How Does Residential Seismic Retrofitting Improve the Home’s Foundation?

Earthquake retrofitting, otherwise known as house bolting, is a service that is extremely important in Southern California. However, many houses lack the necessary safeguards that protect the house from seismic damage. Earthquake retrofitting uses a series of connections, including anchor bolts and shear paneling, to help secure the home to its foundation in case of seismic activity. 


Houses built pre-1979 are highly susceptible to earthquake damage due to a few factors like poor foundation construction in preparedness for earthquakes. When an earthquake hits, it generates seismic waves to pass through the ground; these seismic waves cause your house to shake from side to side. When a foundation is not reinforced up to the current seismic code, serious earthquake risk is involved. 

Retrofitting your foundation will result in less shaking and a higher chance for your home to be protected from earthquake damage. The main goal of reinforcing the home is to stabilize the current poor structure of the house with seismic upgrades. Taking these measures to retrofit your home properly means you’ve reduced the risk of earthquake damage to your home. Most seismic damage occurs when a home slides off its foundation; bolting the home helps prevent sliding and reinforces the structure. Depending on whether the home is a one-story or two-story home, the placement of these materials varies. 

What is a Cripple Wall Foundation?

A cripple wall foundation consists of wooden studs no bigger than 4 feet tall that cover the expanse of the foundation’s perimeter. In order for cripple walls to be structural support and withhold against earthquake damage, they must be properly bolted and braced. This work involves bracing the cripple walls with structural plywood, functioning as a support in the occurrence of an earthquake and preventing the foundation walls from “crippling” to the ground.

Screenshot 2022-06-09 190124.png
IMG_20210329_212204_567_edited_edited.jpg

What is a Stem Wall Foundation?

A stem wall is a short, solid wall that stands along the perimeter of a home, connecting its walls to its foundation. Older homes are not adequately bolted to their foundation, causing a severe risk when an earthquake strikes. A stem wall retrofit consists of bolting the house to its foundation using URFP plates and bolts and A35 brackets. Without this seismic bolt-down, the home has the potential to slide off its foundation during an earthquake, causing severe damage.

20220504_102818.jpg

Before

IMG_20220316_184611_936.jpg

After