Tiling

Plywood backer used for shower cubicle which now leaks .. advice please

Anonymous user 03/03/2024 - 2.59 PM

Our shower was put in by a builder and has been leaking water into the room below for a very long time. We didn't realise as the walls below are very thick and the ceiling below is lath and plaster (old cottage). He installed the shower as a new fitting and used 12 mm plywood as the backer for the tiles. He says he treated the wood with SBR before tiling. I am very uncertain about this SBR as I think he should have water proofed the plywood after the SBR before applying the tiles. Can an expert tell me the correct way to get a water proof shower if plywood is used please ? The whole shower will have to come out which is a nightmare He originally said he used PVA but has now amended this to SBR. When I researched SBR it doesn't seem to be right for water proofing plywood against a shower head sending water onto it. The grouting is cracking up and in areas where the tiles have taken the flow of water the grouting is stained brown ... ? from the ply wood ? THANK YOU SO SO MUCH FOR YOUR ADVICE.