A seismic retrofit is any modification of an existing building that strengthens the building’s resistance to ground motion during an earthquake. During an earthquake, the forces generated by the ground motion send seismic energy travelling through a building. In a properly designed building, the seismic forces will transfer through the structure and back down into the ground, leaving the building intact. The key is to properly connect the building elements so there is a continuous load path from the wood structure to the foundation. The majority of Bay Area housing was constructed before modern earthquake codes were adopted and are therefore susceptible to damage during an earthquake. Nowadays, many programs and cities offer incentives for homeowners to do seismic retrofits, and for a good reason:
A seismic retrofit is the most effective thing you could do to make your home or building more safe in case of an earthquake.
We help homeowners make their homes more earthquake safe by evaluating the existing building and discussing what retrofits would most benefit their structure. Some examples of a retrofit include:
- Bolting the wooden frame of the home to the foundation with epoxied anchor bolts or foundation plates
- Bracing cripple walls with plywood shear walls to strengthen the lateral resistance of the building
- Adding seismic hardware to critical connections to “collect” the lateral forces and transfer them down to the foundation
- Replacing/ repairing areas of substandard foundation
- Installing manufactured shear walls or steel moment frames (only applies to soft story retrofits)
Some cities have incentives in place for homeowners to retrofit their home such as reduced permit fees and even refunds, including Berkeley’s Seismic Retrofit Refund Program and Oakland’s Soft Story Retrofit Program.
Hold Downs and Anchor Bolts
Shear Walls with Foundation Ties
Anchor Bolt Close-up