Plastic shower pan about to crack. Any preventive measures to take before it is too late?
This is happening to one of my tubs.  I discovered that the tub is sitting on a block of styrofoam, and apparently rats chewed holes in it and created unsupported areas that flex when stepped on.  I'm going to have to replace the whole thing sooner or later, but I temporarily fixed it by epoxying fiberglass patches over the weakened areas.

Update: the patches held up for two years before I sprung for a new tub.