Main Vent or Stack Vent Required?

Discussion in 'Plumbing Code Questions' started by fxc5, Sep 16, 2013.

  1. fxc5

    fxc5 New Member

    Sep 16, 2013
    New Jersey

    Is a main vent or stack vent required in a residential building with 2 floors? (New Jersey)

    I'm renovating my house and will have two bathrooms on the opposite side of the house. one bath will be on the first and one on the second. The original floor plan had the bathrooms right above each other, so they shared a 4" soil stack, that vented right to the roof. A lot of the venting examples I looked up use this methodology, however my baths are not be located above the other.

    Since I now have two baths located on opposite sides of the house can run a 3 inch PVC line to each bath and then run a 2" vent from each bath group to the roof? The way I read the code is that only residential building with 4 or more floor require a vent stack and require that you run the main sewer line from the basement directly to the roof without any vertical or horizontal offsets. My brother recently renovated his house and the plumbing plans showed a no 3" stack directly from the main line to the roof. The mainline branched out to 4 baths and each bath had a 2" vent. I presume this is okay since it was approved and passed inspection.

    The 3 inch pipe that comes from the second bath comes down the exterior wall and needs to be offset when it reaches the foundation wall. Is it okay to use two 45 degree elbows to offset waste pipe?

    Thanks for the help!!!
  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    Vents have no waste going down them.

    If you have a bathroom, it needs to be vented through the roof. The UPC code allows four bathroom sets on a 2" vent as long as you make up a composite elsewhere.
    For a four bath home, I would need four 2" vents to equal the 4" waste line going out.
    IPC may be different than that.

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