Last night my second-floor walk-in shower backed up and overflowed while I was in another room waiting for the water to heat up. The water ran along the faux-wood laminate floor to the bedroom doorway, where it apparently started draining through some hidden gap under the doorframe.

By some miracle, there is an air duct in the first-floor ceiling almost directly underneath that doorframe, and (at least most of) the water that leaked from the second floor seems to have run down the duct and dripped to the floor below, rather than pooling on the ceiling.

I caught the flooding and shut off the water relatively quickly, but I think somewhere around a half-gallon of water ended up leaking through to the first floor. Immediately afterward, about an inch of the ceiling around the air boot was wet and soft to the touch. I tried blotting it with a paper towel, and then pointed a fan at it and left the fan running overnight.

Duct boot

Today, there is some of the typical yellow discoloration where the ceiling was wet (not very visible in the photo), but otherwise doesn't appear to be any significant damage. However, I realize there may still be water sitting on/soaking into the top of the ceiling, which could cause long-term damage or mold issues.

If there's a way to remove the duct boot, I imagine it would be easy to look around at the extent of the damage and dry out any remaining moisture. Otherwise I don't think there's anything to be done besides cutting a hole in the ceiling. I have never done ductwork and don't know if this type of boot is removable or how to remove it.

  1. Is there any practical way to remove the boot without damaging the ceiling?
  2. If there's no easy way to remove the boot, how likely concerned should I be about moisture in the ceiling? I live in a relatively dry climate, if that matters. Would there be any way to address moisture issues that didn't involve cutting into the ceiling (or the floor of the 2nd-story)?

1 Answer 1


I just had a new vent installed in my office. The boot was nailed in with 4 roofing nails. They ran flex duct to it, so that's held on with a gigantic zip tie. Yours may have rigid duct leading to it (depends a lot on how old the house it and when the HVAC was last redone), and if that's the case, the boot is also screwed to the duct from the outside with at least 1 sheet metal screw on each side and/or push-fit clips that are difficult to remove.

I'd suggest that your best bet is to keep the fan pointed at it for a couple of days to dry out the surface, and, if you can tolerate it, turn the heat on to warm & dry the interior by heat from the ductwork itself. With as little water as you think went down there, you'll probably be just fine.

Monitor it for a couple of weeks after it seems dry to the touch. Keep an eye out for any additional moisture that seems to be soaking through and any signs of mold growth. If you do see some mold, don't panic - there's mold all around you, it's part of life. There are a few species that are bad for you, so have it tested if you're really worried, then give it a soaking with a dilute bleach solution to kill it.

  • Thanks! I pointed a strong fan at the area for a few days and then bought a pinless moisture meter to check the moisture level. The meter is telling me that the moisture level around the boot is only slightly higher than arbitrary spots along the ceiling (currently I'm reading 3.6% from arbitrary spots vs. around 4% next to the boot). My understanding is that nearby metal can artificially increase the reading, and I actually get a higher reading (5.5%) next to another boot in a different spot of the ceiling, so maybe the true moisture level is the same as the rest of the ceiling.
    – Kevin
    Sep 9, 2021 at 17:31
  • Good news, @Kevin! Glad it's working out well for you.
    – FreeMan
    Sep 9, 2021 at 18:12

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