Two quick questions, I am seeing a lot of job sites doing different things. First do you or do you now use house rap over rigid foam sheathing? And two I was at a seminar last week where the presenter was suggesting that you do not need to use vapor barrier if you are sheathing with rigid foam.
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Replies
Hmm . . House rap. Isn't that what M.C. Hammer does? ;-)
Mike Hennessy
Pittsburgh, PA
PS: I agree with the presenter, provided seams are properly sealed.
Was the presenter talking about an air infiltration barrier or a vapor diffusion retarder? Big difference.
But where are you located? Using the rigid foam as a vapor retarder will be fine if you are in a cooling climate (ex. FL or TX), where the normal vapor drive is from outside in.
If you are talking about a heating climate, the answer is maybe, maybe not. If you have insulation in the wall, and it is porous (ex. FG batt or cellulose), and the drywall inside is not sealed well so that the cavity is open to inside humidity in the winter, then the inside face of the foam may not be warm enough to prevent condensation.
In most cases, the most accurate answer to such questions is "It all depends."