Tl;Dr: I have a can light fixture with a water stain that after 20 months just started dripping yesterday. We were told it's likely a bad seal allowing condensation to build up and drip, but I am curious how plausible that is. More details below, but could sealing the can light fix or rule out condensation? Or would it risk catching water from a leak?

I live in a narrow 4 story townhome. The second and third floors are completely finished and on central air. The second floor hasa flat, 12' high ceiling that has can light fixtures sprinkled over it like rice at a wedding. When we moved in, one light had a water stain around it but over the first 20 months of living here it has remained the exact same. We had someone come look at it and best he could figure, it had a bad seal and the cold air from the air conditioned living room was seeping into the space between the floors and causing condensation on the light fixture, resulting in the water stain.

We're in Houston and it's a very hot summer, and just yesterday water started dripping from the light at a good clip; about a drip every other second. None of the other lights have this issue, just the one. To complicate things, this light is directly below a wall shared with a bathroom sink and near the washer drain and the dryer vent. The washer and dryer had both been running along with the AC when the drip started. The washer had finished, we turned the AC and the dryer off and the drip stopped, it started again when we turned just the dryer on, turning the dryer off and the AC back on stopped the drip, then turning the dryer back on did not result in the drip resuming.

The drip had been going consistently for about 20 minutes. So I am thinking

  1. The bathroom sink is no longer a culprit.
  2. Condensation could be exacerbated by the dryer vent when it's running, potentially causing the drip.
  3. The washer drain could be the cause; we need to run it again to see if it for whatever reason has started to leak, but it seems odd that just now we'd have an issue with the drain.

Considering the heat in Houston right now, I'm thinking it's condensation and wondering if fixing the seal would resolve the issue. If it were just renting a ladder and sealing the light, I'd have taken care of that by now. But could there be that much of a difference in temps/humidity between the rooms and the space between the floors that it would cause such a steady drip? If I seal it, could I be creating a perfect drip catch for some other leak and give myself a bigger problem? This is my first home, and I'm scared of taking a misstep and don't even really know who to call. Any input or advice would be appreciated, and let me know if I was sparse in the details anywhere.

Here are photos of the fixtures, as well as a photo zoomed in on the problem fixture: Smattering of can lights

Water spot and problem can

  • Some photos would help to visualise the extent of the problem Jun 29, 2023 at 12:22
  • Are the can lights in question below the attic? If so, what's the insulation situation?
    – Huesmann
    Jun 29, 2023 at 13:04
  • They are not below the attic. The third floor is finished (the floor above the can lights). The problem light is below a wall shared between the master bathroom and the laundry closet. I'll add photos as soon as I'm home.
    – Mjg6y5
    Jun 29, 2023 at 15:15
  • 1
    look carefully at the dryer venting for holes or leaks and ensure especially it is actually venting to the outside
    – Yorik
    Jun 29, 2023 at 16:06
  • Are you able to access the can easily, or is it above a deep stairwell or something?
    – Huesmann
    Jun 30, 2023 at 14:28

1 Answer 1


No (to answer the subject question).

A can light would generate some amount of heat, and the reality I live in and its laws of physics condensation would not be caused as a result of the can light operating (with or without seals).

Condensation is the result of hot and humid air coming into contact with a cold surface

this light is directly below a wall shared with a bathroom sink and near the washer drain and the dryer vent

I live in a narrow 4 story townhome.

Builder did not properly and adequately use insulation. Ccold air from air conditioning, (AC vent within the wall?) is causing condensation of hot humid summer air in your location, then that water is running down where your can light is. Or you have a drain link but is less likely to explain a persistent drip; in the case of a drain leak you'd see more water infrequently as in when the sink is used. Persistent drip is more of the nature of cold uninsulated air conditioning ducts. The can light, with or without a seal, would not cause condensation.

  • This is sort of what I was thinking. Sure, the cold air seeping into the space between floors could maybe cool off that can light, but would it cool it any more than it already is just by virtue of facing the air conditioned room? And while this summer is very hot, that can light is almost smack dab in the middle of the house. It seems unlikely that the conditions would be different enough to cause a 20 minute drip when we've never seen another. Leaning towards needing a way to shore up the dryer vent and the washer drain, I'm just not sure how to do that without some serious drywall work.
    – Mjg6y5
    Jun 30, 2023 at 4:21
  • from the pic showing return duct (larger) at top of the pic and supply duct (smaller) further away at bottom of pic, I would guess the ducts run from top to bottom in the pic such that the cold supply is running alongside and past the return. uninsulated cold duct is condensing above the can light. Pull the can light, run and don't run the AC and see if that affects the wetness, then you know. remove the return grill and seal up the duct within using foil tape so it cannot cause any air movement above the ceiling
    – ron
    Jul 3, 2023 at 11:53
  • and insulate however possible the cold duct
    – ron
    Jul 3, 2023 at 11:54
  • you will eventually get mold there if it continues
    – ron
    Jul 3, 2023 at 11:55
  • and if you think the light (heat) is causing it, just unscrew the light bulb there and that should clear it up... but undo the can light as much as possible and then feel when the AC is on if you have cold air escaping from the cold duct up above the ceiling, if whatever other work up there may have penetrated the cold duct.
    – ron
    Jul 3, 2023 at 12:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.