Got The Damp Basement Blues?

A friend of mine called me up a few months ago with a problem he knew I had wrestled with several times: water seeping into the basement of his house.

His two-story house had been built around 1926, and while it had a full basement, that portion of the house had never been finished. His plan was to cover the block walls and exposed joist ceiling with paneling to turn it into a laundry room and storage area.

First, however, he had to find the source of the water that kept the basement feeling damp – and might soon foster mold and mildew.

In the middle of the concrete basement floor was a twelve-inch wide hole leading down to bed of rough gravel about a foot beneath the floor. A heavy metal grate set into the concrete prevented us from making a key determination: was it a true floor drain leading to a drainage pipe or was it simply a ‘seep’ hole, designed to allow water to slowly dissipate into the ground beneath the floor? I suspected it was a seep hole – or at best a blocked drainage pipe.

My experience with wet basements had taught me this: 10% of the time the water comes from an underground spring, 10% of the time it is coming from ground run-off, and 80% of the time the water in the basement had just minutes earlier been on the roof of the house.

When I arrived I could see that my friend had concentrated his efforts on caulking cracks in the basement floor and walls, so I went outside. The yard sloped slightly from the higher ground in the back to lower ground in the front of the house. At each corner of the house I found a downspout and in each case it disappeared into a clay tile buried in the ground next to the foundation. It only took a garden hose and about ten minutes of experimenting to determine that water traveling down a downspout in the back of the house soon began rising up through the gravel bed in his basement drain.

We grabbed a pair of shovels and in just a few minutes time had uncovered the eighty-four year old line of clay tile leading from the downspout to the street. Just twelve feet from the house we spotted the culprit: a crushed tile. Instead of heading to the street, the rainwater had carved a tunnel from the broken tile over to the foundation, where it traveled down, seeking the path of least resistance: the drainage hole in the basement floor.

The solution was easy: we dug up the old clay tile and replaced it with 4-inch PVC pipe. Problem solved.

To solve or, perhaps, to prevent water from ruining your basement, I suggest you take the following steps:

1.) Check or clean your rain gutters twice a year. Buy quality leaf guards – but don’t trust them entirely. Clogged gutters quickly overflow, depositing rainwater next to your foundation.

2.) Inspect your downspouts for water stains on the siding behind them; test them by running water from a garden hose down each of them. Leaves and bird nests can easily clog them – again, depositing rainwater next to your foundation.

3.) Make sure the water exits your downspouts at least five feet from the foundation – more if the ground slopes back toward the house. Otherwise you’re pouring water down the outside of your basement wall.

4.) Make sure the ground around your foundation is sloped away from the house. If necessary, create dirt berms (its Dutch, for earthen dike) or raised planting beds to direct water away from your foundation. Note: a heaping bed of mulch is not the same as dirt, and will not stop water from entering your basement.

5.) Finally, next time it rains, grab an umbrella and take a walk around your house, making sure that all of the water running off your roof and across your yard is not being directed against your basement walls.

- bj