tiling a tub/shower - waterproofing a bench

Hello

I am re-tiling a shower in my 2-flat in Chicago. I have done several of these jobs and know to put tar paper up, tape and mud the cement board joints, etc.

This shower has an anomaly - for whatever the reason, the tub is a good 8" shorter than the whole shower opening. So, at the non-plumbing end of the tub, there currently is a little tile shelf that the tenants use for shampoo and soap. It is only 3 or 4" high off the tub, so consider it like a little bench at the end of the tub.

I just want to know how to "treat" it when I do the re-tile. Should I treat it like a shower bench, and put a small shower lining membrane over it and up 6" along the 3 walls that surround it? If I do this, how do I attach the cement board without piercing holes in the membrane?

One thought I have is that I will go to landscape supply place and get a nice thick chunk of bluestone or limestone and install that on this shelf rather than tiling it. But, I would still like to make sure that any moisture that might get through the stone does not leak through.

Thanks!

Liquid waterproofing.

What's the name of the product? Should I just apply it right over the framing/plywood?

Try Redgaurd, I think the Depot sells it. You paint it on the backerboard after its install. Read the directions on the can.

Thanks! Sounds good. I assume that I apply it AFTER I have taped and mudded the joints?

SS

Correct.