In alt.home.repair, on Sat, 05 Oct 2019 08:01:33 -0400,
wrote:

On Sat, 05 Oct 2019 05:05:32 -0400, micky
wrote:

How to open bathtub wall, with least amount of damage?

I have a leak in the bathtub between the hot or cold faucet and the pipe
that goes to the spout.

I'd like to take it apart with the least damage to the tiles that are
there, because they're already cut to fit the valves, and because I have
a little OCC (that's like OCD but not as strong).

The tiles are 4", what looks like plastic, and the grout lines are
narrow. All that comes to mind is using a utlity knife to cut through
the grout and backer board. Will that work? Built in 1979, before
there was green board iiuc so that just leaves sheet rocK????

The way I figure, there is no way to tell in advance if it's the hot or
cold that is leaking other than letting it run and going downstairs to
check if the water coming through the ceiling is hot or cold, and I
don't want any more water to come through the ceiling.

But maybe the leak is in the pipe to the shower head?? When it's
leaked, the diverter was set to the bathtub spout, not the shower head.
Is that enough proof that the leak is not in the vertical pipe to the
shower head? That is, does turning the diverter to one, close off water
access to the other? Or does the valve just open and close the water to
the spout, and when open, it doesn't come out of the shower head because
it's easier to come out the spout?

Wouldn't it come out both the spout and the shower if the pipe were open
to both??

I don't think I'm being clear but maybe I am. I'll try again if you say
I'm not.

What is on the other side of the wall? Back in the olden days they
used to have a plywood access behind a tub. That practice may have
gone away by the late 70s tho.

If the house were bigger, it might have that.

As for the valve, the diverter only plugs up the spout, gravity does
the rest and keeps water from coming out of the shower when the spout
is open. Some designs had the diverter in the spout and nothing at all
on the valves.

Oh, yeah, I've seen that.

So it's possible that even with the spout open, the water pressure might
not be enough to reach all the way to the shower head, but it might be
enough for the water to go up 8 or 12 inches and then leak out there.
If it's not the spout, though, it's probably a connection, a failed
solder joint** and not the middle of a pipe????

**One piece hot/cold/diverter/with shower and spout outputs still used
soldered joints, didn't they????

You can prove this by sticking your toe in the spout while you are in
the tub with the water running. It will come out the shower. The fire
department knows how to get your toe out if the stick it in too far.

Oh, good. So I should take a phone with me when I do this.