We live in North America's second most active earthquake zone. Yet our homes have not been built with the stability to resist the magnitude of earthquake we've been warned to expect. Should the Cascadia Fault rupture, tens of thousands of homes are at risk of sliding or collapsing off their foundations, putting everyone inside each home at extreme risk of traumatic injury or worse. The good news is that this can be prevented. Quickly, effectively, and fairly economically.
Seismic Retrofits Address Three (3) Specific Structural Weaknesses
Beneath the main floor, sitting on the foundation of most homes, are short pony walls that support the entire weight of the house. These walls are held in place by gravity and little more. Like open utility shelving, horizontal force would tip them over like dominos if it were stronger than the weight holding them down. And earthquake's vertical forces break the grip of gravity while it's horizontal forces push at the walls until they collapse.
In addition to the instability of the walls, the other two weaknesses are found in the connections to the floor framing above and the foundation below. The goal of seismic retrofitting is to keep the house on its foundation and habitable. We do this by applying earthquake engineering principles, specially designed hardware, and unique construction practices that have already proven effective in strong earthquakes.
Three (3) Main Components of A Seismic Retrofit
1. Convert the pony walls (aka cripple walls) to seismic shear walls. This is done with an application of plywood in a specific manner according to the size and weight of your house, and the anticipated quake force for the geographic region.
2. Bolt the newly sheared walls to the foundation with foundation bolts and special 3" earthquake plates
3. Secure the newly sheared walls to the floor joists with shear transfer ties.
How We Know Retrofits Work
The most famous story told about seismic retrofitting of houses took place near San Francisco in 1989 when the Loma Prieta earthquake hit, severely damaging 40,000 homes. A well-known architect had purchased two identical Victorian homes which sat side-by-side on a corner. He managed to get only one retrofit in time. The retrofit home survived the earthquake with only $5,000 worth of damage and remained habitable. By contrast, the twin house was knocked from its foundation and cost $260,000 to jack up, repair, and slide back onto a new foundation.
Shear Seismic Team Has First-Hand Experience
Members of our team have lived through destructive earthquakes in California and analyzed structural failures in thousands of homes. Engineer Thor Matteson SE, was awarded for his shear wall bible "Wood-Framed Shear Wall Construction" published by the International Code Council. He and retrofit expert Howard Cook have participated in seismic code development and seismic testing in North America's earthquake capital. Our method of retrofitting will strengthen your home's resistance to damage by almost 1,000 times.
FREE Seismic Assessments
Shear Seismic offers a FREE assessment to determine the most practical, effective and cost-efficient retrofit plan for your home. You will then be provided with an overview of the our recommendations including a scale drawing with the retrofit mapped out and a firm quote to perform the install.
DON'T WAIT UNTIL IT'S TOO LATE... CALL TODAY!