: Thanks Deb. That's also what I inferred from the reading I've done. The problem is that I think the previous remodel moved the original wall so now the main waste stack lines up about 2 feet inside the bathroom floor, so no direct vertical path is available from the top of the waste stack to any point above the fixtures.

: With my remodel the sink & the toilet will have separate venting that won't offset till they're above the fixtures. The trap arm for the tub/shower has a short run to the stack and I wasn't going to give it a separate vent. Should give it a vent line anyway to avoid issues?

: Thanks, I know this would be easier with pictures!

You can 90 a waste stack. You cannot 90 a vent stack. If there is plumbing above on the stack you want to tie the tub shower into, it must be vented. Otherwise this constitutes wet venting between floors.
Deb
The Pipewench