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-   -   insulating crawlspace (http://www.diychatroom.com/f103/insulating-crawlspace-133547/)

Roundeye 02-12-2012 10:47 PM

insulating crawlspace
 
My house sits on block and beam and my crawlspace has no insulation. The floors are very cold, im not sure what I need to do to make them warm I can feel cold air by the base boards. I was gonna have a company use some spray foam on the rim joists and the crawlspace walls but have read that moisture gets between the foam and the wood and causes wood rot and mold and carpenter ants make nests with the foam. I just would like to do it the right way instead of spending a bunch of money and cause more problems.

joecaption 02-12-2012 11:30 PM

There has to be at least 100 post on this one subject. Please look around and check them out.

Gary in WA 02-13-2012 12:16 AM

If worried about SPF, you could just DIY with foamboard, if the crawl is vented: http://www.buildingscience.com/docum...n-crawlspaces/

You would have to build chutes for the vents at the perimeter locations. Be certain the dirt is covered with plastic vapor barrier. Air seal canned foam all wiring/plumbing holes through the floor above to stop the stack effect (the cold you feel under the base trim): http://www.wag-aic.org/1999/WAG_99_baker.pdf

Will you go with -vented or conditioned crawlspace?

Gary

Roundeye 02-13-2012 12:30 AM

Its gonna be hard to put a vapor barrier down as there is a lot of huge debris under there that wont fit out the crawl space opening. There are no vents built in to open or close, but It wont be a conditioned space.

moneymgmt 02-13-2012 09:45 AM

Quote:

Originally Posted by Roundeye (Post 852209)
Its gonna be hard to put a vapor barrier down as there is a lot of huge debris under there that wont fit out the crawl space opening. There are no vents built in to open or close, but It wont be a conditioned space.

You're getting more moisture and cold from the ground than you realize. Put the vapor barrier down or the rest is pointless.

Nailbags 02-14-2012 04:06 PM

Like has been said lay down a vapor barrier first 6-8 mil thick black plastic. Then buy R-30 faced batts and place the paper side up in the floor joist cavities. make sure that the paper is flush to the underside of the floor.

jklingel 02-14-2012 06:14 PM

I think you'd be better off w/ a layer of foam over the joists (taped) than just batts w/in them. If I recall, that may lead to the joists being cold at the outer most surface, gathering condensation and mold/rot. The foam should keep the joists warm and avoid that. buildingscience.com has a good article about that; check it (them) out to see if I remember right. It's been a year since I read it, and I won't/don't have a crawl space, so I didn't commit it to my memory banks. The link(s) was/were probably posted here, too.

Gary in WA 02-16-2012 09:45 PM

First link in post #3........ If using foamboard check with local AHJ for ignition barrier or accept foil-faced. Any batt will let the air move through it, even if you cover the dirt with plastic. Moving air degrades f.g. by 66%. If impossible to cover the dirt/debris, cover the joists with foamboard---- air-tight. Still way better than exposed f.g. to get radiation from the ground and moving air. F.g. batts are the worst to use anywhere, if you have a choice: http://www.diychatroom.com/f98/bigge...ulation-90438/

Gary


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