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  1. #1
    Join Date
    Dec 2007
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    6

    Default moisture in my garage attic

    I had a garage built on to my house 2-3 years ago. All was fine until I put the drywall up. Now this only happens in the winter months, I noticed that there was condensation build up in my attic and it turned into mold this winter. It got so bad that in started to grow inside my garage where the ceiling and wall meet. I called the contracter and he came out and said that I wasnt getting enough ventilation and he doesnt know why not. He didnt offer to fix the problem or even try to help me out. I had a liscensed roofer come out and he noticed right away that the shingles he laid wasnt right. He said that I might have to tear the roof, sheathing insulation and even my drywall inside my gargae out. I have almost $20,000 invested in my garage, shouldnt the responsibilty lay on the contracter for fixing my problem. I paid him to have a functinal garage now all I have is mold and a garage I cant use and he suggested on ways that "I" could fix it. (makes me a little mad) What should I do and how to handle this...Any response or comments would be appreciated.Thx guys
    The contracted built everything, all I did was the electrical, insulation inside the garage and the drywall

  2. #2
    Join Date
    Dec 2007
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    28

    Default Re: moisture in my garage attic

    I would contact the Better Business Bureau in your area, but in reality it could be the insulation that you installed. I would check and make sure that you have good airflow coming up the underside of the roof. Make sure that the eaves are properly vented with soffit vents and that the insulation is not packed into these areas. If need be use attic bay vent, available at any home store, in each and every cavity where the Roof rafter meets the ceiling joist and exterior wall. Make sure that there is enough airflow coming through this area with a place for it to exhaust. Ridge vents are common in my area, but I have seen gable vents and roof fans and vents. Airflow is key. The air flow coming up through the vents drys the back side of the roof sheathing. If this is not happening, you will see your roof wear out from the inside out, ice dams if your in a cold climate and mold and mildew for sure.

    In this order this is what I would do, Walk around the perimeter of the building and check for correct venting of the soffits, check and make sure that a ridge vent or some other sort of venting is installed, I would recommend a ridge vent personally. Make sure that your contractor left a gap in the roof sheathing of about 2inches on either side of the Ridge to allow the exhausting of the air and then check your insulation job to make sure that you haven't closed off any of the soffit. Your insulation should only go to the the outside of the exterior wall and not extend into the soffit bay or close off the gap between the roof sheathing and the top plate, there should be a few inches between the two. This is where the attic bay vent should be installed.

    As for the mold and mildew, depending on how bad it is, you might need to have professionals with negative air machines,dehumidifiers and air movers come in and clean it up. I have seen them soda blast the backsides of roofs to get rid of the mold as well. This could be an extensive remediation job. It is not something I would recommend you tackle on your own. Make sure that the contractor that does this work is IICRC certified in Mold and water remdeiation and check their credentials.

    Good Luck and I hope this helps.

  3. #3
    Join Date
    Dec 2007
    Posts
    6

    Default Re: moisture in my garage attic

    Every 3rd one is vented on my eaves,and my insulation stops probably 5-6 inches before my eaves.( u can see plenty of daylight from the attic)The contractor installed 6 roof vents (the garage is 24x20)
    What do u suggest about the shingles that were laid, should I ask the contractor if he can come out and fix the problem. I'm just looking for some more opinions on this matter. I have 2 more contratctors and a rep coming out from Owens Corning so he can look at the shingles. I just dont wanna spend more money on this if I dont have to.
    Is there anyway I can get the contractar that built the garage and hold him responsible for it if it comes out that I'm not getting the ventilation I need and thats where the trouble is?
    Thanks Sean for your reply, very useful information u provided.

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

    Default Re: moisture in my garage attic

    The main issue is warm air entering the attic space which is colder than the interior of the garage. This is compounded by having open vents in the attic space allowing that space to be a cold zone. Once the warmer air enters the cold attic space condensation will occur ... it's the law of nature .... this will continue regardless how much ventilation exists.

    This sounds like the insulation and vapor barrier is leaking the warmer air from the garage into the cold attic space .... unfortunately this will have to be addressed.

    As for the shingles ... if they were improperly installed ... then yes the contractor should be correcting this.

    Hope this helps.

  5. #5
    Join Date
    Dec 2007
    Posts
    28

    Default Re: moisture in my garage attic

    Yep, canuk is absolutely correct, your having issues with the thermal break. If you have holes in the vapor barrier or insulation it will compound the problem.

    What kind of pitch do you have on the garage slope. If the pitch of the roof is not enough your shingles will not shed the water fast enough and create issues as well.

    What did the contractor say about the roofing being done incorrectly? There are dozens of ways to install them incorrectly.

  6. #6
    Join Date
    Dec 2007
    Posts
    6

    Default Re: moisture in my garage attic

    I havent contacted the contractor yet, I'm waiting for the Owens Corning rep to come out so I know exactly what to say. He's on vacation till the 1st of the year. I have a couple of squirrel fans up in the attic now drying things up. (looks alot better). When u guys say thermal break what exactly is that? I appreciate the replies, very helpful...thx fellas

  7. #7
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: moisture in my garage attic

    The contracted built everything, all I did was the electrical, insulation inside the garage and the drywall

    When u guys say thermal break what exactly is that?
    The thermal break is basically the insulation and vapor barrier.

  8. #8
    Join Date
    Dec 2007
    Posts
    6

    Default Re: moisture in my garage attic

    I live in Ohio,the mold has appeared inside my garage through the drywall. I have spots of it everywhere where the wall and ceiling meet inside the garage.The only place I do not have mold is where the garage is actually attached to my house. (bridged part that attaches the two)
    Let me see if I can post some pics on here so it'll clear things up and I can better explain myself

  9. #9
    Join Date
    Jun 2007
    Location
    Coventry, RI
    Posts
    340

    Default Re: moisture in my garage attic

    It sounds to me like there is no moisture barrier on the ceiling or as was said it may be compromised with holes (for lights, or a stairway). I can't say for sure but if you aren't getting water dripping in from the roof I doubt it is the roof shingles.

    When you put up the insulation and drywall what did you use for a vapor barrier (just the paper faced insulation or plastic sheeting)? In my opinion you can't get a really good seal with the paper faced insulation. If you used the plastic sheeting did you tape all the seams and seal anywhere it was cut such as for light fixtures?

  10. #10
    Join Date
    Aug 2007
    Posts
    612

    Default Re: moisture in my garage attic

    Just a thought on the source of all the moisture....
    Since this is a garage, the cement slab may not have a layer of poly under the stone which is under the cement. If not, you will probably always have a large amount of moisture coming up through the slab itself. As the others have said, if your ceiling is not sealed well enough it will migrate to the attic space. If your slab is the source of the moisture then when the ceiling is sealed better, the moisture will stay in the garage space itself and you may need a dehumidifier to take care of it.

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