We have a shower enclosure that is 29 years old so yes we will be replacing it soon, it has had leak issues off and on over some years but I always could fix them with caulk. Well, it leaked in a few other places a bit ago so I removed any old caulk that came out and replaced it with silicone UNLESS it was the DAP kind of caulk that is not silicone, if it was in good shape I just went over it with the same kind, I have done this many times and it has worked, we had no leaks for about 3 weeks so I thought it was fixed but wouldn't you know it today after the wife showered I saw a small amount of water stain again dripping under the unit in the basement. I looked closely at the caulking that is to the right going up the side wall inside the shower where I suspect the issue had been and it looked fine, this is an old unit that snapped together it is not a one piece like is made today that we will be replacing it with, but I just can't fathom WHY the leak would've stopped for about 3 weeks and now started again? And if it is something other than the caulk what is it? Weeks ago the wife was downstairs watching as I ran just the water (no shower), no leak.....have taken baths with a full tub of water in, no leaks....ran the shower on hot water only, no leaks, ran it on cold water only no leaks until a bit went by then she said "it's leaking", so I caulked the afore mentioned area which seemed to have been the problem spot in the past, used the DAP caulk because it always did correct the problem before even though it's not silicone and we had no leaks for 3 weeks, if it had not dried we would've had leaks before this I would think right away, WHY is it leaking again? If there were cracks in the fiberglass itself the caulk wouldn't have stopped that, if it was a pipe we would see that as there is a cutaway section in the floor under it that I can look up and also feel for leaks, but it seems to be fine.... Again we are going to replace it as it has more than served it's time but I just can't wrap my head around what it is that is causing this now after 3 weeks of no leak!!!!