Is condensation on a flat roof drain enough to cause a "leak"

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by speeder, Jan 23, 2013.

  1. speeder

    speeder New Member

    Oct 23, 2010
    Is it possible for there to be enough condensation on a copper or cast iron roof drain pipe to cause enough dripping so that it looks like the roof is leaking? Drywall is stained and water is dripping, but it is sporadic. Doesn't always leak when it is raining.

    1. uninsulated ceiling space
    2. flat roof copper spun drain.
    3. I will assume copper or cast iron drain pipe as it is fairly old commercial building
    4. outdoor temps are between 0 and 5 degrees celcius
    5. No plumbing pipes in the ceiling space.

    if this is not likely then roof must be leaking from somewhere.

    thanks for any help/advice. sorry if this is the wrong section.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Depending on the interior humidity levels, it is entirely possible that if enough moist air came in contact with a cold pipe that it would sweat. It all depends on the humidity levels and the dew point...think iced tea at the beach...the glass will get quite wet. A leak could also be in the picture. Insulating the pipe to prevent the humid air from coming in contact with the pipe should prevent this, but won't help with a leak.
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  4. zillfat

    zillfat In the Trades

    Jan 22, 2013
    home maintenance contractor
    queens NY
    look at sevral things, 1,all tar work on roof esp corners.seams,couping.2,flat roofs only last 10 15 years tar breaks down in 5yrs 3, flat roofs with wood carrier beams tend to worp leaving puddles on roof.a hard wind going up the roof could cause a leak.4 look inside of copper box may need some tar from caulking gun(not as messy as trawl)5 if roof appers deteriorated replace roof.
    there are ways of fixing roof puddling when installing a new lay over roof. call a roofer before inside becomes moldie you may not see it but it may be there.
  5. speeder

    speeder New Member

    Oct 23, 2010
    didn't rain today, but still dripping from the ceiling.

    opened up the drywall, and it was soaked. problem is there's another false ceiling above the finished ceiling, so couldn't directly see the roof drain or pipe.

    thanks for the advice. going to check all the areas where there are puddles.
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