House haver expertise wanted

November 5, 2023 2:19 PM

Can ceiling drywall be wet without an active leak?

I’m buying my first place (a second floor apartment in a 1916 three story building) and the inspection came back pretty clean, except for a damp area on the kitchen ceiling (pics). The owners/listing agent said it had been there for ages, but they agreed to open it up and see if there was an active leak. There was an old radiator pipe back there that was no longer in use - the third floor apartment doesn’t have a radiator there anymore and it wasn’t hot to the touch, and the cardboard they put down underneath was dry after a couple days. The agent said that the drywall can retain the elevated moisture readings we saw even without an active leak but I know jack shit about this stuff and just wanted a second opinion before we close it back up and forget about it. Thanks!!

posted by theodolite to Home & Garden (12 answers total)

I would recommend hiring a qualified inspector, if you haven't already, to check it out. Do NOT hire any inspector recommended by the owner / selling agent if you can help it, and look to see if you can find reviews for inspectors in your area. It's important to realize that water flows to the lowest point - so a leak from a location somewhere under the third floor can flow downhill before dripping to your ceiling. Also look for sources of steam that might be rising to hit that area from the second floor apartment
posted by TimHare at 2:39 PM on November 5, 2023 [5 favorites]

Something is leaking, it may not be at the moment (and sellers may be disguising it) but it will again.

water is the #1 enemy of any homeowner.
posted by noloveforned at 2:40 PM on November 5, 2023 [15 favorites]

Did they remove or cap off the pipe they believe caused this leak? And if so, how long ago? I wouldn’t expect drywall to stay wet for weeks or months.
posted by walkinginsunshine at 2:41 PM on November 5, 2023

Funny you should ask: we just had three leaks in our condo caused by bad pipes in the unit upstairs. They were fixed, thanks to the upstairs owner, but it was a rough day.

So, as it happens, I can do some science. I just felt the drywall where one of the leaks was, two days ago. It's dry to the touch.

Also, TimHare is absolutely right: one of the bad pipes was 10 feet from where the water spilled into our unit.

The cardboard test is reassuring, but I'd ask: is the unit above occupied? Is it also a kitchen just above you? (Kitchens have lots of things that can leak.)
posted by zompist at 2:50 PM on November 5, 2023 [1 favorite]

The water is coming from somewhere. Either get it tracked down before buying the place, or budget in for troubleshooting and fixing it after you buy it, but don't ignore it.
posted by Dip Flash at 2:51 PM on November 5, 2023 [2 favorites]

Response by poster: Some additional notes/responses:

- we had our own inspector take a look already - he's the one who originally indicated that this was a problem and took the moisture % measurements in the photos I linked.

- it's hard to see in the last photo, but the radiator pipe behind the ceiling comes up from the wall, jogs to the left, and goes up through the floor of the apartment above, and the area where it's above our ceiling is the exact size/orientation of the water damaged area. So it seems very likely the water is coming from that pipe (a leak? condensation?) even though when we visited today, the pipe was room temperature and dry.

- The unit above is occupied and there is a kitchen up there, but

Thanks for all the responses confirming my suspicions that the "drywall can registered a moisture reading for years without an active source of water" spiel from the agent was BS - we'll definitely make sure we try to find and fix the issue before we get it plastered back up.
posted by theodolite at 4:00 PM on November 5, 2023 [1 favorite]

Oh, yeesh, not YEARS. I would be willing to buy something like "drywall can be damp for 10-15 days after the leak is repaired" but years (or even months, unless you are in a damp climate and season) is absolutely beyond possibility. This is most likely still an active leak.
posted by pullayup at 6:17 PM on November 5, 2023 [4 favorites]

You have an active water source of some kind. If it's palpably damp or its state is changing, it's happening now or on a regular/predictable time. The leak needs to be found ASAP.
posted by panhopticon at 10:48 PM on November 5, 2023

Ceiling drywall can easily be wet without a leak, if it is in a multi-unit building. All it takes is a catastrophic overflow upstairs.

One place I lived the kids above us blocked the toilet on a pretty regular basis for a few weeks.

At another place one of the university students in the shared flat above ours put his jeans in the bathtub and left the water running and went to school in an attempt to wash them because he couldn't manage to get them to a laundromat. The jeans shifted until they blocked the drain and the water kept running for a couple of hours until one of the students got home.

And at one place the janitor was pouring buckets of water out above our kitchen to try to encourage us to move out so they could demolish the building, and claiming it was just a pipe leak in the old decrepit plumbing.

It's a very good idea to talk to the neighbours. You want to know who your upstairs neighbour would be anyway, because introducing yourself to them could either provide you with reassurance, or throw up so many red flags you know why the currant owner was glad to tear the ceiling open in the desperate hope that you'd buy the place and they could get it off their hands.
posted by Jane the Brown at 4:51 AM on November 6, 2023 [3 favorites]

The repair might be something a simple as a leaking water supply valve to a tap or toilet but it needs to be investigated. Water can travel horizontally along complicated paths (could be old lino underneath and existing floor or running along the underside of a joist) so it needs to opened up to be certain the wood structure hasn’t rotted.
posted by brachiopod at 8:56 AM on November 6, 2023

Yeah, my upstairs neighbor let her bath run over a few months ago which soaked my living room ceiling. It was dry to the touch within a week.
posted by mareli at 12:25 PM on November 6, 2023

What you want to be very very wary of is that if the leak has been going on for a long time, there can be an enormous amount of rot that is completely hidden behind drywall. Literally cost us $100,000 to deal with. Three separate inspectors missed it. Quite frankly, i wouldn’t touch anything with even a hint of water damage ever again.
posted by congen at 4:44 PM on November 6, 2023 [1 favorite]