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Existing Basement Floor Waterproofing

slightner's picture

I am working on a house with a damp basement floor.  What is the best method of water proofing?  Membrane, epoxy coating, or paint?  What brand names?   I will be placing carpet tile down over the waterproofing. Thanks in advance.

slight (post #207452, reply #1 of 11)

If you have a moist floor, the best method is to correct how the water is getting under there.

Have you done anything outside to correct the problem?

Is there a high water table in this area?

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The best method is to build (post #207452, reply #2 of 11)

The best method is to build the house where it ain't wet.

The second-best method is to throughly tile the footing and put a drain plain on the outside walls.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Yes it is a high water table. (post #207452, reply #3 of 11)

Yes it is a high water table. The bay is 400 yards away. I think it is as much condensation as moisture penatration. If the floor is left uncovered it is never wet or damp. If covered for a while, I assume there is moisture, only because there is mold under the old carpet. It looks like the mold is living off the glue. I did tape a piece of plastic to the slab to see if moisture ever formed under the plastic. I left it there for over a week and checked often. There was never any moisture under the plastic. I also know that there is a vapor barrier under the existing slab. Outside all downspouts are ran a long way, away from the house. The house has one foot overhangs all the way around. The basement walls don't leak and there is an interior french drain. That is why I asked about the typical products applied directly to the top of the slab.

I would never carpet a (post #207452, reply #4 of 11)

I would never carpet a basement slab that has a history of moisture issues, particularly if I wasn't 110% certain of the moisture source. You're just asking for trouble. At the very least, you're likely to create a perfect envinronment for dust mites. Taunton's book (Wood Flooring, by Charles Peterson and me) has a detailed section on how to test concrete slabs for moisture, but personally, I wouldn't be comfortable installing carpet or wood flooring without having tested the moisture content several times over the course of a year.

Bottom line: Unless you're willing to test, I'd go with tile, paint, or some sort of concrete finish that wouldn't hide any moisture issues.

Andy

Senior Editor, Fine Homebuilding

Well, there's a difference (post #207452, reply #5 of 11)

Well, there's a difference between a basement that has had "moisture issues" and a web basement.  Our basement may get wet in a couple of corners due to heavy rains about once every five years (not counting the time the toilet tank split down the side), but I see no problem with using synthetic carpet with foam padding there.

This is different from a slab that is constantly wicking large amounts of moisture.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

It's your house. I wouldn't (post #207452, reply #6 of 11)

It's your house. I wouldn't do it in mine, though.

Andy

Senior Editor, Fine Homebuilding

Best method is to throughly (post #207452, reply #9 of 11)

Best method is to throughly tile the footing and put a drain plain on the outside walls.

unless you address the (post #207452, reply #10 of 11)

unless you address the moisture problem, whatever it is, you will more than likely be coming back asking how to get moldy smells out of flooring in about 8 months.

 

if you have mold on tape glue in just weeks then a coat of paint wont do you any good. like other have said, you need to figure out where this moisture is coming from before you do anything on the floor. 

 

you sound certain there is plastic under the slab, when was the home built? where?

dry bathtub approach (post #207452, reply #11 of 11)

If you can't tackle the source of the moisture from the outside (best bet), then you might consider the follwoing:

1.installing interior foundation drain tile and sump pump system. That will relieve any hydrostatic pressure of any infiltrating moisture on the slab.

2.Follow that by intalling Shcluters kerdi membrane or ditra with kerdi band seams) on your well prepared concrete floor substrate. You might have to run the mebrane up the exterior walls as well if the vapor drive is strong enough. The Kerdi and Ditra material isn't cheap, but it is 100% waterproof and will seal very well  if you bond it properly to your substrate and lap the seams by min. 2".

Think of this solution as similar to placing a plastic bowel down into a bathtub without allowing the rim of the bowl to dip below the surface of the water. However in this case the bottom of the bowl is fixed height. How high the water rises is how hight you have to run the membrane.