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jimechols
moisture mitigation in a slab

We live in NE Florida where the water table is 3 feet below the surface. My house was built in 1974 and is on a monolithic slab. Recently while redoing the dining room, we laid 6 mil poly over the carpet to protect it and then covered that with 3/4 plywood to erect scaffolding. After the project was completed we noticed the carpet was damp under the poly. It had been down about a month. So it looks as if moisture is wicking up through the slab.

Is there a product to seal the floor? I know of Dryloc but wasn't sure if it would be the best for under all types of floors. We plan on wood, tile and carpet. I only want to do this once so I'll pay for the best!

dj1
Re: moisture mitigation in a slab

First find out the source of the moisture: underground water or rain water. If it's rain water, improving the removal of the run off water away from the house will help (good gutter system, good drainage, maybe a french drain around the house, better grading, etc). But if the problem is underground water, it's more serious. I wouldn't lay wood floor, no matter what. Tile will be the only choice, and even tile might fail.

There are paints and sealants that might help, but do fail eventually when the water pressure (hydrostatic pressure) builds up. Some will last longer, like epoxy, but there may not be a permanent solution. I trust these paints and sealants as much as I trust this president to solve our immigration disaster.

The best solution is a functioning barrier under the slab. Many times the plastic barrier under the slab gets ripped during the concrete pour, opening the door to possible future moisture issues. When I was building, I made sure I was there during the pour and I watched the plastic like a hawk - if it got torn, I stopped the pour and rushed to install a piece of plastic to cover the rip. Concrete workers just don't care if they rip the plastic, while walking on it or using their shovels.

dj1
Re: moisture mitigation in a slab

One more thing: there is a product called THOROSEAL, which might work better than paints and sealants.

Thoroseal is actually cement, that when mixed with water can be applied directly on the concrete with a brush, just like paint.

You can find it in masonry outlets. Read the label to make sure it's good for your particular application. I've been using it for 30 years on walls, blocks, stucco - you name it, but never on a slab. And I've always used it on the exterior side, that's why I said read the label or contact the mfg.

Clarence
Re: moisture mitigation in a slab

I use Thoroseal Super Waterproofing on foundations.
It is a foundation waterproofing not sure it can be used on floors?
You may want to check on these.
Applied Technologies or
Xypex.

HoustonRemodeler
Re: moisture mitigation in a slab

Tiling your floor over an anti-fracture membrane will give you a great measure against the water migration.

But I'm Italian and we tile everything. ;)

dj1
Re: moisture mitigation in a slab
HoustonRemodeler wrote:

Tiling your floor over an anti-fracture membrane will give you a great measure against the water migration.

But I'm Italian and we tile everything. ;)

Just tile over Thoroseal and membrane.

Then send us some pics.

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