Why Earthquake Seismic Retrofit And How Much Does It Cost
Foundation Bolting Cripple Wall Bracing Universal Foundation Plates Seismic Upgrade
A home is the most personal element of our lives; it represents the last refuge, the one place where we know we’re safe from the outside world. For most of us it’s also the most sizable financial investment we’ll ever make. The investment is so significant that we don’t even want to think about what may happen to that investment, that home, during an earthquake. But we live in an area where the threat of a serious earthquake increases each day. Scientists can only guess, not predict, when the next quake will occur, and we all know that sooner or later the next quake is going to be “the big one.” It’s vital to think about protecting our homes against catastrophic loss.
How safe is your home during an earthquake?
If it’s an older home, especially pre-1939, chances are it’s deficient with respect to modern building codes. Your home may lack foundation anchorage, framing connections and adequate bracing. During a sizable quake like the 1994, 6.7 Northridge temblor, your home could actually slide off the foundation and experience partial collapse. That’s a frightening prospect. Yet, it happens too often for anyone to be complacent. During the 1989, 7.1 Loma Prieta earthquake in Northern California, over 23,000 homes were damaged or completely destroyed. After an extensive study the State Legislature found and declared that “lack of anchorage and cripple-wall failure were the avoidable causes.” Simply put, it means foundation bolting & cripple wall bracing.
We know of no properly earthquake retrofitted homes that suffered from sliding or from collapse.
Not until 1941 did building codes require proper anchorage and bracing. Most local jurisdictions began to recognize the new codes as early as 1939. The Northridge quake resulted in a national record of 365,118 applications for federal assistance. While not all of those were for structural damage, you can be sure that the number of homes damaged or completely destroyed will exceed the 1989 Loma Prieta quake figure.
The good news is that a home without adequate structural protection can be reinforced. One very effective method is a procedure called “house bolting” and it dramatically increases the safety of your home during an earthquake.
Words of Wisdom:
t’s a good idea to have safety equipment in your car, like seat belts, windshield wipers, and maybe a horn; but none of those will do much good if you don’t have brakes. Likewise, it is equally important to prepare for emergencies at home by storing extra food and water and strapping your water heater. Sadly, this planning will be a total waste if you lose your whole house because it wasn’t bolted. We have seen it happen.
Allan G. Lindh, Chief Seismologist at the U.S. Geological Survey in Menlo Park has stated: “Recent quakes in the Mojave Desert, among the largest in state history, are a ‘final warning’ that the Big One on the southern end of the San Andreas is just around the corner. In addition, he has said, “It’s time to act as if the damn thing will happen tomorrow. For citizens of California or other earthquake-prone regions,” Lindh says, “safety is a simple matter of bolting houses to foundations and paying attention to the ‘duck and cover’ drills that have been part of Earthquake Preparedness Week every April since 1985”.
If most of your assets are in an unbolted home, this is something you need to think about. In most cases, for less than the cost of a paint job you can help protect your investment. What are the odds of your home surviving a large earthquake? If it is an older home – built before 1938 – it may lack vital connections that would keep it on the foundation during the next earthquake.
If you have a raised foundation with poorly braced cripple studs, bolted or not bolted, the severity of the above damage scales would be greater, and could occur in much lower-magnitude quakes.
Just suppose your carefully collected emergency supplies are stored in a poorly protected home, as was the case with some victims of the 7.1 Loma Prieta earthquake of 1989. During a future quake, these supplies could be damaged or contaminated, if they haven’t been consumed by fire. Under emergency circumstances, authorities often deny homeowners access to dangerously damaged homes – and stored supplies are worthless if they are unavailable.
- To avoid struggles with insurance collection.
- To lessen a need for temporary housing.
- To decrease the load on emergency response personnel.
- To avoid those nagging worries of:
“Will it happen tonight?”
“Will it happen while I’m not at home with the family?”
- AND Self-recriminations such as:
“I should have called Golden Gate Enterprises, Inc. !”
“I wish I would have called Golden Gate Enterprises, Inc. !”
“I told my wife to call GoldenGateEnterprises, Inc.!”
“I really and truly was going to call Golden Gate Enterprises, Inc. next week!”