i've just ripped off the tiles in my shower room ,around the cubicle the walls where dot and dabbed and the water had blown the plasterboard so i was going to stud it out then screw backerboard to the studs but the block work is so uneven ive had to dot and dab it again with plasterboard ,the bloke down at topps says i cant stick backer board onto bare plasterboards even if i plaster which i wasnt going to ,he says it has to be screwed with special screws .my plan is to stick the boards on with a rapid set or somekind of no nails also screw staright to the bloack walls just to be sure it holds ...................................any advice welcomed