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-   -   Crawlspace Vapor Barrier (http://www.diychatroom.com/f103/crawlspace-vapor-barrier-126414/)

cbaur88 12-12-2011 02:53 PM

Crawlspace Vapor Barrier
 
2 Attachment(s)
If I was going to install a new vapor barrier on the floor of my crawlspace and I also wanted to install rigid foam board on the foundation wall for insulation, given the choice would I want to attach the vapor barrier directly to the foundation wall first then install the foam board over top? Or Should I install the foam board directly to the foundation wall and bring vapor barrier up past the foam board like attached photo?

Browsing online & youtube I've seen companies do it both ways, not sure if there is a gain one way or the other. I attached a pic of one companies recommendation. I also have a sill ledge (see attached photo) where I can come up that far and attach the barrier to that as well but not sure if there are any downfalls to that besides using more material. Thanks in advance!

Windows on Wash 12-12-2011 04:25 PM

Seal the vapor barrier to the crawlspace wall. It is easier and and you don't want any of the moisture/earth smells moving inside gaps in the foam board if you don't get it sealed up perfectly.

cbaur88 12-14-2011 01:11 PM

Quote:

Originally Posted by Windows on Wash (Post 792253)
Seal the vapor barrier to the crawlspace wall. It is easier and and you don't want any of the moisture/earth smells moving inside gaps in the foam board if you don't get it sealed up perfectly.

Thanks WW, what's the best way to attach the foam boards to the foundation wall? I'll try a sealant but the wall is not flush flat, allot of excess mortar sticking out which I guess I can chip away but just in case is there some type of nail,screw, sinker that will hold these babies up against the wall. Thanks a bunch once again! :thumbsup:

titanoman 12-14-2011 02:06 PM

Liquid nails or Eagle Grip.

Sent from a Samsung Galaxy S2

Gary in WA 12-15-2011 09:23 PM

Additional work may be required if in a termite or radon zone; http://energy.cr.usgs.gov/radon/rnus.html
http://termites101.org/termite-basic...ites-by-region
You may need a p.t. plate holding the plastic to the concrete at exterior grade level with the top open for termite tunnel inspections.....

Gary

cbaur88 12-16-2011 07:45 AM

Quote:

Originally Posted by GBR in WA (Post 795045)
Additional work may be required if in a termite or radon zone; http://energy.cr.usgs.gov/radon/rnus.html
http://termites101.org/termite-basic...ites-by-region
You may need a p.t. plate holding the plastic to the concrete at exterior grade level with the top open for termite tunnel inspections.....

Gary

Thanks for the info Gary but that's all greek to me. I think I understand what a P.T. plate is but not sure what you mean by it holding the plastic to the concrete. From what I've read the PT plate should be somewhere on the sill ledge and installed at construction. So far I see no signs of termites down there so that is good news. Perhaps a termite inspection and regular preventative maintenance will keep it that way going forward.

Gary in WA 12-17-2011 09:31 PM

You may want the plastic to extend up the wall only 6" or so. The plastic is stopped from completely covering the wall to inspect the wall for termite tunnels. If not a concern, fully cover with insulation. Supply exhaust air if converting to a conditioned crawl...

Treat it as a basement wall, no plastic above-grade to condense water in Summer; http://www.buildingscience.com/docum...ce-insulation/

http://www.buildingscience.com/docum...ance-and-codes


Gary


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