The Solution

As we mentioned in The Problem section, our older homes have 3 areas below the first floor that are the weak links in the structural chain for the house to stay together during a catastrophic earthquake. Seismic retrofitting is designed to address each of these 3 weaknesses and bring the house up to a level that we can count on them staying put during an earthquake. They have been doing retrofits in California for over 40 years, with a great deal of success if it is done properly. We in the Northwest seem to have missed the memo that we are also in Earthquake country and so retrofitting didn't take off here until 1998-9. At that time the City of Seattle got a federal grant to assist with EQ preparedness and created Project Impact. After much study and bringing in experts from WA and the rest of the country, they published a prescriptive plan to allow homeowners to have their house retrofitted without the need and expense of having a structural engineer custom design the work. The only problem was this was a basically one size fits all approach - great if your house matched the criteria, but no help if, like most, it did not.

Still, they were out raising public awareness and started a good work. In its simplest form, a seismic retrofit has 3 parts. The first is bolting down the wood structure to the foundation per a formula based on the size and structure of the house. Second is the bracing of any pony or cripple walls with plywood to minimize lateral movement during the quake. Finally, there is the attachment of the flooring system above to the braced pony wall or sill. It sounds simple, but as with most remodeling projects on older homes it is usually an adventure - a noisy, dusty, physically demanding, intense adventure. Check out the Retrofit 101 section for more on the nuts and bolts of it, complete with illustrations.