I have a shower and tub combo with a single valve control for hot/cold. After about 15 minutes of use the shower begins to leak from behind the fawcett, leaking down the fiberglass and onto the ceiling below. Any ideas what may be causing this leak? It's not leaking from the pipe but from somewhere between the metal plate (where the pipes go into the fawcett and the fiberglass?

Remove the chrome face plate and let the water run until the leak shows up. Feel the valve body. Is it wet? No? Then feel the supplies. Are they wet? No? That would seem to put the problem in the drainage. Let me knbow what you find. Regards, Tom