My neighbor and I are doing the work. She has settled on building a stud wall on the block side of the shower wall. We are going to put a plastic vapor barrier up as well as insulation before we attach the cement board.

So, back to the liquid waterproofing...Do you always use this on the cement board before you start tiling? I didn't do this with the shower in my basement. I just started tiling with thinset after I built the shower pan(followed directions from this website) and walls.

A reputable tile setter would recommend a topical waterproofing as standard practice or as an upgrade option. Whether its cement board doesn't matter. It's just good practice to waterproof.

Depending on the brand of liquid waterproofing your planing on using will determine if the poly barrier should be installed over the studs and insulation. What you do not want to create is what is known as a moisture sandwich.

Thanks for all the info. I've learned a lot! Amy