I just finished insulating an interior shower wall and will start cutting the hardi backerboard to go over it. Do I have to put up a vapor barrier or can I just red guard it before installing the 12x12 porcelain tiles? Also is Versabond fortified thinset mortar the correct mortar to use? I will be butting the tiles as close together as they can be in a running brick pattern so what do I use for a grout? I have a vapor barrier of 15lb felt on the exterior wall with hardi backerboard over it. I already know to tape the seams but I'll do that as I'm tiling.

Pattty,

Why are you insulating an interior wall. Vapor barriers are to keep hot and cold air masses from mixing and creating condensation, not to prevent moisture from penatrating. Won't hurt to use but should not be necessary.

Pattty,

Why are you insulating an interior wall. Vapor barriers are to keep hot and cold air masses from mixing and creating condensation, not to prevent moisture from penatrating. Won't hurt to use but should not be necessary.
It's more for soundproofing since that is also a kitchen wall.