wet room tanking height

[ivorbigun0]

Hi all

I have a quick question for you.

Im having to strip out a leaking wet room which was done using a tile safe membrane that had been cut at floor level causing the leak.

Im going to remove the floor tiles and re membrane with a 75mm up stand up the wall. The walls are cement board 12mm and was wondering if these walls need to be tanked and to what height?

Many thanks

Ivorbigun0