Our home is built on expansive clay. We have significant cracks in the
foundation walls and floors. We have dry wall cracks and our windows
and doors stick. Other houses in our neighbourhood have the same
problems. We have had a soil boring test and a geotechnical engineered
solution to fix the problem. The enigeer and subsequent 2nd opinions
have confirmed our house is sinking due to the expansive clay. The
recommendation is to retrofit the foundation with helical piers. We
have a rectangular, poured concrete foundation approximately 30 x 40 in
size. We have a full basement with 8" walls and 24" wide footers. The
house is a 2 story of approximately 1650 sq ft. There is also a 2 car
attached garage. It has a 4' foundation underneath - the basement does
not extend underneath the garage.
The soil test shows that our soil is hard clay from the surface to
about 8'. Then is it softer clay down to about 15'. From that point
on, we have hard clay and then bedrock / glacial till.
The engineered solution calls for piers every 5 feet. There were a
total of 32 piers recommended. We have installation estimates of about
$2500 / pier. This adds up to $80K. I've read in a news group that a
pier support weight 5 linear feet from the center of the pier.
If this is true, then wouldn't having piers 10 feet apart be enough?
This would cut the cost approximately in half.
We want to do the repair right, but we also don't have a lot of money
and don't want to spend more than is necessary.
Thanks in advance for your opinions,