Mystery about leaky ceiling

[CGD]

My 1st floor hall ceiling has a leak. It leaked 1 cup of water from an opening (the opening in the ceiling is for a chandelier) few weeks ago. It again leaked about a cup of water 10-12 days from then and again about the same amount of water in another 10 days. We removed the chandelier altogether to catch the leakage live, but it just randomly leaks. Right above the leaking spot is our 2nd floor bathroom. So it was our primary suspect. But our plumber friend did the testing for all possible causes in the bathroom and found nothing. Tried it on different days...sink, toilet and bathtub shower one by one...still nothing. Also checked through the dry wall hatch but found nothing. He doesn't want to tear open the hall ceiling without knowing the source of the leakage coz cutting open the ceiling would mean redoing the entire ceiling and hence a lot of work and expense. He said he could change the toilet's wax ring but the toilet is probably not causing the leak coz he did the blue dye testing with the toilet flush and found no signs of blue water leakage. The hoa called a roofing guy and he found nothing in the attic or the roof. So, we have absolutely no idea where this leak is coming from and why is it not continuous and happens only at 10-15 days. Any ideas or suggestions? In desperate need of help!

 

[Terry]

What fixture is being used randomly?
Sometimes it's someone taking a bath with the water as high as the overflow. The rubber seal leaks past and that's your leak.
I start high and work my way lower. I've seen shower arms leaking, the plate around the tub/shower valve letting water by, a tub spout that pushes water back into the wall.

 

[Sponsor]

 

[CGD]

What fixture is being used randomly?
Answer-
It's a light fixture..a simple one. It was fitted in by previous owner by cutting a small circle in the ceiling. I can see a pipe carrying electrical wires for this fixture. The wires and the inside of the pipe are completely dry. The water leaks from just outside of it through the ceiling.

Sometimes it's someone taking a bath with the water as high as the overflow. The rubber seal leaks past and that's your leak.
Answer- but we have never filled the tub as high as that. We usually use the shower only which never causes that much water to collect in the tub. Moreover, the dry wall hatch shows that the tub area is completely dry.

I start high and work my way lower. I've seen shower arms leaking, the plate around the tub/shower valve letting water by, a tub spout that pushes water back into the wall.
Answer- we thought of it and poured mugs and mugs of water to test all of tgat. But it didn't cause any leak. Checked it 2..3 times...but coyldnt find the leak. And again, the dry wall shows no signs or leakage from all these places.

Please correct me if I am wrong or if there are any other ways to check for the source of the leak.

 

[Dj2]

What fixture is being used randomly?
Sometimes it's someone taking a bath with the water as high as the overflow. The rubber seal leaks past and that's your leak.
I start high and work my way lower. I've seen shower arms leaking, the plate around the tub/shower valve letting water by, a tub spout that pushes water back into the wall.

Add: the bath drain itself, the flange and could even be the trap.
If you find nothing, you will have to open the ceiling and stop guessing.

 

[CGD]

Add: the bath drain itself, the flange and could even be the trap.
If you find nothing, you will have to open the ceiling and stop guessing.

@dj2 -
I already opened the dry wall hatch. ..Which is right being the tub. I checked it thoroughly. There are no signs of leakage there...totally dry. The floor beneath it -dry, all the pipes and the joints are dry. So correct me if I am wrong coz I am new to all this...but won't the kind of leakage you mentioned show itself when I checked through this hatch?

 

[FullySprinklered]

The symptoms don't make sense, you've covered all the possibilities, welcome to the Twilight Zone.

Go back to square one and check your house pressure.

Turn your water heater wide open and see what happens as the pressure rises.

Often the house pressure goes sky-high after a shower or a load of laundry on hot, if the PRV is defunct or going out. See if that tells you anything.

 

[CGD]

The symptoms don't make sense, you've covered all the possibilities, welcome to the Twilight Zone.

Go back to square one and check your house pressure.

Turn your water heater wide open and see what happens as the pressure rises.

Often the house pressure goes sky-high after a shower or a load of laundry on hot, if the PRV is defunct or going out. See if that tells you anything.

@fullysprinklered - thanks for your input. I am interested in exploring this possibility. Something we had not thought of. Could you please elaborate a bit. And also if the hot water is causing the house pressure to rise, won't it cause a leak every time we shower or do laundry?

 

[Dj2]

Water has to come from somewhere. If not from plumbing - pipes, connectors, faucets, etc. - could be from a roof leak.
We can't tell you from where, sitting in front of a monitor.
Call a competent plumber and find the leak. Then fix it. The other option is to leave it alone and save the plumber charge.

 

[Cwhyu2]

Pour water outside the tub at the apron where it meets the floor like at the end of the tub where it meets the faucet wall.
I have seen many leaks at this spot because it is outside the tub no one thinks of that.
It could also be why it is so random.

 

[CGD]

Pour water outside the tub at the apron where it meets the floor like at the end of the tub where it meets the faucet wall.
I have seen many leaks at this spot because it is outside the tub no one thinks of that.
It could also be why it is so random.

Already ruled it out ...but thanks

 

[FullySprinklered]

@fullysprinklered - thanks for your input. I am interested in exploring this possibility. Something we had not thought of. Could you please elaborate a bit. And also if the hot water is causing the house pressure to rise, won't it cause a leak every time we shower or do laundry?

Not if someone in the house runs water soon after. Running cold water should cancel out the excess pressure buildup from thermal expansion.