Spout Leak

I have a Kohler slip style spout which has developed a leak between the pipe and the spout. I tried just tightening the set screw, no joy. I have two concerns:

First, the water has been leaking behind the fiberglass shower wall. Is there supposed to be a pan or something else to catch water if it leaks there? It seems like an obvious place for a leak and with the caulk between the rim of the spout and the wall you would never see it until that seal tore. That is what happened in my case.

Second, how do I reinstall the spout? I assume I need a gasket or seal between the pipe and the spout seat (?). I may need a new spout I suppose, but there is no obvious damage to the spout or pipe. I am also wondering if the gap between the edge of the hole in the shower wall and the pipe is supposed to be filled or sealed somehow. That seems like it would be tricky but there is some material in that space but it only covers a portion of the gap (1/3). I know I will need to re-caulk between the shower wall and spout again but obviously I want to ensure the installation is leak free. How do I do that if the spout is up tight against the shower wall?

Any help will be greatly appreciated. Thanks.

Normally the only water that will get behind the fiberglass wall is from that which is splashed on the wall and drips down and wicks through a hole. The spout is usually caulked around the top 3/4 or so to prevent that from happening. There isn't anything behind the fiberglass, the assumption is that it is waterproof. You'd probably find bare studs, and the flanges of the thing screwed or nailed (or maybe if it is panels, not a one-piece) glued to the existing wall (which would require something to support the wall). The push-on tub spouts only use the set screw to keep it from turning, it has nothing to do with the water seal. Tightening it too much could dimple the pipe and make it harder to put a new one on, I supposed (I don't have any practical experience in this!). My unprofessional opinion.

This particular spout is leaking back through the set screw fitting along the pipe and behind the fiberglass as well as down into the tub (there is approx 3/8 inch gap all around between the pipe and the hole in the fiberglass wall of the shower). I guess what I am wondering is what normally keeps the water from leaking back through the set screw area when the diverter is pulled, i.e. where does it seal? The spout was caulked along the base to prevent water from seeping in from the outside but the leak is within the spout itself.

a properly installed/not defective spout doesn't leak. If the pipe was bent slightly, then the push on spout can't make a good connection. As I said, I don't have much experience with this. But from a practical point, if they all leaked, nobody would use them...Either you had a defective spout, the pipe was bent sometime (could have happened after installation - it is NOT a handle). Take it off, check out the pipe, I'd bet that it is not round anymore or has scratches or dimples in it where the seal is. One of the pros may have some good experience with this and has other ideas, but that is what I'd do if it were mine!

A slip on spout seals around the copper tubing with an O ring. Chances are you need to replace this. However, as Jim has mentioned, if the pipe is out of round or damaged in some other way the O ring may not seal.

There was no o-ring present when I pulled the spout, obviously this is the problem. The pipe looks good. The builder is sending a plumber out tomorrow, it will be interesting to get his take.

Thanks for the replies.

Plumber showed up today, replaced spout, works 4.0

Brass Pipe

Your post seemed to indicate that the pipe coming out of the wall for the tub was unsuitable for the set-screw to hold onto.

I've seen this and agree - if the pipe is copper. My mother's house had a bathtub spout pipe that was copper. This was bad because the set screw punctured the copper easily (copper being a soft metal).

I've recently found (at my local Ace HW) to my amazement they had brass nipples (a 'nipple' being a pipe with threads on both ends). In soldering up a new bathtub spout in my home, I've installed a FIP (female adapter, a place you can screw a threaded (male) pipe into). Into that I screwed the brass nipple that came with the tub spout.

If you're having similar troubles with mangled copper, I'd suggest replacing a straight copper pipe with a brass nipple. The set screw won't puncture a thick brass piece like that.

Oh - and make sure to put a gasket around the nipple with a big glob of silicone sealant to prevent water from leaking from the shower into the wall. I have 3 toddlers and if the sealant were only around the top 3/4 of the spout opening, the splashing would quickly flood behind the wall area.