So I keep seeing conflicting answers on this. I'm renovating a bathroom that was torn down to the studs. On the exterior wall I have siding-tyvek-plywood sheathing-fg insulation inside studs.
My plan is for an alcove tub with cement board backer above waterproofed with redgard prior to tiling that sits above the flange of the tub. Do I put plastic all the way up to the ceiling behind the backer board? Some say that will trap moisture in the cement board. If not do I just put the vapor barrier on the bottom half up past the tub? What about the two interior walls?