Insulate Underfloor

[June]

My hardwood floor is all warped. Could that be from the moisture in the crawl space? Will insulate the underfloor help?

[Larry]

Hello: It is likely more of a moisture problem than an insulation problem. If the floorboards are cupped (edges higher than the center) they are wetter on the back side. This suggests a damp crawl-space. Putting a good vapor barrier down on the ground and sealing it well will dry things out. Sealing off the vents and putting a dehumidifier down there will speed things up. If you go to http://www.buildingscience.com , you'll find good discussions on controlling water.

You could insulate by spraying closed cell foam on the under-side of the floor. That would act as a vapor barrier, but I'd dry things out first.

Yours, Larry

[June]

THANKS, Larry. I was out of town and did not get to check the forum. Now, I know it is not my fault the floorboards are cupped. I will have someone come to take a look in the crawl space about the moisture (I can probably do it by following your instructions, but I don't like crawl space.) before repairing the floor.

[dagrenda]

Our floor has the same problem too. Can we do the vapor barrier only or insulate the under floor only? Doing both can be expensive.

[Kate]

Yes, in order to be effective, you have to cover the ground of the crawl space wtih 6 mil or 10 mil plastic and air seal all the gaps and cracks. you condition your crawl space. Then you don't have cold or hot air leaking into your house. You'll feel the difference. If you want insulation underfloor you can always add it later.

[Stanleys]

Well, underfloor means the floor above an unheated crawl space or basement. Once the underfloors are properly insulated, you will increase the overall comfort of your home because floor insulation provides valuable sound control and thermal control...