As GC, my glamorous jobs include sweeper, garbage collector and gopher.
Today, I ran an errand to the plumbing supply house. We're still having problems with the Master BA vent stack. Still trying to get the 4" stack below the concrete subfloor and have it reduced to a 2" dia vent above the subfloor. This way we can fit it into a 2x4 framed wall instead of a 2x6 wall.
The plumber keeps saying it can't be done w/o having to break out all the concrete and dig down 3 feet, because of all the unions. So, last night I found a photo I took of the section, before it got covered up with dirt and concrete.
I took the photo to the plumbing supply store and asked them it they thought it would be possible. The guy thought we might be able to do it, so I think it's worth chipping out some of the concrete, getting down to the first hub, and seeing if we can't cut off more of the 4" pipe before attaching the reducing hub. It will be very close.
If it doesn't work, then I'll have to have a 21" deep bathroom cabinet with a notched toekick to hide the vent stack.