Home Improvement--General/Bathroom Remodelling


I have a 4 part question regarding the fit of our shower room:

1 - we have lathe and plaster walls and they have been stripped and lined with ply. I believe it's marine play but I have some doubts ... how can I tell the difference between marine ply and normal ply?

2 - the room is not completely square and I noticed when the room was lined it remained off-square. I discussed this withe fitter and was told it was no problem as it would be squared off with the tile work and building up with adhesive ... is this ok?

3 - in order to make corners square I noticed that in one particular area the tiles had to be built up by 10mm or more with adhesive (could get my finger behind tile easily) ... is this acceptable?

4 - when tiling, should the walls be completely covered with adhesive (ie, there should be no voids or pockets behind tiles), and if there are a few might it cause problems?

More often than not older houses are not perfectly square. This is not a problem and usually the walls can be tiled without rectifying this.

I would not recommend using plywood, marine or otherwise on your bathroom walls. Water vapour will pass through the plywood and you will get interstitial condensation (condensation building up inside the wall). This can cause mould growth and rot.

I would suggest removing the lathe and plaster and replacing with vapour board (foil backed plasterboard). The foil acts as a vapour barrier, preventing water from passing through the wall.

Tiles should be laid on a thin and even coat of adhesive. usually just 1-2mm. 10mm is far too much. Tiles are brittle, if there is a void behind them, there is a very good chance that overtime they will get damaged - if they stay on the wall that long! Also it is going to be nearly impossible to grout the tiles. If he does manage to do this then there is a good chance it will soon start to fall away. This will allow excessive water to build up, causing problems with the adhesive and to the timber behind.

You are right to be concerned about the workmanship of your tiler. I would suggest getting a reputable builder to take a look at it. Do not pay any money for this work until it has been checked.

Home Improvement--General

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Martin Owen


Anything relating to the design or construction process, as well as questions about general maintenance, contracts, planning permission and building regulations.


10 years' construction experience. I am a qualified Architectural Technologist

Degree in Architectural Design and Technology

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