Shear Walls for Light Frame Construction

Building Strong Garage Door Walls, Journal of Light Construction, April 2004, describes the APA Narrow Wall Bracing Method for providing lateral bracing for garage wall openings where only short lengths of wall are available for developing resistance to seismic and wind lateral loads.

Background
The relatively new, but increasingly broadly adopted, International Residential Code (IRC) provides extensive guidance on lateral bracing requirements for light wood framed residential structures. Typically, all exterior walls and some interior walls require bracing. Braced wall panels are required at wall ends and at regularly spaced intervals along the length of the wall. Bracing can take various forms such as 1x4 diagonal strapping, diagonal board sheathing, structural panel (plywood or OSB) sheathing, and other materials. Such braced panels are normally required to be at least 48 inches wide.

In the case of garage walls with large openings, there is often insufficient length of solid wall to meet the IRC's standard bracing requirements. In such circumstances, one option is the APA's Narrow Wall Bracing Method.

APA Narrow Wall Bracing Method
In brief, this method consists of the following:

• Fully sheathing the building structure in plywood or OSB panels
• Extending garage header beams beyond the framed opening to the corners of the wall (By extending the headers into the wall framing and providing adequate nailing, a semi-rigid moment frame is created around the garage opening.)
• Special, detailed requirements for stud layout, header straps, nailing, and foundation anchor bolt placement

According to the article, braced wall panels constructed with this method may be as little as 1/6 as wide as they are tall. In other words, panels 16 inches wide may be used for a wall 8 feet tall, or panels 20 inches wide may be used for a ten-foot tall wall.

The article also discusses several noteworthy practical considerations. The braced panels cannot have holes drilled or other penetrations, such as for the mounting of exterior lights; and an unusual degree of accuracy is required in the placement of foundation anchor bolts.

More Information
APA's Wall Bracing page provides links to their Narrow Walls That Work technical brochure, and to related information.
Information on Simpson StrongTie's proprietary narrow shear wall solutions is available on their Strong-Wall Shearwall page.