One thing that is bugging me: if I am using waterproof plasterboard (Knauf) in bathrooms, presumably I do not need to Tank it and could(?) apply the tile adhesive straight onto it. But how can the paper support the tiles? If I stick a piece of masking tape on it and pull it, it will pull the paper easily.

If it is being used in a shower area, then it would be best to tank it first.

The paper supports the tiles because it is all bonded together, if you use a piece of masking tape it does not cover a large surface area, like a wall full of tiles would do.

You can see the weights that certain substrates can support here-


Wall tiling

Correctly braced aquapanel can supporg 50kg per square meter

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DIY | Donnas dream house

i saw my builder tiling on waterproof plyboard is that normal (obviously he put PVA first) is that ok for the bathroom? (it is a partition wall)

He should not of used the PVA, unless it was external PVA. Chances are it will be ok, unless the area gets really wet-

http://www.ultimatehandyman.co.uk/tilin ... se_pva.htm

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DIY | Donnas dream house