Hi. I've just had the bathroom re-plastered and will be tiling soon. We have a shower above the bath and are wondering about what to use to waterproof before tiling. The plan was to use the mapei waterproofing kit on the walls (but not the tape as from what I've read this can peel off the edge of the bath after a period of time) and then use the mapei keraflex adhesive. Is this actually necessary or could I just use mapei primer for plaster and tile straight on. The tiles we took off recently didnt have any waterproofing under them and everything was dry. I'm not sure of waterproofing is necessary for a shower over a bath or just on shower cubicles. Thanks