I am trying to tile the lower half of my bathroom wall, but have run into a couple of problems. The main problem is that when the bathtub was installed, the excess length was for some reason shoved into the closet that has the access to the water lines making the visible length (also the width of the room itself) 65". The backerboard and the tile would end up hanging over then ends of the tub if installed over the existing wall. The walls are plaster, but the part that I would like to tile also has and addition 3/16" of what one guy referred to as "king's cement" (or king's concrete- i can't remember which) where lines were traced in the material to make it look like tile. I am just wondering if it would be possible knock the plaster out off the bottom half of the wall and install the concrete board directly to the studs or if doing this would destroy the remaining plaster... I'm not sure if I've sufficiently explained, so if anybody needs any clarification of anything before offering any suggestions, just let me know. Any ideas at all would be appreciated!