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Thread: drain/venting question

  1. #1

    Default drain/venting question

    I am currently redoing a bathroom and have a drain/venting question.The toilet is about 2' from the 3" stack. The 3" stack has a 1 1/2" vent coming out of the top of it (just above the toilet tee)and through the roof. There is a shower and lavatory that tie into the 3" toilet line and both are vented with above where the lavatory drain lineties in. I have no problem venting the new lavatory and shower, but the toilet need to move to the other side of the bathroom. I will be about 4' from the stack. I want to know if I can get rid of the vent coming out of the top of the stack above where the toilet ties in, and add a vent in the 3" elbow for the toilet. This vent would go up a new wall and tie back in to the existing in the attic. I have no problem adding a vent, I just don't want it to be in the same wall that it is now. Any help would be greatly appreciated.
    Last edited by rbird7282; 06-29-2008 at 08:15 PM.

  2. #2
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    San Diego


    The 1" vent is too small, although it probably works fine. You should keep the 1 and add a 2" vent for the toilet. You cannot vent the toilet with a heel inlet elbow, though. You will need a tee on the vertical, or a wye off the horizontal branch, with the wye rolled up 45.

  3. #3


    Actually the vent coming out of the top of the stack is 2". You are saying need to add a vent for the toilet as well? That would make three separate vents for the bath. I was hoping to keep the one for the lavatory and the shower and then have one other, preferably near the toilet (coming off a wye as you have indicated) and eliminate the one above the stack if possible. I guess I can't do do that?

  4. #4
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    Each fixture should have its own vent, but some places will allow a wet vent.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  5. #5


    Can I vent the shower and lavatory with a 2" vent & keep the 2" vent coming out of the top of the stack? Will that be enough without addind another vent for the toilet? The 2" drain line will tie into the 3" line with a wye which will be right next to the stack. The toilet will be about three feet from the wye and stack. Thank you in advance for your advice.


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