Adding new bathroom to exterior stack?

Discussion in 'IPC Plumbing Code Questions' started by JohnnyPerry, Jan 20, 2021.

  1. JohnnyPerry

    JohnnyPerry New Member

    Joined:
    Jan 20, 2021
    Location:
    Pennsylvania
    Hi everyone! I have a house in Philadelphia where the 4" pack n' pour sanitary stack and vent are on the exterior of the building. It serves a 2nd floor bathroom and serves as the main vent for the home. If I were to add a second bathroom to that second floor can I cut in a sani tee on the vertical, run PVC along the side of the house to new bathroom (new bath would be right next to existing bath, so total distance to stack is not far but would probably require a vent) and back vent up to roof, all on the exterior wall? Paint the PVC to protect against sun?

    My concerns are that while the current situation is grandfathered in, does adding a new bathroom to that exterior system violate code?

    If I can run all new pipe, is painted PVC preferred to painted no hub cast iron in an exterior setting?

    I am under the impression Philadelphia just recently adopted the 2018 IPC code with a few exceptions.

    Thank you so much for your help!

    John
     
  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    I suspect the famed Philadelphia single-stack might be an exception.
     
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  4. JohnnyPerry

    JohnnyPerry New Member

    Joined:
    Jan 20, 2021
    Location:
    Pennsylvania
    Indeed it is. And this stack in question is a Philly single stack piped on the outside of a brick wall.
     
  5. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Sounds like what the IPC calls a "Single-Stack Vent System," Section 917. I'm not really familiar with them, but I would think the first question about tying into it would be how long the new horizontal branches would be. If they are under the length allowed, you could tie in the drains while relying on the stack for venting. After checking that any other capacity limits in Section 917 wouldn't be exceeded:

    https://up.codes/viewer/philadelphia/ipc-2018/chapter/9/vents#917.4

    Cheers, Wayne
     
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