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Old 02-24-13, 02:59 PM   #20
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Originally Posted by S-F View Post
The situation you describe is a code violation in MA. 1" of XPS is a class 2 vapor barrier and the foil is class 1.
I'm not familiar with the MA code. What is the definition of a class 1 and 2 vapour barrier in MA. And why would a radiant barrier be an issue (or maybe it is not, by itself)?

The sandwich, I expect, is the problem so if you have a semi permeable outer skin and a proper barrier on the inside, is the code satisfied?

Last edited by Mikesolar; 02-24-13 at 03:10 PM..
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