Rotting shower wall boards

[Chris R]

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

[Ret.]

You have me worried now!

I replaced our bathroom three years ago, and put in a corner 'offset quadrant' shower cubicle (which replaced the old airing cupboard).

Wanting to avoid discoloured grout, I also used laminated boards (Mermaid) for the two internal shower walls. The boards extend outside the edges of the shower by about 1/2" and the bottom of the boards sit on proprietary Mermaid 'Transeal' profiles:

This profile keeps the bottom of the boards well up from the shower tray and so the lower edge of the boards are never 'sat in water'. The slight gap between the bottom of the boards and the Transeal profile is sealed with silicone.

I cannot see any way that I could check to see if water is getting in and rotting the plywood. The outer vertical edges of the boards have aluminium 'end caps' covering them from top to bottom and I have tiled up to those end caps.

So if my boards are rotting - I would have no way of knowing!!

[Ret.]

Further to the above. I note that Mermaid panels have a ten-year guarantee:

1. What does the ten year guarantee cover? Mermaid panels have a high-performance laminate surface which is guaranteed to remain waterproof. We also guarantee that the panels will not crack or delaminate during the ten-year period. The substrate of Mermaid panels is WBP plywood, which is moisture-resistant and provided that all joints and cut edges are correctly sealed when fitted, Mermaid panels are also guaranteed to be watertight. Full details of the warranty are available on request.

I don't know what make of panels you have - but it would be worth a check to see what guarantee they have.

[Chris R]

Further to the above. I note that Mermaid panels have a ten-year guarantee:

1. What does the ten year guarantee cover? Mermaid panels have a high-performance laminate surface which is guaranteed to remain waterproof. We also guarantee that the panels will not crack or delaminate during the ten-year period. The substrate of Mermaid panels is WBP plywood, which is moisture-resistant and provided that all joints and cut edges are correctly sealed when fitted, Mermaid panels are also guaranteed to be watertight. Full details of the warranty are available on request.

I don't know what make of panels you have - but it would be worth a check to see what guarantee they have.

-------------------------------------- Thanks, but it's the "correctly installed" bit that will be the problem. The boards are installed inside the shower tray with no bottom edge (or rear) protection other than a bit of sealant.

Chris R

[Ret.]

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OK