Tile Installation: Backer Board Around a Bathtub
Finally – the tile backer/tub lip problem resolved
Cement Board Detail
The best approach when installing cement board or other tile backer around a tub is to keep the cement board out of the lip area. Apply it to the wall with the bottom edge about 1/4 in. above the lip of the tub. Then apply a generous amount of thin-set to the bottom bathtub tile and position it 1/8 in. above the tub. Fill the gap between the tile and the tub with caulk.
What is Backer Board?
Cement backer board is used as a sub-surface for tiling, usually for showers or bathtubs. Backer boars are generally placed against plywood or OSB board. This treatment is unnecessary if there is already cement backing.
Figure out the whole process behind a weekend bathroom remodel here.