I have one side of my house that is unfinished. It has two roughed in bathrooms and the plumbing is in concrete. The stack is 2" because they didn't plan on a bath upstairs. I want to add a bathroom upstairs so can I cut the concrete and put in a 3" Wye to create my waste and vent stack, re-cement it?

There's no stack yet, just the 2" fitting in the floor. The wall is not even framed yet but it would go up the wall, then attic and out. It's located just behind the toilet drain and ties into the toilet before going horizontal to the septic. I'm not sure if they put in 2 x 3 Wye or Tee. So again, would I just cut up the concrete and replace that with a 3 x 3 wye and re-cement it? I'm assuming I'd have to stud it out with 2x6's?

What you propose to do is to convert a first floor vent stack into a whole house stack vent. This you can do, however you just removed the first floor vent from that bath. You can't use the same stack for a first floor vent any more. You will either have to run a new 2" first floor vent or, if AAV's are allowed in your area you could vent the first floor bath with a Studore Vent. Good luck, Tom

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Originally Posted by speedball1

What you propose to do is to convert a first floor vent stack into a whole house stack vent. This you can do, however you just removed the first floor vent from that bath. You can't use the same stack for a first floor vent any more. You will either have to run a new 2" first floor vent or, if AAV's are allowed in your area you could vent the first floor bath with a Studore Vent. Good luck, Tom

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Thanks, I do believe AAV's are allowed but hadn't thought about the problem I was going to create with no stack for first floor.