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‘Dry Basement’ Springs a Leak

Q: Our basement was outfitted as a “dry basement” several years ago and then finished to become additional living space, which we use as a rec room and for storage. I’ve noticed a musty smell for some time, and after heavy rains last week I saw water pooling near a corner of the basement. However, I can’t find the source of the leak. What can I do? — Tara in St. Louis

A: It sounds like there is a leak somewhere in the foundation. You’re right to be looking at that one corner as the most likely source of the water leak, but determining where the water is entering may be difficult.

Dry basements are made so through a number of techniques, including directing rainwater away from your home’s foundation. This is accomplished through surface drainage (such as your home’s gutter system) as well as subsurface drainage, which stops water which has percolated through the surface from entering the basement.

Subsurface drainage is typically put in place at the time of a home’s construction. This includes sloping the ground beneath the planned basement floor to direct water away from the house, adding a gravel layer and a nonpermeable layer above that, and then pouring the basement’s concrete floor. Basement walls should be sealed on the outside at the time of construction.

Over time, concrete basement walls can develop tiny cracks that let more moisture through. This may be happening in your basement. There may be a larger crack near your home’s foundation that is letting more water in, or perhaps something has changed in the way runoff moves away from your home’s foundation. Patch larger cracks in the driveway or in masonry or concrete surrounding your home.

Check the exterior of your house. Is the gutter system in good repair? Where do the drainspouts end? They should extend out from the foundation. If rainwater is pouring directly onto the foundation, it could be seeping more rapidly into the basement.

If none of these seem to be a problem or don’t clear up the leakage issue, contact a professional contractor who specializes in basement moisture problems to snoop out deeper issues.

(c) 2012 King Features Synd., Inc.