What type of polyiso insulation to use over sheathing?
SquakMtn
| Posted in Energy Efficiency and Durability on
I would like to know what type of polyiso rigid board to use over the exterior of sheathing, assuming a rainshield will be placed over that? Does foil covered improve with radiant heat or does it trap moisture and create mold problems on the sheathing interface as some blog responses claim? Hunter makes H-shield which has fiber reinforced surfaces, but no foil. Would there be deterioration concerns?
Thanks,
Steve
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Replies
Steve,
Any type of polyiso will work fine. If you can install two layers of polyiso with staggered seams, you'll get a more airtight installation with less thermal bridging.
If you install foil-faced polyiso and the foil faces an air space, the foil will raise the R-value of the air space from R-1 to R-2 -- a slight thermal improvement.
Martin --
Would the "airspace" you refer to above be the gap formed by the proposed rainscreen in Steve's original post?
Jeff,
Q. "Would the 'airspace' you refer to above be the gap formed by the proposed rainscreen in Steve's original post?"
A. Yes.