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

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7 ROOFING Mitigation Guidance Soffit Vents Key Issues n It is important to keep the soffit material in place. While some water can be blown into the attic through almost any type of soffit vent, the amount of water intrusion increases dramatically when the soffit material is missing (Figure 1). n Plywood or wood soffits are generally adequately anchored to wood framing attached to the roof structure and/or the walls. However, it has been common practice for vinyl and aluminum soffit panels to be installed in tracks that are frequently very poorly connected to the walls and fascia at the edge of the roof overhang. When these poorly anchored soffits are blown off, water intrusion increases significantly. Properly installed vinyl and alumi- Figure 1. Missing soffit material. num soffit panels are fastened to the building structure or to nailing strips placed at intervals specified by the manufacturer. Proper Installation The details of proper installation of vinyl and aluminum soffits depend on the type of eave to which they are attached. The key elements are illustrated in Figure 2. 2 of 8 12/10 A. Roof truss or rafter framing should extend across the bottom of the eaves, or be added to create a structural support for the soffit. As an alternative, soffits can be attached directly to the undersides of the angled rafters. B. Nailing strips should be provided, if necessary, to allow attachment of the soffit at the ends. Intermediate nailing strips may be needed, depending on the maximum span permitted for the soffit. If this is not known, the span between attachment points should not exceed 12” in high-wind regions. C. A J-channel (illustrated), F-channel, or other receiver as specified by the manufacturer should cover the ends of the soffit panels. Fasteners should be those specified by the manufacturer. Fasteners should be used through the nailing strip of each panel and at any other points (such as in the “valleys” of the soffit) if specified. Figure 2. Key soffit installation points. D. The overall span (eave depth) of the soffit should not exceed any limits specified by the manufacturer, and any required intermediate attachment points should be used. 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS C D B HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION A
Checking Soffit Material Installation As previously noted, the most critical soffit installations to check are those where vinyl or aluminum soffit panels are used. Soffits should be fastened to the eave structure; they should not be loose in the channels. Pushing up on the soffit material and the channels used to support the material can be revealing. If it moves readily or is easy to deform, it probably is not attached very well. Similarly, if the width of the overhang is greater than 12 inches, there should be an intermediate support running along the middle of the soffit and the panels should be attached to this support in addition to the supports at the ends of the panels. If the reader is concerned about the installation but cannot be sure, there are a couple of tools with a viewing screen connected to a small camera lens and light mounted at the end of a flexible tube that can be used to observe the connections. These devices allow inspection through a small hole that is drilled in an inconspicuous location that can be later filled with sealant. In order to ensure that there is a strong connection at the wall, there should be wood blocking running along the wall above the track where the soffit channel is attached and the channel should be fastened to that blocking. If there is no wood blocking, and there is either no vertical nailing surface on the channel or occasional tabs that have been cut and bent up to allow fastening to the wall, strengthening of the anchorage of the soffit material is clearly indicated. Remedial Measures If the inspection indicates a poorly attached soffit, the best way to ensure that the soffit material is adequately anchored in place is to remove it and install adequate wood blocking to allow solid anchorage of the soffit material. In some cases, it may be possible to remove the soffit material and reinstall it. However, it is also likely that some or all of the material will need to be replaced, so make sure that it can be matched before it is removed. Short of removing and properly reinstalling the soffit material, testing has shown that the anchorage can be greatly improved by applying a bead of sealant (Figure 3) along the bottom edge of the wall channel to adhere it to the wall surface below followed by applying large dabs of sealant in indentations between the soffit panels and the wall channel at one end (Figure 4) and the fascia flashing at the other end. Surfaces receiving sealant should be cleaned in order to facilitate bonding. Extra resistance can be gained by installing screws that mechanically tie the soffit panels to both the fascia flashing and to the wall channel (Figure 5). Note that use of sealant is a remedial measure only and is not a substitute for proper installation and fastening of soffits in a new installation. 7.5: MINIMIZING WATER INTRUSION THROUGH ROOF VENTS IN HIGH-WIND REGIONS HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION Figure 3. Applying a bead of sealant. (Note: Black sealant was used so that it would be visible in the photograph. Normally a matching sealant color would be used.) Figure 4. Applying dabs of sealant. Figure 5. Screws through wall channel. 3 of 8 12/10 ROOFING 7
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Home Builder’s Guide to Coastal C
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G GUIDE 2 of 6 12/10 Fact Sheet No.
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G GUIDE 4 of 6 12/10 Fact Sheet No.
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G GUIDE 6 of 6 12/10 Category Categ
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1 GENERAL What Should Owners and Ho
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Summary of Coastal Construction Req
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Foundation Orientation of Lowest Ho
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Certification Elevation NFIP 60.3(b
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Coastal Construction Requirements a
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Coastal Construction Requirements a
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Using a Digital Flood Insurance Rat
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Sample DFIRM This map is a portion
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Lowest Floor Elevation HOME BUILDER
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V Zone Design and Construction Cert
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Designing for Flood Levels Above th
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FIRMs depict the limits of flooding
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Figure 6. Mold and biological/chemi
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Other Considerations As previously
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Coastal Building Materials HOME BUI
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Location of Material Use Name of Ma
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n Metal-plate-connected trusses sho
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Non-Traditional Building Materials
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Things to consider if building with
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Figure 5. An example of a wall cavi
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Moisture Barrier Systems HOME BUILD
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How Do Siting and Design Decisions
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Selecting a Lot and Siting the Buil
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Foundations in Coastal Areas HOME B
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prohibited in V Zones but are recom
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3 FOUNDATIONS Table 1. Example foun
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3 FOUNDATIONS Additional Resources
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3 FOUNDATIONS 2 of 6 12/10 Figure 2
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3 FOUNDATIONS 4 of 6 12/10 Figure 4
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3 FOUNDATIONS Additional Resources
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3 FOUNDATIONS Piers vs. Piles Pier
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HOME BUILDER’S GUIDE TO COASTAL C
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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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Page 89 and 90: Housewrap HOME BUILDER’S GUIDE TO
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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: Minimizing Water Intrusion Through
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 154 and 155: 8 ATTACHMENTS n Siding used on the
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,
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FEMA P-499: Home Builder's Guide to Coastal Construction

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