The Problem: Strengthening an Older Home for Earthquake Safety

Many homes throughout Castro Valley were built before current seismic building standards were adopted. While these homes may have performed well for decades, strengthening key structural connections can significantly improve how they respond during an earthquake.

Working from preliminary engineering plans prepared by Dave Olnes, Ward Construction developed a comprehensive seismic retrofit designed to strengthen the home’s structural framework without replacing the existing foundation. The focus was on improving the connections that allow the house and foundation to work together during seismic events.

The Solution: Eight New Engineered Shear Walls

The primary structural improvement involved constructing eight new plywood shear panels at strategic locations throughout the home.

The rear four shear panels were installed on the exterior of the residence, while the remaining panels were incorporated into other areas identified by the engineering plans. Positioning the shear walls in multiple locations helps improve the home’s ability to resist side-to-side forces generated during an earthquake.

Reinforcing the Foundation Connection

A seismic retrofit involves much more than adding plywood.

Ward Construction installed epoxy-set anchor bolts, hold-down hardware, additional framing members and structural clips wherever required by the engineering plans. Together, these components strengthen the connection between the home’s wood framing and its concrete foundation, helping the structure perform as a unified system during seismic activity.

Coordinating the Work Throughout the Home

Projects like this often require access to existing walls and structural framing.

To complete the retrofit, portions of the stucco siding were removed and replaced as needed. New drywall was installed over the shear panels located in the garage after the structural work was complete. The proposal also noted that cabinets and the existing water heater would need to be temporarily removed to provide access to portions of the work area. Interior finish painting was intentionally excluded from the project scope.

Optional Improvements Identified During Planning

In addition to the primary seismic retrofit, the proposal identified several optional improvements that could be completed at the same time.

These included:

• Capping approximately eight feet of foundation along the right side of the home.
• Removing approximately 200 square feet of brick veneer and a front planter to improve access for future work.
• Replacing an existing concrete access ramp near the rear of the home with a new four-foot-wide concrete staircase.

Including these optional items gave the homeowner flexibility to combine structural improvements with related site upgrades during a single construction project.