Hello I found this site searching for the answer to my question so I'm a very new. Did a site search also and couldn't find a answer to my question.
I'm installing 12"X12" porcelain tile in our bathroom. Our house is 5 years old. The bathroom is on the second floor with a 3/4" plywood subfloor. I'm going to install it over Hardibacker but I'm wondering about a vapor barrier. Is one necesarry if you are using Hardibacker? And does it go over the plywood or over the Hardibacker? The vapor barrier I was looking at was at Lowe's and was called AquaDefense by Mapei. Thanks for any help.
A vapor barrier is different from a moisture barrier, but while neither is a necessity in a bathromm floor, it is not a bad idea. If the grout and tile are intact, the floor is essentially waterproof, but then you are not going to be flooding the floor everyday, in theory.