Hi, I'm framing in a new stall shower, have looked at web sites on the subject and most experts suggest putting a moisture barrier under the cement board. I can see why that would be good. One company, which produces a thick (15 mil) membrane for this application, also shows a detail in which a silicone sealant is used between the membrane and the backer board. There is no mention of brand of sealant, and it doesn't seem they sell it. This is a first for me, and I'd like to learn (from an impartial third party) if this is standard practice.

Thank you

Tony Tammer