Wind-Resistant Framing Techniques
Cost-effective details to help houses weather the storm.
As an engineer for APA-The Engineered Wood Association, Bryan Readling spends a lot of time traveling to places where tornadoes and other violent storms have damaged or destroyed houses. In investigating the wreckage caused by two storms in 2011, he and his colleagues discovered that most of the structural failures were caused by a lack of continuity in the load path from foundation to roof. In this article, he identifies the specific places where he observed the most structural failures: houses pushed off their foundation from lack of anchor bolts; foam-sheathed gable ends damaged from lack of drywall on the interior or structural panels on the exterior; roof framing pulled from the walls from a lack of connectors or from connectors being fastened to the inside of the top plate rather than the outside. Readling then shares several strategies for designing for high-wind resistance: tying down rafters with properly installed connectors; using enough nails in the sheathing; extending the sheathing to the sill plate; using anchor bolts to attach the house to the foundation; using ring-shank or deformed-shank nails on the roof; sheathing gable ends with plywood or OSB; tying gables to walls; connecting the first and second floors by breaking the sheathing at the band joist; and strengthening garage doors. Taking these steps, Readling believes, will prevent houses from being destroyed in storms rated EF-0, EF-1, or EF-2, which constitute 95% of all tornadoes in the United States.