Shower Pan Liner and wall Cementboard meet where?

[das8150x]

I'm about to install my shower pan line liner. A few questions:

1) I've read that the liner should go up 3 inches on the walls. I've read in other places that it should be as high up as 9 inches. Which is correct?

2) When putting the cementboard on the walls, how far down does it go? Does it overlap the shower pan liner? Do I mud up to the cementboard? Can the mud go over the cementboard? Or, do I mud the floor first and then put the cementboard on the walls? If so, is there a gap between the mud floor and the cementboard?

3) I'm going to use 1/2 inch cementboard on the walls. When putting it up, do I screw it directly to the studs, or do I need plywood (or sheetrock) over the studs first? I know that I put the vapor barrier directly behind the cementboard.

Thanks in advance!

[TileArt1]

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.

[das8150x]

perfect, makes sense. Thanks for the quick response!