i guess that's why i'm confused as heck on the subject
What would be the second so-called "barrier"?
i'm in the middle of using greenboard for the walls and ceilings in my bathroom, EXCEPT for the immediate tub and shower surround where i'll attach fiberglass panels directly to the (interior wall, non-insulated) studs. i don't plan on installing tile on any of the greenboard, just priming and painting.
the ceiling - which is directly below attic space - as well as the one exterior wall are both insulated with kraft-faced insulation, vapor retarder facing in.
my question is, do i need to remove the greenboard i've already installed on the ceiling/exterior wall just to remove the kraft-facing?before posting on this forum (but halfway through my job - i had always assumed greenboard was the default for bathrooms) this is what i had read in drywall books, read from USG's website, etc., which is what got me confused to begin with:
IF using greenboard as a backer for an impervious finish such as ceramic tile,(which i now know isn't a good idea...use CBU, etc. for the backer), the greenboard should NOT be installed over a vapor retarder like kraft facing since that would cause a double vapor retarder and trap moisture. i'm assuming retarder #1 is the kraft facing, and retarder #2 was the tile/grout (or the other "impervious finish" referred to by USG). this made me assume that it's ok to install greenboard over a vapor retarder when NOT covering with tile
IF installing greenboard on the CEILING - even with no tile - it should NOT be installed over a vapor retarder since that would ALSO create a a double vapor retarder. in this case, retarder #1 would the kraft facing, and it implies retarder #2 is the greenboard. but that would mean that in Scenario #1, it's actually a triple vapor retarder (kraft facing is #1, greenboard is #2, and tile is #3)?
Any help on this topic would be much appreciated