From: Mike Armstrong )

I was thinking about tiling onto 12.5mm plasterboard and then
attatching the tiled plasterboard to the wall using plasterboard
adhesive in a continuous daub around the opening thus ensuring that
the whole thing is airtight.

Does this sound acceptible?

I havent tried it, so may be wrong, but I would assume the PB would
bend during lifting and either the tiles would come unstuck or the PB
break. Why not fit PB then tile it?

NT