# Crawl Space insulation, encapsulation



## Boneill230 (Feb 11, 2015)

New to the forum here. I recently purchased a home and my first project is already in my head. The house was built in 1991 and there was no insulation on the walls of the crawlspace or the floor joists. I did some research and found for this application it would be better to seal off the crawlspace (seal vents) and put up ridged foam insulation on the walls. Question being with sealing the crawl space, the floor is concrete and has plastic coming up MOST of the sides but not everywhere. Second, I honestly think the concrete floor in maybe 2" thick. The thought I Had (where I need help)
1. Replace crawlspace vents with cinder block, mortar and parge outside
2. Drylock the walls of the crawlspace (and the floor?)
3. Use great stuff or expanding foam to seal any holes in the rim joist and floor
4. Seal the Floor to wall seam (need help with that)
5. Install rigid foam insulation with the reflective face on both sides, all seams sealed and filled with expanding foam.

Thinking that is it, could be wrong and I am open to discussion or other ideas. Below I have pictures of the crawlspace as a whole and where the plastic from the floor is visible and not visible. Another note to add is that the soil in my area is very sandy and there are no issues with a high water table.

I will also be posting this on the construction tread as well, wasn't 100% sure where to put this

Thanks!:thumbup:


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## Windows on Wash (Aug 30, 2011)

Don't bother with #2.

If the vapor barrier is down, dryloc won't do anything but mess things up. 

I wouldn't dryloc the walls either.

Seal all the gaps and cracks, insulate the stem walls, seal and insulate the ribbon boards. 

The connection between the wall and the floor and just be caulk with a mild sealant but there is probably little to no soil gases coming there there or moisture. 

http://www.buildingscience.com/docu.../crawlspace-insulation/?searchterm=crawlspace


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## Boneill230 (Feb 11, 2015)

Windows on Wash said:


> Don't bother with #2.
> 
> If the vapor barrier is down, dryloc won't do anything but mess things up.
> 
> ...


So just the vapor barrier under the concrete is good? the ridged foam more or less acts as the vapor barrier on the walls I am guessing. That link was exactly what I was looking for. Back to the floor/wall seam, something such as this
http://sanitred.com/shop/liquid-rubber-base-lrb/lrb-liquid-rubber-base-1-gallon-pail/


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## Windows on Wash (Aug 30, 2011)

Just a good sealant, I.e. caulking should work fine. You just need to seal the gap and the vapor barrier.


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## Gary in WA (Mar 11, 2009)

Leaving out 2 things that jump right out; 

1. you need an air exchange with the house to meet minimum code, since 2004 by BSC- pick one of five choices; http://www.google.com/url?sa=t&rct=...cxhZUUbjb19gdOLGMmhxgpg&bvm=bv.59026428,d.cGU

2. Radon; where are you located?

Gary
PS. Welcome to the forums!


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## Boneill230 (Feb 11, 2015)

Thanks Gary, as far as radon I ha that tested prior to purchasing the home and it came to 0.2 pCi/l. The inspector told me that NJDEP says the "action level" where you need to take measures to get it out is at 4.00 PCI/I. And for the things you said to pick from for code, you are more or less making the crawl space a conditioned part of the house from what it looks like correct?


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## Gary in WA (Mar 11, 2009)

Yes, IF you close the vents- you need the air exchange with the house to keep the moisture under there in check. Gary


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