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I am thinking about earthquake-proof my house. I am finally convinced that earthquake cannot be predicted, but can be prepared. I am in SF Bay area, my house is about 5 years old, built by K&B.
Any suggestion? Thanks.
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Yes, go to your city building inspector, building & saftey dept, or whatever they call it in SF.
They will have specific guildlines for earthquake retrofit. The code here in SoCal is only for new construction or additions, but it is helpfull to see for a retrofit.
Here are some tips:
b 1. Shear Walls
80% of the cripple walls must be sheered with 3/4"cdx. Same is true for interior cripples/knee walls, if you have them.
b 2. Hold Downs
The bottom plate (sill plate) must be physically attached to the foundation with bolts. There are 3-4 methods, depending on whether the foundation is poured or is block. The cripple studs must be bolted to the sill plate. The floor joists must be all be blocked and bolted to the top of the cripple wall.
b 3. Framing First Floor
The first floor exterior and bearing wall framing must all have Simpson tie downs, including all studs, and tie downs to the bottom and top plates. The outside walls must be shear walls, although they will let you get away with 1/2" sheathing. 3/4"cdx is preferred.
b 4. Second Floor Issues
If there is a second floor, a threaded steel rod, at least 1" must go from the cripple to the top plate of the second story. These must be installed about every 8'.
San Francisco should have a whole pamplet detailing this stuff, and may be different (probably more stringent) than above.
*Hi Jim B.I agree with Scooter.I would like to add that you should know that the purpose for all the information you are about to become familiar with is to keep the house from shaking.When you have rigidly connected all there is to connect, then the house will become "tuned". You will be able to hear it when you hit your hammer anywhere. It is truly a wonderful experience, to listen and feel that hum. You will see!To help in your understanding, get the Well-Connected Structure catalog from Simpson Strong-Tie at 800-999-5099 or http://www.strongtie.com. They will also give you a free copy of a tape entitled Home Safe Home, if you ask.Also, go to the FEMA website at http://www.fema.org.You are about to embark upon a truly enlightening experience. Have fun with it!Hope this helps.
*I'm curious, if the house is only five years old and in the SF Bay area, shouldn't it have been built to some fairly stringent earthquake codes to begin with?Rich Beckman
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Hi, Rich:
It was (and still is) my question and I think it should be my first step. I will call the building department to find out. I hope it is built to the code. If it is not, does anyone know how much it is going to cost me? Thanks.
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Jeez Jim,
The home is only five years old? Musta missed that one. The code down here has been in effect since the "big one" (Northridge) and I assume your home is code, since it was built after the whatitsname quake during the world series.
If you are its second owner and you don't know, hire a good inspector for a couple hundred bucks. He'll poke around in the basement.
As for how much it will cost? Thats a tough one? How much does a car cost? How much is a college education? the answer is "it depends" Too many variables to answer in this space.
*There is no reason a 5 year old house should not be to code, unless the contractor was a crook, an idiot or both and the building inspector was one of the above also. If you want to spend more money for earthquake preparedness, buy insurance.
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I am thinking about earthquake-proof my house. I am finally convinced that earthquake cannot be predicted, but can be prepared. I am in SF Bay area, my house is about 5 years old, built by K&B.
Any suggestion? Thanks.