My garage has some water damage, which needs addressing (see photos below). I have a good attitude but no experience with this sort of repair. Does it make sense to try to do this myself? And if not, who do I call? A mason? A GC?

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Here are photos of the wall material.

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  • where did the water come from?
    – jsotola
    Commented May 27, 2020 at 3:11
  • Is it wet now or are we looking at long ago dried water stains? The answer will bear on the urgency of the situation.
    – Michael Karas
    Commented May 27, 2020 at 4:14
  • 1
    @jsotola Not sure, but I think that duct has something to do with it.
    – crmdgn
    Commented May 27, 2020 at 11:05
  • @MichaelKaras Both.
    – crmdgn
    Commented May 27, 2020 at 11:05
  • I see wet spots but no damage, that is a lot of moisture for condensation is that duct for air conditioning? Heat would not cause that. Where is the duct routed?
    – Ed Beal
    Commented May 27, 2020 at 14:07

1 Answer 1


The source of the problem is that's an uninsulated duct running in unconditioned space (the garage). Every time your AC kicks in, the cold air cools the metal which then condenses the humidity in the garage. That humidity runs down the duct as water and soaks into the drywall causing the damage you're seeing.

The fix will involve:

  • removing the duct
  • repairing the drywall
  • reinstalling the duct with insulation to prevent this from happening again

Whether you should do it or hire it out would depend on:

  • how comfortable are you with some mechanical skills and learning new things?
    • you indicate that you don't have experience. These aren't difficult things, but doing a nice job on the drywall will take time and patience.
    • you'll need good spacial relations to be able to visualize the repair necessary, draw it out, estimate your materials (hello 3rd trip to Lowes this week today! don't ask me how I know), cut, fit, fiddle, install.
  • how accessible are the other ends of the duct?
    • where it disappears into the walls - you'll need access to the top at least
    • the bottom looks like you can unscrew the vertical just above the elbow
  • how comfortable are you with drywall repair?
    • It's a garage, it probably doesn't have to look too pretty, though someone may balk at an absolute bodge job when it comes time to sell the place
  • how comfortable are you with replacing bits of the duct?
    • you may need to extend the elbow out to get some insulation wrapped around the vertical piece. A pro probably would, if you DIY, you might get away with "adjusting" the existing piece a bit.
    • you'll probably want to insulate the elbow, too, or it will condense and drip
    • you'll need to get insulation into the section that goes into the ceiling

If you hire it out:

  • A GC isn't a bad option, but would probably be the most expensive
    • If he doesn't have the skills, he'll handle getting an HVAC guy and a drywall guy and getting them coordinated.
  • A general "handyman" type repair service would probably be good, too.
    • be sure to ask for some references and check 'em - you don't want to spend good money on more bad work.
  • You could be your own "GC"
    • hire an HVAC guy to take the duct work apart (he can handle getting into the walls as necessary)
    • rip out cut out the damaged drywall back to the nearest stud where you've got dry, undamaged material. (This will save some time for the drywaller and probably some expense. He'll adjust your cuts as he sees necessary.)
    • hire a drywall guy to repair
    • call the HVAC guy back to reinstall the insulated duct

The more I look at your pictures, the more convinced I become that this is concrete/block, not drywall (hence your mention of "mason", I suppose). In that case, replace all mentions above of "drywall guy" with "mason".

Personally, I've done a lot of projects on my house, but I'm not certain I'd want to take on this level of masonry repair, especially as a "first house project". Others may indicate that it's a fairly straightforward masonry fix. If so, I might feel confident enough to take on, you may too...

Based on the last two images added, that's definitely plaster over drywall. They drywall repairs are simple enough. Doing the plaster on top is a bit more work and skill, but you've got the fact that it's a "rough" and "random" pattern working for you - it doesn't have to be perfect to blend in well enough, and if you really don't like it, you can sand the plaster back off (making a huge mess) and try again (just don't sand through the paper of the drywall).

The most important part is finding the source of the leak and getting that fixed. Until you do that, the rest is just putting a bandaid on a sinking ship. If left unresolved for too long, you'll end up damaging framing, not just the drywall. If that happens, you're in for a fairly large repair bill. Much cheaper to track it down now, even if that means hiring someone.

  • I don’t see any damage just some wet spots. If it is condensation from the AC causing condensation, adding insulation to the duct is all that is needed.
    – Ed Beal
    Commented May 27, 2020 at 14:12
  • @EdBeal in the first image, the plaster/drywall does seem to be falling off. Also, the answer was written with the assumption that it was drywall, and that this much water will damage drywall. The realization that it may be plaster/masonry came later (as noted by the comment at the end). The amount of moisture could be enough to cause the surface layer of plaster to be coming off whatever's supporting it. Hard to know without being physically present.
    – FreeMan
    Commented May 27, 2020 at 14:17
  • @FreeMan The home inspection report says the wall is gypsum, for what that's worth. I believe that duct was built for a heating system that no longer functions, but I'm not sure about that. In any case there's never anything running through that duct.
    – crmdgn
    Commented May 27, 2020 at 15:09
  • @crmdgn in a comment on your OP, you indicate that this is partially prior damage, but that the wall is currently damp in these spots. If this is really unused duct, then removing it (simply cutting back below wall/ceiling level) will be sufficient for that, but you'll still need to identify the source of water. Are there other wet/damp spots in the garage, or is it just here?
    – FreeMan
    Commented May 27, 2020 at 15:24
  • 1
    That looks like Sheetrock with a skim coat, sometimes sand is at Ted for a tougher / plaster like texture. I would be looking in the ceiling for the leak.
    – Ed Beal
    Commented May 27, 2020 at 16:43

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