FEMA P-499: Home Builder's Guide to Coastal Construction

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1 GENERAL Is There Anything Else I Should Know About Coastal Flood Hazard Areas and Flood Elevations? n Many DFIRMs are digital conversions of FIRMs produced during the past few years without improved analysis of flood hazards. While some corrections were made, the maps may not accurately represent coastal flood hazards. Sections 7.8 and 7.9 of FEMA’s Coastal Construction Manual (FEMA-55, 2005) describe how coastal flood hazards are mapped and how to determine whether coastal FIRMs reflect present-day flood hazards. n DFIRMs do not incorporate the effects of longterm shoreline erosion. This information should be obtained from other sources. n Recent post-storm investigations and studies have shown flood forces and damage in Areas of Moderate Water Action (MOWAs) or Coastal A Zones can be very similar to those in Zone V. Some communities have adopted DFIRMs that show MOWAs as a white line on the DFIRM that depicts the LiMWA. Although DFIRMs (and minimum NFIP building standards) do not differentiate between Zone A in coastal areas and Zone A in riverine areas, builders should consider using Zone V foundation and elevation standards for new construction in the MOWA. These flood zones are depicted as white boundaries on DFIRMs where communities are encouraging use of Zone V standards in MOWAs. n Many communities and states require that the lowest floor elevations are above the BFE, offering an additional level of protection known as Freeboard. The term used to describe the higher elevation level is Design Flood Elevation (DFE). n Many property owners have voluntarily constructed their buildings with the lowest floor several feet above the BFE because of the potential for flood waters to exceed the BFE and enter the building. Flood insurance is not available in areas designated as being in the Coastal Barrier Resource System (CBRS). Only structures constructed prior to the designation of the area as being in the CBRS are allowed to purchase federal flood insurance. 4 of 4 12/10 Where Can I Get FIRMs, DFIRMs, Flood Studies, and Other Information? Community floodplain administrator. The community’s DFIRMs and its local floodplain management regulations, should be on file and available for viewing at the office of the community floodplain administrator. FEMA’s Map Information eXchange, or FMIX. This service center serves as a one-stop shop for a variety of information, products, services, and tools that support the National Flood Insurance Program. To contact a FEMA Map Specialist, please call 1-877-FEMAMAP (1-877-336-2627) or email FEMAMapSpecialist@riskmapcds.com. DFIRMs and FISs can be accessed at www.msc.fema.gov. Index sheets and specific FIRM panels can be viewed online at the FEMA Map Service Center website by entering either a parcel address or the specific DFIRM panel number, if known. A user-selected portion of flood maps (called a FIRMette) such as the previous sample can be created, saved, and printed. An effective tutorial on interpretation and use of the old FIRM product is available at www.FloodSmart. gov. While not specific to the newer DFIRM platform, the tutorial defines basic flood hazard map terminology and will be helpful to those less experienced with using flood hazard maps. Information regarding FIRMs, DFIRMs, FISs, and related products can also be obtained from FEMA through FMIX at: 1-877-FEMAMAP (1-877-336-2627) Or FEMAMapSpecialist@riskmap.cds.com Developed in association with the National Association of Home Builders Research Center 1.3: USING A DIGITAL FLOOD INSURANCE RATE MAP (DFIRM) HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION
Lowest Floor Elevation HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION Technical Fact Sheet No. 1.4 Purpose: To describe the benefits of exceeding the National Flood Insurance Program (NFIP) minimum elevation requirements; to identify common construction practices that violate NFIP regulations, which result in significantly higher flood insurance premiums; and to discuss the NFIP Elevation Certificate. Why Is the Lowest Floor Elevation Important? In riverine and other inland areas, experience has shown that if the lowest floors of buildings are not elevated above the flood level, these buildings and their contents will be damaged or destroyed. In coastal areas, wave action causes even more damage, often destroying enclosed building areas below the flood level (and any building areas above the flood level that depend on the lower area for structural support). Once waves rise above the lowest structural member in V Zones or Coastal A Zones, the elevated portion of the building is likely to be severely damaged or destroyed. Recommended Lowest Floor Elevations* Because of the additional hazard associated with wave action in V Zones and in Coastal A Zones, it is recommended that the elevation requirements of ASCE 24 (that exceed the minimum elevation requirements of the NFIP) be followed: n The bottom of the lowest horizontal structural member of a building in the V Zone is elevated 1 foot or more above the Base Flood Elevation (BFE) (i.e., add freeboard). n The lowest horizontal structural member of a building in the A Zone in coastal areas is elevated 1 foot or more above the BFE (i.e., add freeboard). A Zones in Coastal Areas: Subject to Breaking Waves and Erosion During the Base Flood Lowest Horizontal Structural Member Above BFE (Freeboard) Top of Lowest Floor BFE A-Zone Building (Open Foundation) Recommended Practice: Bottom of Lowest Horizontal Structural Member Freeboard * NFIP minimum elevation requirements: A Zones – elevate top of lowest floor to or above BFE; V Zones – elevate bottom of lowest horizontal structural member to or above BFE. In both V Zones and A Zones, many people have decided to elevate a full story to provide below-building parking, far exceeding the elevation requirement. See Fact Sheet No. 1.2 for more information about NFIP minimum requirements in A Zones and V Zones. 1.4: LOWEST FLOOR ELEVATION V Zones: Bottom of Lowest Horizontal Structural Member Above BFE (Freeboard) V-Zone Building (Open Foundation) HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION BFE 1 of 2 12/10 GENERAL 1
Page 1: Home Builder’s Guide to Coastal C
Page 4 and 5: G GUIDE 2 of 6 12/10 Fact Sheet No.
Page 6 and 7: G GUIDE 4 of 6 12/10 Fact Sheet No.
Page 8 and 9: G GUIDE 6 of 6 12/10 Category Categ
Page 10 and 11: 1 GENERAL What Should Owners and Ho
Page 13 and 14: Summary of Coastal Construction Req
Page 15 and 16: Foundation Orientation of Lowest Ho
Page 17 and 18: Certification Elevation NFIP 60.3(b
Page 19 and 20: Coastal Construction Requirements a
Page 21 and 22: Coastal Construction Requirements a
Page 23 and 24: Using a Digital Flood Insurance Rat
Page 25: Sample DFIRM This map is a portion
Page 29 and 30: V Zone Design and Construction Cert
Page 31 and 32: Designing for Flood Levels Above th
Page 33 and 34: FIRMs depict the limits of flooding
Page 35 and 36: Figure 6. Mold and biological/chemi
Page 37 and 38: Other Considerations As previously
Page 39 and 40: Coastal Building Materials HOME BUI
Page 41 and 42: Location of Material Use Name of Ma
Page 43 and 44: n Metal-plate-connected trusses sho
Page 45 and 46: Non-Traditional Building Materials
Page 47 and 48: Things to consider if building with
Page 49 and 50: Figure 5. An example of a wall cavi
Page 51 and 52: Moisture Barrier Systems HOME BUILD
Page 53 and 54: How Do Siting and Design Decisions
Page 55 and 56: Selecting a Lot and Siting the Buil
Page 57 and 58: Foundations in Coastal Areas HOME B
Page 59: prohibited in V Zones but are recom
Page 62 and 63: 3 FOUNDATIONS Table 1. Example foun
Page 64 and 65: 3 FOUNDATIONS Additional Resources
Page 66 and 67: 3 FOUNDATIONS 2 of 6 12/10 Figure 2
Page 68 and 69: 3 FOUNDATIONS 4 of 6 12/10 Figure 4
Page 70 and 71: 3 FOUNDATIONS Additional Resources
Page 72 and 73: 3 FOUNDATIONS Piers vs. Piles Pier
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If a stemwall and floor slab system
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4 LOAD PATHS If a connection fails,
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4 LOAD PATHS Gable end wall - cut c
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Use of Connectors and Brackets HOME
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Important These are examples of typ
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Housewrap HOME BUILDER’S GUIDE TO
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n Improper integration with flashin
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5 WALL SYSTEMS 2 of 3 12/10 Figure
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Siding Installation in High-Wind Re
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n Use aluminum, galvanized steel, o
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Figure 8b. Wood siding installation
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Energy Conservation and Air Barrier
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Attachment of Brick Veneer in High-
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Construction Guidance The brick ven
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Table 1. Brick Veneer Tie Spacing N
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6 OPENINGS Although not discussed i
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Protection of Openings- Shutters an
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What Types of Shutters Are Availabl
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Are There Special Requirements for
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Roof Sheathing Installation HOME BU
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Common Sheathing Attachment Mistake
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7 ROOFING 5. Apply a single layer o
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Asphalt Shingle Roofing for High Wi
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After the shingles have been expose
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7 ROOFING Design and Construction G
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Minimizing Water Intrusion Through
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Checking Soffit Material Installati
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Figure 8. This metal ridge vent was
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Gable Rake Vents Key Issues n Gable
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Metal Roof Systems in High-Wind Reg
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Construction Guidance n Consult loc
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Additional Resources For general in
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8 ATTACHMENTS Space Below the BFE
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8 ATTACHMENTS n Siding used on the
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Decks, Pools, and Accessory Structu
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uildings. Pools can be designed to
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Purpose: To identify the special co
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Fuel n Fuel tanks should be install
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9 REPAIRS n Pre-FIRM or post-FIRM b
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9 REPAIRS n If a lateral addition c
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9 REPAIRS Enclosures of Areas Below
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Repairs, Remodeling, Additions, and
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Vertical additions may also impose
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n Soffits should be inspected follo
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References and Resources HOME BUILD
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FEMA. NFIP Technical Bulletin 5-08,
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FEMA P-499: Home Builder's Guide to Coastal Construction

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