# How to stop water coming up through a garage floor



## oh'mike (Sep 18, 2009)

You might be better off finding a way to get the water out from under the slab---is there any way to add a perimeter drain and run that out to daylight?

Any surface membrane might well get pushed up by the hydrolic pressure from under the slab----

Post a picture of the outside of your garage and the grade of the land---perhaps a proper solution can be found.---Mike----


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## joed (Mar 13, 2005)

I can not imagine 1" of water coming up through the slab. Are you sure it is coming up through the slab and not running in from outside? You need to deal with getting the water out from under the slab instead of trying to seal it there.


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## ADaniLion (May 24, 2011)

I'm pretty certain it's coming up from underneath. Two good friends who were excellent home builders in their days have given it a thorough look and they both said the same thing. Maybe an inch is an exageration - I should measure the next time it rains lol! I will have to post a photo over the weekend.


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## SCengineer (Jul 16, 2013)

*Drainage*

For water to come from under your slab would mean that the ground water is raising due to the rain. For this to happen, the water must be collecting up grade and flowing to this area. I have seen home that were landscaped around the permitter of the house thus deflecting the runoff water from the roof to the foundation. If this is happening then you need to regrade the site to get the water away from the foundation. 

Another cause could be vapor drive. If the garage is conditioned or is much cooler than the outside, a dew point could be created above the floor slab thus causing the moisture. This problem could be fixed by venting the space.

Sealing the surface will do little to nothing. As said before, the hydrostatic pressure will create a problem after awhile.


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## SCengineer (Jul 16, 2013)

Tp find out where the water is coming from. Dig a hole outside of your house next to the garage. Find out where the groundwater is before it rains. Cover the hole so no rain water or runoff gets into the hole. When you see the water in the garage check and see if the hole is full. If the hole is full then the water is coming from below the slab.


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