mysterious massive ceiling leak

I woke up last Wednesday and went downstairs after showering to find several wet spots on my first floor ceiling below the second floor bathrooms, with water dripping all the way through in a couple spots. There was no visible indication of moisture above the ceiling previously. That night was unusually cold (around 15 degrees) but dry, and the heat was running most of the night at a moderate temperature (68 degrees; the heat pump is on the roof). I called the contractor who renovated the house before I purchased it four months ago. When he cut into the first floor ceiling, he was unable to find any leaks in the pipes above, even when the upstairs bath, shower, and sinks were left running for an hour. We resumed using the water again later that day and have not experienced any water coming down since.

In addition to water pipes, the HVAC ducts also run through the house in that space between the first and second floors. I suspected condensation on the ducts and/or the pipes might have been the problem, but the contractor is skeptical. It certainly would have to have been a massive amount of condensation for one night. Anyone out there have any ideas? We haven't patched up the ceiling yet and are understandably wary of doing so before we've found the source of all that moisture.

Do you have a high efficiency gas backup furnace? If so, perhaps the condensate drain was plugged with ice causing an overflow... Just a guess.

any 6 yr olds playing in the tub?

Leaks like that have been from water bouncing off a body and onto a shower valve, getting past the screws that hold the plate on.
A leaking tub diverter pushing water into the wall.
A leak from a shower head that lands outside the enclosure.
Somebody showering with the curtain or door open.
Overfilling a tub with a bad or misplaced overflow washer.
A loose shower drain, moving when weight is moved near it.

Those are just a few that I sometimes find. It's fun trying to find them.

good list
to see if a tub leaks most people would fill it up, but maybe taking a shower would be a better test

we had a slight shower sliding door leak that ran sideays then past the edge of the tile and thru the floor, hard to find, starte d5 min after shower started,

Water in a shower will act very differently when someone is in it, compared to just turning it on and looking for leaks.

Thanks for the responses. The water came through the ceiling in various spots, but most if not all of them were beneath the upstairs bathroom with the tub; I was the only person that used that bathroom that morning. I definitely did not get the floor very wet, would have noticed that. I did fill up the tub last night and climbed up into the ceiling while the tub drained; not a drop of water leaked out. I've showered in the same tub every day since the initial problem, and it has not reoccurred, though next time I shower I will climb up into the ceiling immediately afterward to see if I can detect any new moisture.

As for the suggestion about a furnace: our heat pump is on the roof, two floors above where the leak occurred. The HVAC guys checked it out and said there were no problems, it was functioning as it should. And there were no leaks in the second floor ceiling, which one might have expected if the problem was emanating from the roof.

Is it possible that the tub drain/connection to the drain pipe may have constricted in the cold weather in such a way as to create a substantial leak? And that the leak would disappear once the temperature warmed and things returned to their normal size?

Is there an access port to the plumbing on the other side of the wall from the tub? Many people have a closet there with a removable panel. If you have the closet, but not the panel, you might want to add a panel. That would make inspection easier.

I wonder if there is some kind of inorganic powder you could spread under the tub plumbing that would later show if it had been wet to disclose a water path. Maybe chalkline chalk, or talcum powder? Maybe laundry detergent powder? Not flour or corn starch.

Non-pro; just musing.

Checked the drain right after I took a shower tonight (from the access port and the ceiling below). Doesn't seem to be any water escaping. Does anyone recommend getting someone in here with one of those infrared cameras that can help track moisture, or is that a waste of time one week later when the leak or whatever it is doesn't seem to be releasing water in anywhere near the extent it was last week?

nabbasza said:

That night was unusually cold (around 15 degrees) but dry, and the heat was running most of the night.

Click to expand...

Ice dam on the roof???