Venting Questions

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by saltworks, Mar 18, 2013.

  1. saltworks

    saltworks New Member

    Messages:
    5
    Location:
    Michigan
    I have a couple of bath venting questions that I could use some help on.

    1. I have a bath on the first floor that has vents running through the attic to the main vent. The lavatory vent runs across the joists to the main vent. I am adding a bath on the second floor. I have been able to accomodate all the vents from the first floor into the new walls on the second floor bath with the exception of the first floor lavatory vent which will run through the middle of the new bath. Am I correct in thinking that I cannot run that vent horizontally through the floor joists to pick up a new vent in the walls of the second floor? I know that the vent cannot run horizontally until it is 6 inches above the flood plain of the fixture being vented (which it is), but something I read makes me think that now it must run vertically until it is 6 inches above the flood plain of the new fixtures of the second floor. Is that correct or will I be able to run it to a wall to catch a vent there?

    2. Is it correct that I can jog a vent no more that 45 degrees and it will still be considered vertical? In other words can I jog the vent to get closer to the wall using two 45's without violating the horizontal restrictions?

    Hope I made the issue clear. Thanks in advance for any advice.

    Bill
  2. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,309
    Location:
    Maine
    You can run it horizontally across the floor and tie in above the 2nd floor ceiling.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,242
    Location:
    Cave Creek, Arizona
    You cannot go horizontal until you are above the fixtures connected to THAT vent. In your case, there is absolutely no prohibition against running it horizontal in the upstairs floor, but it DOES have to connect to the upstairs vent at least 42" above the floor or 6" above the overflow rim of the upstairs sinks, whichever is higher. Almost ANY angle will avoid it being horizontal.
  4. saltworks

    saltworks New Member

    Messages:
    5
    Location:
    Michigan
    Thank you both for your replies - it certainly makes my life easier by clearing up my misunderstanding.
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