If I put a 800x800 shower tray in a 1200x800 space (on ply base over a
t&g floor) what is best for bringing up the level of the extra 600mm
floor to the rim of the tray, ready to tile?
A concrete slab would do it but how to avoid edge cracks and water
penetration to the base?
Lay the whole thing in a 1200 x say 1000 concrete base with a bit of
re-enforcing mesh perhaps?

cheers

Jacob