I've been chasing and chasing a shower stall leak in a shower stall installed about 15 years ago (fiberglass, one-piece). First I found a leak in the floor drain flange. Had to chisel it open from the top given the hardened "sealant" previously used. Replaced top and bottom pieces, followed proper order of gaskets and sealed top flange with plumber's putty.
Next found leak in P-joint connection where ring tightens, fixed that. Next found slight leak in 2 inch pvc connection. Got that to stop with cleaning and re-swabbing with PVC glue (nearly impossible place to try to rip out and replace without lots of dry-wall/frame tear-out).
Also, sealed up the faucet wall plate much better.
But I still have a slight leak. I'll do better inspection, but I am about sure it is coming again from the floor drain. Only have a leak when I shower. Not when I just run water, or my small children use the shower. I'm about 160lbs.
I do not believe the shower floor was well reinforced (packed). However, I really cannot see any noticeable deflection.
Is it advised that I try to reinforce the shower floor from underneath (I have some tight access through a hole in the ceiling below) even though deflection is not really noticeable? Is there a practical way to do this with very limited access from underneath?
Is there a product to use better than plumber's putty to seal that drain flange that will stay in place well while the flange is screwed down, and will subsequently better handle a little possible floor movement?. and will let go if I need to again remove the flange.