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  1. #1

    Default What is going on up there?

    I have a situation with an addition approx. 14 years old.

    Every drywall screw, and I mean every one, on the ceiling of this entire addition is shadowing through.

    There is no water damage or apparent leaks, and the shadowing is so even throughout the entire space.

    I am thinking frozen or wet trusses at the time of installation?

  2. #2
    Join Date
    Nov 2007
    Posts
    28

    Default Re: What is going on up there?

    Are you in a cold part of the world? It may be from thermal transfer. If the space above the ceiling is very cold, the lumber the screws are fastened to are very cold, the screws transfer that cold to within 1/8" of the warm space, the warmth of the room allows these "cool spots" to grab moisture and the airborne dirt in the room collects on these spots. Are you also seeing shadowing of the trusses outlined on the ceiling? You may have to look really hard to see this.

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: What is going on up there?

    In a cold climate this is very common and usually referred to as Ghosting ..... due to a poor job of insulation.

    The wood used to frame the house is about 1/3 as effective as fiberglass in stopping the cold. The cold will come through where the studs or joists are, more than anywhere else. 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 or ceiling in front of the framing will attract the moisture. This will attract and trap more dust than the rest of the wall forming the shadows or ghosting. In this case the drywall screws are the coldest points.

    It's likely the tops of the rafters are not covered with insulation (or enough) to provide a thermal break in the colder attic space.

    Hope this helps.

  4. #4

    Default Re: What is going on up there?

    Thank you for your advice, it is much appreciated and has confirmed some of my suspisions.

  5. #5
    Join Date
    Aug 2007
    Posts
    1,131

    Default Re: What is going on up there?

    Burning candles or oil-lamps or other carbon-producing fuels will only exacerbate the visual tell-tale signs. Wood-burning fireplaces are another common source as a little smoke will frequently leak off into the room before a good draft is established up the chimney.

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