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  1. #1
    Join Date
    Feb 2011
    Posts
    2

    Default V aulted Ceiling Condensation what to do.

    I read a thread from 2010 that showed the exact problem I have.
    http://advice.thisoldhouse.com/showthread.php?t=100984
    Marks on the ceiling. I think its condensation from the ceiling rafters being attached directly to the drywall as I have black lines and black circles (from screws) forming where the walls and ceiling joists meet. (Its Chicago we get some cold temperatures). So what to do about this? I am worried the dry wall will weaken from this or the joists will rot. I plan to be here another 15 years. If I was to redo is there a picture of the proper way the ceiling should have been built?
    One other thought. If I hang rigid insulation over the drywall then drywall over that will that fix the problem?
    Thanks for any ideas..

  2. #2
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: V aulted Ceiling Condensation what to do.

    This is unfortunately very common and it relates to a poor job of insulation in a cold climate. You see, the wood used to frame the house is about 1/3 as effective as fiberglass in stopping the cold. So the cold will come through where the wood used for framing are, more than anywhere else. This is due to the framing used in walls (and for cathedral ceilings ) is coupled directly to the exterior and interior --- known as thermal bridging.

    If the humidity is fairly high in the house, but not necessarily bad enough to get wet all over the windows, the cold parts of the wall in front of the studs will attract the moisture. This in turn will attract and trap more dust than the rest of the wall, and hence what we call *Ghosting*. It can look like the framing is coming right through the wall.
    It usually doesn't indicate any issues with liquid moisture creating rotting or any other problems associated to moisture.

    Thicker walls, or better yet, insulated sheathing over one side or the other of the wall will stop the problem. So if you are building new, or residing, make sure to add about 1-1/2 inches of foam insulation board over the whole wall or ceiling. That gives great insulation over the insulated part of the wall, and at least the minimum necessary to stop the ghosting over the framing areas.
    If you are refinishing a room, or a cathedral ceiling, even as little as 1/2 inch of foam over the existing drywall and then new drywall will make a difference. One inch would be much better.
    Last edited by canuk; 02-12-2011 at 04:52 PM.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Feb 2011
    Posts
    2

    Default Re: V aulted Ceiling Condensation what to do.

    Thanks a bunch I will attack this when it warms in the summer.

  4. #4
    Join Date
    Feb 2011
    Location
    Brown county, Ohio
    Posts
    52

    Default Re: V aulted Ceiling Condensation what to do.

    Hello, until you fix this permently i would just run a fan in there trying to get some air moving up there. good luck to you friend.

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