Exterior rigid foam insulation
I am well into a 2 year build of a cottage near Ottawa Canada which I believe makes it equivalent to zone 6. I say cottage, but I am trying to build to the standard of a house.
The cottage is 2*6 framed 24 inch on centre with OSB sheathing. The exterior of the cottage is wood siding with a 3/4" of air flow behind it (installed on 1*3), then Typar house wrap and then 1.5" of R7.5 rigid XPS. I am still working on the inside of the cottage and thus the stud bays are still open. I planned to insulate them with Roxul batts as I can't find anybody who does dense pack cellulose in the area, and I don't think you can rent equipment needed to try a DIY install. After reading all your posts I am going to try to avoid the poly vapour barrier on the inside altogether and if forced will go Membrain which I think you are OK with if pressed.
I just read your article on calculating required XPS thickness and now I am worried mine isn't thick enough. I see all kinds of R7.5 installed around here but recognize that doesn't prove it is right. Is there anything I can do here (please don't say tear down my 20K siding) ideally from the inside to help with potential dew point issues? I read somewhere R7.5 was good enough for Dew Point in Canada (Jon Eakes I think) but your chart is pretty straightforward.
Posted Mon, 03/17/2014 - 13:03
Edited Mon, 03/17/2014 - 13:19
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