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

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3 FOUNDATIONS Piers vs. Piles Pier foundations are most appropriate in areas where: n Erosion and scour potential are low. n Flood depths and lateral forces are low. n Soil can help resist overturning of pier. The combination of high winds and moist (sometimes salt-laden) air can have a damaging effect on masonry construction by forcing moisture into even the smallest of cracks or openings in the masonry joints. The entry of moisture into reinforced masonry construction can lead to corrosion of the steel reinforcement bars and subsequent cracking and spalling of the masonry. Moisture resistance is highly influenced by the quality of the materials and the quality of the masonry construction at the site. Good Masonry Practice If a masonry pier is determined to be an appropriate foundation for a building, there are some practices that should be followed during construction of the piers. n Masonry units and packaged mortar and grout materials should be stored off the ground and covered. n Masonry work in progress must be well protected from exposure to weather. n Mortar and grouts must be carefully batched and mixed. The 2009 International Building Code (IBC 2009) and 2009 International Residential Code (IRC) specify grout proportions by volume for masonry construction. n Connectors should be selected that are appropriate for masonry to wood connection. It is important to maintain a sufficient load path from the building into the ground. The connectors and fasteners should be a corrosion-resistant material or have corrosion protection at least equivalent to that provided by coatings in accordance with the 2009 IRC. Connectors should be properly embedded or attached to the pier. Wood in contact with masonry pier should be naturally durable or preservative-treated. Figure 3 illustrates the importance of maintaining a proper load path between the pier and the building’s beams. n Properly sized steel reinforcing bars should be installed throughout the masonry piers. Piers should be fully grouted and steel reinforcing bars 2 of 3 12/10 Figure 2. Pier breakage (Long Beach, Mississippi) should not be left exposed to weather for excessive amounts of time prior to installation. Lap splices should be properly located and of sufficient length to meet the standard masonry industry details and requirements to sufficiently carry the loads imposed on the structure. n Consider incorporating grade beams into the foundation in order to achieve greater structural stability in the pier system. n If the design of the pier system or any details are unclear, contact a structural engineer or appropriate design professional to clarify the foundation details. Pros and Cons of Grade Beams Grade beams are horizontal structural members cast against the ground or “grade.” Grade beams can be a useful foundation method in areas with limited potential for erosion and scour. The type of force resisted by grade beams varies by application, but can range from continuous vertical and horizontal loads to axial loads. The grade beams used in this example are used primarily for axial loads generated by stability demands of the piers. The grade beams should be placed below the elevation of anticipated eroded grade so that there is no effect on scour and erosion of the supporting soils. The pros of using grade beams with pier foundations are that they: n Provide vertical and lateral support. n Are less prone to rotation and overturning. n Transfer loads imposed on the elevated home and foundation to the ground below. 3.4: REINFORCED MASONRY PIER CONSTRUCTION HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION
Some cons of using grade beams with pier foundations are that they: n Are susceptible to erosion and scour if too shallow n Can become obstructions during flood events and can increase scour Figure 3. Failure of pier-to-beam connections due to wave and flood forces acting on the elevated building (Long Beach, Mississippi) Are grade beams allowed in the V Zone? Yes, although the NFIP states that the lowest horizontal structural member is to be constructed above the BFE, it is referring to the lowest horizontal structural member above erodible grade. Based on this, both grade beams, cross bracing and knee bracing are allowed by the NFIP. Grade beams can provide significant structural support to an open foundation system provided they are placed below the expected eroded surface. Additional Resources American Concrete Institute, 2004, SP-66(04): ACI Detailing Manual. (http://www.concrete.org) Concrete Reinforcing Steel Institute. Placing Reinforcing Bars – Recommended Practices, PRB-2-99. (http://www.crsi.org) International Code Council. International Building Code. 2009. (http://www.iccsafe.org) International Code Council. International Residential Code. 2009. (http://www.iccsafe.org) The Masonry Society. 2008. Building Code Requirements for Masonry Structures. TMS 402-08/ACI 530-08/ASCE 5-08. (http://www.masonrysociety.org) The Masonry Society. 2008. Specifications for Masonry Structures. TMS 402-08/ACI 530.1 08/ASCE 6-08. (http://www.masonrysociety.org) Developed in association with the National Association of Home Builders Research Center 3.4: REINFORCED MASONRY PIER CONSTRUCTION HOME BUILDER’S GUIDE TO COASTAL CONSTRUCTION 3 of 3 12/10 FOUNDATIONS 3
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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
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 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
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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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