I will be expanding my bathroom and moving the bathtub, meaning I need to prepare a new bathtub alcove.
I know how to frame and plumb – but preparing for tile is new to me.
I know that there are different products out there to use to prepare for tile, such as concrete backer-board which would apply direct to the studs and get sealed with thinset, vs. waterproof membranes which would be applied directly to greenboard without the backerboard.
What I don't know is – what are the advantages/disadvantages to each approach? Is one better than the other?
The plan is to use ceramic and glass tiles – does that make a difference?
Best Answer
First of all, greenboard is no longer accepted as a suitable product for wet areas. It has been replaced with "purpleboard" or glass-backed products without paper for mold growth.
Consider doing to tub alcove in a cementicious board like Hardi500 or a fiber-glass backed gypsum like DensGuard.
Do not apply a vapor barrier behind these if you intend to seal them from the room side. This will promote the dreaded "moisture sandwich." where any moisture which does get through the first barrier cannot escape the second.
From recently doing a similar project I am a supporter of the Kerdi membrane. You set the wall boards and seam them as usual (any board will do, but I like mold-resistant and water-resistant board)... then you "shingle" on the kerdi membrane with thinset.
EDIT: I changed where I said "blueboard" to "purpleboard" as some googling showed I was using the wrong slang....