Ever since the 1989 Loma Prieta Earthquake, which registered 7.1 on the Richter Scale, seismic codes for new construction in California have become stricter. It's now common to see engineered seismic bracing details even on plans for a simple addition. The most common detail is the shear wall, a framed wall with structural sheathing, designed to resist the lateral forces that an earthquake exerts on a building (see Figure 1). Any wall properly sheathed with plywood has considerable shear strength, but the term "shear wall" is reserved for walls designed by engineers. A shear wall incorporates special construction details and materials specified by code to resist the forces that rack a building during an earthquake or high winds (see Figure
