Drying Potential of Brick-Faced Wall with Blueskin Wrap
I have a new construction in Toronto, Canada. I decided to use blueskin to house wrap. In doing so, I used the wrong product on one wall of the house. I used the normal plasticized blueskin rather than the VP100.
I am afraid the that side of the house although is water tight, the wall is not able to breath. The wall has mostly been bricked and is to late to remove the wrong blueskin. Is there any possible solutions and what is the possibility of condensation once poly-vapor barrier is applied to the inside of the house over the bat insulation and under the drywall.
Should I skip the poly-vapor barrier all together thus allowing the wall to breath from the inside.
Any suggestion is greatly appreciated
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Replies
I would use membrain or intello smart vapor barriers in place of the poly. They will allow drying in higher humidity.
Thanks for the advice. Would you know if intello smart vapor barriers is allowed under the building code in Ontario, Canada?
Thanks again
I’m not that familiar with Canadian building codes, but a quick search seems to indicate it is.
https://foursevenfive.ca/blog/intello-plus-complies-with-national-building-code-of-canada-2010/
I've had no issues with my inspector with Membrane. My only beef with it is the price up here in the great white north is silly.
The safest approach in your case is to flash the wall with enough closed cell SPF for condensation control. This will limit the moisture that can get into the wall and the presence of a cold side vapor barrier won't matter. If you already have an R5 rigid on the exterior, you pretty close to done (ideal is R7.5 for 2x6 wall) but a bit of SPF won't hurt, otherwise you should get about 2" of cc SPF on the inside. With 2" of SPF, the rest of the insulation can be standard 2x4 batts.
Akos and Kyle,
I'm a bit confused (and the problem is probably mine) by the explanation of it's compliance with 9.25.4.2. Isn't Intello a variable-perm membrane? It seems like it would comply when it was vapour-closed, but when it open doesn't it exceed the required perm rating ?
Hi Malcom,
It needs to be under 1 perm under the dry cup method, which the Membrain and Intello are. Check out a thorough explanation here:
https://www.certainteed.com/resources/CT_RCIVapRet_web.pdf
Kyle,
Thanks - and again this is probably just me being dense, but from the link:
"the permeance increases to greater than 10 perms when tested in accordance with ASTM E96". I don't see any language in our BC code that speaks to the material being allowed to exceed the 1 perm when it opens.
This is of course entirely independent of any discussion as to whether it's a good idea. More of a what do I do when the inspector says the membrane doesn't meet code question.
Hi Malcom,
When I look at 9.25.4.2 here is what I see.
Vapour Barrier Materials
Vapour barrier shall have a permeance not greater than 60 ng / (Pa·s·m2) measured in accordance with ASTM E 96/E 96M, “Water Vapor Transmission of Materials,” using the desiccant method (dry cup).
Both Membrain and Intello have a permeance less than 60 ng / (Pa·s·m2) using ASTM E 96/E 96M dry cup method. They do not exhibit greater permeance until the wet cup method is used.