Your earthquake kit is packed, you’ve secured furniture to the walls, and your family has agreed on an emergency meeting place. Those of us living in tremor-prone areas know how important it is to be ready for the next big quake, but do you know how well your house itself would fare? If the answer is “no,” continue on to find out why we encourage all Bay Area homeowners to consider the benefits of a seismic retrofit.
What is a seismic retrofit?
Seismic retrofitting is like wearing a cast on your leg when you have a broken bone. The cast keeps the broken bone in place and prevents the area around it from moving. In the same way, when you seismically retrofit your house, you are modifying your existing structure so that it will stay in place when faced with seismic activities such as earthquakes.
Above, a home in Napa, damaged by a 6.0 earthquake in 2014. (Alvin Jornada / EPA)
Here’s another way to think about it:
If you have a deck of cards handy, play along! Imagine three playing cards, one lying flat on the table in front of you, the second card standing vertically in the center of the first card, its thin edge facing you. Now, lay a third card flat on top of the second parallel to the first card. What you should have in front of you is three cards forming an uppercase serif “I.” If you were to shake the top card you can see how unsteady the foundation is, and your house of cards may even collapse!
Let’s try this experiment again, this time add a fourth card vertically along the side of the middle card, face pointing towards you. Now shake away! This fourth card is the difference between a livable structure or a sturdy home that could save your life. In other words, earthquake reinforcement will limit the amount of damage and ensure that at the end of the chaos, those dishes will STILL be waiting for you to clean.
In the grand scheme of things, we never truly know when seismic activity will occur and home is where we should feel safest!
In short, a seismic retrofit increases your home’s safety factor, keeps your largest investment safe (Protect the Batcave!), and minimizes any damage during the next quake. It’s a lot more cost effective to retrofit now than to repair later.
What does a typical seismic retrofit project look like? We recently had a client come to us for a seismic retrofit because they were acutely aware that their home sat on the Hayward Fault line. Historically, we’ve seen five earthquakes occur along this fault line every 150 years.
Is a seismic retrofit worth it?
Well, if a seismic retrofit is like wearing a cast on your broken leg then we’d have to say yes. Ha! In all seriousness, earthquakes can happen when we least expect them and their aftershocks can be catastrophic. Take the 1989 Loma Prieta Earthquake, located on the San Andreas Fault line, for example. The 6.9 magnitude quake lasted 20 seconds. The aftershocks? Over 1,000 were reported ranging from 2.5 to 5.2 in magnitude. 18,306 homes were damaged and 963 were completely destroyed.
Strengthening California’s structures to withstand earthquakes is so important that programs incentivizing property owners to seismically retrofit their homes and businesses have popped up throughout the state. For example, Oakland has a New Homeowner Voluntary Seismic Strengthening Incentive Program and the California Earthquake Authority offers the Earthquake Brace and Bolt grant program.
When it comes down to it, the safety of your home and the lives of your loved ones is always worth it.
We completed our client’s seismic retrofit in two main stages:
1. The first stage consisted of securing the house to the concrete foundation, which is what anchors the structure to the ground. We did this by using heavy duty hardware to bolt the house down to the concrete. That’s right, there will be no chance of our clients waking up in the Land of Oz with a Wicked Witch under their house!
2. The second stage focused on reinforcing the wood structure. In order to strengthen the studs, we attached a sheet of plywood to them. This is a key component in ensuring that the home undergoes less shake and damage when faced with an earthquake.
The goal of retrofitting is to allow homeowners to shelter in place and survive a major earthquake. The difference between sheltering in a reinforced structure compared to a non-reinforced structure is monumental.
