XPS/Plywood on floor or just carpet?

gbig2June 10, 2010

I'm debating whether to spend $800 to put one inch XPS rigid foam and 1/2 plywood on the floor or not. We are finishing 700 sq ft and about half will be carpet and half laminate. I know building science says to put XPS/Plywood down but I'm not sure it's worth the cost. Basement floor stays dry, no standing water. What did you do when you finished your basement? Just looking for opinions on whether it's worth the time and $ or if I should just put the laminate and carpet right on the concrete?


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On new houses I've built with 5 ins. stone and 4-5 ins. concrete as basement flooring, I've been successfully using low pile synthetic commercial carpeting with synthetic backing. I've installed the same carpet on older homes that I've renovated and resold or used as rental. It's absolutely essential to use a humidifier to inhibit mould growth.

    Bookmark   June 10, 2010 at 2:04PM
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I have heard the xps and plywood make for a toasty warm floor and keep humidity way down but....if there is any chance of any appliance leak or flood I would imagine it would be a costly mess to replace.

any kind of synthetic pad avaialable anywhere?

    Bookmark   June 10, 2010 at 9:42PM
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I haven't come across any that will not trap the moisture and feed mould growth.

Some "luxury" homebuilders here still use heavy underpads under plush carpet, all directly applied to the concrete floor. Looks and feels great while the home is for sale.

Whenever I read comments at GWB that "we have thick underpads under basement carpets and no problems," I'd bet the owners are inured to the musty stench. (Or perhaps they live in the desert.) When I was a real estate broker, "basement stink" was the "standard" for finished basements.

In the month we've been living in our current pre-teardown home (plans are under way) the dehumidifiers have been pulling out up to two gallons a day of water. Quite the improvement! Or are we becoming used to the odour??

    Bookmark   June 11, 2010 at 11:45AM
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yes, I guess you can get used to odors..I am more concerned about the allergens you do not see!

    Bookmark   June 22, 2010 at 2:11PM
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I have completed 17 finished basement projects, all of which had the carpet installed directly over the concrete slab. Not to say that plywood over extruded polystyrene over the slab would not help in some ways, but it also is much added cost in materials & labor. In addition, maintaining minimum ceiling height is already a challenge in some cases - adding thickness to the floor will make areas such as soffits around ducts even more problematic.

    Bookmark   June 23, 2010 at 9:09AM
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