Shear Wall

Wind pushing on the side of a house tries to slide the top of each wall sideways relative to the bottom. A shear wall is a wall built to take that push and pass it down to the foundation without leaning, racking or tearing loose. In a wood-framed home it is usually a run of studs covered with structural sheathing such as plywood or OSB, nailed at a tight, specified spacing, with the ends of the wall tied down to the foundation.

Shear walls and braced wall panels do the same job in two ways. The International Residential Code's Section R602.10 gives prescriptive bracing: set lengths and methods a builder can follow without an engineer. When a design goes beyond those tables, such as a wall of glass facing a view, tall walls, or a large open great room, an engineer designs shear walls with calculated nailing, sheathing and hold-downs. Several of the IRC's narrow-wall bracing methods, such as portal frames beside a garage door, also call for hold-downs at the panel ends.

People searching for a strap wall or strap shear wall usually mean one of these narrow-wall solutions: steel strap bracing or strap-style hold-downs that let a short length of wall resist the same force a longer sheathed wall would. Simpson Strong-Tie's testing found that tying down the end posts with hold-downs made walls stiffer and stronger, reaching higher loads with less movement.

For example, a Desert Contemporary home in Cave Creek with sliding glass walls across the back may have very little solid wall on that side. The engineer makes up for it with short, heavily nailed shear walls and hold-downs, or a prefabricated shear panel, at the ends of the glass. That is why the wall plan and the window plan have to be settled together. The full code text is summarized in IRC R602 wall construction and bracing.