Dual lav on 2" line - cleanout required?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Gimper, Apr 14, 2020.

  1. Gimper

    Gimper New Member

    Joined:
    May 21, 2019
    Location:
    Blue Springs, Missouri
    I'm working on my finishing my basement and am adding a dual lav, and was hoping to get a check of my plan and confirmation of the cleanout requirement. I've looked at all of the dual lav threads that I could find, and couldn't find a whole lot on the cleanout requirements other than some where they say one is needed.

    Attached is a drawing. The blue lines are what is existing, all in 2". I assume that the 2" line also vents the stool, shown stubbed out in green. The horizontal vent line at the top comes from the shower on the left, and runs off to the right and through the roof as a dry vent. I was planning on adding the lines in pink, all in 1.5" other than the 2" connections on the santees where they tie into the existing. (I'll use a long turn 90º, I just couldn't find a model for one)

    I'm under the 2012 IPC, and in reading 708.7 on cleanout size, is the 1.5" trap connection sufficient as a cleanout as long as I have a SJ connection where it leaves the wall? If I put a 2" cleanout between the two santees, I don't think it would be very accessible being behind drawers.

    If this doesn't work, what should I do? Should the left lav trap arm be 2" with a cleanout, then reduce to 1.5" for the SJ connection. (Since I can't seem to find a 2" -> 1.5" SJ fitting. I suppose I could do a spigot reducer in the 1/8th bend coming out of the wall?)

    I think it was originally roughed in with the intention of a 48" or 60" single vanity, and of course going to a dual 84" makes it a bit more difficult. Also, any advice on offset from the sink centerline if coming out of the wall with a 45º? I'll play with the trap arm to see where it'll fit best if there's not a sort of standard of practice. I figure as long as it passes within a couple of inches of the tailpiece then I can align it using the trap.

    Thanks!
    -Kris

    Lav Plumbing.jpg

    A long sweep 90 below the pink lav where the vertical turns to horizontal.
     
  2. Zack

    Zack New Member

    Joined:
    Apr 14, 2020
    Location:
    Michigan
    You could use a studor vent on the pink line if you don’t want to tie that back into the main stack. I’ve used studor vents in 2 places in my house and they have worked great. To answer your question, I believe a trap would be sufficient as a clean out for the second sink.
     
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  4. Gimper

    Gimper New Member

    Joined:
    May 21, 2019
    Location:
    Blue Springs, Missouri
    Thanks for the reply Zack. I don't really see a need for a valve with a much shorter lifespan than joined piping, and suspect that they can't be used inside of a closed wall. They weren't legal in my last jurisdiction (UPC) so I've never looked into them much. Tieing the vent in isn't a big deal. I could also run horizontally back over to the original line as long as it's above 42", but it seems easier to bore one hole in the top plate than 3 through the studs, especially with the one stud only ~1/4" from the vertical line.

    I'm sure that the trap adaptor is sufficient for the 1.5" line, but I'm not completely clear on the left sink's trap adaptor being sufficient as a cleanout for the 2" line. It couldn't be run from the roof, since it would surely go straight past the santee and toward the shower.

    I guess my question boils down to clarification on exception 1 to section 708.7:
    "P" trap connections with slip joint or ground joint connections. or stack cleanouts that are not more than one pipe diameter smaller than the drain served, shall be permitted.​

    Does that mean that a 1.5" trap adaptor is okay on a 1.5" trap arm connected to a 2" line as I've shown, or only a 1.5" trap adaptor on a 2" trap arm to the 2" line?
     
  5. Gimper

    Gimper New Member

    Joined:
    May 21, 2019
    Location:
    Blue Springs, Missouri
    Well a framing change has changed things for me slightly, but I think for the better (easier, at least) and I think that the 1.5" SJ coming straight out of the wall is sufficient as a cleanout for the 2" line. Anybody see any issues with this?

    Thanks,
    -Kris
     

    Attached Files:

  6. Jeff H Young

    Jeff H Young In the Trades

    Joined:
    Feb 27, 2020
    Location:
    92346
    If its not drywalled Id build it like the picture. Put a clean out tee on the pink lav it will serve both. or just use an aav and forget clean out you can allways fix it if inspector calls it. a lot of inspectors dont know or care .
     
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