I'm doing a kitchen renovation and moving the location of the sink so that the plumbing stub-outs (supply and drain) need to exit the wall one stud-bay over. I'm also replacing the old galvanized pipe existing as the vent stack in the process.

My plan was to notch out the stud (not load bearing) between the two bays,and run a short horizontal section to a 90 degree elbow, exiting the wall at the new sink location.

Are there any issues (code or practically speaking) with the 90 degree turn in the horizontal at the sink drain?

See attached photo. My proposed modification is drawn poorly in red :).enter image description here

1 Answer 1


Code in my area(Toronto) allows that. Just make sure to use the proper fitting and deburr the pipe inside and out before final assembly. And 1/4 inch per foot slope. It's not a minimum or maximum figure. That's the only allowable slope. That allows the water running in the pipe to wash the pipe as it flows. Too much slope creates a build up of crud on the side walls.

  • I mostly agree with what Joe said, above. I would add something about avoiding horizontal 90's where possible. It may be code compliant, but in my limited experience most blockages in kitchen drains occurred at a horizontal 90° elbow. I, instead, now use two 45° elbows glued together. This allows for a more gradual bend and less likelyhood of trapping debris in a sudden, sharp turn of a 90. For this configuration I would use a normal 45° elbow (HUB X HUB) and a 45° street elbow (HUB X SPIGOT). One end of the street elbow fits right into the regular 45 elbow. Commented Feb 17, 2019 at 20:32
  • Curious why you're using PVC for drains and vent? Is this room shown in your picture below grade, ie; in the basement? What country are you in? PVC in my country (Canada) is generally required for use in dwv systems when used below grade or in commercial construction. Commented Feb 17, 2019 at 20:37
  • Agreed, more sweep = less chance of things getting stuck. Higher degree of difficulty if you aren't used to using plumbing fittings but definitely the way to go.
    – Joe Fala
    Commented Feb 17, 2019 at 20:43
  • they remind me of LEGO, but for grown men .... Commented Feb 17, 2019 at 20:48
  • 1
    Thanks all. I bought a long sweep 90 fitting to use. I didn't see any other good way of doing this other than adding in the horizontal 90. The only other option I could think of was to move the vertical drain over one stud bay, then drop to a horzobtal section to take the drain back in line with the floor penetration in the basement. Would this be preferable? This is on the first floor, above grade. I'm replacing the entire vent stack with PVC, as I discovered several sections of the steel vent pipe rotting out, after removing the wall covering. Commented Feb 18, 2019 at 16:45

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