Washing machine venting

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Rich B, Apr 25, 2009.

  1. Rich B

    Rich B DIY Senior Member

    Messages:
    283
    Location:
    New Jersey
    I have two washing machine drains to plumb and vent. I am upgrading them to the proper size 2" using wyes into a short 4" horizontal C.I. section. I can go straight up with a vent. The two washer drains are seperated by a block wall in the basement, as this is a 2 family house. Can I use 1-1/2 for the vents, go straight up and join the two together in the common wall above? From there it would join with a common vent for one of the bathrooms upstairs. A tub and a sink....then up thru the roof and increased to 2"....The existing washer drains had no vents and are 1-1/2" and are poorly done in galvanized pipe.
    Last edited: Apr 25, 2009
  2. leejosepho

    leejosepho DIY scratch-pad engineer

    I believe what you have planned will work fine, but a real plumber will have more insight as to codes.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,045
    Location:
    Cave Creek, Arizona
    vents

    One thing about the common wall between units, is that it may be considered a fire wall and, if so, any penetrations should be made and sealed with fire resistant materials.
  4. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    Under my codes, once you connect the two vents together you'll need to be at 2" for the vents.

    What is your location or what codes are you under?
    A sketch or picture would likely help further.
  5. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Which code is that?
  6. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    Florida Plumbing Code 2007, based on IPC.
    Common, wet and/or waste stack 1-1/2" Vent is only good for 1 dfu.

    Also under FPC the min vent for 1 clothes washer is 2".
  7. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Me thinks you have mis-interpreted the IPC. You can wet vent an entire bath group off an 1 1/2 pipe.
  8. FloridaOrange

    FloridaOrange Plumbing Designer

    Messages:
    1,317
    Location:
    SW Florida
    I may have. I only have the FPC, the foreward in the FPC indicates its basis on IPC.
    FPC2007 Table 909.3
    Wet Vent/DFU=
    1-1/2"/1 dfu
    2"/4 dfu
    2-1/2"/6 dfu
    3"/12 dfu
  9. techinstructor

    techinstructor New Member

    Messages:
    81
    Location:
    North Carolina
    North Carolina code is similar to FL.
    Table: 908.3
    1/1/2"/1 dfu
    2"/4 dfu
    2 1/2" to 3"/6 dfu
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