Question on venting for a double vanity

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by REXAMUS, Sep 12, 2012.

  1. REXAMUS

    REXAMUS New Member

    Messages:
    20
    Location:
    North Carolina
    So I had someone finish some plumbing for me since I have been too busy to mess with it.

    He finished yesterday and I had time to go review the work today. Correct me if I am wrong but unless something changed recently...Terminating the vent pipe in the crawl space is no bueno right? :mad:

    Also, would using an AAV off a dual sink and putting it in the wall cavity also be incorrect?

    IMAG07562.jpg IMAG00052.jpg
    Last edited by a moderator: Sep 12, 2012
  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,001
    Location:
    Bothell, Washington
    The AAV only works if it's accessible and ventilated.
    They make boxes with grills for that purpose.

    Also, two lavs should be run with 2" pipe, and then the individual trap arms and the vent can be 1.5"

    [​IMG]
    Last edited: Sep 24, 2012
  3. REXAMUS

    REXAMUS New Member

    Messages:
    20
    Location:
    North Carolina
    Running the pipe to the attic and using the AAV up there would be acceptable though right? Also, did you agree with the vent pipe terminating in the crawl space in picture #1 being COMPLETELY wrong?
  4. Terry

    Terry Administrator Staff Member

    Messages:
    15,001
    Location:
    Bothell, Washington
    That seemed so crazy I didn't think to respond.
    No vents should terminate in a crawl space. Vents should go through the roof.

    If the AAV in the attic can be accessed, that would be okay. A vent lets out gas though, so a "vent" would extend through the roof. I used to install five or six vents through a roof a day. It's not that hard.
  5. REXAMUS

    REXAMUS New Member

    Messages:
    20
    Location:
    North Carolina
    Well the sad part is that there is already a vent exiting the roof above the area where he just left it in the crawl space. He said that he just capped the vent on the top of the roof and didn't need it because of the way he ran the plumbing. Unfortunately that was on Monday and I have been working and just now got time to go look at everything.

    Quite sad that someone who calls themselves a plumber could be such an idiot.
  6. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,172
    Location:
    Maine
    That vent in the crawlspace can't be a vent either because it's horizontal
  7. REXAMUS

    REXAMUS New Member

    Messages:
    20
    Location:
    North Carolina
    Lol, I just noticed that too. Definitely not planning on giving them the rest of the money until they fix all of the issues.
  8. Terry

    Terry Administrator Staff Member

    Messages:
    15,001
    Location:
    Bothell, Washington
    It may be useful to pull a permit on the job. That way you have a local plumbing inspector looking at it.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,623
    Location:
    Cave Creek, Arizona
    I am not sure which line is the terminated vent, but it is almost impossible for a line under the floor to be called a "vent" in the first place, especially if there are no traps under the floor for it to "vent". He must also have been in too much of a rush to "anchor" the water stubs through the wall. OR maybe he doesn't know how to do that either.
  10. REXAMUS

    REXAMUS New Member

    Messages:
    20
    Location:
    North Carolina
    Yea...good times. Perfect reason why I have done everything myself in the past. Just haven't had time to mess with the plumbing.

    I've got another question. I have two different places to run a vent pipe but they are both where the bottom plate sits on a floor joist so I can't really go through it. Any ideas? I can get pictures if necessary.
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,623
    Location:
    Cave Creek, Arizona
    I assume you will have a cabinet under the sinks. If so, then run the vent on a 45 against the joist and into the wall inside that toe space. we do it all that way all the time.
  12. REXAMUS

    REXAMUS New Member

    Messages:
    20
    Location:
    North Carolina
    Would this work? Black = Drain line, Red = Vent pipe, Yellow = Approx floor joist location

    Excuse my terrible drawing. Basically a wye for the vent to come off the drain line from the tub and then i would have to figure out how to bring it back towards the wall cavity and then back vertical. Maybe a couple of 45 degree elbows?

    Attached Files:

    Last edited: Sep 25, 2012
  13. REXAMUS

    REXAMUS New Member

    Messages:
    20
    Location:
    North Carolina
    *Bump*

    Looks like some 22.5 degree elbows would work better with the previous picture I posted. Any suggestions?
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