Seismic Retrofitting Basics San Francisco Bay Area
The horizontal (or lateral) motion in earthquakes create the forces that can be damaging to our wood framed homes. Homes tend to fail in one of three ways – all between the foundation and the first floor joists. First, the sill plate can slide off of the foundation. Second, the cripple wall (or pony wall) can collapse (or rack). Third, the floor joists can slide off of the mudsill or cripple wall.
There are a few variations on these themes, but most of our work involves installing structural elements proven to prevent these three types of failure. These standards and methods, developed in 1999 by Seattle Project Impact, are consistent with other building department permit requirements. Insurance providers and structural engineers generally ask that the same methods be used.
It is important to note that work must be done on all four sides of the house, but not necessarily every bit of each wall.
Basic Concepts: How a Seismic Retrofit Works
To keep a house from falling off its foundation in an earthquake, seismic retrofit strengthens three different areas of the house. These areas are all located in the basement and/or crawl space as defined in the two terminology illustrations above. If any one of these three areas is not adequately retrofitted, the house will be susceptible to damage in an earthquake.
These three areas are:
- Bracing the cripple walls with plywood.
- Bolting the braced cripple walls to the foundation.
- Attaching the floor of the house to the braced cripple walls.
Some diagram of information: (click to enlarge)
Why Choose Walnut Creek Construction for your Earthquake retrofit?
- Licensed, bonded and insured.
- Every member of our team is trained and certified.
- Experienced with all types of retrofit.
- References available upon request.
- Works in conjunction with a licensed structural engineer.
- Always secures a building permit for retrofit work.
- Familiar with recent changes to the retrofitting code.
- Familiar with Project Impact standards.
- Qualified to address all your structural needs.
- “One stop shopping” for all retrofit related tasks, including sheetrock & siding.
- Maximizes dust control, minimizes time disruptions, cleans up properly.
- In and out in less time than any other contractor.
To schedule an appointment, please give us a call today at (925) 497-2687