Check out this thread at GWeb, including comments from Dr. Lstiburek from Building Science Corp.

Here's the opposing view of the Carpet and Rug Institute.

Yeah those are definitely two opposing articles. I'm not an expert by any means, but from what I'm reading or seeing... I can't find a single person that has had issues with this setup unless a flood or leak becomes a problem to which them the carpet/pad would need to be pulled up because the pad couldn't dry itself.

Is carpet/padding vapor permeable? If they are and water can pass through the two... why would there be so many concerned about it?

I've read that a few people are putting plastic vapor barriers on top of the concrete or just rolls of flat rubber. I definitely I think this is bad practice.... you want the vapor to pass through the materials to the dehumidifier... not to trap the moisture.

I thought about doing the entire XPS floor or the rubber squares with plywood attached... but not only is it a price concern... but ceiling height as well. With the duct work... we're already at 7'... another inch or two would be a deal breaker.

"But after a few years in a non-dehumidified basement, the distinctive musty smell of mould is pervasive"

What if a dehumidifier was running as well as the central AC? Both of those should pull a lot of moisture out of the basement and keep the air moving.

I'm going to toss a curve ball into the factor... doesn't the temps have to be above 50 for mold to grow? The basement is naturally cooler (58-60 year around with heat/AC running)... but the concrete is very cold which would also make the padding cooler. If the concrete/padding stays cool (lets say under 50) wouldn't this help prevent mold?

I'm reading so many things about the padding/no padding question... here's one I found about delta-FL...
"I know they claim their product allows air flow, and to a certain extent it does. However, it is not adequate to allow wicking unless you have something pulling or pushing air through the cavity. Otherwise the air is stagnant and moisture will be trapped. I have removed floors with Delta's systems and others. I am about to rip up another next week for the same reason...trapped water led to stachybotrys"

Originally, I was going to do no padding and just have carpet. Then my dad told me to get padding because I wouldn't like the feel of carpet/concrete and it'll make it last longer. Then I started to research the subject and found that others said the carpet would bubble up in places, in particular where the doors are. That would drive me crazy. We did a very high quality job in the basement... archways sconces, French doors, oak trim, etc. I definitely don't want the carpet to look like it's flat or if it starts to bubble. I've never seen carpet without padding... so I don't know if I could tell a difference or not.

We've finished the entire basement ourselves (it's been a huge learning process)... but for the good. It taught us a lot of stuff. But I think the final step, the carpet, will be one of the toughest decisions

it boggles my mind how there is no such thing as a permeable pad...how about putting $ saved on the pad into a plusher carpet that might fell more cushiony underfoot? If more plush is a no no for breathability, what would be the most comfortable? We are in the same position...

doesn't the temps have to be above 50 for mold to grow?

You've never cleaned out your fridge?

Interesting comment that sounds plausible from BobVila forum on the Delta FL. However, it's very possible that, having installed the material, the homeowner then never runs a dehumidifier, thinking the problem is solved. The stand-off membrane reduces the capillary action through the concrete, and provides a way for the moisture to dissipate. But if nothing more is done, the moisture remains in the basement air and feeds mould growth.

Without the padding, a pile carpet will not feel "right". If that's your top priority, install the pad and the cheapest carpet you can find--look for discounters who sell odd lots. Dehumidify to less than 50% rh. And if, every few years, you have to replace it, so be it. I used to manage rental housing and that was simply a fact of life.

This post was edited by worthy on Tue, Apr 23, 13 at 13:28

You have a point... we have had moldy cheese and stuff. It boggles my mind at some of the stuff you can read. I didn't even think of that

I'm definitely not worried about it feeling right. We have area rugs on our hard floor upstairs, and you can't tell a difference between walking on our area rugs on a hard surface VS our other cheap carpet/pad. The house was built a few years ago, but we didn't have a choice in the type of carpet used. My main concern is installation and it not looking right. Or after the installation if it starts to unravel or come loose. Ours is an open concept basement, they will need to have carpet seemed together. Plus they wouldn't stretch it or use tack strips, just lay it down. It would look horrible if it started to come up or bubble in stops.

That could be correct about the Delta FL.... regardless of what type of sub floor, one must run a dehumidifier to get the moisture out of the air.

The carpet/pad I was quoted was the cheapest (but still nicer than what they tossed in my house a few years ago). $1.39/SQ Foot.

what a 'pile' carpet...or what is an example (picture of something) that is not....

I'm no expert by any stretch, but I have personal experience.

Half my basement is finished, about 600-700 square foot. I have a synthetic cut pile carpet down there with pretty standard synthetic foam padding. I had it installed about 7-8 years ago.

I had the misfortune of a leak after a bad rain storm under part of the carpet. I cut it, pulled that section up and dried it in mty garage. I immediately disposed of the saturated padding. Since I had it up, I was able to see everything under there....Looked great other then the part that got wet.

I bought a new roll of padding, and reinstalled the carpet. A pain in the a$$, but not a real big deal.

My basement isn't overly humid, and I run a dehumidifier to keep it where it should be. I also have an active radon remediation system that is pulling the air from under the slab out, and I suspect that helps my situation. My carpet doesn't smell musty....maybe I'm just lucky.

All that said, when this carpet is shot, I'll probably install tile, and use some area rugs for the den area. If I need carpet in a section, perhaps I'll use the tiles. That one situation having to pull it up was enough of a hassle so I don't want to recarpet wall to wall....plus 2 of my kids are a bit older and fall down less now :-)

If my floor was really nice and smooth like is more common in new construction, I would look into having it stained and use large area rugs over it.

I will toss my 2 cents in, especially after hearing about all the supposed issues with carpets in basements.

We had a synthetic cut pile carpet installed, Karastan, about 6 years ago. Went with a heavy rebond pad. Basement is half below grade and other half above. We run the dehumidifier often during the summer months being in the Northeast. Also, I think since the upstairs is air conditioned, this also helps the basement.

Conclusion.. Could not be happier; never had any sign of smell, etc. As a matter of fact, even our piano located there loves it. It requires a little effort, but to us, it has been worth it. The carpet is still like new, even with 3 kids, 3 pets etc.

If the problem is condensation or seepage through a concrete slab, I would like to know why an AREA carpet and pad (whether on top of the concrete or tile) wouldn't also get damp. Or should we never put pads under carpets in these places? Please clarify!

Just looked on the HomerDepot site I see a "Healthier Choice 6 ft. x 45 ft. Green Premium Carpet Cushion" which lists "Unique built-in breathable moisture barrier stops liquid spills and pet accidents while allowing moisture vapor from beneath to escape. Ultra-Fresh antimicrobial prevents mold, mildew, bacteria and dust mites..." There are also 4 other thicknesses of their "Healthier Choice" branded pads which are made of " 100% solid polyurethane memory foam" and tout similar breathable qualities.

Is this like the memory foam stuff that mattresses are made of?

I plan on cleaning/disinfecting the concrete surface to remove organic materials that could feed mold and mildew. Then laying down a subfloor of modular polyproprylene tiles with a grid on their bottoms (modutile.com) to create a 1/2" airspace between the slab and the surface of the subfloor. Hopeful that any moist air will be able to dissipate across the surface and evaporate without collecting or turning into liquid water. Then tack strips with a breathable pad and a man made carpet facing the room. This *should * allow any water vapor coming through the slab to not collect under the pad, but instead pass through the pad and carpet. I will control humidity in the room with a humidifier.

Wish me luck!