Is drainage or foundation problem to blame?
Bill and Kevin Burnett
Inman News
Q: We have a small 1924 cottage that continues to shift and settle, resulting in cracks in the walls. There is a minor slope of no more than 5 percent, and probably less. There is a high water table where we live.
We have talked to both foundation and drainage contractors. The foundation guy says drainage won’t help but foundation work will solve all our problems. The drainage guy says a French drain and other work will solve all and no foundation work is needed.
We only have so much money. Which option will provide us the most benefit for the cost?
A: A new foundation or a French drain system are big-ticket items. You definitely don’t want to make a mistake and choose one, only to find it was the wrong choice. In our view, you should do a little more investigation.
Objectively speaking, the house should have settled in the almost 90 years since it was built. The fact that it hasn’t stopped moving leads us to believe it’s shifting with the expansion and contraction of the soil as it gets saturated during the rainy season and dries out in the summer.
At first blush it would seem to favor installing a drainage system to redirect any groundwater flowing down the slope away from the building’s foundation. Installing a French drain usually stabilizes the moisture in the soil, thereby retarding expansion and contraction.
But we hesitate to point you in this direction without suggesting you take one more step to verify that this is the right course to take.
With both contractors pitching their services as the solution, we sympathize with your uncertainty about which way to go.
First, do a visual inspection of the foundation. Are there large cracks in the footing or does it seem to be in pretty good condition?
Large cracks might indicate a lack of rebar in the footing and could be the cause of the house shifting. Also, crawl under the house. Is the crawl space dry or is the soil wet? Wet soil could indicate the need for a drainage system.
The high water table in the area might render a drainage system next to useless. On the other hand, a standard single-story foundation with a 12-inch footing may just ride on top of the earth as it moves and still allow the walls to crack.
To find out the proper course of action, we suggest you consult a civil engineer in your area. An engineer will cost a bit of money, but what you will get is professional direction about the best option to stabilize your house.
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