Carpet in basement

clayfarmerFebruary 20, 2009

What's the proper way to install carpet in a basement? It's a 2 year old house with no water issues. We run a de-humidifier, and I have drylocked the floor.

Pad? No pad? (Can't believe no one has come up with a water-resistant, mold-resistant carpet pad for basements)

Any type of barrier between the concrete and the carpet?


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All pads I know of will absorb water vapour coming up through the concrete. (I don't have the faith in Drylock that seems to permeate these threads.)

I've used carpet (preferably low pile) in some portion or other of basements in new homes I've built over the last 20 years with no problems. Be sure to use a dehumidifier.

    Bookmark   February 21, 2009 at 9:27PM
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Won't the carpet be cold underfoot without some sort of barrier between the concrete and the carpet. Without a pad it seems to me that it would be cold but I don't see a whole lot of people insulating their floors

    Bookmark   February 22, 2009 at 9:31AM
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I just put my bare foot on the carpet here and it's warm, though outside it's -2ÃÂC. I can't say the same thing about the slate and icy polished marble elsewhere in the basement.

If you're still sceptical, you can always use 1" XPS on the floor, followed by one or two layers of 1/2" ply as per Building America's guidelines prepared by Building Science Corp. (See link.)

Here is a link that might be useful: Renovating Your Basement--Building America

    Bookmark   February 22, 2009 at 11:56AM
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We have pad under our carpet in the basement. A ten year old home with no water issues. We have the heavy weight padding and a berber carpet. We do not use a de humidifier as we've never needed to. We have never had problems.

What have your neighbors done in your area? What has been their experience?

    Bookmark   February 25, 2009 at 12:52PM
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We have pad under our berber carpet in the basement. 13 year old home. We use a dehumidifier from early spring till early fall and I empty it daily. It helps both with moisture removal and air movement and makes it smell more fresh.

    Bookmark   February 25, 2009 at 4:37PM
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"Installing carpet on cold, damp concrete floor slabs can lead to serious allergic reactions and other health-related consequences. It is not recommended that carpets be installed on basement concrete slabs unless carpets can be dry and warm. In practice, this is not possible unless basement floor slab assemblies are insulated and basement areas are conditioned. Installing carpet on concrete slab foundations located at grade typically does not pose a risk if the carpet and associated carpet pad are vapor permeable."

Builder's Guide to Cold Climates, Dr. Joseph Lstiburek Taunton Press, at p. 34.

    Bookmark   February 25, 2009 at 7:44PM
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Actually there are sub0floor products that are specifically develop to act as thermal and moisture protection for carpet and padding.
The raise the carpet and padding slightly off the floor to allow the slab to breath and protect your carpet.
There are two such products that I know of, just google basement sub-floors.
Whatever you do, do not lay wooden sub-floors, particle board faced sub-floors or anything organic. Even the driest basement can have a water accident and anything organic favors mold growth.

    Bookmark   February 26, 2009 at 5:13PM
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Thi interesting. I have seen dricore but its expensive and if you get a bad enough leak / flood you still have water on wood. If the water comes from above you definitily have a mess; especially if you have put 4 X 8s over the dricore. Ditto the XPS method.

The best method to me would be to put plastic down, then your carpet. If it got wet then you either pull it up and dry it or remove and replace. I'd bet you could do 3 replacements before it cost you waht the dricorse costs.

Now what would be nice is if they sold some sort of padding you could lay right on the concrete that acted as a barrier.

BTW worthy----I put that drywall over the xps in my rim joist last night---almost hate to cover it up!

    Bookmark   February 27, 2009 at 8:59AM
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Poly sheeting (and XPS) under the slab will greatly reduce moisture migration. But putting plastic sheeting above the slab will trap the moisture that was otherwise evaporating and convert it into liquid water.

Be sure to post any pics.

Here is a link that might be useful: Renovating Your Basement

    Bookmark   February 27, 2009 at 9:38AM
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I hear ya but if you have a flood, it one thing to toss a rug and another to pull up the rug, pad, 4 X 8 sheets of wood and XPS...there must be some sort of pad or something that can sit under the carpet....otherwise there must be something (paint/stain ect) that can be applied to seal the floor and area rugs put in place....

    Bookmark   February 27, 2009 at 10:12AM
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If the room is conditioned or at least humidity controlled, I would carpet with a pad with no other barriers.

    Bookmark   February 27, 2009 at 10:56AM
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The point many don't want to or don't seem to get is that, unless there is a poly sheet and insulation under the basement slab, water vapour is migrating in the form of vapour into the basement. You just don't see it because it is evaporating. But put a poly barrier down on that concrete floor and it will accumulate and turn into liquid water. That's why, for instance, Building Codes require the use of pt wood or poly under basement framing, to keep that moisture away from the wood.

Of course, if you have a flood from whatever cause, all moisture sensitive materials may have to be replaced. Dri-Core and similar products do not provide protection against floods, only against water vapour migration.

I've been in so many basements where no attempt is made to keep humidity controlled yet the owners are convinced there's no problem. "My basement is dry. I never see water." All I can figure is that they've grown insensitive to the pervasive musty odour. Smells like home.

    Bookmark   February 27, 2009 at 6:21PM
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so if one put a thick sheet of plastic down, water would migrate up but be stopped by the platic, pehaps forming droplets under the plastic. Wouldn't it justseep back into the concrete, ie what harm comes from the water under this plastic?

I am not seeing a solution other than the XPS route and I bet less than 10% of the homes have that or could afford it. What are people doing? Stain he concrete and go with area rugs...would not the condensation form under them as well....?

    Bookmark   February 28, 2009 at 2:02AM
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Once the water vapour has condensed into water, it won't turn back into vapour and go from a low pressure area (the basement) back through the concrete into a high pressure area. Eventually, the water will accumulate and find its way around the relatively impermeable plastic into the living space. That's what happens when people put impermeable vinyl tiles down on their "dry" floors and can't understand why they're lifting and where the water is coming from.

Mould spores are everywhere. Once you provide an enticing damp dark environment, they will multiply. Mould can be a health hazard and can deteriorate building materials.

What are people doing?

That's a really interesting question! From all the mouldy dank basements--bathrooms and kitchens too--I've been in over the years, I'd say nothing much. At least, not in my community, which I can't imagine is all that different from most others in the US and Canada.

    Bookmark   February 28, 2009 at 12:38PM
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I would agree, the idea of keeping water vapor out of basements with vapor barriers is out dated and not practical. Most modern techniques rely on good site prep techniques to elminate liquid water from the basement and concede to limiting and managing water vapor. Managing the water vapor means no barrier or maybe a vapor retarder combined with some humidity control system. Ultimately you need to be able to keep the humidity below ~70-75% to inhibit mold growth. This is not just the air humidity, but also the local humidity (water activity) at the cement-flooring interface. In the end, it usually comes down to how much water vapor is coming through the floor, to determine if you can successfully manage it.

    Bookmark   February 28, 2009 at 1:39PM
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then I ask you, what solution is sound like the 'right' solution is just a big, if not a bigger hassle if you have a flood than just chancing it with pad an carpet!

How are those cement stains I see advertised...they make the floor look nice and you can put area rugs down...are area rugs just as bad as regular in so far as trapping moisture and creating mold?

    Bookmark   March 1, 2009 at 8:45PM
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If you wanted to you could roll up the rugs and store them somewhere else during the summer so they wouldn't get musty.
I saw a stained concrete floor in a high end house with I think a waxed top coat that looked real good.

    Bookmark   March 1, 2009 at 9:27PM
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