Protect Your Home With a Basic Seismic Retrofit
Strengthening a home in earthquake country means anchoring it to its foundation and adding site-built shear walls.
Synopsis: For homeowners living in seismic zones, there’s no knowing for sure when the next big one will hit. According to structural engineer Thor Matteson, though, you can protect your house with a basic seismic retrofit. This type of work won’t make a house earthquakeproof, but it will help to minimize damage. Some of the basic steps include connecting the mudsill’s to the house’s foundation; securing the floors to the tops of the walls; and building shear walls. This article includes a sidebar on ineffective retrofit methods.
Geologists estimate that the Hayward Fault that runs through the East Bay of San Francisco is due to give way at any moment. When it hits, the earthquake is projected to cause significant loss of life, to cause nearly $165 billion worth of damage, and to leave hundreds of thousands homeless. The last major Hayward Fault earthquake was in 1868. Research shows that five major quakes have occurred along the fault—on average, every 140 years dating back to 1315. The 140th anniversary of the 1868 quake was three years ago.
As a structural engineer in the San Francisco Bay area, I specialize in helping to prepare homes for seismic events. While I work to shore up homes in a very distinct region of the country, the basic lessons that you’ll learn here — how to reinforce the floor framing, properly attach a house to its foundation, and construct site-built shear walls — are broadly applicable.
Keep the house on the foundation
A seismic retrofit does not make your house earthquakeproof, but it does minimize potential damage to the house.
First, it keeps your house from sliding off its foundation. This is accomplished by using specialty hardware to reinforce the transition between the foundation and the floor framing or wall framing. Many older homes are…