I hear a drip in the wall?

Would we need to fill the entire space back there?

Click to expand...

No. Ideally, you would find where the pipe(s) are rattling against each other or the framing. The separate them a little bit with a small shim. Then squirt the foam in the gap, which will fill the gap and prevent the shim from shifting around or falling out.

Verdeboy raises a good point. Pipes don't rattle just for the hell of it. Usually the rattle is caused by a flow of water suddenly stopping, and 99% of the time (unverified statistic) it's caused by a leaky toilet. When the water drops enough to open the fill valve, water flows to fill the tank, but when the float rises and shuts off the flow, the water stops suddenly. The momentum of water moving throughout the system, and suddenly stopping, moves pipes and can make a noise.

An easy way to see if you've got a leaky toilet: put some food coloring in the tank and come by a while later and see if there's any color in the bowl. If there is, you've got a leak. Turn off the valve at the base of the toilet and see if your mysterious noises go away. If so, repairing the toilet is a lot easier than masking the noise, and will save you $$ on your water bill. You could also simulate the problem by pushing the float down to start water flowing, then release it so the water stops suddenly. See if that causes the noise.

I wouldn't use any kind of expanding product behind a closed wall. It's hard to control and you'd be stabbing in the dark with that.
Judging by your level of exasperation with this, perhaps it's time to call in a pro to diagnose. I bet they'll be able to tell you the problem just by hearing it.

Tighten the screws holding the fitting to the backerboard. There should be three screws holding it. If you have enough room that is.

TMG

I thought we were talking about a drip sound, not a rattle.............

I think it became a rattle around post #15.

No, it was never a rattle, always a drip sound...or at least it sounded like a very loud drip to me. Wasn't a drip at all though, it was the pipe behind the shower wall tapping against the wall itself. And it wasn't only after a shower in that particular bathroom, it would happen after a shower in the other bathroom too, which is on the other side of the hallway. My husband did go ahead and use the foam, which worked great by the way, pipes aren't hitting the wall behind the shower anymore......instead the sound just moved to another pipe. Well, to make a long story short, hubby went down the basement and found that quite a few of the pipes were able to move a bit, so he figured that even if he could stop the noise in one spot, it would just travel to another, which is what was happening. So he spent some time down there securing the pipes so none of them move....which also means I don't hear any noises anymore.
You guys have been such a help to us, and we appreciate it more than you know. Thank-you

T'was probably the hot water pipe that supplied both bathrooms, so it didn't matter which one was run. The pipe expands when hot water goes through it, and then contracts after you shut it off. If it can rub on something, it can make noises.

Did we ever determine whether the pipe was copper or otherwise? I was amazed when I saw how much CPVC expanded with temperature.

If your kitchen sink drain drains to the same stack as the bathrooms and you have PVC plumbing and run hot water, the ticking sound will show up.

That's what I hear you say. No easy to fix........