Published on November 20th, 2012 | by Henri


Waterproofing a finished basement

Q.      I read your article on dry basements and am wondering if you can help. My basement block has been treated with DryLock, but the back portion of the basement is filled with stains and efflorescence. Alas, the water is coming from my 2000-square-foot blue-stone patio. I believe that the blue stone is hollow in spots and accumulates water, which then pushes its way to the wall and down the block.

I have called basement waterproofing companies and they talk of digging up and applying pipes all over the basement. This makes no sense since the basement itself is dry and the drainage system around the basement floor is fine. The front of the house, which is graded correctly, has no efflorescence problems. We would like to finish the basement and avoid any major future problems. Can you tell me what can be done so that the problem is solved without major expense and major damage?

The area  involved is about 9 feet high and about 75 feet wide. I know you have suggested putting in holes every few feet at the bottom of the block and applying some kind of drainage system to a sump pump. My guess is that this would be rather unsightly. Can you make any other suggestions?

A.      I am sure that the stains and efflorescence are caused by water filling all or part of your block foundation because the DryLock treatment prevents it from  leaking into the basement; this is a prescription for a far more serious problem than the one you have now.

The holes I suggested to drill at the base of the mortar joints of the block walls in an earlier column are the best solution. But these holes must be connected to a drain system since the water problem is likely to go on until you fix the suspected patio problem. Waterproofing contractors install fiberglass channels and cut a hole in the concrete slab to install a sump pump. Obviously, since the blocks’ cores are probably filled with water now, drilling the holes into the mortar joints will cause leakage on the basement floor. A careful contractor will devise a way to control the leakage. But this is an expensive job.

As to the aesthetics of these channels, they look like an oversized baseboard and can be concealed within a wood chase when you finish the basement.

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