The Problem: Preparing an Older Home for Earthquakes

Many older East Bay homes were built before modern seismic building standards were adopted. While these homes may perform well under normal conditions, they often benefit from additional reinforcement to improve how they respond during an earthquake.

For this Kensington home, Ward Construction developed a seismic retrofit plan focused on strengthening the connection between the home’s wood framing and its concrete foundation. Rather than replacing the foundation itself, the project concentrated on reinforcing key structural components that help the home resist lateral movement during seismic events.

The Solution: Installing New Shear Walls

A major part of the retrofit involved constructing new plywood shear walls in strategic locations throughout the home.

Ward Construction installed two half-inch plywood shear panels in the laundry room—one approximately 30 inches long and another approximately 8 feet long. In addition, a new 16-foot shear wall was constructed beneath the front portion of the house where it meets the porch.

Each shear wall was installed with epoxy-set anchor bolts and hold-down hardware, helping create a stronger structural connection between the framing and the foundation.

Strengthening the Foundation Connection

In addition to the new shear walls, the project included installing 25 Simpson UFRP foundation straps around the perimeter of the home’s sub-area.

These straps were installed at approximately 48-inch intervals, connecting the home’s sill plate to the foundation. Foundation straps help improve the transfer of earthquake forces from the wood framing into the concrete foundation, reducing the likelihood of structural movement during seismic events.

Why Shear Walls Matter

During an earthquake, homes are subjected to powerful side-to-side forces.

Shear walls are specifically designed to resist these lateral loads by stiffening portions of the structure and helping distribute forces throughout the building. When combined with anchor bolts, hold-downs and foundation straps, they become an important part of a comprehensive seismic retrofit strategy.

For this Kensington home, the retrofit focused on strengthening the areas most critical to the home’s structural performance while working within the existing construction.