Common Housing Design in California Could Lead to Collapse During Earthquakes

Posted April 5, 2023, under Blog

It’s probably the most common housing design in California, and across the United States – a living space or a large room on top of a first-floor open space (like a garage).

According to new research, it’s this type of residential design that can cause devastating and deadly vulnerabilities during a large earthquake.

Homes most at-risk of collapse during a large quake are those that have been constructed with a living space that has been “held up” on either the side of the garage door or supported by skinny beams which have shown to bend or break during a sizeable shaker … causing the entire room to crash to the ground.

Whenever there is a living space built above a weakened ground space with an open carport or garage door, this can create a top-heavy structure (also called a soft-story).

Soft-story homes and apartment complexes were a popular type of construction in California up until the 1980s. And while California has made major strides in mandating retrofits for soft-story apartment complexes, single-family homes have been largely ignored.

“If they have full collapse, that’s an 8- or 9-foot drop. … The house is dropping with all the furniture flying around in it,” structural engineer Janiele Maffei, chief mitigation officer with the California Earthquake Authority and president of the Earthquake Engineering Research Institute, told the L.A. Times.

“It’s just really serious, and [could result in] hundreds of thousands of dollars worth of damage. It could be a total loss as well,” she added.

Seismic experts are warning homeowners about this structural defect, and urging those who live in homes built before 1979 to have their properties inspected for earthquake retrofits.

These homes have a much higher risk of collapse during an earthquake because they have been attached to their foundation using a short, flimsy wall (also called a cripple wall), which can create a higher chance of the house sliding off of its foundation and collapsing from the shaking.

California has recently launched a pilot program to address these residential soft story issues, called Earthquake Soft-Story, that will offer select homeowners grants up to $13,000 to retrofit their homes.

“As recent earthquakes in both California and the other side of the world remind us, older homes built before building codes were strengthened are much more likely to be badly damaged in an earthquake,” Glenn Pomeroy, chief executive of the California Earthquake Authority said. “But action taken now can prevent catastrophic loss that could result from the next damaging earthquake.”

If you think your home may be in need of earthquake retrofitting, foundation repair, or foundation replacement, contact Julian Construction today and we will send one of our foundation specialists out to conduct a free, thorough inspection with a quote for repair.

We have extensive experience serving our Los Angeles community and nearby regions. In fact, Julian Construction has inspected over 30,000 structures in the area! Give us a call at (323) 733-3377 to schedule your free inspection or complete the inspection request form.

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