Q: My house has a recurring basement water problem. It does not seem to be caused by misaligned gutters or clogs or too-short downspouts. Rather, the trouble stems from the cement sidewalk that runs between the driveway and the house. The sidewalk is tilted toward the house, which means water running off the driveway forms in pools next to the foundation. Eventually, the water seems to find a path from those pools into the basement.
I have used caulk and a tar sealer between the sidewalk and the foundation in an effort to keep the water out. But with this tilting and pooling, it seems the only place for the water to go is down to the basement. What is the solution here?
M.B., Kalamazoo
A: This is a not-uncommon occurrence around many homes, both old and new. The problem begins when the house is constructed. After the foundation is put in place, fill dirt is pushed into the space between the foundation walls and the existing soil. In many cases, the fill is not compacted, so it settles over time.
In your case, a concrete sidewalk was placed on what may have been uncompacted fill. In addition, soil erosion may have occurred because of water leaking under the slab. In any case, over the years, the level of the soil fell, taking the sidewalk with it.
As youve discovered, trying to stop the water intrusion with caulks and sealants is ineffective. Eventually, standing water makes its way through even the most tenacious materials. And the porous concrete foundation absorbs water, too. The only solution is to tilt the sidewalk so surface water drains away from the house.
If the concrete is in poor condition, the best solution is to replace the sidewalk. However, if the concrete is still largely intact, a mud jacking or slab jacking company can inject material under the slab to raise and realign it.
During this process, workers drill holes approximately one-and-a-half inches in diameter in several spots through the concrete. Through a hose affixed to the holes, a high-pressure hydraulic pump forces a slurry of water, sand, cement and sometimes other materials under the slab. The slurry flows in and fills any voids under the concrete, and the pressure and bulk of the material pushes the slab up.
By carefully monitoring how much material is used and where it is placed, workers can precisely control how far, and in what direction, they tilt the slab. Once proper alignment is achieved, the holes are patched with concrete and the slab can be used immediately.
While not inexpensive (mud jacking can cost up to half the price of having concrete replaced), raising the concrete does eliminate the destructive work inherent in removing and replacing slabs. Plus, it extends the service life of perfectly adequate concrete and keeps it from being broken up and hauled to a landfill.
After a sidewalk along a house has been raised in this manner, it is still a good idea to seal the junction between it and the foundation. But, because it wont be holding back a pool of water any more, the seal will be considerably more effective.
Zolton Cohen is a Kalamazoo-based columnist and former American Society of Home Inspectors-certified home inspector. Write to Cohen at Around the House, P.O. Box 2007, Kalamazoo, MI 49003.
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