Weight limit an issue at low tile height?

[DHTiling]

Use Plasterboard adhesive..

 

[Scott]

You could tank the area with a paint on gum such as Mapeigum.

 

[monkeyhanger]

OK plasterboard adhesive it is then - just got to chip the old stuff off - that's an epic job in itself!

I wish i'd bought less wood for the studwork on the other 2 walls now! I'll find a use for it somewhere.

Don't think i'll tank on a bath that gets used nowhere near as much as the shower. Good grout and good seal around the bath rim should be ok for me.

Why do these new house builders bother plastering over a board they know they're going to be tiling over (assuming the board is flat and level)?

Thanks again to everyone for the advice.