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Rick, General Contractor
Category: Home Improvement
Satisfied Customers: 20960
Experience:  Licensed construction supervisor with 35+ yrs. experience.
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My home is built on a slab. The floors on the ground level

Customer Question

My home is built on a slab. The floors on the ground level sweat terribly in the summer. Not so bad in the rooms I have tiled but have one last room left to remodel and have bare concrete in that room and that's where it is the worst. Is there anything I can put on the concrete before I tile this last room, that would help block the moisture? My husband says they never put vapor barrier between the ground and the concrete and the only solution is to jack hammer up the floor, put vapor barrier and repour the floor.
That is not a viable option.
Submitted: 1 year ago.
Category: Home Improvement
Expert:  Rick replied 1 year ago.

The moisture is coming from the air not the ground. Since the slab is probably colder than the air the moisture in the air condenses on the surface of the slab causing condensation/"sweating". So installing anything on top of the slab to stop moisture coming up through the slab is not going to stop this condition.

Customer: replied 1 year ago.
I have an air conditioner running night and day in that room and it is very cool in there. I also have a dehumidifier running 24/7 in there. If I let it turn off for an hour, the floors are damp. I do not have this problem in the rooms I have tiled. The floors are cool, but not wet and I do not run air or dehimidifier in the other rooms.
Expert:  Rick replied 1 year ago.

Water doesn't migrate up through a slab on grade. What you describe is a common problem in houses like yours and I described why it happens in my original answer.

Customer: replied 1 year ago.
You may find this interesting:
Customer: replied 1 year ago.
Expert:  Rick replied 1 year ago.

Neither one of these articles applies to the conditions you described. The first talks about slabs below grade. The second talks about wet conditions below grade. The latter is not seasonal and wouldn't apply unless the area around the house was poorly drained and rainfall was significant. However it is common for condensation problems to occur during the Summer when relative humidity levels are higher and there is more moisture in the air.