I have a shower cubicle installed about seven years ago. The walls are proprietary waterproof boards - plywood with a laminate surface. The bottom edges are within the upstands that surround the shower tray. They were sealed with silicone sealant, but it seems inadequately - it seems that all three boards are rotting from the bottom, in one case with evidence of mould about 12" up on the edge (I removed the shower door frame to inspect) but most of the way round I suspect the problem in in the bottom inch of plywood which is sodden, black and crumbling. When all is put back no problem is visible - the laminate surface is not damaged.
It would cost well over £1,000 to strip it all out and replace the boards. Question is, do I need to have this work done? I think I can remove the source of the water penetration, eg by fixing a well-sealed plastic trim to the bottom edges of the boards. If there is no further water leakage, am I still storing up problems as rot spreads within the stud wall cavity, eg to the studs or joists? The laminate surface is strong enough to maintain the integrity of the boards even if the bottom edge is rotted behind.
I specified these boards as they were supposed to need less maintenance than tiles!
Chris R