Kitchen remodel, vent is not 6 inches above flood rim

Discussion in 'Canadian Plumbing Code Questions' started by Knowledging, Jun 4, 2021.

  1. Knowledging

    Knowledging New Member

    Jun 4, 2021
    Ontario, CANADA
    Original plumbing

    Current state

    Dry fit

    [Ontario, Canada]

    This is a kitchen remodel. All the cabinets are out. All the sheetrock is removed from the wall.

    Kitchen plumbing has drain coming through kitchen floor several inches from exterior wall. I plan on using this drain. Sink will be centred on a large bay window that is 48 inches wide. The sink cabinet is 36 inches wide centred on the window. The sink is an apron single drain sink. The vent stack, which breaks the plane of the top plate in the wall, is on the right side of the sink and is married to the right of the king stud for the window. The king stud is located 22 inches from the drain in the floor. There is a cripple stud 8 inches to the right of the drain in the floor. All the DWV piping is 1 1/2 inch ABS.

    I elected to remove the drywall due to a number of factors and was fully prepared to reattach everything almost exactly as it was when I had taken it apart. If I hadn't have asked one question, I would have and been none the wiser. However, I ended up posting a picture of my dry fit on another forum for a sanity check and it was pointed out that my current setup does not place my vent 6 inches above the flood rim. The original vent was a vertical from a sanitary tee branching from the p trap arm and down into the drain. From that very short vertical it was a short 90 elbow into the wall then once on the other side of the drywall it went to a 90 elbow horizontal all the way over to the stack. The bottom of the vent is 21 inches up from the floor. The cripple stud, the king stud and the left side of the vent stack have been notched to accept the vent. The notches are 2 inches in a 2 x 6 stud. I could possibly replace the cripple stud, but the king stud and the vent stack are not moving.

    Several questions.

    1) Can I use a 90 short elbow from the top of the drain to get into the wall and then use another 90 to go up the wall?

    2) Regardless of how I use elbows to transition from the top of the drain and move the vent into the wall, the bottom of the sill plate on the window is only 42 inches above the floor. That does not seem to meet the parameters required to put a vent 6 inches above the flood rim. The pipe centre line would be at the 42 inch mark to acheive that. Am I correct?

    3) If I ended up using an AAV, which I don't even know if I am permitted to, it won't get 6 inches above the flood rim. Secondarily I would have to cap the open end of the vent and I don't know what else it services, and whether or not sealing it would be disaster in that there is the potential for water from an unknown source to get stuck there.

    4) Once in the wall, can I use a pair of 45 and 22 elbows (one pair of each on each end to make 2 - 67 degree bends) to create a sloped vent to meet the stack? I thought I may have read that I can only use an angle of 45 degrees or more from horizontal which would cancel that idea.

    5) Can I put new notches in the cripple stud, and the married king stud/left side of the vent stack? Does the height of the notches matter? If the vent is not horizontal, the notches will have to allow a non-horizontal vent to be accepted in the wall. My assumption is that the cripple stud is non-load bearing. Initially I thought of drilling a 2 inch hole through but the flanges on the elbows make that not possible.

    6) Having exhausted all that, what is the best way to tackle this?

    Edit: pictures added
    Last edited: Jun 5, 2021
  2. breplum

    breplum Member

    Oct 2, 2004
    Plumbing and heating contractor
    San Francisco Bay Area
    Pictures and drawings preferred. no narratives for me.
    Kitchen drains must be 2" and have a cleanout provided. Vent is fine with 1-1/2".
    Not knowing what code you use in your area, UPC allows a horizontal vent less than the 6" below flood rim rule, if all the fittings are drainage fittings oriented properly (of course) and running with normal drainage of 1/4" per foot.
    Stud notching: 25% max notch on bearing studs. 40% notch allowed on non-bearing.
    Bearing Stud boring allowed: 2 x 4= 1 3/8" 2 x 6 = 2 1/8" Non bearing studs boring 2x4= 2" 2x6= 3 1/4"
    There are a lot of ways we have to deal with issues but can't teach it all in a few paragraphs.
    Consider hiring a professional plumbing contractor.
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  4. Knowledging

    Knowledging New Member

    Jun 4, 2021
    Ontario, CANADA
    I have got too many time pressures and have decided to put it back together the way I found it. It has functioned like this for 30+ years without any issues. I apologise for wasting forum space.
  5. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
    IMO, being rid of the glued-in trap and putting in a slip joint trap adapter at the wall would have been better.

    Also, since 45 degrees counts as vertical, the vent could have been "vertical" higher than it currently is.

    A trap adapter can be used as a cleanout. Under that kitchen drain pipe the flow turns from vertical to horizontal. At that turn is where clogs tend to happen. A dedicated cleanout above or below the trap adapter would be good, but a trap adapter is a lot better for running a snake down than what you have.

    If the trap adapter were moved to the right, you could even maybe retain vertical and achieve your 6-inches above the flood plane.

    Red and yellow are alternate paths, and the circles represent the trap adapters.

    If you used the yellow path, with the santee at 45 degrees, the red circle or above could represent a good place for a cleanout to give even better access than the trap adapter.

    Attached Files:

    Last edited: Jun 5, 2021
  6. Knowledging

    Knowledging New Member

    Jun 4, 2021
    Ontario, CANADA
    This had given me thoughts. Thanks. I think the biggest one which I neglected is that I can still trim down the drain pipe.

    The trap adapter also seen like a good idea.
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