Double vanity and laundry in 2" PVC

Discussion in 'Plumbing Code Questions' started by Alfred, Dec 30, 2020.

  1. Alfred

    Alfred New Member

    Joined:
    Dec 30, 2020
    Location:
    Dallas, TX
    I am in the process of remodeling a bathroom and would like to add laundry to the same room. The only drain available to me is a 2" line that is currently being used just for the vanities. I would like to add the laundry, be up to code, and not have to replace anything under the slab. I would appreciate any help you could give. I am located in Texas.

    Current:
    - 2" PVC drain to slab w/ 1.5" vent stack
    - 2x Vanity w/ 1.5" drains to double sanitary tee to main 2" drain to slab

    Propose:
    - keep current configuration above
    - add 2" drain for laundry that feeds into a sanitary tee below current vanity double tee
    - add 2" vent stack just for the laundry


    plumbing_config.jpg
     
    Last edited: Dec 30, 2020
  2. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    That's not possible under the IPC, because of the requirement that the drain for the clothes washer standpipe increase to 3" as soon as it joins another drain. Third sentence in 406.2:

    https://up.codes/viewer/texas/ipc-2015/chapter/4/fixtures-faucets-and-fixture-fittings#406.2

    Are you perhaps in a jurisdiction that uses the UPC? I have a vague recollection some cities in Texas do, but I may be mistaken.

    Under the UPC, your proposed drawing is fine. (18" is the maximum height of the standpipe trap above the floor, where to measure that to is unspecified. 6" is the minimum.) The laundry vent doesn't need to be 2", it could be 1.5".

    Also under the UPC, if you want, the laundry doesn't need a separate vent, it could be wet vented by the double lav. You'd lower the trap so its outlet can hit a 2" san-tee below your double lav san-tee.

    Cheers, Wayne
     
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  4. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    I think Dallas is not in the list of UPC in Texas.

    If Alfred had installed that per his drawing before the 2015 IPC was adopted by Texas, it would have continued to work great into the future.

    Alfred, maybe you could ask for an exception.
     
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  5. Alfred

    Alfred New Member

    Joined:
    Dec 30, 2020
    Location:
    Dallas, TX
    Thank you Wayne,

    In my city we are under the IPC 2015 as of right now. I appreciate the input and will try to figure out another solution that will meet the IPC standards. Hopefully nothing too drastic.
     
  6. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    The requirement is in the 2012 IPC. I remember looking up what year it was added to the IPC, but I don't remember the answer. : - )

    Cheers, Wayne
     
  7. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Well, your two options under the 2015 IPC are (1) use a laundry tub or (2) find a 3" drain line to bring the laundry standpipe fixture drain to.

    [Fixture drain means a drain serving only one fixture.]

    Cheers, Wayne
     
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  8. Alfred

    Alfred New Member

    Joined:
    Dec 30, 2020
    Location:
    Dallas, TX
    Just to make sure I am understanding you correctly if the drain line that penetrates the slab was 3" instead of the current 2" right before it goes into the long sweep it would meet the IPC 2015 rules? I will need to verify what size line runs under the slab that feeds this line.

    Thanks,
    Alfred
     
  9. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Yes, if the vertical pipe segment just above the slab were 3", then you could install a 3" x 2" san tee or combo to bring the laundry standpipe drain in, and that would be compliant with IPC 406.2.

    So if there's a horizontal 3" line under the slab near your wall, you can break up some concrete and tie in the laundry fixture drain there instead of in the wall, and that complies with IPC 406.2. Personally, I'm not sure I believe in the IPC requirement enough to break up concrete to comply with it, but I live in a UPC jurisdiction, so I wouldn't have to make that decision.

    Note that under the IPC, I don't believe you can do wet venting with two lavs over a laundry standpipe, so you do need the separate standpipe vent. But the vent still only has to be 1.5".

    Cheers, Wayne
     
    Last edited: Dec 30, 2020
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  10. Alfred

    Alfred New Member

    Joined:
    Dec 30, 2020
    Location:
    Dallas, TX

    I will scope the line and see how easy it is and make the decision at that time. Thank you for guiding a novice through the intricacies of the code.
     
  11. Tuttles Revenge

    Tuttles Revenge In the Trades

    Joined:
    Oct 15, 2014
    Hopefully you don't have a post tension slab.
     
  12. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    1. Was 2015 the IPC version that introduced that 3-inch requirement? If the standpipe had been installed before the code was adopted, it would have been allowed to remain. If it were mine, I might ...

    2. I would think that local code authorities might be willing to make an exception where replumbing to 3-inch would be a hardship. After all, UPC is still OK with 2 inch having standpipe and some other drainage in it.

    3. If you put in a laundry sink, and empty the washer into that, then 2 inch is still allowed.
     
  13. Tuttles Revenge

    Tuttles Revenge In the Trades

    Joined:
    Oct 15, 2014
    I would be tempted to ask for an exemption or use an "alternative method" .. I have gotten exemptions for upsizing a drain from 3" to 4" when adding a 4th toilet on a horizontal drain because there was too much disruption of concrete to upsize the drain. There are millions of installations of laundry on 2" and plenty of codes where its obviously acceptable as evidence.
     
  14. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    No, 2003 IPC.

    Cheers, Wayne
     
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