Help troubleshoot my mystery wet spot

You know, one night I went to get into bed and found my sheets were soaking wet. Under the comforter. As in, no wet spot on the comforter, but a big puddle on the sheets underneath. I assumed that someone had pee’d there (2 cats and 1 dog) but there was no colour and no odour. I finally figured out that my dog had a seizure when I wasn’t home - when she had a seizure she’d shake and drool - and where’s the safest place to go? Under the covers. So is it possible that one of your dogs is having a shake-and-drool seizure when you’re not home and just happened to go to that same spot?

I would go up in the attic again and check very carefully. The last leak I had was in my garage, and I assumed the leak was right over where the water was dripping onto the garage floor, but when I looked more carefully I realized the water was coming from a point well away from the pool in the garage. It followed an almost invisible tiny trail along beams etc. until it hit something that made it drip. I would check up top again and check the electrical conduits and also the skylight for a miniscule trail of water, and look directly over the wall nearest the wet spot. Leaks can be really maddening. I think every leak I’ve ever had took a lot of detective work to puzzle out where it was coming from (and how to get at it).

^^^What s/he said! My son’s errant leak started in the attic roof a good 20 feet away from where it eventually dripped down into the first floor. Took them quite a while to find it, but they were assisted by a couple boxes of random stuff that were on the way there and had absorbed some of the leak trail.

You happen to live next door to the Griswolds?

you’re going to have to go in the attic the next nice, long, soaking rain comes and check things out. if there’s nothing at or around it that could spray to that spot, if it’s for sure not your animals, if no one is fucking with you, above it is where your answer lies.

there are no mysteries, only things that seem mysterious because we haven’t solved the problem yet. apply the scientific method to this.

There is a thing called a moisture alarm (I just googled it, that term works). A plumber recommended one to us, I have no idea why since our leak was in a place you’d expect a leak, with no mysteries, and was easily detectable, but I digress. Anyway, get one of these things, dry out the area, put the moisture alarm there in the trouble area and when it goes off see what’s causing it.

And if it never goes off, no problem!

Huh, this happened here a few years ago. I thought it so bizarre that it couldn’t happen to anyone else.

Huh, this happened here a few years ago. I thought it so bizarre that it couldn’t possibly happen to anyone else.

I love these Kayaker mystery threads, so I’m subscribing to find out the answer.

My bet is on the roof and the light fixture.

Ooh, I know this one! The murder weapon was an icicle.

I was going to make a lewd suggestion referencing your girlfriend, but I thought it thru and decided against it.


Have you cleaned out your gutters?

I agree you need to lay down plastic and a towel.
See if the water is coming from above or seeping in from below. A wet towel means it’s from above.

I suspect there’s water in the wall that is slowly draining onto the floor.

OK, I used our carpet cleaner to extract water from the area, laid down a towel, placed a small tarp over the towel and another towel on top of the tarp.

Going up into the attic is my next step, but it will have to wait until my gf is home to assist. Last night she “had to attend” the Penguin game (entertaining a client). I asked if her seats were any good and it turns out they had a suite! Tonight they are taking the client somewhere else.

My last unexplained wet spot was during a summer drought. There was water coming up in a small garden behind our house. I turned off our home’s water, did all kinds of investigation. Turned out to be a grapevine’s root that I’d transected below ground.

I am sure you would have mentioned this, but perhaps A/C condensate leak? In many houses the condensate line runs down through the air return to a drain pipe. Over time they get clogged and the water is first noticed in the carpet near the return.
But it seems very unlikely-a) you would have figured it out on your own, b) now is not the time to be running the A/C in most parts of the US.

Since this is a mystery thread, I will post mine. With the solution attached.

I had a wet spot in the carpet of the bedroom near the wall between the B/R and the family bath. The obvious culprit was a leak in the bathroom. However, the leak only appeared for a couple of weeks in the spring and then in the fall. The rest of the year there was no leak. Extensive examination of the plumbing-I removed the sheetrock in the bedroom to examine the plumbing closely-showed that there were no plumbing leaks. The clue was that the leak was exactly next to the vent pipe that went up through the roof. It turns out that the installer wanted to keep the vent pipe roof penetration behind the crest of the roof and equipment installed in the attic made that a tight fit. The installer had cut a notch in the vent pipe elbow to bend the pipe around the obstruction. The notch was a bit deeper than needed and resulted in a hole in the vent pipe near the roof. During the cool mornings of the spring and fall, steam from the showers in the bathroom condensed in the vent pipe, rolled down the inside of the pipe until if found the hole, then continued to roll down the outside of the pipe until it got to the bottom of the pipe inside the wall. There it dripped off and happened to run out under the wallboard and into the carpet. During the much hotter and or cooler in the winter periods, the vapor didn’t condense in the pipe. I was proud of myself for discovering the problem.

The laws of physics are tough to circumvent. Gravity dictates that water seeks the lowest level possible. If you’re absolutely sure there are no water lines in the vicinity of the area in question then it has to come from a higher level. Go into the attic and tape off every roof entry point with construction paper. Any water hitting this should leave some sign of entry.

Also pull insulation away from the attic joists to look for signs of water. Particularly next to intersections with walls… As a rule, water marks are easy to spot.

There is no AC in the house, other than a bedroom window unit that is in storage for the winter.

Going into the attic tonight. The towel on the tarp is dry, yet the carpet is wet again. It has to be coming from the attic, down the inside of a wall.

I’m betting on the light fixture. If you can live without the light next time it rains, I’d take out the bulb and tape a newspaper under the ceiling such that the light fixture is covered. If it’s leaking there, it will wet the paper. If the floor wets and the paper doesn’t, then it’s coming from below. If it is the fixture, you might see some corrosion when you unscrew the bulb.

I appears that, if nothing else, you’ll find AncientHumanoid’s mind there…