I am remodeling a bathroom where there was a wall hanging toilet that leaked and ruined wall and some of floor. Unit had a cast bronze wall 3" fitting that had a vertical 1 1/2" copper vent soldered to it. Going to use a floor mount toilet. When inspecting old waste line I discovered it is 3 " copper and from wall mount to waste stack is about 4 feet. Waste stack is closed at top with no pipe running to roof. I would like to add a 1/2 bath on other side of current bathroom wall. Questions are:
Can a 3" waste stack support 2 toilets, shower, 3 vanities?
Should 3" stack be continued thru roof or can 1 1/2" vents be used at or near each toilet/vanity etc...