Drain and vent question

Discussion in 'Shower & Bathtub Forum & Blog' started by Daveclink, Jan 4, 2013.

  1. Daveclink

    Daveclink New Member

    Feb 26, 2012
    Syracuse, NY
    After completely gutting my bathroom I have a number of questions about the original install of the vent and drain pipes and how to fix the issue.

    The drain pipes and vent pipe are 1 1/2 PVC

    The drain pipe to the right will be contected to a double sink with a separate vent connected to the existing stack. Do I need to change all the pipes to 2"?

    about 7 feet away from the double sink will be the shower. Will I need a separate vent for the shower? If so can I connect it to the exixting stack.

    can I connect a 2" drain to a 1 1/2 vent?

    Any help would be greatly appreciated


    Attached Files:

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    The size of the vent is determined by the number and type of fixtures it must vent - for a sink and shower, 1.5" should be okay, but typically, in cold climates, it must be upsized before it goes through the roof to prevent hoar frost from closing it off.

    The shower and in-wall drains for the vanity should be 2", and you may be able to wet vent the shower from the lav, if it is done properly. Otherwise, the shower will need its own connection into the vent.
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  4. Daveclink

    Daveclink New Member

    Feb 26, 2012
    Syracuse, NY
    Thank you, Jim

    I will replace all the 1 1/2" with 2"'

    Can I stay with the same type of connections as in the picture?

    You can't see it in the picture but the drain/vent pipe is connected to the 3" waste pipe about 1 foot below the elbow
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    That picture is almost useless because of all the intervening "stuff" which obscure the drains. Many plumbers, but not me, run sink drains using 1 1/2" pipe. The shower drain should be 2". As for vents, the actual way the drains are installed would determine where vents would be needed.
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