The second coat is being applied horizontally. The first coat of Hydroban was applied up & down. Which cement board do you think will sell better: Brand A (waterproofing unnecessary) or Brand B (waterproofing definitely required)? In fact, they may even be vague on purpose. ~WonderBoard® Lite Backerboard / TDS266 Ĭonsult local building codes. These areas also require proper waterproofing. Nail or staple 15 lb roofing felt or 4 mil polyethylene sheeting to the studs… Any shelf, ledge or horizontal surface subjected to water exposure must have a slight downward slope for water runoff. A moisture barrier must be installed to protect the wall cavity for wet area installations.Update: Custom Building Products has changed its stand on this since I originally wrote it. retarding membrane is optional unless the local building code requires it.Hardiebacker (James Hardie): the use of a waterproof membrane, vapor barrier or vapor.Durock (USG): If waterproofing is desired, use USG Durock™ Tile Membrane or USG Durock™ Brand Waterproofing Membrane.If the area behind the backerboard must be kept dry, use RedGard® Waterproofing and Crack Prevention Membrane or Custom® 9240 Waterproofing and Anti-Fracture Membrane Wonderboard (Custom Building Products): See update below WonderBoard® Lite is not a waterproof barrier.Consult local building code for moisture barrier requirements PermaBase (National Gypsum): PermaBase PLus is not a water barrier.Hence the question “Is cement board waterproof?” Well, here’s what some manufacturers have to say about waterproofing: Yet, it seems like where the confusion comes in is when you look at the different backer board manufacturer’s instructions. B412 Bathtub or shower with prefabricated receptor. Here’s what the TCNA handbook has to say about the matter:Ī waterproof membrane or vapor retarder membrane must be specified to prevent moisture intrusion and protect adjacent building materials. Tile contractors have a “bible” from an organization called the Tile Council of North America (TCNA). However, after researching the manufacturer instructions for each backer board I find the confusion on the matter is understandable.

Furthermore, the last thing a contractor needs is for the whole Facebook community to be criticizing how a shower was constructed.

What side of hardibacker faces out