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Additional attic insulation (vapor barrier) above bathrooms

longfieldl | Posted in General Questions on

I am planning to insulate my attic, emptying everything that is already in place and making sure that there is no air flow before to add blown-in cellulose. On the floor/level below the attic, I have two bathrooms. I was wondering if this is common practice or a good idea to spray polyurethane over the bathrooms area to add extra vapor barrier for these rooms that often contain hot humid air. Is this overkill. I am living in the province of Quebec, Canada. Thank you

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  1. user-2310254 | | #1


    I can't respond to your questions. (My suspicion is that both ideas are ill-advised.) Have you read Martin's article on insulating attic floors?

  2. Jon_R | | #2


    a) use a bathroom exhaust fan (which removes moisture and depressurizes to stop air flow into the walls/ceiling),
    b) apply vapor retarder paint to the wallboard to block most of the moisture before it enters the wallboard.

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