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Installation Quick Links How to calculate coverage areas Recommended Siding Nails & Applications Siding installations at corners, dormers and roof junctions Installing Bevel Siding How to finish solid wood siding Product Quick Links Bevel Siding |
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Wall Construction & Design Considerations
Vapor Retarders It is necessary to design walls so that moisture vapor does not enter and condense within the exterior wall cavity. Proper design will ensure the insulation's thermal efficiency and the overall structure's performance. Design must provide continuous vapor retarding equivalent to a rating of 1 perm installed on the living space side of the insulation. Vapor retarders are also required on the ground in all crawl spaces and under concrete slabs. Acceptable products include: 6 mil polyethylene, asphalt impregnated kraft or foil-backed insulation (tabs must be stapled to the narrow face of the studs, not to the wide face), vinyl-faced or foil-backed gypsum, sandwich-type kraft with an asphalt or polyethylene core, or equivalent. Vapor retarding paints are also available for interior walls. Site Drainage Slope ground away from structure for a minimum of 3 feet. Roof Drainage Incorporate an overhang or drainage system into the structure design to prevent water from running down sidewalls. Ventilation Both attics and crawl spaces require adequate ventilation. Clothes dryers must be vented outside; kitchen and bathroom fans are recommended to vent localized moisture outside. Attics. Attic vents should provide a minimum of 1 square foot of net free vent area for every 150 square feet of attic space. Unrestricted air circulation is best achieved by a combination of soffit vents and ridge or roof vents. Crawl Spaces Crawl space vents should provide a minimum of 1 square foot of net free vent area for every 25 lineal feet of exterior wall. They should be placed to allow for cross-ventilation. Siding Return at Roof (Dormers) Use flashing, allowing at least a 2-inch clearance between siding and roof line. Cut edges of siding must be finished in accordance with finishing instructions described in this guide.
Sheathing It is recommended to apply cypress siding over standard sheathing material with maximum stud spacing of 16 inches on-center. Where building codes permit, siding may be applied over unsheathed walls. A suitable building or felt paper wind barrier is recommended and must be used where building codes require. Foam and Foil-Faced Sheathings. Both rigid foam and foil-faced sheathings can be
vapor barriers. Rigid foam sheathings, however, offer no resistance to sag
caused by the weight of the siding on the nails. For application of cypress over
rigid foam sheathing, use angular threaded ring shank nails long enough to
penetrate at least 1 inch into framing members. For example, siding over 1-inch
foam requires a 3-inch nail (10d). Note: Wood siding applied over foam sheathing may take on a wavy appearance if the siding is compressed by nailing with too much force. |
