Home earthquake retrofitting for foundations, chimneys, gas

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Picture this: You’ve just bought and moved into your first home. You’ve found the right shade of eggshell paint for the walls and family pictures have been hung.

The house is really starting to feel like home. Then the L.A. area is hit by a 5.0 earthquake.

The shaking isn’t bad enough to upend civilization, but your house slides off its foundation. Now you’re stuck with an uninhabitable space — plus significant repair costs and a mortgage payment for a structure you can’t live in.

This scenario is preventable — and prevention is cost-effective.

More than 1 million homes in California need to undergo seismic retrofitting, according to Janiele Maffei, chief mitigation officer for the California Earthquake Authority.

The process is fairly simple and takes about a day, Maffei said. In Southern California, the cost of a standard seismic retrofit can be as low as $5,000. That initial investment is much less expensive than the alternative.

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UPDATED Sept. 12, 2024 | 4:37 PM

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“The cost to actually rebuild a house is night and day,” said Keith Whallett, CEO of the Foundation Works, based in Burbank. Minor earthquake damage can be repaired as long as the house stays on its concrete foundation, he said. “If it slips off, then you can’t put your house back onto the concrete footing.”

The goal of seismic retrofitting is to make sure your home “performs better in an earthquake,” Maffei said, in terms of preserving life and property.

A variety of mandates and regulations exist throughout California, so property owners should familiarize themselves with all applicable local regulations. Skilled do-it-yourselfers (emphasis on “skilled”) can complete the retrofitting on their own, Maffei said. But most people will call an expert.

Here’s what you need to know.

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Before you buy

For any home built before 1980, Maffei said, you should have a reasonable suspicion that retrofitting is needed.

When you purchase a home, you can expect to receive an engineer’s report. Typically, this should mention whether there’s proper bolting and plywood installed. It does not necessarily mean the unit is up to code, however, Maffei said.

Maffei said the best thing you can do is ask your real estate agent. You can also take a flashlight and check things out for yourself in the crawlspace under a home you’re thinking of purchasing. She said to look for plywood and shiny new bolts. If you don’t see any of that, you may need a foundation retrofit.

The same goes for renting, she said. Before moving in, ask your landlord whether the building or unit has been seismically retrofitted to code.

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How to get started

Once you know your home needs retrofitting, you need to decide whether to hire a professional. Either way, you’ll need to acquire a building permit from your city. If you go with a contractor, they will file for the permit and be responsible for the project.

If you’re doing it yourself, you’ll be considered the contractor when you apply for a permit — meaning if anything goes wrong, you’re liable. All the tools you’d need are available on tool rental sites, and the materials can be purchased at home improvement stores. Maffei said if you do it yourself, the overall cost is lower.

But Whallett cautions those considering taking on this kind of project: “A lot of times we do see some work where someone’s tried to do it themselves and made a complete hash of it,” he said.

When it comes to selecting a contractor, Mandro Eslami, Southern California sales manager for SFT Construction, urged property owners to do their research and not necessarily go with the lowest bidder.

“It’s just like going to a restaurant,” he said. “You can probably fill yourself up with five bucks, but are you not going to regret that the next day?”

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What does seismic retrofitting entail?

1. Foundations: The most common type of pre-1980 home in Southern California is a raised foundation house. These have either stem or crawl space walls, both of which require foundation anchor bolts to secure the frame to the concrete. If your house has crawl space walls, you may also have to install plywood bracing to the walls of the inside of the space.

The Standard Plan Set 1 and the FEMA P-1100 are pre-engineered plans that allow for efficient retrofits.

Of all the retrofitting his company does, Whallett said 30% to 40% of the jobs follow Standard Plan Set 1.

Since it’s the most common type of retrofitting, it takes the least amount of time and is the least expensive. All the work is done under the house, so there’s minimal disruption to daily life. Other types of homes may require more time — and more money. Although we’ve illustrated a raised foundation house here, you may have other needs depending on how your home was built.

In the San Francisco Bay Area, living spaces above garages are common. To prevent a house from crumpling, the walls of the garage should be reinforced with plywood and a steel frame should be installed around the garage door. A proper retrofit will cost $10,000 to $15,000, according to the California Residential Mitigation Program.

Hillside homes like those that perch throughout L.A.’s canyons and slopes require much more time and effort. These modifications require an engineer’s eye, and it’s recommended you don’t try to make these renovations yourself. Because of the complexity, the retrofitting process could cost around $10,000.

Houses with an area underneath the main living area are not common in Southern California but are particularly vulnerable to slipping because they don’t have a continuous concrete foundation. Retrofitting for this type of house is more complicated and requires both an engineer and a licensed contractor. A complete retrofitting can cost up to $15,000.

Seismic retrofitting is the bare minimum you can do to ensure the safety of you and your home. You should also consider the following:

2. Gas: Having an automatic natural gas shutoff valve installed on your gas main can help prevent leaks and potential fires post-earthquake.

3. Chimneys: They’re comforting and nostalgic, but brick chimneys pose a huge risk to safety, Maffei said. It used to be recommended that you brace the chimney against the house, but Maffei said the best course now is to demolish it and rebuild.

4. Water heaters: Strapping your water heater to wall studs is another easy fix that you can do on your own to reduce the risk of water damage, gas leaks and fires. Replacing water and gas lines leading to the heater with flexible options also is recommended by Earthquake Country Alliance.

Here are links where you can do further research:
californiaresidentialmitigationprogram.com
earthquakebracebolt.com

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Californian pro tip

While you have people working on your chimney and foundation, you can do a little safety work yourself.

Earthquake putty, also known as museum putty, isn’t just for invaluable treasures at museums. It can also be used to hold your priceless heirlooms and other important items in place during the shaking.

Make sure your flower pots, vases, trophies and picture frames survive by placing a small wad of putty at their base and securing them to wherever they’re displayed.

Although extremely durable, museum putty isn’t fail safe. Keep larger, heavier objects on lower shelves in case they do fall.