Venting In-wall water closet: stacked bathrooms

Discussion in 'UPC Plumbing Code Questions' started by B_Neiles, Jul 14, 2021.

  1. B_Neiles

    B_Neiles New Member

    Joined:
    Jul 14, 2021
    Location:
    Rapid City, SD
    Hello all,

    Currently remodeling and replacing all plumbing (failing) in a 1945 ranch home in South Dakota (UPC). Bathrooms are stacked on top of each other, and will have the exact same layout almost to the inch. We chose an in-wall toilet for the upstairs to meet clearances code.

    My question is what is considered the trap-arm for an in-wall toilet? I have attached two models, one with dry vents. The other with wet vents. But, I'm pretty sure I have broken the rules concerning the upstairs toilet trap arm by running the upstairs lavatory waste through it. This option, though, would give me more options for plumbing the downstairs and ultimately save some elevation below the poured concrete floor.

    Showers, kitchen and utility room are all serviced by another vent through the roof on the opposite wall.

    If you catch anything else, I would love to know.
     

    Attached Files:

  2. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Option 1 is fine, the upper WC is being wet vented by the upper lav, just like in the lower bathroom. If you don't need the full 3" vent through the roof to comply with the aggregate vent area rule, you could delete the upper story 3" vertical segment--it's not part of the vent path of any fixture.

    Cheers, Wayne
     
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  4. B_Neiles

    B_Neiles New Member

    Joined:
    Jul 14, 2021
    Location:
    Rapid City, SD
    Thanks for the quick reply!
     
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