Sealing / Repairing Basement Floor Cracks

Old 08-10-06, 12:48 PM
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Location: Omaha, NE
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Sealing / Repairing Basement Floor Cracks

Hello – I have a 2 year old Nebraska home with a sump pump and drain tile around the foundation. I am finishing my basement and want to repair / seal several cracks in my basement floor. The cracks vary from 1/16" to maybe 1/4" at the largest. Sometimes after a heavy rainfall, there are dark damp spots adjacent to the cracks. I have never had a problem with water on the floor except for these damp spots (dark in color) where it appears that water is seeping or weeping in from hydrostatic pressure from the water table. Can anyone advise the best methods and products to repair / seal these basement floor cracks? I think that most of these cracks are too small to fill with caulk or mortar. I have read about products like Thoroseal and Drylok - Are these good products to use? Also, I was planning on just sealing the cracks and areas surrounding them. Would it be better to seal the entire floor? Thank you for your advice.

Last edited by KennethW; 08-10-06 at 01:17 PM.
Old 08-10-06, 01:40 PM
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Sealing / Repairing Basement Floor Cracks

Products like Thoroseal and DryLok are meant for walls.

Your problem is a high water level under your concrete floor. If you have exterior drain tile (outside the footings), interior drain tile would definitely help. Some builders use both. If you already have interior drain tile, it is a general condition that you have to face.

Since the home is two years old, you have some sort of short term history. It sounds like you do not have a vapor barrier under the slab.

First, do the classic, proven steps of having long downspout extensions (8 - 10') to carry the roof water away and make sure your general drainage is away from the house.

If you want to finish AND complete the floor now, the only reliable method would be to raise your wood floor (P.T. sleepers/supports) or accept the possibility of having to toss the carpeting every 5 to 20 years when you get a huge rain situation. A dehumidifier would help.

A few more years of history after you know you have good exterior control of the water, you could have a better idea of what could happen.


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