Xps and fiberglass on basement exterior wall, problematic?
Thumbhammer
| Posted in General Questions on
Am I making a dire mistake using 2in xps and fiberglass on my basement exterior wall? Also not intending on using poly..
Seems the more I try researching it the more conflicting it becomes.
Walk out is 2×6 framing the rest is concrete. Exterior is just sheeting and vinyl siding.
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Replies
Thumbhammer,
Your wall is safe. Your fluffy-to rigid insulation ratio is within dewpoint-guidelines, even if you live in Nunavut.
The XPS insulation will serve as a Class II Vapor retarder which is more than sufficient to keep your sheathing dry. No poly needed.
Its a laborious wall but it works.
Thumbhammer,
I agree with Rick that the wall cavity would be safe from humidity because of the xps acting as a vapor contol layer. However, I wonder what is behind the stud? The xps looks like its between the studs and not behind it. If the wood is touching the concrete or exposed to an air gap with high humidty, which is now going to be higher, the framing may not be able to handle the amount of moisture.
What is behind the studs? Is it isolated from the foundation?
Shawn
Shawn, the foundation is a concrete slab and this walk out is basically the only wood framing as far as the basement goes. What you see is Xps between 2x6 framing and behind that is just sheathing and vinyl siding. Which also happens to be under our addition in the carport area, if that makes any difference.
Thumbhammer,
I misunderstood and thought it was placed next to a concrete foundation wall.....good luck!
Shawn
Awesome thanks for the response Rick. Also for the sake of transparency, I live in NH. Seems like vapor barriers are a kind of controversial here.
TH,
You may find this article useful: https://www.greenbuildingadvisor.com/article/three-ways-to-insulate-a-basement-wall
Thanks Malcolm, this is exactly how I'm working towards doing things. Already have an good majority of the sills done. Plan to put mineral wool up behind it as well.