Tips/tricks for vents in attic?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by pghsebring, Oct 7, 2011.

  1. pghsebring

    pghsebring DIY Member

    Oct 23, 2008
    Never had to combine vents in attic before. Always went straight out roof with one stack. Now i have 3 vents going up 3 walls i need to combine in attic. Any tricks to this? Is it as straight forward as it seems? Flip a sanitee over, make sure there's 1/4" pitch on the horizontal? Since i have 2 lines that need to come to the third one that goes out roof, how high above the joists would you put the first horizontal? A couple inches or a foot? I've never seen this done in person, just in books, that's why i'm asking. Anything i need to watch out for?

    Thanks in advance.
  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    The vents can rest on the framing.
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  4. Tom Sawyer

    Tom Sawyer In the Trades

    Nov 29, 2010
    Yea, they need to pitch back towards the drain(s) but not necessarily a quarter inch per foot. Just enough to make them drain. Most guys use upside down plastic J hangers. I like to use strips of 3/4 plywood with holes drilled in them.
  5. Gary in NJ

    Gary in NJ Member

    Apr 11, 2010
    Also, the three vents do not need to connect at the same location.
  6. LLigetfa

    LLigetfa DIYer, not in the trades

    Feb 6, 2011
    NW Ontario, Canada
    Use lots of supports as the pipe can sag from the heat. I watched an episode of "Ask This Old House" recently where Richard had to redo a horizontal vent in an attic that had a sag which completely filled with water.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    It is pretty much, "do it however it works best for you". There are few "regulations" regarding vents as long as they do NOT turn downward before connection together.
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