mr gyp in residential bathrooms.

[codeworks]

i've read the 2006 irc(r702.3.8) where it says a water resistant gypsum backer board is required behind tile, etc, i can't find where it says the stuff is actually required (specifically mr type gyp on walls and ceilings). most folks here are using concrete backer board behind tile, and i've seen mr gyp fail if exposed to too much moisture, so my question is, in shower/bath areas, above tiled surfaces which are installed on a concrete backer board, is mr gyp required or "just a good idea" thanks

 

[fatboy]

Not a requirement for MR unless as a backer for tile, in non-tub/shower areas which require will cement, fiber cement or glass matt gypsum.