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Thread: vapor barrier

  1. #1
    Join Date
    Mar 2009

    Default vapor barrier

    ok, i want to re drywall my garage celing, its all falling down and had water lines burst in the past before i owned it.. needs cleanin up.. so my garage is actually part of the basement, the master bedroom/bathroom is directly above the garage. while im redry walling it i wanna putin new insulation, move the water lines as tight to the upperfloor as possible to help from freezing. my biggest question is the vapor barrier, i konw i need one. what i dont know is the proper way of installing it? do i just insulate and put the barrier accross the joists directy under the drywall. or do ya try and tuck the barrier tight to the upper floor, then insulate?? any help would be great!

    also is there a better alternative than 5/8 drywall?? the garage is commonly damn

  2. #2
    Join Date
    Aug 2007
    The Great White North

    Default Re: vapor barrier

    The wrong way would be to put a vapor barrier on the garage side ( between the drywall and insulation ).

    Forget about the vapor barrier it's really not needed in your case.
    Providing the subfloor is sheathing like plywood or OSB these materials are considered an acceptable vapor retarder. If there is a feeling to need more vapor retarder then use faced batts with the facing against the floor above.

    The main thing ---- aside from moving your plumbing further into insulation ---- ensure you seal any penetration from the outside allowing cold moving air within the ceiling space which is a major contributer for cold rooms above.

    Another area to consider is making sure that all penetrations from the garage into the rooms above are also sealed. Things like electrical , plumbing , cable TV line , etc. need to be sealed not only to prevent cold drafts but preventing carbon monoxide getting into the rooms above.

    In this case you might install Tyvec or similar housewrap ( making sure to tape all seams ) over the insulation before the drywall. This will add an air/moisture barrier for the insulation but will allow things to breath.

    Drywall is the fire barrier of choice mainly because it's realatively inexpensive and easy to install than some other materials like plaster or stucco.

    When the drywall is installed make sure to use at least two coats of joint compound ----- use a primer / sealer and then a quality interior / exterior paint.

    Hopefully this helps.
    "" an ounce of perception -- a pound of obscure "
    - Rush

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