Drain For Garage Sink & Standing Pipe

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Leaky1, Sep 27, 2011.

  1. Leaky1

    Leaky1 New Member

    Messages:
    22
    Location:
    California
    I am in the process of installing a sink in my garage and I will be trying the drain into the 3†vertical drain that services a toilet, tub and sink in the bathroom above. There was a standing pipe connected to the 3†vertical drain via a 3â€x3â€x2†santee which I will use to connect the new sink and a standing pipe. Because there is no practical way to connect into an existing vent or run a new vent I will use a Studor Mini-Vent.

    Does anyone here see any code conflicts for the components and arrangement I propose?

    Thanks for taking the time to read my post and consider my questions.

    [​IMG]

    [​IMG]
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,831
    Location:
    Cave Creek, Arizona
    You are going to have to raise the sink because it is too LOW for those fittings to fit under it.
  3. Leaky1

    Leaky1 New Member

    Messages:
    22
    Location:
    California
    HJ,

    They fit fine. The top of the sink is at 37-1/2" and the center line of the existing 2" horizontal drain is at 11-1/2". There is 6" between the bottom of the basket strainer and the top of the 1-1/2" p-trap.
    Last edited: Sep 27, 2011
  4. Terry

    Terry Administrator Staff Member

    Messages:
    15,129
    Location:
    Bothell, Washington
    In Washington State, being UPC code like California, they wouldn't allow wet venting the sink over the 2" standpipe.
    They would want to see a vent for each, which could then tie together and then be vented with one AAV or Studor Vent.

    In Arizona where hj plumbs, it may be okay.
  5. Leaky1

    Leaky1 New Member

    Messages:
    22
    Location:
    California
    Terry,

    I don't understand. Why is the sink considered wet vented? The Studor AAV attaches to the top of the santee for the sink.
  6. Terry

    Terry Administrator Staff Member

    Messages:
    15,129
    Location:
    Bothell, Washington
    The 2" standpipe needs to be vented.

    If you have a sink plumbed into that vent, then the portion between the two is the wet vented section.
    You are allowed to wet vent a lav, but not a sink.
    A lav would use a 1.25" tail piece, and the sink uses a 1.5" tail piece.

    The "fix" that works in any state, is to vent each one, not trying to vent both with one vent, and then tying the two vents together above the flood level of the highest fixture.
  7. Leaky1

    Leaky1 New Member

    Messages:
    22
    Location:
    California
    Terry,

    I have to go to a meeting, but I will get back to this thread later this evening. I appreciate you trying to help.

    Howard
  8. Leaky1

    Leaky1 New Member

    Messages:
    22
    Location:
    California
    Good Evening Terry,

    Thanks, I now understand you are not permitted to wet vent the 2†drain for the standpipe. I also got my hands on a copy of the chapter on venting from the California plumbing code and it says I cannot run the vent pipe horizontal until I am 6†above the flood-level rim of the fixture served. Sounds like my only option is to install separate Studor vents for each P-Trap. NOTE: All drainpipes will be exposed within the garage (not inside the stud bays) and the stud bays will be sheathed with 3/8†structural sheathing and 5/8†fire code drywall to maintain fire rating between my garage and the adjoining townhouse garage.

    According to Studor the Mini-Vent should be located a minimum of 4†above the weir of the fixture trap so both Mini-Vents can be located under the sink. How do you fell about this proposed change? See new photos below.

    [​IMG]

    [​IMG]
  9. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,249
    Location:
    Land of Cheese
    I would put the studors up as high as possible over the sink. If you put them down low, at some point the line will back up and contaminate the inside of the studor, causing it to leak.

    You can also bring the vents up and tie them together, then you would only need one studor.
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,143
    Location:
    New England
    Run a vent line up each side of the sink, tie them together and use one AAV on it, with the cross-over connection at least 6" above the flood rim. If you ever get a backup, it will get into the AAV and it may never work again, especially with lint and stuff from the WM.
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