Russell from Madison WI here.
I'm creating a master bath out of a bedroom and two closets in our 90-year-old Arts and Crafts hybrid. I'm doing a custom shower and need to put a 2-inch trap between the existing 2x8 joists (I have sistered and blocked them with 2x6s). The plumber I'm considering hiring for the rough-in says that I need to raise the shower floor by 3-inches (2 2x4s) to make it work. I really don't want to raise it. Any alternatives or is this the only way? Thanks in advance.