical,financial, floods and emotional strain that • May result in'more damage than flooding if design loads are exceeded, accompanies flood events walls collapse,floors buckle, or the building floats • Retains the structure in its • Prohibits the building from being occupied during a flood present environment and may ' avoid significant changes in • May adversely affect the appearance of the building if shields are not appearance • , aesthetically pleasing • May not reduce damage to the exterior of the building and other . property • May lead to damage of the building and its contents if the sealant system leaks SOURCE:FEMA 259 NFIP=National Flood Insurance Program DFE=design flood elevation A r 15.3.4 Wet Floodproofing WARNING Wet floodproofing involves modifying a building to allow Wet floodproofing is not allowed floodwaters to enter it in such a way that damage to the under the NFIP for new and structure and its contents is minimized.A schematic of a home substantially damaged or that has been wet floodproofed is shown in Figure 15-12. See improved structures located in an Table 15-4 for a list of the advantages and disadvantages of wet SFHA. Refer to FEMA FIA-TB-7, floodproofing. Wet Floodproofing Requirements , for Structures Located in Wet floodproofing is often used for structures with basements Special Flood Hazard Areas in Accordance with the NFIP(FEMA and crawlspaces when other mitigation techniques are 1993b). technically infeasible or too costly. Wet floodproofing is generally appropriate if a structure has space available to temporarily store damageable items during the flood event. Utilities and furnaces situated below the DFE should be relocated to higher ground while remaining sub-DFE materials CROSS REFERENCE vulnerable to flood damage should be replaced with flood For additional information about damage-resistant building materials. FEMA TB-2, Flood wet floodproofing, see FEMA Damage-Resistant Materials Requirements (FEMA 2008b), P-348, Protecting Building provides guidance concerning the use of flood damage-resistant Utilities From Flood Damage: building components. ; Principles and Practices for the Design and Construction of Rood Resistant Building Utility Systems (FEMA 1999). 15-12 COASTAL CONSTRUCTION MANUAL 9 Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 • Figure 15-12. Wet floodproofed structure First floor door Living area , —J H Ground [ BFE y• Furnace and other Subgrade basement —utilities relocated to F-_ =--� living area or utility Openings '1' room addition provided to let ' '- '' '�' 1-_.i-a floodwaters enter • Table 15-4.Advantages and Disadvantages of Wet Floodproofing Advantages Disadvantages • Reduces the risk of flood • Does not satisfy the NFIP requirement for bringing substantially damage to a.building and its damaged or improved structures into compliance contents, even with minor • Usually requires a flood warning to prepare the building and contents mitigation for flooding • Greatly reduces loads on walls • Requires human intervention to evacuate contents from the flood- and floors due to equalized : prone area hydrostatic pressure • Results in a structure that is wet on the inside and possibly • May be eligible for flood. : contaminated by sewage, chemicals, and other materials borne by insurance coverage of costof floodwaters and may require extensive cleanup relocating or storing contents, • Prohibits the building from being occupied during a flood except basement contents, after • a flood warning is issued • May make the structure uninhabitable for some period after flooding • •Costs less than other measures • Limits the use of the floodable area • Does not require extra land • May require ongoing maintenance • Reduces the physical, financial, • May require additional costs to bring the structure up to current and emotional strain that building codes for plumbing, electrical, and energy systems accompanies flood events • Requires care when pumping out basements to avoid foundation wall collapse SOURCE:FEMA 259 NFIP=National Flood Insurance Program 15.3.5 Floodwalls and Levees Another retrofitting approach is to construct a barrier between the structure and source of flooding.The two basic types of barriers are floodwalls and levees. Small levees that protect a single home can be built to any height but are usually limited to 6 feet due to cost, aesthetics, access, water pressure, and space. The height of floodwalls is usually limited to 4 feet. Local zoning and building codes may also restrict use, size, and location. COASTAL CONSTRUCTION MANUAL 15-13 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II A levee is typically a compacted earthen structure that blocks floodwaters from coming into contact with the structure. To be - WARNING effective over time, levees must be constructed of suitable materials While floodwalls and levees (i.e., impervious soils) and have the correct side slopes for stability. are allowed under NFIP Levees may completely surround the structure or tie to high regulations,they do not make ground at each end. Levees are generally limited to homes where a noncompliant structure floodwaters are less than 5 feet deep. Otherwise, the cost and the compliant under the NFIP. land area required for such barriers usually make them impractical _ - for the average owner. See Table 15-5 for a list of the advantages and disadvantages for retrofitting a home against flooding hazards using floodwalls and levees. Table 15-5.Advantages and Disadvantages of a Floodwall or Levee Advantages Disadvantages • Protects the.area around the structure • Does not satisfy the NFIP requirements for bringing substantially from inundation without significant damaged or improved structures into compliance changes to the structure; • May fail or be overtopped by large floods or floods of long • Eliminates pressure from floodwaters duration that would cause structural damage • May be expensive to the home or other structures in the . Requires periodic maintenance protected area •Costs less to build than elevating or • Requires interior drainage relocating the structure _ , • May affect local drainage, possibly resulting in water problems •Allows the structure to be occupied for others during construction . • Does not reduce flood insurance premiums • Reduces flood risk to the structure • May restrict access to structure and its contents • Requires considerable land (levees only) :• Reduces the physical; financial, and • Does not eliminate the need to evacuate during floods emotional strain that accompanies • May require warning and human intervention for closures flood events • May violate applicable codes or regulations SOURCE:FEMA 259 NFIP=National Flood Insurance Program Floodwalls are engineered barriers designed to keep floodwaters from coming into contact with the structure. Floodwalls can be constructed in a wide variety of shapes and sizes but are typically built of reinforced concrete and/or masonry materials. See Figure 15-13 for an example of a home protected by both a floodwall and a levee. 15.3.6 Multihazard Mitigation The architect, engineer, or code official must recognize that retrofitting a residential structure for flooding may affect how the structure will react to hazards other than flooding. Non-flood-related hazards such as earthquake and wind forces should also be considered when retrofitting for flood-related hazards such as water-borne ice and debris-impact forces, erosion forces, and mudslide impacts. Retrofitting a structure to withstand only floodwater forces may impair the structure's resistance to the multiple hazards mentioned above. Thus, it is important to approach retrofitting with a multi-hazard perspective. 15-14 COASTAL CONSTRUCTION MANUAL Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 Figure 15-13. Floodwall is reinforced and anchored Home protected by a to withstand flood load floodwall and a levee Levee is compacted 1111116. 1111111. fill with 2:1 or 3:1 - - slope(for stability) >JUL" Sump pump removes seepage Backflow valve prevents and internal drainage sewer and drain backup 15.4 High-Wind Mitigation The high-wind natural hazards that affect the hurricane-prone regions of the United States are hurricanes, tropical storms, typhoons, nor'easters, and tornadoes. This section addresses protecting existing residential structures from hurricane damage. The evaluation process and implementation methods for wind retrofit projects discussed in this section are described more fully in FEMA P-804, Wind Retrofit Guide for Residential Building(FEMA 2010c) (see Figure 15-14). la NOTE i111hb, .4` ,� ` Unless otherwise stated, all t' iii`r.. wind speeds in FEMA P-804 are uM Ull 1' ASCE 7-05 3-second gust wind ! ---- _,_ speeds and correspond to design requirements set forth in ASCE 111 ; i• 7-05 and 2006 IRC and 2009 IRC. Because of the changes in 11 II _ r �- the ASCE 7-10 wind speed map, - $ a; it is not appropriate to use the ��, ASCE 7-10 wind speed map in combination with the provisions Wind Retrofit Guide for of ASCE 7-05 and the older codes. Residential Buildings - — -- FEMA P-804/December 2010 Figure 15-14. 0 FEMA FEMA P-804, Wind Retrofit Guide for Residential Buildings COASTAL CONSTRUCTION MANUAL 15-15 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II Hurricane-force winds are most common in coastal areas but also occur in other areas. ASCE 7-05 defines the hurricane-prone regions as the U.S. Atlantic Ocean and Gulf of Mexico coasts where the design wind speed is greater than 90 mph, and Hawaii, Puerto Rico, Guam, Virgin Islands, and American Samoa. 15.4.1 Evaluating Existing Homes Executing a successful retrofit on any home requires an evaluation of its existing condition to determine age and condition;overall structural integrity; any weaknesses in the building envelope,structure,or foundation; whether the home can be retrofitted to improve resistance to wind-related damage; how the home can be retrofit for the Mitigation Packages (see Section 15.4.2); how much the Mitigation Packages would cost; and the most cost-effective retrofit project for the home. A qualified individual should evaluate the home and provide recommendations to the homeowner. Qualified professionals may include building science professionals such as registered architects and engineers, building officials, and evaluators who are certified through other acceptable wind retrofit programs such as the FORTIFIED for Existing Homes Program from the Insurance Institute for Business & Home Safety (IBHS 2010). The purposes of the evaluation are to identify any repairs that are needed before a wind retrofit project can be undertaken,the feasibility of the retrofit project,whether prescriptive retrofits can be performed on the home or whether an engineering solution should be developed, and whether the home is a good candidate for any of the wind retrofit Mitigation Packages described in Section 15.4.2. The purpose of the evaluation is not to determine whether the building meets the current building code. 15.4.2 Wind Retrofit Mitigation Packages The wind retrofit projects described in this section, and more 4111 fully in FEMA P-804, are divided into the Basic Mitigation NOTE Package, Intermediate Mitigation Package, and Advanced Mitigation Package. Additional mitigation measures are In wind retrofitting, the most presented at the end of this section. The packages should be normally involeve techniques strengthening P g normally involve strengthening implemented cumulatively,beginning with the Basic Mitigation the weakest structural links and Package. This means that for a home to successfully meet the improving the water penetration criteria of the Advanced Mitigation Package, it must also meet resistance of the building envelope.To identify the weakest the criteria of the Basic and Intermediate Mitigation Packages. links, the designer should start at The retrofits in each package are shown in Figure 15-15. the top of the building and work down the load path. The wind mitigation retrofits for each package, if implemented MIPMcorrectly, will improve the performance of residential buildings �"""'� - when subjected to high winds. Although the information in this section can be helpful to homeowners, it is intended primarily for evaluators, contractors, and design professionals. The retrofits described for each Mitigation Package and throughout this section are not necessarily listed in the order in which they should be performed. The order in which retrofits should be performed depends on the configuration of the home and should be determined once the desired Mitigation Package is chosen. For example, when the Advanced Mitigation Package is selected, the homeowner should consider retrofitting the roof-to-wall connections when retrofitting the soffits (part of the Basic Mitigation Package). 15-16 COASTAL CONSTRUCTION MANUAL Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 Basic Mitigation Package Retrofits Figure 15-15. Wind Retrofit Mitigation Option 1: OR Option 2: Packages Improvements Improvements SOURCE:FEMA P-804 with roof covering without roof covering replacement replacement Additional Required Retrofits • Strengthening vents and soffits •Strengthening overhangs at gable end walls - ■ Protecting openings per the Intermediate Package, if located in the windborne debris region Intermediate Mitigation Package Retrofits • Protecting windows and entry doors from windborne debris • Protecting garage doors from wind pressure and garage door glazing from windborne debris • Bracing gable end walls ■Strengthening connections of attached structures t c,_lL ed Mitigation Package Retrofits • Developing a continuous load path • Protecting windows, entry doors, and garage doors from windborne debris and wind pressure 15.4.2.1 Basic Mitigation Package The Basic Mitigation Package focuses on securing the roof system and improving the water intrusion resistance of the home. Figures 15-16 and 15-17 show two retrofits that fall into the Basic Mitigation Package. One of the first decisions to make when implementing the Basic Mitigation Package is whether to use Option 1 or Option 2. The evaluation will identify whether the roof covering needs to be replaced (see Section 3.1.1 of FEMA P-804 for more information). If the home is located in a wind-borne debris region, the opening protection measures described in the Intermediate Mitigation Package should be performed for the Basic Mitigation Package in addition to the other retrofits. The opening protection measures include installing an approved impact-resistant covering or component at each exterior window, skylight, entry door, and garage door opening. FEMA P-804 includes procedures, material specifications, and fastening schedules (when applicable) to facilitate implementation of the Basic Mitigation Package. Alternative methods and materials are also discussed to facilitate installation for a variety of as-built conditions. COASTAL CONSTRUCTION MANUAL 15-17 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II Figure 15-16. - Bracing gable end No less than Roof sheathing minimum overhangs overhang distance nominal 7/16 inch thickness t " F--Roof framing members ___- at maximum 24 inches 1 o.c.typical Nominal 2x4 continuous overhang 1 Saddle-type 0 2x4 joist face hanger minimum at maximum I hurricane clip C. 24 inches o.c. typical I j Typical Typical joist Structural saddle- sheathing type clip • Gable end Ni 1 Note: Saddle-type clip may be installed on the exterior face of gable end wall. Removal of soffit may be required. Notes A and B indicate new construction. Figure 15-17. ,r' Sprayed polyurethane foam adhesive to secure roof deck panels _ „,Ili",-• f 4 :\ ,,,/:I i \h.' i . ,. -.. i 411116 ' i \k 1 ' ' 1.' I ; 1ti COASTAL CONSTRUCTION MANUAL Volume II RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 15.4.2.2 Intermediate Mitigation Package' For the Intermediate Mitigation Package to be effective, the measures in the Basic Mitigation Package must first be successfully completed.The Intermediate Mitigation Package includes protecting windows and entry doors from wind-borne debris, protecting garage doors from wind pressure and garage door glazing from wind-borne debris, bracing gable end walls over 4 feet tall, and strengthening the connections of attached structures such as porches and carports. 15.4.2.3 Advanced Mitigation Package The Advanced Mitigation Package is the most comprehensive package of retrofits. This package can be effective only if the Basic Mitigation Package (with or without replacing the roof covering) and Intermediate Mitigation Package are also implemented.; The Advanced Mitigation Package requires a more invasive inspection than the other two packages. Homes that are undergoing substantial renovation or are being rebuilt after a disaster are typically the best candidates for the Advanced Mitigation Package. The Advanced Mitigation Package requires the homeowner to provide a continuous load path as shown in Figure 15-18 and further protect openings. 15.4.2.4 Additional Mitigation Measures The wind retrofit Mitigation Packages include important retrofits,that reduce the risk of wind-related damage, but the risk cannot be eliminated entirely. By maintaining an awareness of vulnerabilities of and around a home, the homeowner can reduce the risk of wind-related damage even further. Although the mitigation measures prescribed to address these vulnerabilities are important to understand, they are not a part of the Mitigation Packages and are not eligible for HMA program funding.These additional measures,described in greater detail in FEMA P-804, include securing the exterior wall covering,implementing tree fall prevention measures, and protecting exterior equipment. 15.4.3 FEMA Wind Retrofit Grant Programs Despite the significant damage experienced by all types of buildings during high-wind events, grant applications for wind retrofit projects have focused more on non-residential and commercial buildings than on residential buildings.FEMA developed FEMA P-804 to encourage wind mitigation of existing residential buildings. FEMA administers two HMA grant programs that fund wind retrofit projects: HMGP and the PDM Program. Hazard mitigation is defined as any sustained action taken to reduce or eliminate long-term risk to people and property from natural hazards and their effects. The HMA process has five stages, starting with mitigation planning and ending with successful execution of a project (see Figure 15-19). Through FEMA's HMA grant programs,applications for an individual home or groups of homes undergoing wind retrofit projects can be submitted for approval.If applications are approved,Federal funding is provided for 75 percent of the total project cost, significantly reducing the homeowner's expenses for the project. The remaining 25 percent of eligible project costs can be paid for directly or covered by donated labor, time, and materials. Refer to current HMA guidance for more details on cost-sharing (FEMA 2010a). More information on Federal assistance through HMA programs is also available in Chapter 5 of FEMA P-804. COASTAL CONSTRUCTION MANUAL 15-19 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II Figure 15-18. Continuous load path Vertical uplift component for wind-uplift of a Wind uplift A A A residential,wood-frame pressure building / / / /60/ / lir°rjir Design G wind uplift load path _I _ llr _iir' . !; ®0 , The foundation transfers all building loads to the ground ` Main floor ., . beams �, , . ., I Homeowners should consider both qualitative and quantitative benefits and costs when deciding on a wind retrofit project. Applying for Federal assistance through HMA programs (as described in Chapter 5 of FEMA P-804) requires an analysis or comparison of the benefits to society compared to the cost of the project. Benefits such as reduced insurance premiums are not considered because they are an individual benefit. To assist with calculating the quantitative benefits and costs of implementing a project, FEMA developed Benefit-Cost Analysis (BCA) software, Version 4.5.5 (FEMA 2009). See Appendix C of FEMA P-804 for additional information on using the BCA software. Communities are encouraged to use the software regardless of whether they will apply for Federal funding. The software can be used to calculate project benefits such as avoided damage to the home,avoided displacement costs,and avoided loss of building contents.The evaluation discussed in Section 15.4.1 should identify all of the necessary input data needed for using the BCA software.Appendix C of FEMA P-804 provides a step-by-step guide to using the software to evaluate the cost-effectiveness of a wind retrofit project. 15-20 COASTAL CONSTRUCTION MANUAL Volume II i RETROFITTING BUILDINGS FOR NATURAL HAZARDS 15 Figure 15-19. M HMA grant process SOURCE:FEMA P-804 1 iainnig gatiohg pl ti G C Q! a S 1111) tCt3 • �•o 0. 1/ A 3c •0 .4% o,��ron 1 p J�`a9 3ae 15.5 References ASCE (American Society of Civil Engineers): 2005.Minimum Design Loads for Buildings and Other Structures. ASCE 7-05. ASCE. Seismic Evaluation of Existing Buildings.ASCE 31 ASCE. Seismic Rehabilitation of Existing Buildings. ASCE 41. FEMA (Federal Emergency Management Agency). 1993a. Non-Residential Floodproofing—Requirements and Certification for Buildings Located in Special Flood Hazard Areas in Accordance with the National Flood Insurance Program. FIA-TB-3. FEMA. 1993b. Wet Floodproofing Requirements for Structures Located in Special Flood Hazard Areas in Accordance with the National Flood Insurance Program. FIA-TB-7. FEMA. 1999. Protecting Building Utilities from Flood Damage. FEMA P-348. FEMA. 2005. Earthquake Safety Guide for Homeowners. FEMA 530. FEMA. 2006. Homebuilders'Guide to Earthquake-Resistant Design and Construction. FEMA 232. COASTAL CONSTRUCTION MANUAL y 15-21 15 RETROFITTING BUILDINGS FOR NATURAL HAZARDS Volume II FEMA. 2008a. Home Builder's Guide to Construction in Wildfire Zones. FEMA P-737. FEMA. 2008b. Flood Damage-Resistant Materials Requirements. Technical Bulletin 2. FEMA. 2009. Benefit-Cost Analysis Tool, Version 4.5.5.Available at http://www.bchelpline.com/ Download.aspx.Accessed January 2011. FEMA. 2010a. Hazard Mitigation Assistance Unified Guidance.Available at http://www.fema.gov/library/ viewRecord.do?id=4225.Accessed June 2011. FEMA. 2010b. Substantial Improvement/Substantial Damage Desk Reference. FEMA P-758. FEMA. 2010c. Wind Retrofit Guide for Residential Buildings. FEMA P-804. FEMA. 2011.Engineering Principles and Practices of Retrofitting Floodprone Structures. FEMA 259. IBHS (Insurance Institute for Business &Home Safety). 2008.Mega Fires: The Case for Mitigation— The Witch Creek Wildfire, October 21-31, 2007 IBHS. 2010. FORTIFIED for Existing Homes Engineering Guide. ICC (International Code Council). 2006. International Residential Code for One-and Two-Family Dwellings. 2006 IRC. ICC. 2009a. International Residential Code for One-and Two-Family Dwellings. 2009 IRC. ICC. International Wildland-Urban Interface Code(IWUIC). NFPA (National Fire Protection Association). Code for Fire Protection of Historical Structures. NFPA. Standard for Fire Protection Infrastructure for Land Development in Suburban and Rural Areas. NFPA 1141. NFPA. Standard for Fire-Retardant Treated Wood and Fire-Retardant Coatings for Building Materials. NFPA 703. NFPA. Standard for Reducing Structure Ignition Hazards from Wildland Fire. NFPA 1144. 15-22 COASTAL CONSTRUCTION MANUAL 1 COASTAL CONSTRUCTION MANUAL Acronyms AAMA American Architectural Manufacturers Association ACI American Concrete Institute AF&PA American Forest &Paper Association AHJ Authority Having Jurisdiction AISI American Iron and Steel Institute ANSI American National Standards Institute ASCE American Society of Civil Engineers ASD Allowable Stress Design ASTM American Society for Testing and Materials AWPA American Wood Protection.Association BCA Benefit-Cost Analysis BCEGS Building Code Effectiveness Grading Schedule BFE base flood elevation BUR built-up roof C&C components and cladding COASTAL CONSTRUCTION MANUAL s A-1 ACRONYMS Volume II CBRA Coastal Barrier Resources Act CBRS Coastal Barrier Resource System CCM Coastal Construction Manual CEA California Earthquake Authority CMU concrete masonry unit CRS Community Rating System DASMA Door &Access Systems Manufacturers Association DFE design flood elevation EIFS exterior insulating finishing system ELF Equivalent Lateral Force FBC Florida Building Code FEMA Federal Emergency Management Agency FIRM Flood Insurance Rate Map FIS Flood Insurance Study FM Factory Mutual FRP fiber-reinforced polymer FS factor of safety GSA General Services Administration A-2 COASTAL CONSTRUCTION MANUAL Volume II ACRONYMS HMA Hazard Mitigation Assistance HMGP Hazard Mitigation Grant Program IBC International Building Code IBHS Institute for Business and Home Safety ICC International Code Council IRC International Residential Code ISO Insurance Services Office lb pound(s) LEED Leadership in Energy and Environmental Design LiMWA Limit of Moderate Wave Action LPS lightning protection system LRFD Load and Resistance Factor Design MEPS molded expanded polystyrene mph miles per hour MWFRS main wind force-resisting system NAHB National Association of Home Builders COASTAL CONSTRUCTION MANUAL A-3 ACRONYMS Volume II NAVD North American Vertical Datum NDS National Design Specification NFIP National Flood Insurance Program NFPA National Fire Protection Association NGVD National Geodetic Vertical Datum NRCA National Roofing Contractors Association NRCS Natural Resources Conservation Service o.c. on center OH overhang OSB oriented strand board PDM Pre-Disaster Mitigation (Program) plf pound(s) per linear foot psf pound(s) per square foot psi pound(s) per square inch SBC Standard Building Code SBS styrene-butadiene-styrene S-DRY surface-dry lumber with <=19 percent moisture content SFHA Special Flood Hazard Area SFIP Standard Flood Insurance Policy SPRI Single-Ply Roofing Institute A-4 COASTAL CONSTRUCTION MANUAL Volume II ACRONYMS TMS The Masonry Society UBC Uniform Building Code UL Underwriters Laboratories USACE U.S.Army Corps of Engineers USDN U.S. Department of the Navy USGBC U.S. Green Buildings Council USGS U.S. Geological Survey UV ultraviolet WFCM Wood Frame Construction Manual Wind-MAP Windstorm Market Assistance Program (New Jersey) WPPC Wood Products Promotion Council yr year(s) COASTAL CONSTRUCTION MANUAL A-5 COASTAL CONSTRUCTION MANUAL Glossary 100-year flood— See Base flood. 500-year flood— Flood that has as 0.2-percent probability of being equaled or exceeded in any given year. Acceptable level of risk— The level of risk judged by the building owner and designer to be appropriate for a particular building. Adjacent grade— Elevation of the natural or graded ground surface, or structural fill, abutting the walls of a building. See also Highest adjacent grade and Lowest adjacent grade. Angle of internal friction (soil) — A measure of the soil's ability to resist shear forces without failure. Appurtenant structure— Under the National Flood Insurance Program, an "appurtenant structure" is "a structure which is on the same parcel of property as the principal structure to be insured and the use of which is incidental to the use of the principal structure." Barrier island— A long, narrow sand island parallel to the mainland that protects the coast from erosion. Base flood— Flood that has as 1-percent probability of being equaled or exceeded in any given year.Also known as the 100-year flood. Base Flood Elevation (BFE) — The water surface elevation resulting from a flood that has a 1 percent chance of equaling or exceeding that level in any given year. Elevation of the base flood in relation to a specified datum, such as the National Geodetic Vertical Datum or the North American Vertical Datum. The Base Flood Elevation is the basis of the insurance and floodplain management requirements of the National Flood Insurance Program. COASTAL CONSTRUCTION MANUAL , G-1 GLOSSARY Volume II Basement— Under the National Flood Insurance Program, any area of a building having its floor subgrade on all sides. (Note: What is typically referred to as a"walkout basement,"which has a floor that is at or above grade on at least one side, is not considered a basement under the National Flood Insurance Program.) Beach nourishment— A project type that typically involve dredging or excavating hundreds of thousands to millions of cubic yards of sediment, and placing it along the shoreline. Bearing capacity(soils) — A measure of the ability of soil to support gravity loads without soil failure or excessive settlement. Berm— Horizontal portion of the backshore beach formed by sediments deposited by waves. Best Practices— Techniques that exceed the minimum requirements of model building codes; design and construction standards; or Federal, State, and local regulations. Breakaway wall— Under the National Flood Insurance Program, a wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces without causing damage to the elevated portion of the building or supporting foundation system. Breakaway walls are required by the National Flood Insurance Program regulations for any enclosures constructed below the Base Flood Elevation beneath elevated buildings in Coastal High Hazard Areas (also referred to as Zone V). In addition, breakaway walls are recommended in areas where flood waters flow at high velocities or contain ice or other debris. Building code— Regulations adopted by local governments that establish standards for construction, modification, and repair of buildings and other structures. Building use— What occupants will do in the building. The intended use of the building will affect its layout, form, and function. Building envelope— Cladding, roofing, exterior walls, glazing, door assemblies,window assemblies, skylight assemblies, and other components enclosing the building. Building systems— Exposed structural, window, or roof systems. Built-up roof covering— Two or more layers of felt cemented together and surfaced with a cap sheet, mineral aggregate, smooth coating, or similar surfacing material. Bulkhead— Wall or other structure, often of wood, steel, stone, or concrete, designed to retain or prevent sliding or erosion of the land. Occasionally, bulkheads are used to protect against wave action. Cladding— Exterior surface of the building envelope that is directly loaded by the wind. Closed foundation— A foundation that does not allow water to pass easily through the foundation elements below an elevated building. Examples of closed foundations include crawlspace foundations and stem wall foundations, which are usually filled with compacted soil, slab-on-grade foundations, and continuous perimeter foundation walls. G-2 COASTAL CONSTRUCTION MANUAL Volume II GLOSSARY Coastal A Zone— The portion.of the coastal SFHA referenced by building codes and standards, where base flood wave heights are between 1.5 and 3 feet, and where wave characteristics are deemed sufficient to damage many NFIP-compliant structures on shallow or solid wall foundations. Coastal barrier— Depositional geologic feature such as a bay barrier, tombolo, barrier spit, or barrier island that consists of unconsolidated sedimentary materials; is subject to wave, tidal, and wind energies; and protects landward aquatic habitats from direct wave attack. Coastal Barrier Resources Act of 1982 (CBRA) — Act (Public Law 97-348) that established the Coastal Barrier Resources System (CBRS). The act prohibits the provision of new flood insurance coverage on or after October 1, 1983, for any new construction or substantial improvements of structures located on any designated undeveloped coastal barrier within the CBRS. The CBRS was expanded by the Coastal Barrier Improvement Act of 1991. The date on which an area is added to the CBRS is the date of CBRS designation for that area. Coastal flood hazard area— An area subject to inundation by storm surge and, in some instances,wave action caused by storms or seismic forces. Usually along an open coast, bay, or inlet. Coastal geology— The origin, structure, and characteristics of the rocks and sediments that make up the coastal region. Coastal High Hazard Area— Under the National Flood Insurance Program, an area of special flood hazard extending from offshore to the inland limit of a primary frontal dune along an open coast and any other area subject to high-velocity wave action from storms or seismic sources. On a Flood Insurance Rate Map, the Coastal High Hazard Area is designated Zone V,VE, or V1-V30. These zones designate areas subject to inundation by the base flood, where wave heights or wave runup depths are 3.0 feet or higher. Coastal processes— The physical processes that act upon and shape the coastline. These processes, which influence the configuration, orientation, and movement of the coast, include tides and fluctuating water levels, waves, currents, and winds. Coastal sediment budget— The quantification of the amounts and rates of sediment transport, erosion, and deposition within a defined region. Coastal Special Flood Hazard Area— The portion of the Special Flood Hazard Area where the source of flooding is coastal surge or inundation. It includes Zone VE and Coastal A Zone. Code official— Officer or other designated authority charged with the administration and enforcement of the code, or a duly authorized representative, such as a building, zoning, planning, or floodplain management official. Column foundation— Foundation consisting of vertical support members with a height-to-least-lateral- dimension ratio greater than three. Columns are set in holes and backfilled with compacted material. They are usually made of concrete or masonry and often must be braced. Columns are sometimes known as posts, particularly if they are made of wood. Components and Cladding(C&C) — American Society of Civil Engineers (ASCE) 7-10 defines C&C as "... elements of the building envelope that do not qualify as part of the MWFRS [Main Wind Force Resisting System]." These elements include roof sheathing, roof coverings, exterior siding,windows, doors, soffits, fascia, and chimneys. COASTAL CONSTRUCTION MANUAL G-3 GLOSSARY , Volume II Conditions Greater than Design Conditions— Design loads and conditions are based on some probability of exceedance, and it is always possible that design loads and conditions can be exceeded. Designers can anticipate this and modify their initial design to better accommodate higher forces and more extreme conditions. The benefits of doing so often exceed the costs of building higher and stronger. Connector— Mechanical device for securing two or more pieces, parts, or members together, including anchors,wall ties, and fasteners. Consequence— Both the short- and long-term effects of an event for the building. See Risk. Constructability— Ultimately, designs will only be successful if they can be implemented by contractors. Complex designs with many custom details may be difficult to construct and could lead to a variety of problems, both during construction and once the building is occupied. Continuous load paths— The structural condition required to resist loads acting on a building. The continuous load path starts at the point or surface where loads are applied, moves through the building, continues through the foundation, and terminates where the loads are transferred to the soils that support the building. Corrosion-resistant metal— Any nonferrous metal or any metal having an unbroken surfacing of nonferrous metal, or steel with not less than 10 percent chromium or with not less than 0.20 percent copper. Dead load— Weight of all materials of construction incorporated into the building, including but not limited to walls, floors, roofs, ceilings, stairways, built-in partitions, finishes, cladding, and other similarly incorporated architectural and structural items and fixed service equipment. See also Loads. Debris— Solid objects or masses carried by or floating on the surface of moving water. Debris impact loads— Loads imposed on a structure by the impact of floodborne debris. These loads are often sudden and large. Though difficult to predict, debris impact loads must be considered when structures are designed and constructed. See also Loads. Deck— Exterior floor supported on at least two opposing sides by an adjacent structure and/or posts, piers, or other independent supports. Design event— The minimum code-required event (for natural hazards, such as flood, wind, and earthquake) and associated loads that the structure must be designed to resist. Design flood— The greater of either (1) the base flood or (2) the flood associated with the flood hazard area depicted on a community's flood hazard map, or otherwise legally designated. Design Flood Elevation (DFE) — Elevation of the design flood, or the flood protection elevation required by a community, including wave effects,'relative to the National Geodetic Vertical Datum, North American Vertical Datum, or other datum. The DFE is the locally adopted regulatory flood elevation. If a community regulates to minimum National Flood Insurance Program (NFIP) requirements, the G-4 COASTAL CONSTRUCTION MANUAL Volume II GLOSSARY DFE is identical to the Base Flood Elevation (BFE). If a community chooses to exceed minimum NFIP requirements, the DFE exceeds the BFE. Design flood protection depth— Vertical distance between the eroded ground elevation and the Design Flood Elevation. Design stillwater flood depth— Vertical distance between the eroded ground elevation and the design stillwater flood elevation. Design stillwater flood elevation— Stillwater elevation associated with the design flood, excluding wave effects, relative to the National Geodetic Vertical Datum, North American Vertical Datum, or other datum. Development— Under the National Flood Insurance Program, any manmade change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation, or drilling operations or storage of equipment or materials. Dry floodproofing— A flood retrofitting technique in which the portion of a structure below the flood protection level (walls and other exterior components) is sealed to be impermeable to the passage of floodwaters. Dune— See Frontal dune and Primary frontal dune. Dune toe— Junction of the gentle slope seaward of the dune and the dune face,which is marked by a slope of 1 on 10 or steeper. Effective Flood Insurance Rate Map— See Flood Insurance Rate Map. Elevation— Raising a structure to prevent floodwaters from reaching damageable portions. Enclosure— The portion of an elevated building below the lowest floor that is partially or fully shut in by rigid walls. Encroachment— The placement of an object in a floodplain that hinders the passage of water or otherwise affects the flood flows. Erodible soil— Soil subject to wearing away and movement due to the effects of wind,water, or other geological processes during a flood or storm or over a period of years. Erosion— Under the National Flood Insurance Program, the process of the gradual wearing away of land masses. Erosion analysis— Analysis of the short- and long-term erosion potential of soil or strata, including the effects of flooding or storm surge, moving water, wave action, and the interaction of water and structural components. Exterior-mounted mechanical equipment— Includes, but is not limited to, exhaust fans,vent hoods, air conditioning units, duct work, pool motors, and well pumps. COASTAL CONSTRUCTION MANUAL G-5 GLOSSARY Volume II Federal Emergency Management Agency(FEMA) — Independent agency created in 1979 to provide a single point of accountability for all Federal activities related to disaster mitigation and emergency preparedness, response, and recovery. FEMA administers the National Flood Insurance Program. Federal Insurance and Mitigation Administration (FIMA) — The component of the Federal Emergency Management Agency directly responsible for administering the flood insurance aspects of the National Flood Insurance Program as well as a range of programs designed to reduce future losses to homes, businesses, schools, public buildings, and critical facilities from floods, earthquakes, tornadoes, and other natural disasters. Fill— Material such as soil, gravel, or crushed stone placed in an area to increase ground elevations or change soil properties. See also Structural fill. Flood— Under the National Flood Insurance Program, either a general and temporary condition or partial or complete inundation of normally dry land areas from: (1) the overflow of inland or tidal waters; (2) the unusual and rapid accumulation or runoff of surface waters from any source; (3) mudslides (i.e.,mudflows) that are proximately caused by flooding as defined in (2) and are akin to a river of liquid and flowing mud on the surfaces of normally dry land areas, as when the earth is carried by a current of water and deposited along the path of the current; or (4) the collapse or subsidence of land along the shore of a lake or other body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels or suddenly caused by an unusually high water level in a natural body of water,accompanied by a severe storm, or by an unanticipated force of nature,such as flash flood or abnormal tidal surge,or by some similarly unusual and unforeseeable event which results in flooding as defined in (1), above. Flood-damage-resistant material— Any construction material capable of withstanding direct and prolonged contact (i.e., at least 72 hours) with flood waters without suffering significant damage (i.e., damage that requires more than cleanup or low-cost cosmetic repair, such as painting). Flood elevation— Height of the water surface above an established elevation datum such as the National Geodetic Vertical Datum, North American Vertical Datum, or mean sea level. Flood hazard area— The greater of the following: (1) the area of special flood hazard, as defined under the National Flood Insurance Program, or (2) the area designated as a flood hazard area on a community's legally adopted flood hazard map, or otherwise legally designated. Flood insurance— Insurance coverage provided under the National Flood Insurance Program. Flood Insurance Rate Map (FIRM) — Under the National Flood Insurance Program, an official map of a community, on which the Federal Emergency Management Agency has delineated both the special hazard areas and the risk premium zones applicable to the community. (Note: The latest FIRM issued for a community is referred to as the "effective FIRM" for that community.) G-6 COASTAL CONSTRUCTION MANUAL Volume II GLOSSARY Flood Insurance Study(FIS) — Under the National Flood Insurance Program, an examination, evaluation, and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation, and determination of mudslide (i.e., mudflow) and flood-related erosion hazards in a community or communities. (Note: The National Flood Insurance Program regulations refer to Flood Insurance Studies as "flood elevation studies.") Flood-related erosion area or flood-related erosion prone area— A land area adjoining the shore of a lake or other body of water, which due to the composition of the shoreline or bank and high water levels or wind-driven currents, is likely to suffer flood-related erosion. Flooding— See Flood. Floodplain— Under the National Flood Insurance Program, any land area susceptible to being inundated by water from any source. See also Flood. Floodplain management— Operation of an overall program of corrective and preventive measures for reducing flood damage, including but not limited to emergency preparedness plans, flood control works, and floodplain management regulations. Floodplain management regulations— Under the National Flood Insurance Program, zoning ordinances, subdivision regulations, building codes, health regulations, special purpose ordinances (such as floodplain ordinance, grading ordinance, and erosion control ordinance), and other applications of police power. The term describes State or local regulations, in any combination thereof, that promulgate standards for the purpose of flood damage prevention and reduction. Floodwall— A flood retrofitting technique that consists of engineered barriers designed to keep floodwaters from coming into contact with the structure. Footing— Enlarged base of a foundation wall, pier, post, or column designed to spread the load of the structure so that it does not exceed the soil bearing capacity. Footprint— Land area occupied by a structure. Freeboard— Under the National Flood Insurance Program, a factor of safety, usually expressed in feet above a flood level, for the purposes of floodplain management. Freeboard is intended to compensate for the many unknown factors that could contribute to flood heights greater than the heights calculated for a selected size flood and floodway conditions, such as the hydrological effect of urbanization of the watershed. Freeboard is additional height incorporated into the Design Flood Elevation, and may be required by State or local regulations or be desired by a property owner. Frontal dune— Ridge or mound of unconsolidated sandy soil extending continuously alongshore landward of the sand beach and defined by relatively steep slopes abutting markedly flatter and lower regions on each side. Frontal dune reservoir— Dune cross-section above 100-year stillwater level and seaward of dune peak. COASTAL CONSTRUCTION MANUAL G-7 GLOSSARY Volume II Gabion— Rock-filled cage made of wire or metal that is placed on slopes or embankments to protect them from erosion caused by flowing or fast-moving water. Geomorphology— The origin, structure, and characteristics of the rocks and sediments that make up the coastal region. Glazing— Glass or transparent or translucent plastic sheet in windows, doors, skylights, and shutters. Grade beam— Section of a concrete slab that is thicker than the slab and acts as a footing to provide stability, often under load-bearing or critical structural walls. Grade beams are occasionally installed to provide lateral support for vertical foundation members where they enter the ground. High-velocity wave action— Condition in which wave heights or wave runup depths are 3.0 feet or higher. Highest adjacent grade— Elevation of the highest natural or regraded ground surface, or structural fill, that abuts the walls of a building. Hurricane— Tropical cyclone, formed in the atmosphere over warm ocean areas, in which wind speeds reach 74 miles per hour or more and blow in a large spiral around a relatively calm center or "eye." Hurricane circulation is counter-clockwise in the northern hemisphere and clockwise in the southern hemisphere. Hurricane clip or strap— Structural connector, usually metal, used to tie roof, wall, floor, and foundation members together so that they resist wind forces. Hurricane-prone region— In the United States and its territories, hurricane-prone regions are defined by The American Society of Civil Engineers (ASCE) 7-10 as: (1) The U.S. Atlantic Ocean and Gulf of Mexico coasts where the basic wind speed for Risk Category II buildings is greater than 115 mph, and (2) Hawaii, Puerto Rico, Guam, the Virgin Islands, and American Samoa. Hydrodynamic loads— Loads imposed on an object, such as a building, by water flowing against and around it.Among these loads are positive frontal pressure against the structure, drag effect along the sides, and negative pressure on the downstream side. Hydrostatic loads— Loads imposed on a surface, such as a wall or floor slab, by a standing mass of water. The water pressure increases with the square of the water depth. Initial costs— Include property evaluation, acquisition, permitting, design, and construction. G-8 COASTAL CONSTRUCTION MANUAL Volume II GLOSSARY Interior mechanical equipment— Includes, but is not limited to, furnaces, boilers, water heaters, and distribution ductwork. Jetting(of piles) — Use of a high-pressure stream of water to embed a pile in sandy soil. See also Pile foundation. Jetty— Wall built from the shore out into the water to restrain currents or protect a structure. Joist— Any of the parallel structural members of a floor system that support, and are usually immediately beneath, the floor. Lacustrine flood hazard area— Area subject to inundation from lakes. Landslide— Occurs when slopes become unstable and loose material slides or flows under the influence of gravity. Often, landslides are triggered by other events such as erosion at the toe of a steep slope, earthquakes, floods, or heavy rains, but can be worsened by human actions such as destruction of vegetation or uncontrolled pedestrian access on steep slopes. Levee— Typically a compacted earthen structure that blocks floodwaters from coming into contact with the structure, a levee is a manmade structure built parallel to a waterway to contain, control, or divert the flow of water.A levee system may also include concrete or steel floodwalls, fixed or operable floodgates and other closure structures, pump stations for rainwater drainage, and other elements, all of which must perform as designed to prevent failure. Limit of Moderate Wave Action (LiMWA) — A line indicating the limit of the 1.5-foot wave height during the base flood. FEMA requires new flood studies in coastal areas to delineate the LiMWA. Littoral drift— Movement of sand by littoral (longshore) currents in a direction parallel to the beach along the shore. Live loads— Loads produced by the use and occupancy of the building or other structure. Live loads do not include construction or environmental loads such as wind load, snow load, rain load, earthquake load, flood load, or dead load. See also Loads. Load-bearing wall— Wall that supports any vertical load in addition to its own weight. See also Non- load-bearing wall. Loads— Forces or other actions that result from the weight of all building materials, occupants and their possessions, environmental effects, differential movement, and restrained dimensional changes. Loads can be either permanent or variable. Permanent loads rarely vary over time or are of small magnitude.All other loads are variable loads. COASTAL CONSTRUCTION MANUAL G-9 GLOSSARY Volume II Location— The location of the building determines the nature and intensity of hazards to which the building will be exposed, loads and conditions that the building must withstand, and building regulations that must be satisfied. See also Siting. Long-term costs— Include preventive maintenance and repair and replacement of deteriorated or damaged building components.A hazard-resistant design can result in lower long-term costs by preventing or reducing losses from natural hazards events. Lowest adjacent grade (LAG) — Elevation of the lowest natural or regraded ground surface, or structural fill, that abuts the walls of a building. See also Highest adjacent grade. Lowest floor— Under the National Flood Insurance Program (NFIP), "lowest floor" of a building includes the floor of a basement. The NFIP regulations define a basement as "... any area of a building having its floor subgrade (below ground level) on all sides." For insurance rating purposes, this definition applies even when the subgrade floor is not enclosed by full-height walls. Lowest horizontal structural member— In an elevated building, the lowest beam, joist, or other horizontal member that supports the building. Grade beams installed to support vertical foundation members where they enter the ground are not considered lowest horizontal structural members. Main Wind Force Resisting System (MWFRS) — Consists of the foundation; floor supports (e.g.,joists, beams); columns; roof raters or trusses; and bracing, walls, and diaphragms that assist in transferring loads. The American Society of Civil Engineers (ASCE) 7-10 defines the MWFRS as "... an assemblage of structural elements assigned to provide support and stability for the overall structure." Manufactured home— Under the National Flood Insurance Program, a structure, transportable in one or more sections, built on a permanent chassis and designed for use with or without a permanent foundation when attached to the required utilities. Does not include recreational vehicles. Marsh— Wetland dominated by herbaceous or non-woody plants often developing in shallow ponds or depressions, river margins, tidal areas, and estuaries. Masonry— Built-up construction of building units made of clay, shale, concrete, glass, gypsum, stone, or other approved units bonded together with or without mortar or grout or other accepted methods of joining. Mean return period— The average time (in years) between landfall or nearby passage of a tropical storm or hurricane. Mean water elevation— The surface across which waves propagate. The mean water elevation is calculated as the stillwater elevation plus the wave setup. Mean sea level (MSL) — Average height of the sea for all stages of the tide, usually determined from hourly height observations over a 19-year period on an open coast or in adjacent waters having free access to the sea. See also National Geodetic Vertical Datum. G-10 COASTAL CONSTRUCTION MANUAL Volume II GLOSSARY Metal roof panel— Interlocking metal sheet having a minimum installed weather exposure of 3 square feet per sheet. Minimal Wave Action area(MiWA) — The portion of the coastal Special Flood Hazard Area where base flood wave heights are less than 1.5 feet. Mitigation— Any action taken to reduce or permanently eliminate the long-term risk to life and property from natural hazards. Mitigation Directorate— Component of the Federal Emergency Management Agency directly responsible for administering the flood hazard identification and floodplain management aspects of the National Flood Insurance Program. Moderate Wave Action area(MoWA) — See Coastal A Zone. • National Flood Insurance Program (NFIP) — Federal program created by Congress in 1968 that makes flood insurance available in communities that enact and enforce satisfactory floodplain management regulations. National Geodetic Vertical Datum (NGVD) — Datum established in 1929 and used as a basis for measuring flood, ground, and structural elevations, previously referred to as Sea Level Datum or Mean Sea Level. The Base Flood Elevations shown on most of the Flood Insurance Rate Maps issued by the Federal Emergency Management Agency are referenced to NGVD or, more recently, to the North American Vertical Datum. • Naturally decay-resistant wood— Wood whose composition provides it with some measure of resistance to decay and attack by insects, without preservative treatment (e.g., heartwood of cedar, black locust, black walnut, and redwood). New construction— For the purpose of determining flood insurance rates under the National Flood Insurance Program, structures for which the start of construction commenced on or after the effective date of the initial Flood Insurance Rate Map or after December 31, 1974,whichever is later, including any subsequent improvements to such structures. (See also Post-FIRM structure.) For floodplain management purposes, new construction means structures for which the start of construction commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such structures. Non-load-bearing wall— Wall that does not support vertical loads other than its own weight. See also Load-bearing wall. Nor'easter— A type of storm that occurs along the East Coast of the United States where the wind comes from the northeast. Nor'easters can cause coastal flooding, coastal erosion, hurricane-force winds, and heavy snow. North American Vertical Datum (NAVD) — Datum established in 1988 and used as a basis for measuring flood, ground, and structural eleyations. NAVD is used in many recent Flood Insurance Studies rather than the National Geodetic Vertical Datum. COASTAL CONSTRUCTION MANUAL G-11 GLOSSARY Volume II Open foundation— A foundation that allows water to pass through the foundation of an elevated building, which reduces the lateral flood loads the foundation must resist. Examples of open foundations are pile, pier, and column foundations. Operational costs— Costs associated with the use of the building, such as the cost of utilities and insurance. Optimizing energy efficiency may result in a higher initial cost but save in operational costs. Oriented strand board (OSB) — Mat-formed wood structural panel product composed of thin rectangular wood strands or wafers arranged in oriented layers and bonded with waterproof adhesive. Overwash— Occurs when low-lying coastal lands are overtopped and eroded by storm surge and waves such that the eroded sediments are carried landward by floodwaters, burying uplands, roads, and at-grade structures. Pier foundation— Foundation consisting of isolated masonry or cast-in-place concrete structural elements extending into firm materials. Piers are relatively short in comparison to their width, which is usually greater than or equal to 12 times their vertical dimension. Piers derive their load-carrying capacity through skin friction, end bearing, or a combination of both. Pile foundation— Foundation consisting of concrete, wood, or steel structural elements driven or jetted into the ground or cast-in-place. Piles are relatively slender in comparison to their length,which usually exceeds 12 times their horizontal dimension. Piles derive their load-carrying capacity through skin friction, end bearing, or a combination of both. Platform framing— A floor assembly consisting of beams,joists, and a subfloor that creates a platform that supports the exterior and interior walls. Plywood— Wood structural panel composed of plies of wood veneer arranged in cross-aligned layers. The plies are bonded with an adhesive that cures when heat and pressure are applied. Post-FIRM structure— For purposes of determining insurance rates under the National Flood Insurance Program, structures for which the start of construction commenced on or after the effective date of an initial Flood Insurance Rate Map or after December 31, 1974, whichever is later, including any subsequent improvements to such structures. This term should not be confused with the term new construction as it is used in floodplain management. Post foundation— Foundation consisting of vertical support members set in holes and backfilled with compacted material. Posts are usually made of wood and usually must be braced. Posts are also known as columns, but columns are usually made of concrete or masonry. Precast concrete— Structural concrete element cast elsewhere than its final position in the structure. See also Cast-in-place concrete. G-12 COASTAL CONSTRUCTION MANUAL Volume II GLOSSARY Pressure-treated wood— Wood impregnated under pressure with compounds that reduce the susceptibility of the wood to flame spread or to deterioration caused by fungi, insects, or marine borers. Premium— Amount of insurance coverage. Primary frontal dune— Under the National Flood Insurance Program, a continuous or nearly continuous mound or ridge of sand with relatively steep seaward and landward slopes immediately landward and adjacent to the beach and subject to erosion and overtopping from high tides and waves during major coastal storms. The inland limit of the primary frontal dune occurs at the point where there is a distinct change from a relatively steep slope to a relatively mild slope. Rating factor (insurance) — A factor used to determine the amount to be charged for a certain amount of insurance coverage (premium). Recurrence interval— The frequency of occurrence of a natural hazard as referred to in most design codes and standards. Reinforced concrete— Structural concrete reinforced with steel bars. Relocation— The moving of a structure to a location that is less prone to flooding and flood-related hazards such as erosion. Residual risk— The level of risk that is not offset by hazard-resistant design or insurance, and that must be accepted by the property owner. Retrofit— Any change or combination of adjustments made to an existing structure intended to reduce or eliminate damage to that structure from flooding, erosion, high winds, earthquakes, or other hazards. Revetment— Facing of stone, cement, sandbags, or other materials placed on an earthen wall or embankment to protect it from erosion or scour caused by flood waters or wave action. Riprap— Broken stone, cut stone blocks, or rubble that is placed on slopes to protect them from erosion or scour caused by flood waters or wave action. Risk— Potential losses associated with a hazard, defined in terms of expected probability and frequency, exposure, and consequences. Risk is associated with three factors: threat, vulnerability, and consequence. Risk assessment— Process of quantifying the total risk to a coastal building (i.e., the risk associated with all the significant natural hazards that may impact the building). Risk category— As defined in American Society of Civil Engineers (ASCE) 7-10 and the 2012 International Building Code, a building's risk category is based on the risk to human life, health, and welfare associated with potential damage or failure of the building. These risk categories dictate which design event is used when calculating performance expectations of the building, specifically the loads the building is expected to resist. Risk reduction— The process of reducing or offsetting risks. Risk reduction is comprised of two aspects: physical risk reduction and risk management through insurance. COASTAL CONSTRUCTION MANUAL G-13 GLOSSARY Volume II Risk tolerance— Some owners are willing and able to assume a high degree of financial and other risks, while other owners are very conservative and seek to minimize potential building damage and future costs. Riverine SFHA— The portion of the Special Flood Hazard Area mapped as Zone AE and where the source of flooding is riverine, not coastal. Roof deck— Flat or sloped roof surface not including its supporting members or vertical supports. Sand dunes— Under the National Flood Insurance Program, natural or artificial ridges or mounds of sand landward of the beach. Scour— Removal of soil or fill material by the flow of flood waters. Flow moving past a fixed object accelerates, often forming eddies or vortices and scouring loose sediment from the immediate vicinity of the object. The term is frequently used to describe storm-induced, localized conical erosion around pilings and other foundation supports,where the obstruction of flow increases turbulence. See also Erosion. Seawall— Solid barricade built at the water's edge to protect the shore and prevent inland flooding. Setback— For the purpose of this Manual, a State or local requirement that prohibits new construction and certain improvements and repairs to existing coastal buildings in areas expected to be lost to shoreline retreat. Shearwall— Load-bearing wall or non-load-bearing wall that transfers in-plane lateral forces from lateral loads acting on a structure to its foundation. Shoreline retreat— Progressive movement of the shoreline in a landward direction; caused by the composite effect of all storms over decades and centuries and expressed as an annual average erosion rate. Shoreline retreat is essentially the horizontal component of erosion and is relevant to long-term land use decisions and the siting of buildings. Single-ply membrane— Roofing membrane that is field-applied with one layer of membrane material (either homogeneous or composite) rather than multiple layers. The four primary types of single-ply membranes are chlorosulfonated polyethylene (CSPE) (Hypalon), ethylene propylene diene monomer (EPDM), polyvinyl chloride (PVC), and thermoplastic polyolefin (TPO). Siting— Choosing the location for the development or redevelopment of a structure. Special Flood Hazard Area(SFHA) — Under the National Flood Insurance Program, an area having special flood, mudslide (i.e., mudflow), or flood-related erosion hazards, and shown on a Flood Hazard Boundary Map or Flood Insurance Rate Map as Zone A,AO,Al-A30,AE,A99,AH,V, V1-V30,VE, M, or E. The area has a 1 percent chance, or greater, of flooding in any given year. Start of construction (for other than new construction or substantial improvements under the Coastal Barrier Resources Act) — Under the National Flood Insurance Program, date the building permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition placement, or other improvement was within 180 days of the permit date. The actual start means either the first placement of permanent construction of a structure on a site such as the pouring of slab or footings, G-14 COASTAL CONSTRUCTION MANUAL Volume II GLOSSARY the installation of piles, the construction of columns, or any work beyond the stage of excavation; or the placement of a manufactured home on a foundation. Permanent construction does not include land preparation, such as clearing, grading, and filling; nor the installation of streets or walkways; excavation for a basement, footings, piers, or foundations or the erection of temporary forms; or the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main structure. For a substantial improvement, the actual start of construction means the first alteration of any wall, ceiling, floor, or other structural part of a building, whether or not that alteration affects the external dimensions of the building. State Coordinating Agency— Under the National Flood Insurance Program, the agency of the State government, or other office designated by the Governor of the State or by State statute to assist in the implementation of the National Flood Insurance Program in that State. Stillwater elevation— The elevations of the water surface resulting solely from storm surge (i.e., the rise in the surface of the ocean due to the action of wind and the drop in atmospheric pressure association with hurricanes and other storms). Storm surge— Water pushed toward the shore by the force of the winds swirling around a storm. It is the greatest cause of loss of life due to hurricanes. Storm tide— Combined effect of storm surge, existing astronomical tide conditions, and breaking wave setup. Structural concrete— All concrete used for structural purposes, including plain concrete and reinforced concrete. Structural fill— Fill compacted to a specified density to provide structural support or protection to a structure. See also Fill. Structure— For floodplain management purposes under the National Flood Insurance Program (NFIP), a walled and roofed building, gas or liquid storage tank, or manufactured home that is principally above ground. For insurance coverage purposes under the NFIP, structure means a walled and roofed building, other than a gas or liquid storage tank, that is principally above ground and affixed to a permanent site, as well as a manufactured home on a permanent foundation. For the latter purpose, the term includes a building undergoing construction, alteration, or repair, but does not include building materials or supplies intended for use in such construction, alteraion, or repair, unless such materials or supplies are within an enclosed building on the premises. Substantial damage— Under the National Flood Insurance Program, damage to a building (regardless of the cause) is considered substantial damage if the cost of restoring the building to its before-damage condition would equal or exceed 50 percent of the market value of the structure before the damage occurred. . Substantial improvement— Under the National Flood Insurance Program, improvement of a building (such as reconstruction, rehabilitation, or addition) is considered a substantial improvement if its cost equals or exceeds 50 percent of the market value of the building before the start of construction of the improvement. This term includes structures that have incurred substantial damage, regardless of the actual repair work performed. The term does not, however, include either (1) any project for improvement of a structure to correct existing violations of State or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary to ensure COASTAL CONSTRUCTION MANUAL G-15 GLOSSARY Volume II safe living conditions, or (2) any alteration of a"historic structure," provided that the alteration will not preclude the structure's continued designation as a"historic structure." Super typhoons— Storms with sustained winds equal to or greater than 150 mph. Threat— The probability that an even of a given recurrence interval will affect the building within a specified period. See Risk. Tornado— A rapidly rotating vortex or funnel of air extending groundward from a cumulonimbus cloud Tributary area— The area of the floor, wall, roof, or other surface that is supported by the element. The tributary area is generally a rectangle formed by one-half the distance to the adjacent element in each applicable direction. Tropical cyclone— A low-pressure system that generally forms in the tropics, and is often accompanied by thunderstorms. Tropical depression— Tropical cyclone with some rotary circulation at the water surface. With maximum sustained wind speeds of up to 39 miles per hour, it is the second phase in the development of a hurricane. Tropical disturbance— Tropical cyclone that maintains its identity for at least 24 hours and is marked by moving thunderstorms and with slight or no rotary circulation at the water surface. Winds are not strong. It is a common phenomenon in the tropics and is the first discernable stage in the development of a hurricane. Tropical storm— Tropical cyclone that has 1-minute sustained wind speeds averaging 39 to 74 miles per hour (mph). Tsunami— Long-period water waves generated by undersea shallow-focus earthquakes, undersea crustal displacements (subduction of tectonic plates), landslides, or volcanic activity. Typhoon— Name given to a hurricane in the area of the western Pacific Ocean west of 180 degrees longitude. Underlayment— One or more layers of felt, sheathing paper, non-bituminous saturated felt, or other approved material over which a steep-sloped roof covering is applied. Undermining— Process whereby the vertical component of erosion or scour exceeds the depth of the base of a building foundation or the level below which the bearing strength of the foundation is compromised. Uplift— Hydrostatic pressure caused by water under a building. It can be strong enough lift a building off its foundation, especially when the building is not properly anchored to its foundation. G-16 COASTAL CONSTRUCTION MANUAL Volume II GLOSSARY Variance— Under the National Flood Insurance Program, grant of relief by a community from the terms of a floodplain management regulation. Violation— Under the National Flood Insurance Program (NFIP), the failure of a structure or other development to be fully compliant with the community's floodplain management regulations.A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required in Sections 60.3(b)(5), (c)(4), (c)(10),, (d)(3), (e)(2), (e)(4), or (e)(5) of the NFIP regulations is presumed to be in violation until such time as that documentation is provided. Vulnerability— Weaknesses in the building or site location that may result in damage. See Risk. Water surface elevation- Under the National Flood Insurance Program, the height, in relation to the National Geodetic Vertical Datum of 1929 (or other datum, where specified), of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas. Wave— Ridge, deformation, or undulation of the water surface. Wave height— Vertical distance between the wave crest and wave trough. Wave crest elevation is the elevation of the crest of a wave, referenced to the National Geodetic Vertical Datum, North American Vertical Datum, or other datum. Wave overtopping— Occurs when waves run up and over a dune or barrier. Wave runup— Is the rush of water up a slope or structure. Wave runup occurs as waves break and run up beaches, sloping surfaces, and vertical surfaces. Wave runup depth— At any point is equal to the maximum wave runup elevation minus the lowest eroded ground elevation at that point. Wave runup elevation— Is the elevation reached by wave runup, referenced to the National Geodetic Vertical Datum or other datum. Wave setup— Increase in the stillwater surface near the shoreline due to the presence of breaking waves. Wave setup typically adds 1.5 to 2.5 feet to the 100-year stillwater flood elevation and should be discussed in the Flood Insurance Study. Wave slam— The action of wave crests striking the elevated portion of a structure. Wet floodproofing— A flood retrofitting technique that involves modifying a structure to allow floodwaters to enter it in such a way that damage to a structure and its contents is minimized. COASTAL CONSTRUCTION MANUAL G-17 GLOSSARY Volume II Zone A— Under the National Flood Insurance Program, area subject to inundation by the 100-year flood where wave action does not occur or where waves are less than 3 feet high, designated Zone A,AE,Al- A30,AO,AH, or AR on a Flood Insurance Rate Map. Zone AE— The portion of the Special Flood Hazard Area (SFHA) not mapped as Zone VE. It includes the Moderate Wave Action area, the Minimal Wave Action area, and the riverine SFHA. Zone B— Areas subject to inundation by the flood that has a 0.2-percent chance of being equaled or exceeded during any given year, often referred to the as 500-year flood. Zone B is provided on older flood maps, on newer maps this is referred to as "shaded Zone X." Zone C— Designates areas where the annual probability of flooding is less than 0.2 percent. Zone C is provided on older flood maps, on newer maps this is referred to as "unshaded Zone X." Zone V— See Coastal High Hazard Area. Zone VE— The portion of the coastal Special Flood Hazard Area where base flood wave heights are 3 feet or greater, or where other damaging base flood,wave effects have been identified, or where the primary frontal dune has been identified. Zone X— Under the National Flood Insurance Program, areas where the flood hazard is lower than that in the Special Flood Hazard Area. Shaded Zone X shown on recent Flood Insurance Rate Maps (Zone B on older maps) designate areas subject to inundation by the 500-year flood. Unshaded Zone X (Zone C on older Flood Insurance Rate Maps) designate areas where the annual probability of flooding is less than 0.2 percent. Zone X(Shaded) — Areas subject to inundation by the flood that has a 0.2-percent chance of being equaled or exceeded during any given year, often referred to the as 500-year flood. Zone X(Unshaded) — Designates areas where the annual probability of flooding is less than 0.2 percent. G-18 COASTAL CONSTRUCTION MANUAL COASTAL CONSTRUCTION MANUAL Index, Volume Bold text indicates chapter titles or major headings. Italicized page numbers indicates a figure or table. Astillwater elevation of, 8-8 Base flood elevation (BFE) Acceptable level of risk,7 4 building elements allowed below, 9-38 Access to elevated buildings,7-7, 8-6, 9-34, 9-38, 9-39 buildings elevated above, 7-10,7-19,7-20, 9-30 Allowable Stress Design (ASD), 8-2, 8-17, 8-48, 8-55, deck, 9-38 Example 8.5,8-74, 10-9, 10-13 designing for flood levels above, 7-10 Anchor elevators, 9-40, 12-1 air-conditioning condenser, 12-4 flood-damage-resistant materials below,9-34 bolts, 9-11 flood insurance rates for buildings above the,7-16 building envelope, 13-29 foundation,below the, 10-2 concrete and masonry walls, 9-27, 15-5, 15-7 freeboard above, 8-6, 8-10 corrosion of, 11-7, 11-13, 11-17, 12-3 exterior-mounted mechanical equipment in high items below,covered by NFIP,7-17 winds, 12-2 FIRMS, BFEs on, 8-6 wave setup included in, 8-15 hillside house bracing, 15-7 Basement, 7-14, 7-17, 7-19, 13-12, 15-6, 15-12, 15-13 hold-down, 15-6 NFIP definition of, 7-13 masonry chimney, 15-5, 15-7 Beach nourishment,7-7,7-20, 8-11,Example 8.1 sill plate anchor bolts in foundations, 15-6 Bearing capacity(see Soils) split-level floor, 15-7 Benefit-cost model, 7-12 stainless steel frame, 11-7, 11-13 BFE(see Base flood elevation) spacing,9-11 Blockage coefficient, 8-33 truss, 9-27 Breakaway walls,7-8,7-16, 9-1,9-30, 11-20 Anchorage system,7-17, 11-6 areas with no earthquake hazard,breakaway walls in, Angle of internal friction, 10-9, 10-10, 10-15 13-9 Appurtenances,9-38 access to elevated buildings, 9-39 collapse of, 11-21 decks and covered porches, 9-38 designing, 8-24 enclosures,7-16,9-30, 11-20 handrails, 9 39 failure,9-32 pools and hot tubs, 9-40,9-41 flood and wind mitigation, 7-8 stairways, 9 39 flood openings in, 11-20 Attic vents, 11-50, 12-3, 14-5 foundation issues, 13-18 garage doors in, 11-4 high winds, 11-20 Binspection,7-25 not covered by NFIP, 7-18 Base flood,7-10, 8-5, 8-6 solid,7-21 breakaway walls, 11-20 utilities and wiring on, 12-7 erosion and subsidence as a result of, 8-8 wave loads, 8-21 COASTAL CONSTRUCTION MANUAL I-1 INDEX Volume II Building envelope, 13-29, 15-3 G° breach, 9-2 designing, 11-1 California Earthquake Authority(CEA),7-24 inspection points, 13-31 Cast-in-place concrete, 13-10, 15-11 maintaining, 14-1 CBRA(see Coastal Barrier Resources Act of 1982) substitution of materials, 13-30 CBRS (see Coastal Barrier Resource System) top building envelope issues for builders, 13-31 CEA(see California Earthquake Authority) Buildings Cladding(see also Components and cladding),7-9 Coastal A Zones,buildings in,7-8, 8-24 Closed/shallow foundation, 10-35 coastal,with large number of windows and doors,7-7 breakaway wall enclosures in, 9-30 coastal residential,proper siting,design,and buildings in,7-8, 8-24 Coastal A Zone,7-8, 10-2 construction of,7-1 flood loads in, 8-17, 8-37 8-38, 8-44 costs,7-6 flood openings in breakaway walls in, 11-20 elevated foundation,buildings on,7-6 foundation styles in,7-8, 10-2, 10-3, 10-4, 10-5, 10-10, elevating,7-7,7-110-34, 10-35, 10-36, 13-2, 13-5, 13-9, 13-12, 15-9 elevating,insurance discount points for,7-20 load combinations in, 8-38, 8-74, 8-75,Example 8.10, envelope, 11-1 (see also Building envelope) 8 77 footprint,7-12, 10-7 masonry frames in,9-27 hazard insurance,7-12,7-13,7-21,7-24 height restrictions, 7-8,7-13 septic systems in, 12-11 inspection of,7-25 warning box,buildings in Coastal A Zones, 8-24 L-shaped,9-27 Coastal Barrier Resource System (CBRS),7-15 maintaining, 14-1 Coastal Barrier Resources Act of 1982 (CBRA), 7-15 materials,9-33 Coastal flood hazard areas,7-15, 8-15, 13-9, 13-12 (see also Zone A) materials,selection of,9-33 Coastal flood zones, 8-17 performance and roof system, 11-24 residential,7-1 Coastal hazards,7-4, 9-2, 9-37, 10-45, 13-1 SFHAs,buildings in,7-13 Coastal high hazard flooding,7-14 (see also Zone V) site,7-1,7-2,7 7,7-11 Coastal residential buildings design, 8-1,9-1, 10-1, 11-1 site,inspection of, 7-25 Column foundation (see Foundation) slab-on-grade, 7-25 sustainable design of,7-24 Community Rating System (CRS),7-18 substantially damaged,7-15 Components and cladding(C&C), 8-48, 8-51, 8-52, 8-61 substantially improved,7-16 calculating pressures, 8-50 use of,7-2 definition from ASCE 7-10, 8-61 Zone A,buildings in,7-7,7-15,7-16, 7-19 wind pressures of, 8-62 Zone V,buildings in,7-7,7-10,7-14,7-16,749 Concrete bond beam, 9-12 Zones B, C,and X,buildings in, 7-15 cold weather,concrete in, 13-12 Building Code Effectiveness Grading Schedule(BCEGS), 7-22 columns, 8-68, 10-31, 10-32, 10-33, 10-34 concrete/masonry construction,9-27 Building materials,9-33 cover, 13-11 above the DFE,9-35 damage resistant to flooding, 13-19 below the DFE,9-34 decks, 11-37, 11-38 combinations,9-35 deterioration, 13-2 corrosion, 9-37 embedment of connectors, 9-35 fire safety, 9-36 fire-resistant, 7-22 piles, 10 12 floodwalls, 15-1 selection of,9-33 footings, 10-36, 10-37, 10-38 Bulkhead,7-17,9-38 foundation, 9-30, 10-32, 10-33, 10-34, 13-2, 13-3, 13-10, 13-11, 13-19, 14-5, 14-12 house, 13-11 mat, 10-37 minimum cover, 13-11 I-2 COASTAL CONSTRUCTION MANUAL 1 Volume II INDEX piers, 9-34, 10-36 deck connectors, 14-11 pile caps,9-35 metal connectors, corrosion of, 9-37 piles,9-34, 10-4, 10-11, 10-12, 10-15, 10-24, 13-7 nails in plywood panels,corrosion of, 115 pool deck,9-41 Corrosion-resistant, 9-25, 9-37 pools, 9-40 connectors, 9-24, 9-25, 11-48, 13-20 reinforced,9-33 cost implications of,7-9 roof decks, 11-37, 11-39 materials,9-33,9-37 roofs,7-23, 11-50 recommendations on connectors, 9-25 tile roofs, 11-38, 11-39 solid wood blocking, 13-23 walls,9-11,9-34, 11-7, 11-13, 11-16, 11-20, 11-24, Costs 13-30, 15-5, 15-7, 15-12 construction decisions,cost of, 7-8,7-11 weight of, 8-17 design decisions,cost of,7-7,7-11 Connectors erosion-control measures,cost of,7-7 column, 10-24 initial,7-6 corrosion of metal connectors, 9-37 long term,7-6 corrosion protection for metal connectors, 13-23, maintenance and repair,cost of, 14-2 corrosion-resistant, 9-24 natural hazards in coastal areas,cost of,7-5 design event,connectors in, 13-19 siting decisions, cost of, 7-7, 7-11 failure of, 13-20 operational,7-6 floor framing to support beam,9-17 CRS (see Community Rating System) floor support beam to foundation,9-19 metal, maintenance of, 14-10 roof framing to exterior wall,9-8 roof sheathing to roof framing, 9-4,9-6 D roof to exterior wall, 9-8, 9-9,Example 9.2 Dead loads,8-3 (see also Loads) roof-to-wall uplift, 8-54,Example 8.5 Debris (see also Floodborne debris;Waterborne debris; roof truss-to-masonry wall connection,9-11 Wind-borne debris) roof uplift connector loads, 8-52, 8-54,Example 8.5 floodborne debris, 8-3, 12-5, 12-7, 12-10 structural, 13-19 impact load calculation, 8-32,Equation 8.9 wall sheathing to window header, 9-12,9-13 impact loads, 8-15, 8-31 (see also Loads) wall to floor framing,9-15 velocity, 8-32 wall-to-floor, 8-66,Example 8.8 waterborne, 8-32 wall top plate-to-wall stud, 9-10 Decks wall-to-roof, 8-66, Example 8.8 covered porches and, 9-38 warning box,connections, 13-9 maintenance, 14-9 warning box,corrosion-prone sheet metal connectors, warning box,decks, 9-38 14-11 Defensible space, 15 2 warning box,nail selection and installation, 13-20 Depth coefficient, 8-32, 8-33 window header to exterior wall, 9-12,9-13 Design wood pile-to-beam, 10-26 breaking wave height, 8-15 Constructability, 13-17 building,9-1 Construction, categories of building envelope, 11-1 frame,7-23 coastal environment, 7-2 • masonry 7-23 flood, 8-5 masonry veneer,7-23 flood conditions, 10-5 superior,7-23 flood elevation (DFE),7-11, 8-6 Continuous load paths(see Loads) flood protection depth, 8-9 Contraction joint layout for slab-on-grade below elevated flood velocity, 8-15, 8-16, Equation 8.2 building,9-42 flood velocity vs.design stillwater flood depth, 8-17 Corrosion, 14-2, 10-12, 11-7, 11-13, 11-18, 11-24, 11-38, foundation design criteria, 10-2 11-43 framework, 7-3 corrosion-prone sheet metal, 14-11 process,7-2 corrosion protection for metal connectors, 12-3, 13-23 requirements,7-3 COASTAL CONSTRUCTION MANUAL I-3 INDEX Volume II stillwater flood depth, 8-7, 8-9,8-10,Equation 8.1 loads and resistance, 11-6 stillwater flood depth calculations, 8-11,Example 8.1 sliding glass, 11-5 stillwater flood elevation, 8-10, 8-11,Equation 8.1 swing, 11-8 sustainable building,7-24 wall integration and, 11-8 wind pressure, 8-58,Example 8.6, 8-66,Example 8.8 water infiltration, 11-7 wind pressure for low-rise buildings, 8-50, weatherstripping, 11-8 Equation 8.14 wind-borne debris and, 11-7 Design flood Drag coefficients, 8-29 relationship to base flood, 8-5, 8-6 Dry floodproofing, 15-11 Design flood elevation (DFE),7-11, 8-6 advantages and disadvantages of, 15-12 building,elevating to, 15-8 warning box,dry floodproofing, 15-11 community without, 7-25 Dune design flood protection depth, 8-9 frontal, 8-12, Example 8.1, 8-15, 8-38, Example 8.4 electric utility,telephone,and cable TV systems, primary frontal,regulations for, 9-40 placement of, 12-6, 13-1 reservoir, 8-12,Example 8.1, 8-38, Example 8.4 elevating a building above, cost of,7-11 toe, 8-14,Example 8.1, 8-38,Example 8.4 exterior-mounted mechanical equipment,placement of, Dynamic pressure coefficient, 8-23 12-5 flood damage-resistant materials below,9-34 foundation, 10-5 freeboard, 8-5 E generator,placement of, 12-9 EarthAdvantage,7-24 inspection,7-25 Earthquake(see also Seismic hazard;Seismic hazard area; interior mechanical equipment,placement of, 12-6 Seismic mitigation) materials above,9-32, 9-35 base shear, 8-69,Equation 8.15 materials below,9-32, 9-34 building envelope, 11-3, 13-30 non-100-year frequency-based, 8-10 dead load, 8-3 non-submersible well pumps,placement of, 12-10 elevating a building and damage from,7-7 perimeter walls below, 10-3 insurance,7-13,7-24 piles, 13-5 live load, 8-3, 8-73 pools, 9-40 load, 8-68, 8-70,Example 8.9 utilities, 12-6 low-sloped roofs, 11-49 utilities and furnaces below, 15-12 mitigation, 15-5 Design stillwater flood elevation, 8-10,Equation 8.1, multihazard mitigation, 15-14 10-10 non-load-bearing walls,wall coverings,and soffits, 11-24 DFE (see Design flood elevation) open masonry foundation, 13-8 Diaphragm, 13-24 piles, 14-12 floor framing, 13-24, 13-25 reinforced masonry foundation, 13-10 lateral diaphragm loads, 8-57,Example 8.6 roof framing, 13-27 loads, 8-52, 8-53 roof tiles, 11-45 nailing schedule, 13-20 vertical distribution of seismic forces, 8-70, roof, 13-28, 13-29 Equation 8.16 shear, 13-18, 13-20 Eaves, 11-31, 11-32, 11-38 stiffening,9-20 pressures, 8-48 wall, 13-27 top building envelope issues for builders, 13-31 Doors wildfire mitigation, 15-4 durability, 11-7 EIFS (see Exterior insulating finishing system) exterior, 11-4 • Electric utility,telephone,and cable TV systems, 12-6 flashing, 11-8 design, 12-7 frame attachment, 11-6 electric service meters, damaged, 12-7 gap between threshold and door, 11-8 emergency power, 12-9 garage, 11-6 routing and installation, 12-7, 12-8 high winds, 11-6 wiring methods, 12-7 I-4 COASTAL CONSTRUCTION MANUAL Volume II INDEX Elevation, 15-8 flooding, 12-3 advantages and disadvantages of, 15-9 high winds, 12-2 above BFE,7-10, 7-19, 7-20 maintenance, 14-9 design flood, 8-6 seismic events, 12-6 required,7-8 Elevators,9-39, 12-1 accessory equipment, 12-2 enclosure, 12-2 installation,9-40 500-year flood negative discount points,below the BFE,7-21 elevation, 8-6 NFIP coverage, 7-18 safe rooms, 8-67 one-to four-family residential structures, 9-40 FAIR Plan,7-21 safety, 12-2 Fasteners, 7-9, 8-64, 9-6, 9-11,9-24, 13-10 shaft, 12-2 corrosion, 11-4, 11-48, 14-2, 14 5, 14-6 Embedment,7-8 corrosion resistant, 9-38 connectors, 9-35 felt, 11-28 piles, 7-8,7-21,7-25, 8-3, 10-12, 10-13, 10-20, 10-21, flood and wind mitigation, 7-9 10-23, 13-6, 14-12 frame, 11-6, 11-10 treated timber piles, 10-25 galvanized, 9-35 wood piles, 10-15, 10-18 heads, 11-43 Emergency generator,size of, 12-9 laminated, 11-35 warning box, backfeeding emergency power, 12-10 mechanical, 11-19 Enclosure metal, 7-9, 9-25, 9-37, 14-9 below the BFE,7-14 shingle, 11-25, 11-30, 11-35, 11-37 below the lowest floor,7-14,7-16 siding, 11-17 breakaway walls,7-8 slate, 11-47 breaking wave load on vertical walls, 8-23 spacing, 9-4 flood and wind mitigation, 7-8 stainless steel, 11-23, 11-47, 11-48, 12-3 inspection points,7-25 substitution, 13-28 localized scour around, 8-36, 8-37,Equation 8.12 tie, 11-18, 11-19 NFIP requirements,7-16,7-17,7-180 tile, 11-43 EnergyStar,7-24 vertical, 13-14 Erosion,7-1,7-7,7-8,7-10, 10-4 wood frame building, 13-20 control device,7-20 Fill (see Structural fill),7-8 depth, 10-5 Fire sprinkler systems, 12-12 during base flood, 8-8 FIRM (see Flood Insurance Rate Map) during design flood,8-10 Flashing, 7-8, 11-21 effect on flood hazard, 8-7 door and window, 11-22 effect on ground elevation, 8-8 roof-to-wall, 11-22 flood and wind mitigation, 7-8 deck-to-wall, 11-22 flood loads and, 8-5 Flood hazard areas,7-7 depth parameters, 8-9 long-term,7-7, 8-7, 8-11,Example 8.1 depth,wave setup contribution to, 8-15 primary frontal dune, 8-15 design, 8-5 short-term design flood elevation, 8-6 warning box,erosion,long-term and storm-induced, insurance,7-10,7-13 (see also National Flood Insurance 13-6 Program) wind-induced,7-7 load calculation, 8-44,Worksheets 1,2 Exterior doors, 11-4 load combinations, 8-37, 8-38, Example 8.4 Exterior insulating finishing system(EIFS), 11-16, 11-19 loads, 8-5 Exterior-mounted mechanical equipment, 12-2 mitigation measures, 7-8, 15-8 (see also Flood air-conditioning condenser,damaged, 12-4 mitigation) air-conditioning condenser,elevation of, 12-4 velocities during tsunamis, 8-15 COASTAL CONSTRUCTION MANUAL I-5 • INDEX Volume II Floodborne debris Flood zones,7-19, 10-5 dead load, 8-3 Floor framing, 13-23 electric service, 12-7 horizontal beams and girders, 13-24 piles, 12 5 inspection points, 13-25 water supply line riser, 12-10 substitution of materials, 13-25 Flood damage-resistant material, 9-36, 10-2, 12-2, 13-18 Floors inspection considerations,7-26 elevated buildings,floors in, 11-4 flood mitigation, 15-8, 15-13 framing, 13-23 (see also Floor framing) Flood elevation, 8-5 framing to support beam connection,9-17 advisory, 8-7 lowest floor below the BFE, 9-34 design stillwater, 8-10 support beam to foundation connection,9-18,9-19 regulatory, 8-6 Footings Flood hazard area continuous,9-27, 10-37, 10-45, 14-12 elevators,9-40 Force safe rooms, 8-68 hydrostatic, 8-18,Equation 8.3, 8-19 Flood insurance(see also National Flood Insurance vertical hydrostatic, 8-19,Equation 8.4, 8-20 Program) Foundations (see also Foundation construction), 10-1 Flood Insurance Rate Map (FIRM),7-4,7-10,7-14, 7-15 column,7-8 BFE, 8-6 closed, 10-3 NFIP,7-15,7-19 closed,failure of, 10-4 pre-FIRM,7-15 closed/shallow, 10-35 post-FIRM,7-15,7-16,7-17,7-19 construction, 13-2(see also Foundation construction) use of, 8-6, 8-10 design, 10-1 Flood Insurance Study(FIS) (see also National Flood design criteria, 10-2 Insurance Program),7-4, 8-10 design process, 10-10 500-year flood elevation, 8-6 design requirements and recommendations, 10-4 Flood mitigation,7-8, 15-8 deep, 10-4 dry floodproofing, 15-11, 15-12 erosion,long-and short-term, 10-5 elevation, 15-8, 15-9 open,7-8, 10-3 floodwalls and levees, 15-13, 15-14 open/deep, 10-25 (see also Open/deep foundation) multihazard mitigation, 15-16 open/shallow, 10-34(see also Open/shallow relocation, 15-10 foundation) wet floodproofing, 15-12, 15-13 perimeter wall,7-8 Floodproofing(see Dry floodproofing;Wet floodproofing) pile,7-8, 10-11 (see also Pile foundation;Foundation Flooding(see Flood) construction) Floodplain pier,7-8, 10-36 (see also Pier foundation) 100-year(see Base flood),7-15, 8-5, 8-6, 8-10 shallow, 10-4 500-year, 8-67 site considerations, 10-5 administrator,7-16 site elevation, 10-5 crawlspaces, 14-4 site soils, 10-5 elevators, 12-2 soils data, 10-5 inspection,7-25 style selection, 10-5 management program, 7-18 styles, 10-2 management regulations,7-16, 7-17, 12-6 styles in coastal areas, 10-3 managers,7-25, 9-40 Foundation construction, 13-2 NFIP regulations,7-15 concrete, 13-10, 13-11 ordinances, 8-18,9-40 field preservative treatment, 13-17 relocation out of, 15-10 inspection points, 13-18 septic systems, 12-11 layout, 13-2, 13-3 Flood retrofitting(see flood mitigation) masonry, 13-8, 13-9, 13-10 Floodwalls, 15-13 material durability, 13-13 advantages and disadvantages of, 15-14 pile driving resistance, 13-8 warning box,floodwalls and levees, 15-14 piles, 13-3, 13-4, 13-5, 13-6 I-6 COASTAL CONSTRUCTION MANUAL Volume II INDEX substitutions, 13-17 Gutter top foundation issues for builders, 13-18 blow-off, 11-25 wood, 13-12 Framing system floor, 13-23 townhouse,9-37 H steel frame on wood piles,9-36 100-year stillwater flood elevation, 8-8, 8-15 Freeboard Hail,7-13,7-21, 11-15, 11-36, 11-37, 11-38, 11-45, 11-46, 100-year flood, 8-10 11-48, 11-49, 11-50 design flood elevation, 8-6, 8-11,Example 8.1 Handrails, 9-39 NFIP requirements, 8-6 Hazard insurance,7-12 required by community, 8-6 earthquake,7-24 terminology box, 8-5 flood,7-13 wave slam, 8-25 wind,7-21 High-Velocity Hurricane Zone, 11-7 High-wind mitigation, 15-15 Advanced Mitigation Package, 15-19 GBasic Mitigation Package, 15-17 Gable evaluating existing homes, 15-16 braced gable frames,9-28 FEMA wind retrofit grant programs, 15-19 end bracing,9-26, 13-29 Intermediate Mitigation Package, 15-19 end failure,9-2, 9-25,9-31 wind retrofit mitigation packages, 15-16 gable edge, 13-27, 13-31 Hurricane-prone region gable end overhangs, 13-27, 15-18, 15-19 terminology box, 8-49 gable end vents, 11-52 Hurricanes, 15-16 gable end walls, 15-20 Andrew,7-5,9-2,9 25, 11-1, 11-38 masonry, 9-28 Bertha, 11-48 roof, 8-52, 8-61,9-30 Charley,7-5,9-3,9-4 11-1, 11-3, 11-5, 11-6, 11-9, 11- wall support,9-21,9-24 13, 11-23, 11-25, 11-26, 11-39, 11-40, 11-41, 11-42 Garage doors Eloise,7-4 attachment to frame, 11-6 Fran,9-2 blown out of tracks, 11-6 Frances,7-5 breakaway walls,garage doors in, 11-4 Georges, 11-1, 11-9, 11-37, 12-4 exterior doors, 11-4 Hugo,9-32, 11-1 open-front bracing, 15-7 Ike,7-5, 8-35, 11-1 wind mitigation, 8-61, 15-19 Iniki, 11-1 Glazing(see also Windows), 11-9 Ivan,7-5, 11-1, 11-43 impact-resistant,7-7,7-24, 8-49, 9-39 Jeanne,7-5 maintenance of, 14-7 Katrina,7-5, 8-6,9-4, 10-2, 10-13, 10-24, 10-36, protection from debris, 7-8, 11-10, 11-12, 15-19 10-37, 11-1, 11-46, 11-47 wind-driven rain and,7-7, 11-14 Marilyn,9-30,9-31, 11-1, 12-9 Grade beam, 8-35, 10-11, 10-12, 10-18 Opal,9-32, 12-7 concrete column and grade beam foundation, 10-32 Rita,7-5 continuous, 10-34 Wilma,7-5 open/deep pile foundations, 10-31 Hydrodynamic load, 8-5, 8-15, 8-28, 8-29, Equation 8.8 pier foundations, 10-36 piles vs.breaking wave load on piles, 8-30,Example 8.3 pile foundations, 10-23 Hydrostatic load, 8-17 scour around, 8-35, 8-36, Equation 8.l la, 10-26 lateral, 8-18,Equation 8.3a timber pile treatment, 10-31 Hydrostatic force treated timber pile foundation, 10-25, 10-32 lateral, 8-18, Equation 8.3b Green building programs, 7-24 vertical, 8-19,Equation 8.4 Groundwater septic tanks, 12-11 COASTAL CONSTRUCTION MANUAL I-7 INDEX Volume it ILoad and Resistance Factor Design(LRFD), 8-2 Loads IBHS (see Insurance Institute for Business and Home breaking wave loads on vertical piles, 8-21,Equation 8.5 Safety) breaking wave loads on vertical walls, 8-22, Ice Equation 8.6 loads, 11-25 combinations,8-73, 8-75,Example 8.10 sealant systems, 15-11 combination computation worksheet, 8-80 waterborne, 15-14 concrete/masonry framing system, 9-27,9-29 Initial costs,7-6 continuous load path,9-1, 15-20 Insurance (see Hazard insurance) dead,8-3 Insurance Institute for Business and Home Safety(IBHS);' debris impact, 8-31, 8-32,Equation 8.9 7-5,7-21, 15-2, 15-16 determining for flood,wind,and seismic events, 8-2 Insurance Services Office(ISO),7-22,7-23 diaphragm, 8-52 Interior mechanical equipment, 12-6 flood, 8-5, 8-15 Inspection,7-25 flood load combinations, 8-37, 8-38,Example 8.4 building envelope, 13-31 floor load computation worksheet, 8-44, 8-46 floor framing, 13-25 floor diaphragm, 8-60,Example 8.6 roof framing, 13-28, 13-29 floor support beam to pile, uplift load path,9-19, wall framing, 13 27 Example 9.6 ISO (see Insurance Services Office) floor to support beam framing,uplift load path, 9-18, Example 9.5 gable wall support, 9-24 hydrodynamic,8-28, 8-29,Equation 8.8 hydrostatic, 8-17 Jalousie louvers, 11-13, 11-14 ice, 11-25 Jetting, of piles, 10-20, 10-21, 13-7 L-shaped building, 9-27 Joints lateral connector loads from wind and building end tooled concave and V-joints, 13-9 zones, 8-62, 8-63 Joists lateral connector loads for wall-to-roof and wall-to-floor floor, 13-23, 13-24, 14-5 connections, 8-66,Example 8.8 lateral hydrostatic, 8-18, Equation 8.3 live,8-3 L moment-resisting frames, 9-28,9-29 path,9-5, 9-21 Landslide, 10-6 path failure,9-2, 9-3 Lateral wave slam, 8-25, 8-26, Equation 8.7 platform framing,9-28 Lattice,9-33 roof shape, 9-30 Leadership in Energy and Environmental Design(LEED), roof sheathing suction, 8-64,Example 8.7 7-11,7-24 roof-to-wall uplift connection, 8-54,Example 8.5 LEED (see Leadership in Energy and Environmental roof uplift connector, 8-52, 8-53, 8-54, Example 8.5 Design) seismic,8-68, 8-70,Example 8.9 Levees, 15-13 site-specific,8-1 advantages and disadvantages of, 15-14 snow,8-5 warning box,floodwalls and levees, 15-14 tornado,8-67 Limit of Moderate Wave Action (LiMWA), 8-37, 8-74, tsunami,8-47 8-77,Example 8.10 tributary area,8-4, 8-53, 9-14, Example 9.3 terminology box, 10-2 uplift, 7-24, 8-5, 8-61, 9-1, 9-10, 10-1, 10-15, 10-42, LiMWA(see Limit of Moderate Wave Action) 11-33, 11-37, 13-7 Liquid-applied membranes, 11-37 uplift due to shear wall overturning, 9-21,Example 9.7, Live loads,8-3 (see also Loads) 924 Load-bearing wall wall sheathing suction, 8-64,Example 8.7 exterior, 9-36 wall-to-floor framing,uplift and lateral load path, 9-15, Load combinations,8-73 Example 9.4 I-8 COASTAL CONSTRUCTION MANUAL Volume II INDEX wave; 8-20 exterior walls,7-23,9-27 wave slam,8-25 foundation, 9-30, 13-3, 13-8, 13-18, 14 5 wind,8-47 frames, 9-27 wind,determining, 8-49 gables,9-28 window header, uplift and lateral load path, 9-14, grouted masonry cell,9-11 Example 9.3 joints, 13-8 Localized scour, 8-34 materials, 9-35, 10-36, 15-14 Losses from natural hazards in coastal areas,7-5 piers, 9-34 Lowest floor termites, 11-13 below the BFE, 9-34 unreinforced masonry walls, 8-24 corrosion below, 14-2 veneer,7-23, 14-6 DFE, 15-8 walls, 9-11, 11-7, 13-30, 15-5 elevation of, 7-8, 7-10,7-14,7-15,7-16,7-20, 8-6, 8-28, MEPS (see Molded expanded polystyrene) 15-8 Metal connectors (see also Fasteners), 7-9 elevator,9-40, 10-5 maintenance, 14-10 enclosures below,7-16,7-17 Metal roof panel, 11-45 flood damage above,7-10 Mitigation inspection,7-25 elevation, 15-8, 15-9 penalties related to areas below the lowest floor,7-16 flood, 7-8, 15-8 (see also Flood mitigation) piles, 10-25 floodwalls and levees, 15-13 pool, 9-40 high wind, 15-15 (see also High wind mitigation) Zone A,lowest floor in,7-15 multihazard, 15-14 Zone V,lowest floor in,7-15 relocation, 15-10 Lowest horizontal structural member, 7-8„ 7-14,7-15, retrofitting, 15-2 7-16, 10-23, 13-5 seismic, 15-5 (see also Seismic mitigation) wildfire, 15-2 wind, 7-8 Moisture, 9-35, 11-28, 12-11 M barrier, 11-16, 11-22, 13-9 Main wind force resisting system (MWFRS), 8-48, 8-52 corrosion, 14-2 determining pressures, 8-49, 8-51 exterior, 14-3 elements of shear walls and roof diaphragms, 8-61 framing construction, 13-14 Maintenance, 14-1, 14-5 inspection, 13-18, 13-27, 13-29, 14-6 decks and exterior wood, 14-9 interior, 14-3 exterior-mounted mechanical and electrical equipment, intrusion, 9-33, 11-20, 13-1, 13-8 14-9 penetration or retention, 13-9 glazing, 14-7 stairs, 13-16 inspection checklist, 14-5 sustainable design considerations,7-24 metal connectors, 14-10 termites, 14-4 roofs, 14-8 Molded expanded polystyrene (MEPS), 11-19 siding, 14-7 Municipal water connections, 12-12 techniques, 14-11 (see also Maintenance techniques) MWFRS (see Main wind force resisting system) Maintenance techniques, 14-11 flooding, 14-12 seismic and wind, 14-12 n' Manufactured home,7-14 A Masonry NAHB (see National Association of Home Builders) building material,9-33 National Association of Home Builders(NAHB),7-24 buildings,7-22 National Flood Insurance Program (NFIP), 7-13 chimneys, 15-5, 15-7 building occupancy, 7-14 concrete masonry unit (CMU), 11-16, 11-20 building type,7-14 construction, 9-12, 9-27, 9-32 contents,7-17 deterioration, 13-2 covered items,7-17 COASTAL CONSTRUCTION MANUAL I-9 INDEX Volume II date of construction,7-15 wood pile-to-beam connections, 10-26 discount points,7-20 Open/shallow foundation, 10-34 elevation of lowest floor or bottom,7-16 Operational costs,7-2,7-6,7-7 enclosures below lowest floor,7-16 OSB (see Oriented strand board) flood insurance zone, 7-14 Oriented strand board (OSB) flood rating factors,7-13 factory-applied wax, 11-27 foundations, 10-4 rotted, 11-22 lowering premiums,7-20 sheathing, 11-16 lowest horizontal structural member of lowest floor,7-16 Overwash,7-7 non-covered items,7-18 premiums, 7-19, 7-20 regulations,7-8 replacement value, 7-17 warning box,differences between floodplain Panels management regulations and NFIP flood insurance, plywood, 11-4, 11-5 7-16 Pier foundation,7-8, 10-36, 10-38 Natural hazard risk in coastal areas,7-3 footing under gravity load, 10-41,Example 10.3 losses from natural hazards in coastal areas,7-5 footing under uplift and lateral loads, 10-44, New construction,9-34, 10-11, 11-52, 12-1 Example 10.5 NFIP (see National Flood Insurance Program) footing under uplift load, 10-42,Example 10.4 Non-coastal flood zone soil pressure, 10-43,Equation 10.6 flood loads in, 8-17 spread footing and, 10-38, 10-39 Non-load-bearing walls,wall coverings,and soffits, square footing size for gravity loads, 10-40, 11-15 Equation 10.5 breakaway walls, 11-20, 11-21 Pile foundation, 10-11 brick veneer, 11-18 augering, 10-20, 13-7 concrete and CMU, 11-20 bearing capacity, 10-14 durability, 11-23 compression capacity of, 10-12, 10-14, Equation 10.2 exterior walls, 11-16 column connection failure, 10-24 exterior insulating finish system (EIFS), 11-19 concrete, 10-12 exterior insulating finish system (EIFS), blown off, driving, 10-20 11-20 earth pressure coefficient, 10-14 fiber-cement siding,blown off, 11-18 effects of scour and erosion on, 10-21, 10-23 flashings, 11-21 embedment,insufficient, 10-13 high winds, 11-16 grade beams for, 10-23 seismic,effects of, 11-24 installation, 10-20 siding, 11-17 installation methods, 10-20, 10-21 soffits, 11-22 jetting, 10-20 vinyl siding,blown off, 11-17 lateral capacity, 10-18, 10-19,Equation 10.4, 10-19 Nor'easter,7-6, 15-15 modulus of subgrade reaction, 10-19 scouring around grade beams, 10-25 steel, 10-12 O tension capacity, 10-15,Equation 10.3 wood, 10-12, 10-16,Example 10.1, 10-18 100-year flood(see Base flood), 8-5, 8-6, 8-10 Pile notching,7-21, 10-26, 10-31, 13-4, 13-5, 13-15, Open/deep foundation, 10-25 13-18, 13-21, 13-22, 13-23 diagonal bracing, 10-27, 10-28, 10-29,Example 10.2 Platform framing, 9-27,9-28 knee bracing, 10-30 Plywood, 11-4, 11-16, 11-23, 13-12, 13-14, 13-23 pile bracing, 10-27 decks, 11-37 reinforced concrete beams and columns, 10-33 inspection, 13-18, 13-27, 13-29 steel pipe pile and grade beam, 10-32 sheathing, 11-44, 13-26 timber pile treatment, 10-25, 10-26, 10-30 untreated, 14-12 treated timber piles and grade beams, 10-32 UV degradation, 14-7 I-10 COASTAL CONSTRUCTION MANUAL Volume II INDEX Pneumatic nail guns, 13-20 exterior wall connection, 9-8, 9-9,Example 9.2 Pools fiber-cement shingles, 11-37 coastal high hazard areas,pools in, 9-40 fire-resistant, 11-3 hot tubs and,9-40,9-41, 9-42 framing to exterior wall connection,9-8 insurance coverage,7-17, 7-18 hail, 11-36 Zone V,pools in, 9-40 high winds, 11-25 Precast concrete, 13-7 hip,9-31 Pre-design considerations,7-1 liquid-applied membranes, 11-37 Pressure-treated wood, 13-13, 13-19 low-slope, 11-49 Primary frontal dune, 9-40 maintenance, 14-8 erosion, 8-15 metal panels, 11-46 Protective devices,7-23 metal shingles, 11-46 pressures, 8-62, 8-63 rake, 11-32, 11-33 R roof-to-wall uplift connection load, 8-54,Example 8.5 shakes, 11-48 Rating factor(insurance),7-13,7-18 sheathing nail spacing for wind uplift, 9-6,Example 9.1 Recurrence interval,7-4, 8-52 sheathing suction loads, 8-64,Example 8.7 Reinforced concrete sheathing to roof framing connection, 9-4,9-6 building material,9-34 shingles, 11-30 (see also Shingles) Relocation, 15-10 slate, 11-47 advantages and disadvantages of, 15-12 systems, 11-24 Reroofing tiles,blown off, 11-39, 11-40, 11-41, 11-42, 11-43, 11- in high-wind areas, 11-24 44 Residual risk,7-11 tiles,clay and extruded concrete, 11-38 Retaining wall,7-17,7-18 truss connection to wood-frame wall,9-10 Retrofitting,7-7,7-21 truss-to-masonry wall connection,9-11 flood mitigation, 15-8 (see also Flood mitigation) underlayment, 11-26 (see also Underlayment) high wind mitigation, 15-15 (see also High wind uplift connector load, 8-52, 8-53, 8-54,Example 8.5 mitigation) wall top plate-to-wall stud connection, 9-10,9-11 seismic mitigation, 15-5 (see also Seismic mitigation) warning box,roof structure failure, 13-27 terminology box, 15-2 wood shingles, 11-48 wildfire mitigation, 15-2 Roof deck,9-3, 11-10, 11-24, 11-38, 11-46 Revetment,7-7,7-18 blown off, 11-22 Risk,7-1 concrete, 11-38 acceptable level of,7-4 panels, 15-18 category, 8-48 Roof framing, 13-27 coastal flooding, 13-1 inspection points, 13-28, 13-29 flood, 15-9, 15-10, 12-7 substitution of materials, 13-28 high winds, 13-1 Homeowner's Wildfire Assessment, 15-5 long-term, 15-19 natural hazard risk in coastal areas,7-3 tolerance of owner,7-2 Salt spray, 9-25, 13-23 wildfire, 11-3 Sanitary systems, 12-11 wind-related damage, 15-19 Scour,7-7,7-8,7-10, 8-34, 10-4 Roof(see also Roof framing) deep around foundation piles, 8-35 aggregate roof surfacing, 11-49 localized around a vertical pile, 8-34, 8-35, asphalt shingles, 1125, 11-30 Equation 8.10, 8-36, Equation 8.11 asphalt shingles,wind resistance of, 11-31 localized around vertical walls and enclosures, 8-37, bleeder strips, 11-33, 11-34 Equation 8.12 decking,blown off, 11-22 Sea level rise,7-10 eave, 11-32 Sea spray,7-7 COASTAL CONSTRUCTION MANUAL I-11 INDEX Volume II Seawall,7-7,7-17,7-18 Slate, 11-47 Seismic hazard Snow base shear,8-69,Equation 8.15 loads,8-5 effect of seismic forces on supporting piles,8-69 Soffits, 11-15, 11-22, 11-23, 13-29 load,8-68, 8-70,Example 8.9 Soils mitigation, 15-5 (see also Seismic mitigation) angle of internal friction/soil friction angle, 10-9, 10-10, vertical distribution of seismic forces, 8-70, 10-15 Equation 8.16 bearing capacity, 10-7, 10-14 Seismic hazard area classifications, 10-7, 10-8 building elevation, 15-9 compressive strength, 10-7, 10-8 diagonal bracing,9-37 data from site investigations, 10-6 floor surfaces, 13-24 modulus of subgrade reaction, 10-10, 10-19 reinforced and grouted masonry, 9-27 pressure,determining, 10-43,Equation 10.6 roof sheathing, 11-50 sliding resistance, 10-10, Equation 10.1 warning box,open masonry foundations in earthquake subgrade modulus, 10-10 hazard area, 13-8 Special Flood Hazard Area(SFHA) Seismic mitigation, 15-5 acquisition of buildings in,7-13 anchorage of concrete and masonry walls, 15-7 fills allowed in,7-25 anchorage of masonry chimneys, 15-7 foundation in, 10-42 cripple wall bracing, 15-5 residential structures in, 15-11, 15-12 foundation bolting, 15-5 substantially damaged or improved structures in, 15-11, hillside house bracing, 15-5 15-12 open-front bracing, 15-5 zones outside,7-15 split-level floor interconnection, 15-5 Stairways, 9-39 weak-and soft-story bracing, 15-5 Standard Flood Insurance Policy(SFIP),7-17(see also Septic systems, 12-10 National Flood Insurance Program) warning box,septic tanks below expected level of Steel erosion and scour, 12-11 building material,9-33 SFHA(see Special Flood Hazard Area) Stillwater flood depth, 8-9 SFIP (see Standard Flood Insurance Policy) calculations, 8-9, 8-10,Example 8.1 Shakes, 11-48 Stillwater elevation, 8-7, 8-15, 8-21, 10-10 Shearwall, 8-70,Example 8.9, 13-21, 13-26, 14-7, 14-12 100-year, 8-8, 8-15 sill plates, 14-12 Storm surge,7-4,7-11, 10-1, 10-22 Shingles, 11-30 depths, 8-6 asphalt, 11-25 elevation,8-6 asphalt,wind resistance of, 11-31 evacuation maps, 8-6 fasteners, 11-35 Straps, 12-3, 13-27, 14-10 fiber-cement, 11-37 cast-in, 9-11 loss of underlayment and, 11-31 connector, 13-19 metal, 11-46 metal, 15-7 unzipped, 11-36 stainless steel, 11-37, 11-43, 11-45, 11-47 wood, 11-48 tiedown, 14-10 Shutters, 7-9,7-23, 8-49, 11-10, 11-12, 11-13 twist, 13-23 Skylights, 11-1, 11-15 Structural frame, 13-19 windows and, 11-9 connections, 13-19 Siding, 11-17 connector failure, 13-20 fiber-cement,blown off, 11-18 durability, 13-15 maintenance of, 14-7 floor framing, 13-23 (see also Floor framing) vinyl,blown off, 11-17 maintenance, 14-5 Single-ply membrane, 11-50 roof framing, 13-27(see also Roof framing) Site-specific loads,8-1 top structural frame issues for buildings, 13-28 Siting,7-7 wall framing, 13-25 (see also Wall framing) benefits and cost implications,7-11 Structure,maintaining, 14-1 1-12 COASTAL CONSTRUCTION MANUAL Volume II INDEX Subsidence, 8-7, 8-8 V Substantial damage dry floodproofing, 15-11 Vents attic, 11-50, 12-3, 14-5 tsunami, 8-47 continuous ridge, 11-50, 11-52 Substantial improvement, 9-34 dry floodproofing, 15-11 V Zone Risk Factor Rating Form,7-20 Sustainable building design,7-24 Substitutions, 13-17 warning box, 13-17, 13-28 IAI Wall (see also Wall framing) coverings, 11-15, 11-16 Tfire-resistant, 11-3 Termites, 9-33, 11-7, 11-13, 13-30, 14-2, 14-4 floor framing connection,9 15 Tiles, 11-38 (see also Roof) non-load-bearing, 11-15 Topography, 8-16 sheathing to window header connection, 9-12,9-13 Tornado, 8-47, 11-10, 15-15 suction pressures, 8-62, 8-63 loads,8-67 Wall framing, 13-25 warning box,safe room location, 8-67 inspection points, 13-27 Tributary area and application of loads to a building, substitution of materials, 13-27 8-4 Water and wasterwater systems, 12-10 Tropical cyclones, 8-47 fire sprinkler systems, 12-11 Tropical storms, 7-5, 15-15 municipal water connections, 12-12 Allison,7 5 sanitary systems, 12-11 Tsunamis,7-6 septic systems, 12-11 load,8-47 wells, 12-10 warning box,flood velocity during tsunamis, 8-15 Waterborne debris, 8-32, 9-33 Wave Typhoon, 8-24, 11-37, 15-15 action,7-7 Paka, 11-1 crest, 8-24 height, 8-25 load, 8-20 Usetup, 8-15 Underlayment, 7-9, 11-26 slam,7-10, 8-25, 8-26 attachment, 11-26 slam calculation, 8-27,Example 8.2 enhanced Option 1, 11-26, 11-27 Weatherstripping, 7-8, 11-8 Wet floodproofing, 15-12, 15-13 enhanced Option 2, 11-28 advantages and disadvantages of, 15-13 enhanced Option 3, 11 29 warning box,under NFIP, 15-12 loss of shingles and, 11-31 Wildfire not lapped over hip, 11-30 fire-resistant walls and roof, 11-3 Uplift,8-17, 8-21, 8-37, 8-61,9-21, 14-9, 15-20 mitigation, 15-2 capacity, 13-19 Wind force, 8-3, 9-1, 9-4, 9-6,Examples 9.1 through 9.9, 9-8, design wind pressure for low-rise buildings, 8-50, 9-10, 9-12, 9-17,9-18, 10-34, 10-42,Example 10.4, Equation 8.14 10-44,Example 10.5, 10-45, 12-3, 13-23, 13-27 determining loads, 8-49 inspection, 13-29 effect on enclosed building vs.building with an loads (see Loads) resistance, 10-15, 10-34, 10-38, 11-47, 13-19 opening, 8-48 high-wind mitigation, 15-15 roof uplift connector load, 8-52, 8-53, 8-54, Example insurance,7-21 8.5 load,8-47 shear wall overturning, 9-21 mapped speeds, 8-48 solar panel system,7-24 wind, 9-8, 9-15, 10-22 mitigation measures, 7-8 COASTAL CONSTRUCTION MANUAL ' I-13 INDEX Volume II velocity pressure, 8-50,Equation 8.13 frame,inadequate attachment of, 11-9 Wind-borne debris, 11-7 hail, 11-15 doors and, 11-7 header to exterior wall connection, 9-12,9-13 exterior wall assemblies, 11-16 high winds, 11-9 glazing and, 11-22 installation, 11-14 scars on exterior wall, 11-3 jalousie louvers, 11-13, 11-14 Wind-driven rain,7-7, 11-52 loads and resistance, 11-9 building envelope, 11-4, 11-52, 13-31 seismic effects on, 11-15 concrete and concrete masonry unit, 11-20 skylights and, 11-9 deck connections to structure, 14-10 uplift and lateral load path at window header, 9-14, deck surface,9-38 Example 9.3 door/wall integration, 11-8 water infiltration, 11-14 exterior door assemblies, 11-7 wind-borne debris, 11-10 exterior non-load-bearing walls,wall coverings,and Wood soffits, 11-16 building material,9-33 flood mitigation, 7-8 foundations, 13-13 glazing,7-7 high winds, 11-7 Z rain screen on fiber-cement siding, 11-17 Zone A,7-7,7-15,7-16,7-19 resistance in windows, 11-15 recommended foundation styles in, 10-3 sealant joints protected by a stop, 11-15 Zone AE,7-15 soffit blow-off, 11-15, 11-22, 1123 Zone B,7-15 threshold/door gap, 11-8 Zone C,7-15 vents and fans, 13-31 Zones V1—V30,7-14 wall coverings, 11-16 Zone V,7-14,7-16 windows and skylights, 11-9 recommended foundation styles in, 10-3 Wind-driven saltwater spray, 9-33 Risk Factor Rating Form,7-20 Wind-driven water infiltration, 11-2, 11-7, 11-14 warning box,solid foundation walls in Zone V, 8-24 Wind-MAP,7-21 Zone VE,7-14 Windows(see also Glazing) Zone X,7-15 design pressure and impact-resistant ratings, 11-10, 11-11, 11-12 durability, 11-13 I-14 COASTAL CONSTRUCTION MANUAL