Adding a second drain into existing cast iron riser/vent

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by TheOverThinker, Jul 8, 2020.

  1. TheOverThinker

    TheOverThinker Member

    Joined:
    Aug 20, 2019
    Location:
    Berkeley, CA
    I need to add a second sink mirrored behind the plywood at the back of this sink, using
    the same drain and riser.

    What's the least trouble, mostly code acceptable, way to do this tie in?
    Located in California.
    Sink Behind.jpg

    I see this forum post: https://terrylove.com/forums/index.php?threads/horizontal-double-wye-for-two-sinks-kosher.69261/

    For odd reasons, the sink will never be used, and both sinks will be torn out in a few years... so there's a reluctance to get fancy. At that point the entire under slab cast iron needs to be redone.
     
    Last edited: Jul 9, 2020
  2. TheOverThinker

    TheOverThinker Member

    Joined:
    Aug 20, 2019
    Location:
    Berkeley, CA
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  4. Jeff H Young

    Jeff H Young In the Trades

    Joined:
    Feb 27, 2020
    Location:
    92346
    2 sinks calls for 2 inch . looks like 1 1/2 vent an easy way would be cut the gavinized vent and install an 1 1/2 " abs spigot santee pointed oposite. but its not legal. looks like cast iron is coming thru a stem wall if its 2 inch perhaps you can do it right with out tons of work.
    Im not suggesting the first method but Its been done and could be a way probebly no noticeable negative effect
     
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  5. TheOverThinker

    TheOverThinker Member

    Joined:
    Aug 20, 2019
    Location:
    Berkeley, CA
    It's 2" going down in cast iron, 1.5" going up as a vent. All from 1925.

    There's no way to increase the size of the vent, and no practical way to run a new vent.


    The stacked sanitary T's are a definite code violation.
    How about the Y's as shown in this video?
     
  6. Jeff H Young

    Jeff H Young In the Trades

    Joined:
    Feb 27, 2020
    Location:
    92346
    This old house doesent look legal. You cant y off a trap arm and dump waste in there. video seemed to leave off how trap arm got to new sink .
    Video I dont think helpful if your interested in legal.
     
  7. TheOverThinker

    TheOverThinker Member

    Joined:
    Aug 20, 2019
    Location:
    Berkeley, CA
    What would the code violation of that approach be?

    There are a ton of double sink kits. Are any of these applicable?

    stainless-steel-keeney-tubular-mk-dblbowlsink-64_1000.jpg 642634_K_Lg.jpg snappytrap-tubular-dk-110-64_1000.jpg


    I know they suck.
    This is a temporary sink situation, if it last a year thats good enough.
     
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