Plumbing and Piping - Shower Leak in Wall

Hi Everyone,

I have a strange situation (to me, anyway) that I ran into tonight. I have determined that I have a leak right where the plumbing fixtures are in my shower (the shower is all 4X4 tile, no tub, built in 1978). Luckily, the shower shares a wall with my bedroom, so I figured I would just cut a hole in the wall and access the pipes directly to do the repair. BUT -- after I opened up the wall, there were no pipes to be seen! What's there is a 2X10 that runs across horizontally between the studs. This 2X10 is flush with the SHOWER side of the stud (as opposed to the side that I cut into through the sheetrock). Soooo, where are the pipes? They must be on the other side of this 2X10, on the OUTSIDE of the studs (i.e., the pipes do not pass through the studs in holes drilled through the studs like you would normally see). The strange thing is, I can also see that there is some type of sheetrock or concrete board or something that is also directly on the other side of the 2X10, which would mean that the pipes that run to the H and C faucets are somehow embedded in this layer.

Hopefully someone out there has seen this kind of thing before, and understands what I'm talking about. I've done shower plumbing repair before, but the pipes were always RIGHT THERE when I cut the wall open...

My question(s): how can I access the pipes to repair the leak? I am not up for accessing them by messing with the tile, so I'm wanting to do it from the hole I've cut. I'm thinking that the pipes are attached to the 2X10 with some kind of U-bolt or something. Will I necessarily crack the grout by doing it? Any other suggestions? How do the professionals handle something like this?

Thanks millions in advance!

Have you already done the easy work and removed a cartridge or valve stems to make sure fiber ring gaskets or rubber o-rings or packing is okay at the mixer (s)? And to make sure that the shower arm is teflon taped good?

And have you ruled out the drain or where the tile meets the shower pan?

Hi DaVeBoy,

Thanks for the response!

Actually, I haven't been using this shower for the past three weeks -- I'm doing some painting in there and so the faucets have been turned off. So the leak is not due to any type of backsplash or leaking through the fixtures back into the walls.

And yes, I've been able to rule out the drain itself. I have water marks (on the joists underneath the shower) that are above the drain.