Kitchen sink rough in Plan

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by cruiser, Jan 4, 2012.

  1. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Hi Folks ,

    I'm planning a rough in for new kitchen and am currently working on drain layout. The new sink is on an exterior wall that WAS 2x4 studs I furred this out using 2x 6's purely in order to keep the pipes from interfering with cabinets etc. I plan to stub the 2" drain 14" up from slab to allow for disposal etc. In the photo the sink drain on the right is dropping 1/2' per foot ,the run to the nearest drain (lav) is 5 feet and that point there is a 2' vent up through the roof.

    1st Question is can I wait this long (5 feet) and drain into this and use this existing vent or should I install a vent where I have my red vertical arrow and hook them up in attic?

    I'm also putting a new sink in the lav along that stud wall on the left of photo so my

    2nd Question Can I drain this into the same lav drain as above and use that same vent, distance from sink to lav 4 1/2 feet.

    3rd If I can drain both into this lav drain at that point am I correct in saying the fitting is called a Double combo Y -1/8?

    Thanks

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  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,011
    Location:
    Bothell, Washington
    First,
    Is the 3" cleanout with 2" pipe out of the top a cleanout and a vent for the toilet? That can change things.

    You need a cleanout on a kitchen sink line. You need a cleanout every 135 degrees of change. That would be a 45 and a 90 bend.
    You can't do two 90's without a cleanout.

    A double fixture fitting is used for two back to back fixtures. However in your case here, I would add the vent where the arrow is.
  3. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Hi Terry,

    Yes the 3" cleanout with the 2" pipe vent is the toilet, I'm afraid to read you reply to that :)

    ps just for clarity the toilet is plumbed where it is in the photo I assume the just vented it there because of the window right behind the toilet
    Last edited: Jan 4, 2012
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,647
    Location:
    Cave Creek, Arizona
    quote; I assume the just vented it there because of the window right behind the toilet

    No, they vented it there because that was the best place to do it. Where is the existing sink? At 1/2" per foot, your sink would be too far from the connection, (and so is the lavatory), so you WOULD need the vent at the red line for the kitchen sink, but it would not take care of the lavatory drain.
    Last edited: Jan 4, 2012
  5. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Hi Hj,

    Not sure which existing sink you refer to but the sink that was in the lav was located 3 feet to the left of where you can see that insulation it's drain went under slab at that point.The existing kitchen sink is 20 feet way and exits under slab at that point.

    I'd like to drain both the new lav sink and the new kitchen sink into that 3" drain. The new lav sink will be 41" from the 3" drain and the kitchen sink will be 5 feet from the 3" drain. From what Terry and you have said I need to vent the new kitchen sink where I have my red arrow.

    If I can drain both to the 3" drain do I need to vent the new lav sink through the attic before it hits that 3" drain

    Attached Files:

    Last edited: Jan 4, 2012
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,647
    Location:
    Cave Creek, Arizona
    Use 1/4" per foot, and you will be okay without a lavatory vent. WE have nothing for size reference, so will assume that the sink line is 2", NOT 1 1/2" pipe. I hope you caught Terry's correction to your question, namely, that it is NOT a double combo, but rather a "back to back fixture fitting". They LOOK similar but are two completely different fittings.
    Last edited: Jan 5, 2012
  7. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Hj,

    Thank you for your answer. My plan therefore

    * Slope lav sink 1/4" per foot to the 3" drain... no vent needed
    * I need a vent on the 2" drain from the new kitchen sink where the arrow is, and must join the other vent in the attic to exit the house.
    * I need to get a back to back fixture for the connection

    Off I go :)
  8. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Folks I'm stuck on something...in order to vent vertical from that horizontal drain at that red arrow what is the correct fitting I should use? I believe it to be 'y' and not a santee nor vent 't' but want to be sure.

    Thanks
  9. Terry

    Terry Administrator Staff Member

    Messages:
    15,011
    Location:
    Bothell, Washington
    A Wye fitting on the horizontal and a santee on the verticle.
  10. cruiser

    cruiser Member

    Messages:
    46
    Location:
    California
    Thanks Terry :)
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,647
    Location:
    Cave Creek, Arizona
    A "combination Y-1/8 bend", or combo, is usually the easier fitting to use and saves a couple of joints.
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