2 pedestal sinks - need feedback on drain/vent arrangement

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Robert A., May 1, 2017.

  1. Robert A.

    Robert A. New Member

    May 1, 2017
    San Jose, CA
    I am reworking a bathroom and will be installing two pedestal sinks. There's quite a bit of space inside the wall so I have mounted 1 1/2" ABS behind the framing rather than cutting into it. The studs are part of a balloon framing system that goes all the way to the roof and is load bearing.

    I had to turn some corners with the venting and did so using 22.5º bends where possible and some 45º fittings. Everything below the sink drains is straight or uses long turn elbows. In the lower-right corner the pipe goes from 1 1/2" to 2" to tie in to the drain below the floor.

    The vertical vent pipe above this is ABS for about 15' to a no-hub coupling that connects to a final 5' run of cast iron up through the roof. Nothing else connects to this vent.

    I have a few weeks before I'll be closing up the wall. Please take a look at the photo and let me know if all is well or I should consider changing anything.

    Thanks everyone!


    Attached Files:

  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    With UPC code, they want 2" at the split for the two lavs. That would have been a 2 x 2 x 1.5 combo with a 2 x 1.5 flush bush on the end going to the second lav.
    The revent is 6" above the flood level of the lavs. Most of the time without putting much thought into it, we run them at 42" which covers you for a 36" countertop plus six.
    I try to reduce the turns as much as possible and prefer to change direction at the end. That would look like turning the last long 90 below the second lav at an angle and maybe with a S45 or something like that and then the run into the combo.
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  4. Robert A.

    Robert A. New Member

    May 1, 2017
    San Jose, CA
    Terry, thanks for the feedback.

    I have the 2x2x1.5 combo but couldn't quite make it fit the available space. Should I be concerned about the performance or safety of the two lavs with the 1.5" arrangement?

    The horizontal vent is just a hair above the 42" mark, which sounds like I'm in good shape there.

    I was going for reducing turns as well, though my primary goal was to avoid cutting into the load-bearing framing and the other wood that makes up the back of a built-in china cabinet on the other side of the wall.
    Last edited: May 1, 2017
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