Hi David, welcome to the forum!
1) Your liner needs to go 3" up the wall above your curb. If your curb is 4" high your liner needs to go 7" up the wall.
2) The cement board overlaps the liner down to your mudbed (shower floor). Some guys leave a gap of 1/8" or so and some embed the bottom into the mud bed. Whichever you choose DO NOT nail or screw your backerboard fasteners through your liner. You need to stop them above your liner. The bottom of your boards will not be attached - the mudbed can hold them in place.
Your vapor barrier needs to come down behind your backerboard and over the top of your liner. At the top of your liner the layers will be backerboard, vapor barrier, liner, studs - in that order.
3) Screw them directly to the studs.
Roger (The FloorElf)
Custom Tile & Stone installation
Fort Collins, Colorado
CTEF Certified Tile Installer #847
Social dysfunction can be traced to the abandonment of reason
Last edited by TileArt1; 11-17-2009 at 04:37 PM.
Reason: I can't spell.