Earthquake Retrofit Strengthening - Good Insurance?

Tom PultzSeptember 10, 2009

Our house was built in 1984 and has virtually no positive connection between the 1st floor and the foundation. None, zip, nadda. The floor joists just rest on the imbedded mudsil (there aren't any cripple walls).

Since we are spending more than $100K on remodeling the downstairs I'm thinking it may not be a bad idea to spend another $5-7,000 to have the home retrofitted for Earthquake protection... essentially, help prevent the house from sliding off the foundation during an Earthquake.

If anyone has done this I would like to know how you arrived at the decision to go forward. I don't really want to spend the money to protect against something that will most likely never happen. On the other hand I would certainly kick myself if the house was severely damaged and this retrofit work could have prevented it.

We are hoping to stay in this Seattle area home for another 20 years or more, so I'm looking at it as a long-term insurance policy. Good idea?

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If your house is siding, it's not too complicated for a retrofit. By embedded mudsill, Im taking that as no crawl space? No access to underneath the house? It can all be done on the outside, but again, siding will be removed in strategic areas. You might check in with your insurance co. to see about discount/ rebates to your existing policy if you move forward with the retro.

    Bookmark   September 10, 2009 at 7:34PM
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Tom Pultz

By embedded mudsill I mean the 2x4 sill is flush with the top of the crawl space 8" wide foundation, so yes, we do have a crawl space which is about 42" tall.

The retrofit is fairly straight forward and generally falls into the "prescriptive plan" from Seattle's Project Impact, except for the area of the sunken living room. That requires engineering to design the attachments. The rest is standard joist blocking, metal plates and metal hangers. The estimate I just now received is $6977, including securing the bottom plate of the garage wall.

I plan to call a few of the references this weekend and ask what prompted them to go ahead with the work and see how they felt about the job.

    Bookmark   September 10, 2009 at 7:48PM
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Out here there are also ways to anchor down mid span areas of the joisting as well in crawl space areas that involves pumping in concrete and embedding anchors with strapping that bolts through the joisting. Here in the mojave desert of ca., it's fairly common practice on old homes before the onslaught of concrete slab foundations, which are pretty much the only foundation type you see here these days. Even with slabs though, back when I was framing many moons ago, wall to slab connects were "j" -bolts in the slab that the mudsill bolted down to. Unacceptable practice these days. You can still use "j's" but also have to have simpson strapping from footing up the wall 24" in strategic places depending on load, up lift requiremnets, seismic, etc.

Spot on checking with references and it might be a good idea to check and see if that work was engineered and approved via inspections. If not, you might consider a consult with a structural engineer for a few hundred bucks. Might be dinero well spent!

    Bookmark   September 10, 2009 at 8:32PM
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Tom Pultz

There will be an engineering drawing detailing the fittings, etc. required. The whole job will be permitted and inspected.

The main reason I would like to do this retrofit now as opposed to later when the remodeling is finished is the floors are currently uninsulated because I have cleaned out the entire crawl space due to previous rodent damage.

I'm going to have the floors spray-foamed and need to get the Earthquake retro done 1st, or don't do it at all because the areas needing work will not be accessible after the foam is applied..

    Bookmark   September 10, 2009 at 9:13PM
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I would go for it not only for the safety factor for you and yours, but when you are through with the house, it will make a great selling point. Take lots of pics of the install if you go for it to keep on file for re-sale. Best of luck!

    Bookmark   September 10, 2009 at 9:39PM
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I live in the Seattle area and did an earthquake proofing retrofit of my 1952 vintage house several years ago. The materials aren't that expensive, and the cost would be maybe 20% of that quote if you are going to do the work yourself. Take one of the Project Impact classes, buy the materials, and do it. It's a good idea from a personal safety perspective, an economics perspective, and a re-sale perspective.

    Bookmark   September 11, 2009 at 12:19AM
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Tom Pultz

I've looked at the Project Impact documents and am fully aware of what needs to be done. I just don't have the time as I'm doing all the remodeling on our current project and this would be another big delay in finishing up that work, which my DW is counting on being finished by the end of the year... which is what I said a few years ago... but this year she really means it :-)

    Bookmark   September 11, 2009 at 6:32PM
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Well, if you have the money, but not the time, you should still go for it.

    Bookmark   September 12, 2009 at 12:43PM
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I've been through 2 major earthquakes. Do the retrofit!! You can't believe the damage a 1 minute quake can do. We were here every evening when they built our house & we added extra blocks between the studs(they were supposed to put them in but instead threw them in the yard) insulated, checked everything they did every step of the way. Both quakes, we got less damage than neighbors on either side. So I don't think that was just luck. You will sleep better at night knowing you have done all you can to protect your family. A few yrs ago every state but 2 had had quakes of some kind & I think that has changed by now so it can happen anywhere.

    Bookmark   September 16, 2009 at 1:02AM
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What did you finally decide? We are in the retrofitting business because it works. I have never seen, heard or read of a properly retrofitted house that suffered a catastrophic failure during a quake except one that was on a very steep hill where the whole hill slid down.

    Bookmark   February 15, 2011 at 9:35PM
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