Bathroom group wet vent question

Discussion in 'IPC Plumbing Code Questions' started by DanFL, Nov 7, 2020.

  1. DanFL

    DanFL New Member

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    Orlando, Florida
    I have a DWV plan as shown in the attached image (IPC in my area). I was originally going to connect the shower drain with a 2" vertical wye as shown, but I don't have the clearance under the slab. Can I instead use a horizontal wye as shown? If yes, which position is correct: wye #1 or wye #2. bathroom dwv.png
     
  2. wwhitney

    wwhitney Well-Known Member

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    Location:
    Berkeley, CA
    Position #2. [Edit: but see below, you can't have a vertical shower wye.] The vent connection to the horizontal wet vent should have only one fixture upstream of it, in this case the toilet.

    Some say that both the shower wye [Edit: definitely] and the lav wye should be rolled to be horizontal. I don't believe the IPC explicitly requires that [Edit: for the lav] but it is common to do it that way.

    Cheers, Wayne
     
    Last edited: Nov 7, 2020
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  4. Reach4

    Reach4 Well-Known Member

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    You might rework your picture. I presume the slab is horizontal, so how are you representing a horizontal wye?
     
  5. DanFL

    DanFL New Member

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    Thanks for that fast reply Wayne. Can I roll that wye #2 to 45 instead of horizontal? That area is tight on space horizontal will be a problem.

    Would this be a better option? I have room for this.
    bathroom dwv 2.png
     
  6. wwhitney

    wwhitney Well-Known Member

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    How does horizontal space get tight under the slab? Or is it just to avoid breaking more concrete or removing more soil?

    Anyway, oversight on my part, the shower wye has to be horizontal to comply with the trap weir rule. [Edit: in your original drawing, the fitting marked with an X would have to be a san-tee, not a wye. Then I think that would be acceptable layout, with the shower vertically wet vented, and the toilet horizontally wet vented.]

    Cheers, Wayne
     
  7. wwhitney

    wwhitney Well-Known Member

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    To follow up:

    The most conventional horizontal wet venting arrangement would be take everything in the red box in the last picture and roll it 90 degrees to be in a horizontal (2% slope) plane.

    Failing that, you need to at least roll the 3x2 wye flat if you don't want to get into the issue of whether you can interleave horizontal and vertical wet vent segments without restriction or whether you can have only one vertical wet vent followed by one horizontal wet vent. Most would say the latter, and that is standard practice. I think the IPC doesn't spell it out so I'm agnostic.

    Cheers, Wayne
     
  8. Reach4

    Reach4 Well-Known Member

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    I don't see that. I think that the shower is vented fine in #4. The question is is the toilet then vented OK also?
     
  9. DanFL

    DanFL New Member

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    I spoke too soon regarding the image in post #4. I just dry fitted that and it won't work.

    Just so I'm clear on the rolling horizontal, that means the 3" line and the 2" line are in the same plane, i.e. at the same depth below the slab (whereas with the wye rolled to 45, the 2" would be slightly higher)?

    The horizontal space is tight because I was trying to avoid breaking more concrete to widen the trench (currently 12" wide). I should be able to dig more soil out underneath without cutting though.
     
  10. wwhitney

    wwhitney Well-Known Member

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    In your original diagram, if you replace the "X" fitting with a san-tee, does that fit?

    Cheers, Wayne
     
  11. wwhitney

    wwhitney Well-Known Member

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    That was in reference to the original diagram.

    There is a little controversy as to the shower vent in #4, some people say the wye has to be flat, although I don't find any support for that in the text of the IPC or UPC.

    Cheers, Wayne
     
  12. DanFL

    DanFL New Member

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    Regarding the san-tee, I thought about a street san-tee, but still too tall. I'm planning to proceed with your advice above on rolling the 2nd wye flat.
     
  13. wwhitney

    wwhitney Well-Known Member

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    One last possibility--relative to diagram #1, rotate the "X" wye 45 degrees CCW and swap its position with the 45 shown directly after it.

    Relative to diagram #4--that should work.

    Cheers, Wayne
     
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