A PORTAL FRAME
The APA-developed method relies on conventional materials and techniques. Its added strength comes from three key details: extra anchors into the foundation, closer spacing of nails, and a header that runs past the door opening over the top of the sheathed bracing section. The closely spaced nails into the overlapping header provide resistance to rotation of the header at the corner, thereby stiffening the entire frame. The technical term for this assembly, says Martin, is a portal frame. “We also call that corner a semi-moment-resisting or semi-rigid connection,” he says.
The extra nails add a little labor to the process. But Martin confirms that power-driven nails are allowed: “We build all our test walls with a nail gun. You could also use hand-driven 8-penny nails, or galvanized—no problem. But we've never tested it with staples.”
The APA's downloadable PDF pamphlet on the new bracing method goes beyond garage doors and house corners to address second-story wall segments and framed cripple-walls under first-floor frames (what the APA calls “raised-floor construction”). After its success in adding 16-inch-wide braced-wall segments to the 2004 IRC supplement, the APA was hoping to have the additional bracing details approved at code hearings in September 2005. But suppliers of proprietary engineered bracing components objected to some of the APA's test data and methods, and that approval process is now on a sidetrack. “We're trying to resolve the issues in a committee,” says Martin.
Meanwhile, the additional details and the test reports that the APA has compiled to support them are available from its Web site, and Martin says that builders and engineers can use them as documentation when seeking plan approval from local building officials. Martin maintains that the APA's data is valid, noting, “Every code in the country says that alternates are permitted, provided that they are shown to be equivalent to what is already permitted.”