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

Recommendations

Info

8 ATTACHMENTS n Siding used on the elevated portions of a building should not extend down over breakaway walls. Instead, a clean separation should be provided so that any siding installed on breakaway walls is structurally independent of siding elsewhere on the building. Without such a separation, the failure of breakaway walls can result in damage to siding elsewhere on the building (see Figure 4). n Solid breakaway wall enclosures in V Zones will result in higher flood insurance premiums (especially where the enclosed area is 300 square feet or greater). Insect screening, lattice, slats, or louvers are recommended. It is recommended to use insect screening, open wooden or plastic lattice, slats, or louvers instead of solid breakaway walls beneath elevated residential buildings. n If enclosures are constructed in Coastal A Zones, open foundations with breakaway enclosures are recommended instead of foundation walls or crawlspaces. If solid breakaway walls are used, then they must be equipped with flood openings that allow floodwaters to enter and exit the enclosure. Use of breakaway enclosures in Coastal A Zones (or any A Zone) will not lead to higher flood insurance premiums. It is recommended that flood openings be considered for solid breakaway walls in V Zones, even though they are not required by the NFIP. The presence of flood openings may relieve flood forces against the solid breakaway walls, reduce damage to the walls, and reduce flood-borne debris. n Garage doors installed in below-BFE enclosures of V Zone buildings—even reinforced and highwind-resistant doors—must meet the performance requirement discussed in the Breakaway Walls section of this Fact Sheet. Specifically, the doors must be designed to break free under the larger of the following Allowable Stress Design loads: design wind load, the design seismic load, or 10 psf, acting perpendicular to the plane of the door. If the Allowable Stress Design loading exceeds 20 psf for the designed door, the door must be designed and certified to collapse under base flood conditions. See the Breakaway Walls section for information about certification requirements. 4 of 5 12/10 There are two other enclosure scenarios that should be mentioned, both of which have construction and flood insurance consequences. Contractors and designers should be cautious when an owner asks for either type of enclosure, and consultation with the community and a knowledgeable flood insurance agent is recommended. n Below-BFE enclosures that do not extend all the way to the ground (sometimes called “hanging” enclosures or “elevated” enclosures, occurs when there is an enclosure floor system tied to the building foundation and above the ground – see Figure 6). In V Zones, the enclosure walls must be breakaway, and the enclosure floor system must either break away or the building foundation must be designed to accommodate flood loads transferred from the enclosure floor system to the foundation. In V Zones, the enclosure walls must be breakaway, and the enclosure floor system must either break away or the building foundation must be designed to accommodate flood loads transferred from the enclosure floor system to the foundation. Figure 6. Example of an enclosure that does not extend to grade. This type of enclosure presents special construction and flood insurance issues. Contractors should proceed with caution when an owner requests such an enclosure. n In A Zones, the enclosure walls must have proper flood vents, with the bottom no higher than 1 foot above the enclosure floor. These types of enclosures were not contemplated when flood insurance premium rate tables were constructed, and can result in significantly higher flood insurance premiums than had the enclosure walls extended to the ground. The NFIP is working to correct this rating issue; until then, owners will pay a substantial premium penalty for this type of construction. 8.1: ENCLOSURES AND BREAKAWAY WALLS HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION
n Two-story enclosures below elevated buildings (see Figure 7). As some BFEs are established higher and higher above ground, some owners have constructed two-story solid wall enclosures below the elevated building, with the upper enclosure having a floor system approximately midway between the ground and the elevated building. These types of enclosures present unique problems. In A Zones both levels of the enclosure must have flood openings in the walls unless there is some way to relieve water pressure through the floor system between the upper and lower enclosures; in V Zones, the enclosure walls (and possibly enclosure floor systems) must be breakaway; special ingress and egress code requirements may be a factor; these enclosures may result in substantially higher flood insurance premiums. 8.1: ENCLOSURES AND BREAKAWAY WALLS Developed in association with the National Association of Home Builders Research Center HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION Figure 7. Example of a two-story enclosure below the BFE. This type of enclosure presents special construction and flood insurance issues. Contractors should proceed with caution when an owner requests such an enclosure. Additional Resources FEMA. 2008a. Design and Construction Requirements for Breakaway Walls. Technical Bulletin 9-08, (http://www.fema.gov/library/viewRecord.do?id=1722). FEMA. 2008b. Free-of-Obstruction Requirements. Technical Bulletin 5-08, (http://www.fema.gov/library/viewRecord.do?id=1718). FEMA. 2008c. Openings in Foundation Walls and Walls of Enclosures. Technical Bulletin 1-08, (http://www.fema.gov/library/viewRecord.do?id=1579). FEMA. 2009. Hurricane Ike Recovery Advisory, Design and Construction in Coastal A Zones, (http://www.fema.gov/library/viewRecord.do?id=1569). 5 of 5 12/10 ATTACHMENTS 8
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 and 26:
Sample DFIRM This map is a portion
Page 27 and 28:
Lowest Floor Elevation HOME BUILDER
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
Page 75 and 76:
HOME BUILDER’S GUIDE TO COASTAL C
Page 77:
If a stemwall and floor slab system
Page 80 and 81:
4 LOAD PATHS If a connection fails,
Page 82 and 83:
4 LOAD PATHS Gable end wall - cut c
Page 85 and 86:
Use of Connectors and Brackets HOME
Page 87 and 88:
Important These are examples of typ
Page 89 and 90:
Housewrap HOME BUILDER’S GUIDE TO
Page 91:
n Improper integration with flashin
Page 94 and 95:
5 WALL SYSTEMS 2 of 3 12/10 Figure
Page 97 and 98:
Siding Installation in High-Wind Re
Page 99 and 100:
n Use aluminum, galvanized steel, o
Page 101 and 102:
Figure 8b. Wood siding installation
Page 103 and 104: Energy Conservation and Air Barrier
Page 105 and 106: Attachment of Brick Veneer in High-
Page 107 and 108: Construction Guidance The brick ven
Page 109: Table 1. Brick Veneer Tie Spacing N
Page 112 and 113: 6 OPENINGS Although not discussed i
Page 115 and 116: Protection of Openings- Shutters an
Page 117 and 118: What Types of Shutters Are Availabl
Page 119 and 120: Are There Special Requirements for
Page 121 and 122: Roof Sheathing Installation HOME BU
Page 123: Common Sheathing Attachment Mistake
Page 126 and 127: 7 ROOFING 5. Apply a single layer o
Page 129 and 130: Asphalt Shingle Roofing for High Wi
Page 131: After the shingles have been expose
Page 134 and 135: 7 ROOFING Design and Construction G
Page 137 and 138: Minimizing Water Intrusion Through
Page 139 and 140: Checking Soffit Material Installati
Page 141 and 142: Figure 8. This metal ridge vent was
Page 143 and 144: Gable Rake Vents Key Issues n Gable
Page 145 and 146: Metal Roof Systems in High-Wind Reg
Page 147 and 148: Construction Guidance n Consult loc
Page 149: Additional Resources For general in
Page 152 and 153: 8 ATTACHMENTS Space Below the BFE
Page 157 and 158: Decks, Pools, and Accessory Structu
Page 159 and 160: uildings. Pools can be designed to
Page 161 and 162: Purpose: To identify the special co
Page 163: Fuel n Fuel tanks should be install
Page 166 and 167: 9 REPAIRS n Pre-FIRM or post-FIRM b
Page 168 and 169: 9 REPAIRS n If a lateral addition c
Page 170 and 171: 9 REPAIRS Enclosures of Areas Below
Page 173 and 174: Repairs, Remodeling, Additions, and
Page 175 and 176: Vertical additions may also impose
Page 177 and 178: n Soffits should be inspected follo
Page 179 and 180: References and Resources HOME BUILD
Page 181 and 182: FEMA. NFIP Technical Bulletin 5-08,
show all

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

Create successful ePaper yourself

Delete template?

Save as template?