I previously posted on cutting a cast iron waste line in the attic to tie in a vent, but I might have an alternative to avoid doing this, so here's my dilemma. I'm trying to eliminate a soffit in my kitchen. In this soffit runs a vent line horizontally (parallel to the soffit). This vent pipe picks up the 2 bathroom sinks on the upper level of my split level house. The vent line ties into the main waste stack in the soffit(like this)
I____vent_______________III I III I III I III waste stack Osink III I III
Can I reroute the vent line up to the attic between the wall studs, run horizontal in the attic, then back down between the wall studs to tie into the waste line (like this)
I________vent_____________I III I I III I I III waste stack I I III I I_________III Osink