First time we used the shower in our TT, there was water on the floor. I ran a bead of caulk at the corners of the stall to make sure that leakage around the curtain drained INTO the pan, and that didn't help, so I popped open the little access door, and found that the guy who installed the plumbing had not bothered to tighten the nut on the shower drain. A couple twists later, and the problem was gone. Thank God I found that problem early, before any damage was done. Went round and checked all the drain fittings after that, and found the others OK. My guess is that the installer was just in a hurry.