: I have a 4" cast iron vent pipe running up threw the bathroom and out threw the roof of the house. I plan on cutting the pipe out and converting it to PVC and installing inside the wall rather than exposed like it currently is. My question in the future I'd like to add a secound bathroom above the current one on the secound floor. Can I drain into the vent pipe for the secound floor bathroom or should I run a seperate drainline back to the basement?? Anotherwords I would just T into it and it would still end up venting out threw the roof. Thanks, Tom
As long as all fixtures below are vented 6" above the highest fixture on the second floor your ok. If not cut a wye into the 4" below the lowest fixture and vent as required for second floor bath.
Dale's Plumbing Service Inc