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  1. #1
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    Default Condensation in Garage

    My bungalow was built in 2003. December 2004 I noticed extreme condensation on my garage ceiling. There is no insulation in the garage (like my neighbour's homes, who do not have this problem) & the garage is attached to the front of my house. There is no moisture in the attic. The problem stops when the weather warms. I had an exhaust fan installed last year which runs 24/7 from November to March. I have asked numerous professionals & the Tarion report (our Ontario new builders board) stated that "the home owners admits she frequently drivers her SUV into the garage - unwarranted"... well I thought that was what a garage was for! Has anyone else had this problem & any solutions?

  2. #2
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    Default Re: Condensation in Garage

    Am not there to see all the particulars of your situation, but the physics remain the same wherever one may be. Condensation is the end result of moisture-bearing air coming in contact with a surface that is cold/cool/cooler enough....to cause some of that moisture to drop out of suspension and cling to that surface.

    Take a glass of ice water outside on a humid day and you will have instant condensation on the glass. Take that same glass of ice water outside in the winter and you won't.

    Or...take that same glass of ice water outside into the desert air. No condensation because there is no moisture (or very little) in the air.

    Conclusion = you have moisture-bearing air inside the garage and when it comes in contact with the cool/cold walls or ceiling it condenses out. Somewhere there is a source of moisture and air that is warmer than the walls and ceiling that is being introduced into the garage. Snow melting off your vehicle perhaps? Are you running the vehicle in the garage? (there is water vapor in the fuel exhaust) Where does your clothes dryer and/or bathroom vent fan exhaust? I've seen more than one these critters exhausted into a garage space.

    You say there is an exhaust fan running in the garage 24/7. From where does it get its make-up air? Soffit vents perhaps? Or....? If no provision was made for make-up air then the fan will pull it from wherever it can get it. That might be thru the cracks or under the bottom of the door to living space. That air will be warmer and carrying moisture.

    If there are soffit vents for inlet air.... again...where is your clothes dryer venting? Where does your furnace vent? Gas water heater, maybe? If any of those exhaust close by outside, the moist air they spew out may be getting pulled right in thru those soffit vents....helped along by the exhaust fan running 24/7.

    If a slab floor in this garage, the moisture may be coming up thru that concrete. Wouldn't be the first time this has happened.

    Look, think...and it will come to you.

  3. #3
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    Default Re: Condensation in Garage

    Niagara .... as in Niagara on the lake or the falls?

    You notice this condensation during the cooler season .... is it wet or frost?
    Does the exhaust fan seem to help?

    I'm wondering the same as ****hiller ..... running the vehicle in the garage with the door closed during the colder seasons. Auto exhaust has a significant amount of moisture as you notice the whiteish plume coming from the tail pipe.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  4. #4
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    Default Re: Condensation in Garage

    I think insulation in the roof would help. The insulation may help keep the temp of the ceiling from dropping below the dew point of the garage air.
    The only time I really have any trouble with condensation in my garage is when the car gets driven in really wet or snow covered and the snow melts. Then I try to push out the water the best I can & even run a heater some.

  5. #5
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    Default Re: Condensation in Garage

    Quote Originally Posted by ****hiller View Post
    Am not there to see all the particulars of your situation, but the physics remain the same wherever one may be. Condensation is the end result of moisture-bearing air coming in contact with a surface that is cold/cool/cooler enough....to cause some of that moisture to drop out of suspension and cling to that surface.

    Take a glass of ice water outside on a humid day and you will have instant condensation on the glass. Take that same glass of ice water outside in the winter and you won't.

    Or...take that same glass of ice water outside into the desert air. No condensation because there is no moisture (or very little) in the air.

    Conclusion = you have moisture-bearing air inside the garage and when it comes in contact with the cool/cold walls or ceiling it condenses out. Somewhere there is a source of moisture and air that is warmer than the walls and ceiling that is being introduced into the garage. Snow melting off your vehicle perhaps? Are you running the vehicle in the garage? (there is water vapor in the fuel exhaust) Where does your clothes dryer and/or bathroom vent fan exhaust? I've seen more than one these critters exhausted into a garage space.

    You say there is an exhaust fan running in the garage 24/7. From where does it get its make-up air? Soffit vents perhaps? Or....? If no provision was made for make-up air then the fan will pull it from wherever it can get it. That might be thru the cracks or under the bottom of the door to living space. That air will be warmer and carrying moisture.

    If there are soffit vents for inlet air.... again...where is your clothes dryer venting? Where does your furnace vent? Gas water heater, maybe? If any of those exhaust close by outside, the moist air they spew out may be getting pulled right in thru those soffit vents....helped along by the exhaust fan running 24/7.

    If a slab floor in this garage, the moisture may be coming up thru that concrete. Wouldn't be the first time this has happened.

    Look, think...and it will come to you.
    Hi. Thank you for your reply. My furnace, water heater & clothes dryer all vent outside. I had the dryer completely wrapped & insulated because we thought that maybe why, but no. I never keep the SUV running in the garage. The condensation is worse after a cold rain. I didn't have this problem the first winter. The contractor had to be a new roof on the house the 2nd Spring because they did such a poor job, & then it was the next winter the condensation problem started. I thought they just didn't cut the vents through the roof, but they had. Two summers ago I had a bathroom type vent installed & ran that. It seemed to help a bit but there was still condensation & in extreme temperatures it would freeze on the walls & ceiling. The attic is nice & dry. I do have a poured cement floor, but so do many others. It's very frustrating.

  6. #6
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    Default Re: Condensation in Garage

    Very interesting/puzzling.

    None of these appliances vent where the exhaust could be/is getting sucked in thru the soffit venting... I take it.

    For the sake of elimination...I think I would first try placing a sheet of plastic (4'x4' or larger)on the floor and see if anything develops under it. Floor will have to be pretty clean in this area as you need to (really should) tape the edges of the sheet down. Common duct tape should work okay for this. Leave the sheet in place for 48 -72 hours and see if moisture collects on the underside. I would try to do this during (or just prior to) a time/event (such as rain) when the ceiling condensation problem is usually going to be at its worst...or at the least will confidently appear to some degree.

    Change after new roof being installed will take some time to contemplate for potential causes from that. Might be coincidentally related to other things that changed. Will chew on that.

    Does this roof have gutters or is the rainwater allowed to fall right next to the garage wall/slab?
    Last edited by goldhiller; 11-17-2008 at 11:30 PM.

  7. #7
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    Default Re: Condensation in Garage

    Quote Originally Posted by ****hiller View Post
    Very interesting/puzzling.

    None of these appliances vent where the exhaust could be/is getting sucked in thru the soffit venting... I take it.

    For the sake of elimination...I think I would first try placing a sheet of plastic (4'x4' or larger)on the floor and see if anything develops under it. Floor will have to be pretty clean in this area as you need to (really should) tape the edges of the sheet down. Common duct tape should work okay for this. Leave the sheet in place for 48 -72 hours and see if moisture collects on the underside. I would try to do this during (or just prior to) a time/event (such as rain) when the ceiling condensation problem is usually going to be at its worst...or at the least will confidently appear to some degree.

    Change after new roof being installed will take some time to contemplate for potential causes from that. Might be coincidentally related to other things that changed. Will chew on that.

    Does this roof have gutters or is the rainwater allowed to fall right next to the garage wall/slab?
    Hi...again thank you so much for taking the time to reply. I certainly will try the plastic sheet. As the cold weather is here to stay I expect the condensation to get worse. There were days last year that the condensation was actually dripping onto the SUV. The house has gutters which I regularly clean out (Poplar trees all around. Again thank you.

  8. #8
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    Default Re: Condensation in Garage

    Quote Originally Posted by Niagara View Post
    My bungalow was built in 2003. December 2004 I noticed extreme condensation on my garage ceiling. There is no insulation in the garage (like my neighbour's homes, who do not have this problem) & the garage is attached to the front of my house. There is no moisture in the attic. The problem stops when the weather warms. I had an exhaust fan installed last year which runs 24/7 from November to March. I have asked numerous professionals & the Tarion report (our Ontario new builders board) stated that "the home owners admits she frequently drivers her SUV into the garage - unwarranted"... well I thought that was what a garage was for! Has anyone else had this problem & any solutions?
    Is there a seperate closed off attic in the garage or is the underside of the roof exposed into the garage?
    Is there a room above the garage?
    "" an ounce of perception -- a pound of obscure "
    - Rush

  9. #9
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    Default Re: Condensation in Garage

    Hi. When you go into the attic above the garage it is open through to the rest of the house. There is a 1/2 wall between the garage & the house to hold the rest of the insulation above the house. I've been up there & it is totally dry & I can see the vents in the roof & soffits. I had a company come in with a "heat" sensor & he found nothing. My vacumm cleaner vents in the garage, but so does the other homes like mine without this problem. I also had an insulation company come in to give me a quote on insulating the garage, but he said he didn't think that would help the situation. I've now uploaded 2 pics. Again thank you.
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  10. #10
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    Default Re: Condensation in Garage

    Quote Originally Posted by Niagara View Post
    My bungalow was built in 2003. December 2004 I noticed extreme condensation on my garage ceiling. There is no insulation in the garage (like my neighbour's homes, who do not have this problem) & the garage is attached to the front of my house. There is no moisture in the attic. The problem stops when the weather warms. I had an exhaust fan installed last year which runs 24/7 from November to March. I have asked numerous professionals & the Tarion report (our Ontario new builders board) stated that "the home owners admits she frequently drivers her SUV into the garage - unwarranted"... well I thought that was what a garage was for! Has anyone else had this problem & any solutions?
    Quote Originally Posted by Niagara View Post
    Hi. When you go into the attic above the garage it is open through to the rest of the house. There is a 1/2 wall between the garage & the house to hold the rest of the insulation above the house. I've been up there & it is totally dry & I can see the vents in the roof & soffits. I had a company come in with a "heat" sensor & he found nothing. My vacumm cleaner vents in the garage, but so does the other homes like mine without this problem. I also had an insulation company come in to give me a quote on insulating the garage, but he said he didn't think that would help the situation. I've now uploaded 2 pics. Again thank you.
    i would expect your door from the house to garage is open more often in the winter than your neighbors and may have a sealing problem when it is closed. i would also guess that your neighbor's main car garage door is open less frequently for less time or less often than yours, and remind you that an SUV generally is heavier and has a bigger engine (more mass to the engine and fluids quite warm when driven in to the confined space just refreshed with dry cold air with the door having been opened) with a smoking hot exaust system than a smaller car. the rest is stack effect and condensation. if you're in and out of the garage constantly from both directions in the winter you'll tend to have condensation and frost issues in an unheated garage.

    that's where i'd focus my investigation first, that and the band joist sealing for air infiltration.

    this half wall only dividing the garage attic and house attic AND no insulation over garage ceiling seems VERY STRANGE to me to have an open common attic over both would never pass here would have to have a full insulated wall from attic floor/garage ceiling thru roof deck in the attic here between uninsulated garage and home that could be part of the problem any warmth that was over the house would move to the cooler air over the garage and condense not exit the attic so well. i'd also check for a vapor barrier underneath your attic insulation towards the warm side and look for areas where it isn't sealed.

    this exaust fan that you installed and run in the garage all winter long seems to be a total waste and might even add to your problem. lets assume your garage is well sealed where would the make up air come from? likely extracted and infiltrated from the common garage to house wall - meaning warmer moister air - entering colder air in garage - and condensing/freezing.
    Last edited by Blue RidgeParkway; 11-19-2008 at 07:04 PM.

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