There are so many conflicting reports I have heard when building a custom shower pan. I am stuck on where to start. The guy at Lowes told me vapor barrier, cement board, then build the shower pan, mud, liner, mud, etc.

However, I understood the vapor barrier had to extend past the shower pan liner. In that case, I would have to install the shower pan FIRST, then vapor barrier then cement board on the walls. I am using the standard 6 mil plastic, not kerdi or redguard or any of that.

Can anyone care to comment?