Flooring Tile - Drywall or backerboard or Both for tiling?

I am planning to tile around a bathtub with the tile only getting placed up each wall about 2/3rds of the height. Should I drywall around the entire tub from the tub's edge to the ceiling AND THEN install cement backerboard over the drywall as a base for the tile?

Or is it suffice to install the backerboard directly to the wall studs and have the last 1/3rd of wall be drywall? If I do this, how do I connect the seam between the cement backboard and the drywall?

Thanks

Alan :wall:

Install a vapor barrier over the studs, then 1/2" cementboard where the tile will be and up as high as the shower head or a hair below it.:)

Tape and thinset the seam between the drywall and cementboard with thinset if the tile is going over the seam, drywall compound if it ends on the seam.:)

Use backerboard tape either way.:)

Thanks

ALAN