Venting Questions for the Pros

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Numerick, Apr 30, 2014.

  1. Numerick

    Numerick New Member

    Messages:
    9
    Location:
    New Hampshire
    Need advice for a venting issue. I would like to put the P -trap for my kitchen sink approximately 36"-48" below the sink bowl. Can it be a straight shot down at that distance? I am trying to avoid an AAV valve or Island Kitchen venting option. There is a 2" vent pipe through the roof that I have access to but need to get at it from the crawlspace area. My question is what will the basics of plumbing allow me for distance from the bottom of the sink to the P-trap?
  2. Sean Beck

    Sean Beck Plumber

    Messages:
    68
    Location:
    Toronto, Ontario, Canada
    Not sure about America, but the max length of fixture outlet pipe (drain from sink to top of p-trap) is 48". The Canadian code permits a trap for a kitchen sink to be placed below the floor providing there is a clean out above. Screen Shot 2014-04-30 at 11.25.43 PM.jpg
  3. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,249
    Location:
    Land of Cheese
    We cannot place the trap below the floor here.
  4. Numerick

    Numerick New Member

    Messages:
    9
    Location:
    New Hampshire
    Thanks Sean Beck, the information you provided was very helpful. Thanks Cacher chick for the heads up on code, guess I will need to give a second look at the Island vent option.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,843
    Location:
    Cave Creek, Arizona
    A trap under the floor would be subject to the water's inertial and would probably drain itself everytime water was used. The second drawing is not correct for many areas because it should have a vent in the wall connected to the vent in the 'yoke'.
  6. Numerick

    Numerick New Member

    Messages:
    9
    Location:
    New Hampshire
    Thanks HJ, I was hoping you would add your insight. Would you mind looking at the stack configuration below and offer any advise as to the the layout of the drainage set? I put the Toilet on top in case of backup or stoppage, the other drains would be able to still function. 2" dry vent through roof from top of stack.

    Stack layout.jpg
  7. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    The other drains will function but each one of them needs a vent of its own, not the 2" that your drawing shows
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