I am new here so please bear with me as I learn the ropes. I am building a shower stall with a mud bed where a tub used to be. The mud bed is in, utilizing the rubber sheeting and weep hole drain system. The walls are up with Durock concrete board but I just learned about installing plastic or some kind of waterproof barrier on the studs behind the concrete board. I know I can band-aid that by applying a membrane like Hydro Ban, Redgard and the like but, my question is, seeing the mudbed is installed properly, do I just do the walls with the Redgard or continue accross the mudbed/floor? Thanks ahead of time for your reply. BILL