i am going to be installing tile in my bathroom as a tub surround.i am wondering what backer board is needed. if i am using a membrane such as kerdi, is drywall a good enough backer or do i need cement board. if i need cement board, do i need the membrane? what products do you suggest for best installation. i will also be doing a walk in shower. are there any differences to be aware of compared to the tub surround shower style.
Tile doesn't flex. Drywall does. You need a hard surface to lay tile, or the grout joints will crack, water will get in, and your tile will promptly fall off. Real tile backer board (the kind that's made out of fiber re-enforced cement) is the only decent solution for installing tile over a wood frame. Hardibacker or any other modern garbage designed to make something seemingly easier, just turns into a nasty headache a year later. Also be sure to use real thin-set mortar, and real grout. That adhesive grout is just acrylic caulking with some sand added, tiles will fall off if they get wet.
I am assuming you are going with ceramic tile. If that is the case then you do not need fiberboard. Just tile right to the concrete floor. As for the crack either fill it in or use a product called RedGaurd. RedGaurd is a rubberized product that when applied over the crack will expand and contract and thus keep the crack covered. You can apply RedGaurd then put mortar right over it.
