Greetings!

I have a second-story bathroom shower stall and a small area of water damage on the ceiling of the room below. I measured the spot and it is directly underneath the drain or trap. It is a very peculiar leak. Here is what I attempted so far to nail down its source:

-- Stopped using the shower for several days. During this time, no further water damage appeared. The problem does not appear to involve the trap leaking.

-- I filled a bucket and poured several gallons of water directly down the drain. No additional water damage, so it appears the leak does not involve the drain pipe.

-- I caulked certain areas near the base of the stall along two outer walls where the original adhesive between the tiles had become cracked and/or chipped. If there are additional cracks to caulk, they are not readily visible. This did not stop further water damage from appearing.

The drip is intermittent. Water damage does not appear each time the shower is used. I've not determined if it's tied to how long a shower is taken or how a person is splashing about. But it seems to me that somehow that water is getting underneath the stall and onto the outside of the trap, from where it drips.

That's enough of me going on. The absolute last thing I want to do is cut through the ceiling. Experts, please help!

It's definitely a little peculiar. Obviously the only way to know for sure is to cut the ceiling so you can see exactly what's taking place. Since the leaks not an issue when the showers not used, that takes away the possibility of a water leak in your water lines because they would leak 24/7. If you've poured several gallons of water down the drain and didn't notice any drips, I would check around the shower arm piercing and the valve plate piercing in the wall.

If those aren't covered well(especially the trim plate on the valve) you can get water into the wall and it could be dripping down there. To be safe, you might caulk around the trim plate and shower escutcheon to be certain your not getting water into wall and on to the ceiling from those two places. Hope this helps.

Malex27, thank you for the response!

-- If I were to cut away the ceiling (which is absolutely a last resort because of how impossible it would be match it back up), what would I be able to see as far as where the leak is originating? In other words, opening up the ceiling wouldn't necessarily mean that the leak would be fixable by going up into it, would it?

-- What exactly is the difference between the trim plate and escutcheon?

After reading your post, I examined the valve. It is surrounded by a round decorative piece (the escutcheon, yes?) I undid the two screws holding it in and pulled it forward. There was a little mold on the wall where the decorative piece touched it, but nothing to suggest an inordinate amount of seepage. I could peer into a hole in the wall, too. All the pipes were dry, including the one that runs up to the shower head, and there was no evidence of water damage on the studs. I still might caulk the decorative piece when I put it back together, but I doubt this is the source.

Two other things I'm considering. First is to caulk further between the tiles near the base of the stall. What I'm wondering is, how big does a crack need to be to be the source of a leak?

Second, if the problem were near the head of the drain, how could I find out for certain and what might be a good way to fix it? Is more caulking in order?

I'm so full of questions. But I greatly appreciate the help!

Do a pan test.
PAN TEST- to do a pan test, remove the grid, use a cotton rag, wet it, put it in a baggie and stuff it in the drain to clog it. Then use a bucket to fill the shower with about 2" of water. Use a different source other than the shower for the water. If the pan has failed you will get a leak within 15 minutes.
FAILED PAN TEST- a failed pan test means you are going to removed the shower floor completely to the rough floor and at least 2 tile rows above the shower floor and start over. You will need a drain [possibly] and a new pan at least 6 inches high. No penetrations with nails or screws below the top of the finished curb height. And tile.

Thank you, Doug!

My time is being stretched a little thin, but I have not run a pan test and will do so shortly.

Bump!

To my surprise, the shower stall passed the pan test. I conducted it exactly as described, but no new water stains appeared on the ceiling below. I even left the water sitting for about an hour before draining, and I've gone back periodically since then to see if new damage has appeared. None has.

As I mentioned, I have had little time for this project recently, but my next step is to revisit my caulking job. Any other opinions would be greatly appreciated!

Thanks!

As a rule we leave the pan filled with water overnight to check for a leak. One hour doesn't give a slow leak time to show up. I suggest you do the test again tonight an\d let it set until morning. Get back to us with the results and we'll go to step#2. regards. Tom

I personally feel a one hour pan test is enough. I would not open the ceiling, it will show nothing but the bottom of the floor with a drain hole in it.
There are 4 things you are looking for. 1- drain leak, potable water leak, pan leak, splash leak.
1- drain leak- pour water down the drain only by way of funnel or by hose.
2- potable water leak- leak on shower valve or shower head or piping.
3- pan leak- pan test
4- splash leak- get inside the shower and spray the walls all the way around and check for leaks in wall and caulk and the door sweep. Most leaks are at the door.

Tom: Pan test No. 2 (overnight) is under way. I'll post the results tomorrow.

Doug: I have not caulked the door sweep. I think that is an excellent idea.

Thanks to all for your suggestions!

Pan test No. 2 has shown no new water damage.

I will caulk along the base at the door and anyplace else that I might suspect is the source, then we'll start reusing the shower stall. I'll post the results once they become evident.

Bump!

Eureka. Caulking on the inside of the door track has stopped further water damage from appearing on the ceiling below.

My thanks to you all!