Diagnose shower leak I can't find

Have you checked the caulking between the tub and the walls of shower ? When someone is in the shower, water gets splashed and runs down the walls.

TimR-

I can visualize a leak caused by person's weight warping the tub, bending the drain pipe.

Also consider that a "leak" may actually be condensation on surfaces cooled by the tub above or the drain below. This depends on humidity and how cool the water is at the time.

But isn't high humidity caused by the leak??? The only sure solution is to build a new house!

Fred

That's a thought. When I did the foot joint a couple years ago, I recaulked all the way around. I did a sloppy job, having chosen silicone instead of latex and not used to the difference. But until this week it hasn't leaked.

I still need to experiment with running the shower in normal operation, drain not sealed, with and without a person in. If it drips with a person, then it could be the weight flexing the tub, or as you suggest the splash of spray off the person. The place where it drips is directly under the drain and faucets end.

What is the status of the basement ceiling? If it's open joists, you should somewhat be able to see exactly where the water is coming through the floor. If the ceiling is closed up, I'd be tempted to open it for inspection, depending on how much work and damage that might entail.

Sometimes water runs laterally before it drips, making it more difficult to pinpoint the source. I've seen that especially with roof leaks, where the water runs along a truss and you end up looking for a leak 6 feet away from where it really is.

Check caulking along the wall. When you ran the shower, it was probably going straight to the tub, not the wall.

Next, check caulking at outside base of tub. If the shower curtin tends to be outside and the person splashes a lot, there might be a wet bathroom floor and a leak there.

Another thought, is the tub slow to drain and is there a sink very near? They often have conjoined drains here. Fist sign here that the tub needs to be snaked is the sink backs up ;-)

Likely water leaking where it is being splashed by your daughter when showering - in other words NOT the plumbing but a defect in the surround, or water getting in around the shower controls, oe something like that.

What's a foot joint?

So did I but I was lucky that the sheetrock wasn't affected. It ran down the chain into the spherical glass shade for the dining room fixture.

After 2 or 3 years, it stopped, I think because my body dirt plugged the leak.

But when my brother would visit and take a shower in the tub, it leaked again. I took baths and it no longer leaked. So if any of your drain testing involved filling the tub and emptying it, that's not the same as running the shower with the drain open. I'm guessing draining a tub causes the siphon effect to pull the water down the drain quickly so it doesn't leak out, but the shower water has lots of air with it. I don't see why this would make the difference, but it's all I've got.

Today I hung a piece of a painters drop plastic under the shower head and extending down past the faucets.

The plan was to keep splash from the showerer or drip from the shower head from getting behind any of the controls or against the wall.

After one normal shower, there was no drip underneath. That suggests that diagnosis was correct, but it never did drip every time nor very much, so probably not confirmed yet.

But I think it rules out the drain, which is good, because that is a REAL pain to re-seal.

Update: nope, that wasn't it. It still dripped down through the ceiling. I have a different plumber coming next week, someone who's supposed to be good at old houses.

We had to delay a bit, there were some unexpected expenses - roof replacement and new HVAC.

So today I tried to see if I could tell where it is coming from. I filled the tub, waited an hour, no leak; let it drain, no leak. Ran the shower with the tub drain closed, ran the shower with the drain open, no leak anywhere. It seems to drip only when someone is in it.

Things I've tried: replaced the drain gasket. Had a plumber replace the drain gasket. Had a plumber replace valve stems and repack. Had a plumber caulk the overflow. All of which seemed to work for a little while then didn't.

Can the tub flex enough to open a crack? From underneath it is black and looks like cast iron, but the surface looks like a ceramic that matches tile.

re: "It seems to drip only when someone is in it."

Maybe you mentioned it, so forgive me if I ask: Tile walls?

Within months of moving in to my first house, SWMBO was in the 2nd floor bathroom taking a shower. I was in the basement when water started running down the wall.

Turns out the grout was so bad that when water hit the tile it went right through.

I had her turn the water off and when I pressed on the side wall, all the tiles moved in and out. The drywall behind them was soaking wet. I took all the tile and the drywall down with my bare hands. Just peeled it all off.

Maybe direct the shower water to one wall section at a time or use a garden hose to do it? Any cracks where the tub meets the walls? The weight of a person could open them up. Putting a bead of caulk there couldn't hurt.

If running water doesn't leak out of pipes and the drain doesn't leak, almost has to be something like that.

Yes, tile walls. As soon as I read this I went and looked more closely. The grout looks okay, but I found a couple of hairline cracks, one vertical about six inches long, one horizontal about 15 inches long.

One of the things I did when my drain gasket fix didn't work was caulk all the way around the tub and also where it joins the floor.

The spot on the ceiling below where it drips through is directly below the trap on the drain. But water can run sideways until it hits the low point. I really want to find that before the plumber comes so he can make a good diagnosis.

On the other hand. My daughter got into a yellow jacket nest after i'd done the drain, and I told her it was okay to soak in the tub, the leak was fixed. But it wasn't, it dripped through that time without the shower running. I think.

If I recall my situation correctly, I didn't have any visible damage to my grout, yet lots water was getting behind it, right in the middle of the wall.

Any fixtures, like built in soap dishes? That's another place for water to get behind the tile.

Since I couldn't fix my tile wall right away, I covered the wall with a plastic drop cloth, starting way up high and hanging into the tub. No way water could hit the tiles. That 100% stopped the leak.

A hose (or hand-held shower head) applied directly to the wall may be a good test, but unfortunately, the water still has to go into the tub and drain. Maybe letting the tub fill up while you hose down the wall might point you back to the grout, but be aware that it may not leak every time or right away. If the drywall has dried out sufficiently, it may just absorb the water. It would have to reach its saturation point before you'd notice a leak.

Spray it (a lot) and then wait (hours?). No leak, spray it again. Just don't overflow the tub. ;-)

That sounds like a pretty easy thing to try, cover up the walls and see what happens. Also, if that doesn't work and it gets to the point that a plumber is coming, I would be prepared to have the ceiling opened below and the wall on the other side of the shower, which hopefully is accessible. If it were me, I would just do that myself and save $$$.

No argument, but you'll noticed how TimR ended the post that I responded to:

"...it dripped through that time without the shower running. I think."

"I think" makes it sound (at least to me) that it's not clear under what conditions it leaks. Easy test, worth a try. He's tried just about everything else - other than opening the ceiling below and looking up.

Did that, no leak after a couple hours of full tub, but with nobody in it. Hoping to have the kids take baths or showers when they visit this weekend.

I have an 8x12 inch opening in the ceiling below so I can see the pipes (piece of drywall screwed in there most of the time, but I have it open now while I'm working on this.) I'm hoping when I finally see the water move I can tell something by the direction it moves.

As far as wall access, there's an access panel at the pipe end, the other end of the tub is an exterior wall so no joy there, and the side of the tub has a bedroom on the other side of that wall.

So far I haven't actually seen it leak. But I've run it for a long time and watching the pipes from below. I think if the pipes leaked a drip would follow them down.

I had planned to have the family test it this weekend. Unfortunately I now have Covid and feel awful, will have to postpone the plumber too.

Oh no. Did you go get Paxlovid?