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Posted by Keith in Washington [24.41.41.111] on Friday, March 26, 2010 at 12:41:50 :
In Reply to: Re: Home depot? Lowes? posted by Kaegi [24.113.81.122] on Friday, March 26, 2010 at 11:46:12 :
You will be lucky to find any solid rock in the Puget Lowlands. It is all glacial till and wash. Obviously the hill side is moving to cause the problem. Any fix that you do is going to have to solve the hill stability problem or the house will just do it again. I also assume that the lot is fairly steep since it has a daylight basement. This was a very common foundation solution for the hill sides of Western Washington.
I would suspect that the soil has a high water content and that is the main cause of the hill side moving. Put lots of effort into capturing the surface water and getting it out of there. Stop all water coming off the street that goes onto the lot. You may need to work with the city or county. Make sure that your neighbors are not dumping water onto your lot. Make sure that the water from your gutters is captured and not dumped on to the lot. A couple of french drains on the high side of the lot to capture the deeper water flowing through the lot would be good also. I would consider 10 or so feet deep with drain pipe and back filled with drain rock. Make sure that you have everything protected with drain cloth.
Also make sure that the foundation has a drain system at the footings. If it is an older house it most likely does not or it has plugged over the years. Water against the foundation can literally push the foundation down. Again put a drain at the footing then back fill up the foundation wall with drain rock and drain cloth to stop it from plugging with time.
This will dewater the soil which will go a long way towards stabilizing the lot. Then you need to attack the foundation damage. The only way to really make sure that the house does not move in the future is to basically pin it to the hill. The method you talked about might do it. You have to get the "pins" deeper than the upper layers of the soil that are sliding down hill. This means pilings or drill holes and putting sono tubes down and filling with rebar and cement. You could have a company come in an jack the house back into place with grout. They can get it back to where it needs to be. However, if they do not get the grout below the moving layer of soil, it too will slide.
With 6" of movement from front to rear, I would look for cracks in the foundation. Those will need to be repaired and stabilized.
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