Venting Up and Down in Attic?

Discussion in 'IPC Plumbing Code Questions' started by Scott Yackley, Aug 22, 2020.

  1. Scott Yackley

    Scott Yackley New Member

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    Is venting up then down in the attic to get to main vent stack acceptable? Vent line would be 2" and main vent stack can support these additional fixtures.
     

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  2. Reach4

    Reach4 Well-Known Member

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    From what I had read, that may be OK under IPC but not UPC. MS uses IPC.
     
    Last edited: Aug 23, 2020
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  4. Scott Yackley

    Scott Yackley New Member

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    Thanks! It doesn’t create a trap, so figured it was ok but wanted to check. I couldn’t find this specifically mentioned anywhere in the code.
     
  5. Reach4

    Reach4 Well-Known Member

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  6. wwhitney

    wwhitney Well-Known Member

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    I looked it up:

    IPC
    https://up.codes/viewer/colorado/ipc-2018/chapter/9/vents#905.2
    "Vent and branch vent pipes shall be so graded and connected as to drain back to the drainage pipe by gravity."

    UPC
    https://up.codes/viewer/california/ca-plumbing-code-2019/chapter/9/vents#905.1
    "Vent and branch vent pipes shall be free from drops or sags, and each such vent shall be level or shall be so graded and connected as to drip back by gravity to the drainage pipe it serves"

    UPC makes it clear the vent has to drain back to the drainage pipe served, meaning the OP's configuration wouldn't comply. Since IPC just says "the drainage pipe" I say sloped back to any drainage pipe is OK, meaning the OP's configuration complies.

    Cheers, Wayne
     
    Sylvan, TheOverThinker and Reach4 like this.
  7. Scott Yackley

    Scott Yackley New Member

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    Thanks a lot for your feedback, this makes more sense now.
     
  8. DavidDeBord

    DavidDeBord Member

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    Are offsets allowed in the Vent stack, "above the flood rim" where it could be moved towards the peak of the roof, so as to allow the kitchen vent connection to have fall back towards the kitchen drain?

    Myself, I'd run the Kitchen on a separate vent stack, so as to cut down the Labor, Time, & Material.
     
  9. Reach4

    Reach4 Well-Known Member

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    Yes. You can tilt vent pipe between 2 degrees from horizontal, as long as you are 6 or more inches higher than the fixture you are serving.

    If you were asking if the vent could switch to going down a bit to hit a different drain (forming a shallow inverted V -- perhaps draining to stack-- that would be OK in OH (IPC). If this sentence doesn't make sense to you, don't worry about it. Or if this was what you were asking about, good.
     
  10. Jeff H Young

    Jeff H Young In the Trades

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    Had some comments but see we are talking IPC , So I don't know . It looks like a giant trap to me for light gasses.
     
  11. DavidDeBord

    DavidDeBord Member

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    "If you were asking if the vent could switch to going down a bit " --- No Reach.

    "where it could be moved towards the peak of the roof," meaning as it rose towards the the roof, if it could could 45 over, or whatever degree it took, to maneuver towards the peak of the roof, so as to allow an easier connection above the cathedral ceiling for the kitchen vent.

    But like I said:

    "Myself, I'd run the Kitchen on a separate vent stack, so as to cut down the Labor, Time, & Material. "
     
  12. Reach4

    Reach4 Well-Known Member

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    Was your question in #7 rhetorical?
     
  13. DavidDeBord

    DavidDeBord Member

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    No Reach.
    I'm thinking that we have a failure to communicate.
     
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