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  1. #1
    Join Date
    Nov 2007
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    Default plastic sheating do's and dont's

    I have taken on a large project. I bought a house that was gutted and large 3000+ sq ft. not including basement I live in north central ILLINOIS (LaSalle). Its is a 2 story balloon frame 80+ years old, with 9 ft ceilings and the roof has no ridge vents or eve vents. my question is I have used R19 in the ceiling some of it is kraft faced and some is unfaced. Bought what ever was on sale or given to me. I put plastic sheating over the whole ceiling regardless of having faced or unfaced I plan on putting drywall on the ceiling but some people have told me you shouldn't because it will cause condensation and create mold between the drywall and plastic. I am also plasticing the exterior walls (R13). So should I back up and tear down the plastic before I put up drywall or leave it?

  2. #2
    Join Date
    Aug 2007
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    Default Re: plastic sheating do's and dont's

    Quote Originally Posted by jcavaness View Post
    I put plastic sheating over the whole ceiling regardless of having faced or unfaced I plan on putting drywall on the ceiling but some people have told me you shouldn't because it will cause condensation and create mold between the drywall and plastic. I am also plasticing the exterior walls (R13). So should I back up and tear down the plastic before I put up drywall or leave it?
    If the plastic vapor barrier is sealed and it's on the warm(room) side of the insulation you shouldn't have any moisture issues.... that's the correct method and the same would apply to the walls as well.

    The ceiling vapor barrier should over lap the walls by at least 6 inches ... I like to use 12... then the ceiling vapor barrier should be sealed to the walls vapor barrier using Tuck or similar house wrap tape. Make sure to tape all seams to form a sealed envelope with the vapor barrier.

    The only reason there would be a moisture issue from condensation is if the vapor barrier isn't sealed or used.

    You might consider also increasing the R value in the ceiling to at least 24 ... R40 would be better.

    Hopefully this helps and good luck.

  3. #3

    Default Re: plastic sheating do's and dont's

    [QUOTE=jcavaness;6352]I have taken on a large project. I bought a house that was gutted and large 3000+ sq ft. not including basement I live in north central ILLINOIS (LaSalle). Its is a 2 story balloon frame 80+ years old, with 9 ft ceilings and the roof has no ridge vents or eve vents. my question is I have used R19 in the ceiling some of it is kraft faced and some is unfaced. Bought what ever was on sale or given to me. I put plastic sheating over the whole ceiling regardless of having faced or unfaced I plan on putting drywall on the ceiling but some people have told me you shouldn't because it will cause condensation and create mold between the drywall and plastic. I am also plasticing the exterior walls (R13). So should I back up and tear down the plastic before I put up drywall or leave it?[/QUOTE

    Applying a sheet over another vapor barrier product WILL cause condensation issues. You should go behind the plastic and cut the facing on the insulation to allow moisture trapped to escape. The second Barrier will prevent moisture intrusion. recently I read an article on a 'Smart Vapor Barrier'. It seems to eliminate all of the problems. I found it by googeling smart vapor retarders!
    Robert StackhouseHidden Content

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