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Re: GBlist: Polyisoc



Bruce Sullivan wrote:
> 
> Glenn
> 
> Expert agree that impermeable rigid insulation on the outside of a
> building will not cause moisture problems. The insulating value of the
> foam will keep the cavity temperature above the dew point. You don't
> mention where you're from or what the climate is like. But this rule
> should hold true in all of the US, and I would think southern Canada
> as
> well. (Canadians, please pipe up!)
> 
I'm not sure that I can agree (I'm not an expert but I am canadian for
now) if the ext. foam insul layer is R5 and interior temp/humidity
levels in the 70/35% range condensation could occur with outside temp.
at around 14deg.F. which should be fairly common in western washington
area. I could be off and would like to know if I am as I am dealing with
a similar issue and am curious about information on permeance
characteristics of foam, especially over time.

John
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