Does Your Bay Area Home Need a Seismic Retrofit?

The San Francisco Bay Area sits on some of the most seismically active ground in the United States. The Hayward Fault runs straight through the East Bay, under Oakland, Berkeley, Fremont, and Hayward, and the USGS puts the odds of a magnitude 6.7 or larger quake in the region within thirty years at better than sixty percent. If your home was built before 1980, there is a real chance it was never reinforced.

The two most common weaknesses

Most older East Bay homes fail in one of two ways in a quake.

• Cripple wall weakness. The short wood walls between the foundation and the first floor can collapse sideways, dropping the house off its foundation.
• Soft story construction. A garage or open space on the ground floor leaves too little wall to brace the weight above it.

Is your home at risk?

• Built before 1980, especially before 1975
• Has a raised foundation with a crawl space rather than a slab
• Has a garage or carport tucked under living space
• Sits on a hillside or on fill soil
• Has never had a seismic evaluation or retrofit

What a retrofit actually involves

For most homes it is not dramatic. We bolt the house to its foundation and brace the cripple walls with plywood shear panels and steel connectors. The work happens in the crawl space, so you barely notice it, and it leaves the house far more likely to ride out a quake on its foundation.

What it costs

A standard bolting and cripple wall retrofit is one of the more affordable upgrades you can make, and state grant programs can offset part of it for many homeowners. Soft story and larger structural work costs more. Compared to the cost of a house coming off its foundation, it is one of the best values in home improvement.

Is it required?

For most single family homes it is currently voluntary. That does not mean it is optional in any real sense. Standard homeowners insurance does not cover earthquake damage, so the reinforcement is your protection.

Getting started

Start with an honest evaluation of your home. If it does not need much, a good contractor will tell you that. If it does, you will know exactly what and why.