best surface to tile onto in a bathroom

[John the tile]

hey peeps.

wats the best surface a tiler prefers to tile onto if they had a choice in a bathroom, and whats a no-no.

ta

 

[faithhealer]

Hi Pete
Marine quality plywood used to be the tilers choice, 18mm preferably but 12mm well fastened down. now theres a swing towards 'backerboard' which, at 6mm (if boards are well secured) deals with height issues.