Do I need a vapor barrier behind durock?

When building a steam shower always use a surface membrane. Per Tile Elfs comments, the USG (Manufacturers of Durcok) stated to me that I don;t need a vapor barrier behind their product. This is especially weird since they DO acknowledge that Durock is not waterproof, but rather water-resistant.Click to see full answer. Simply so, do you need a vapor barrier behind cement board?You still need a vapor barrier with cement board, although in this case the barrier can go behind the board. Cement board is heavy enough and breathable enough to take the moisture without a problem. By having the vapor barrier behind the cement board you stop the moisture going further into the wall.Additionally, should I put plastic behind durock? You should NOT place a vapor barrier BEHIND the backer board. Where, pray tell, would any such collected vapor/water go? Answer:There’s nowhere proper for such moisture to egress. The current best practice is to place waterproofing OVER the backetboard and just UNDER the tile. Also asked, do I need a vapor barrier behind Hardibacker? You need to install a vapor barrier to the studs at the very least, and you must alway mud and tape the seams with fiberglass cement backerboard tape. Backerboard is water-permeable, and will not stop moisture from entering the wall cavity.Should cement board go under tub?You don’t need any cement board under the tub. It is far more important to have a sturdy layer of ply under the tub.