Q. What’s the best way to frame outside corners?
A. Tim Uhler, a lead framer for Pioneer Builders in Port Orchard, Wash., responds: Most of the time, we frame walls with a “California” corner — just two exterior wall studs nailed together in an L shape, with another backing stud (see illustration). Compared with a traditionally framed four-stud corner, this method uses less lumber and provides room for some insulation.
In cases where the corner doesn’t have to transfer shear loads between adjoining walls, the IRC allows the backing stud to be replaced with scrap lumber or with metal or plastic drywall clips (R602.3, 2006 IRC). Using drywall clips leaves the corner stud bay completely open for insulation, but it also increases the drywaller’s labor. For this reason — and to reduce framing waste — we typically use scrap material for the drywall backing at corners and intersections.
Because I frame in an earthquake zone, corner framing on many of our jobs is subject to seismic design requirements, which typically call for doubled end studs or solid 4-by or 6-by corner posts, as well as hold-downs. When this is the case, we follow the engineered design but still try to install backing so as to maximize the insulation in the corner bay.