ONTARIO 1 1/2" shower drain??

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Footman_75, Jul 12, 2012.

  1. Footman_75

    Footman_75 Renovating

    Messages:
    36
    Location:
    Ontario, Canada
    Renovating master bath on 2nd floor. Just ripped up a floor only to discover that the original shower drain is 1 1/2". House was built 1987.

    Question: Can I proceed to install shower with 1 1/2" drain? I always thought showers required 2" drains. Thoughts?

    Edit: Turns out OBC 1992 Table 7.4.9.3 permits 1 1/2" drains for showers with only 1 head. Am I reading this right?

    Thanks
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,525
    Location:
    Cave Creek, Arizona
    If it is not being inspected, which I assume is the case, you can do anything you want to. And even if the code DOES permit it, that is a "minimum standard" and you may NOT be happy with the results some time in the near, or disant future.
  3. Footman_75

    Footman_75 Renovating

    Messages:
    36
    Location:
    Ontario, Canada
    Not interested in doing anything I want to. Am interested in doing good work, and understanding physics behind code. Thanks for your reply though.

    Did you read my original post? Original build has 1 1/2 shower drain. Was surprised to see this.

    Anyhow, I'll assume shower with 1 1/2 drain limits the number of shower heads, and lends itself more easily to clogs.

    Thanks
    Last edited: Jul 12, 2012
  4. centurion

    centurion New Member

    Messages:
    10
    Location:
    New Jersey
    I can's speak for Canada, but here in NJ 1 1/2 is allowed if there is 1 shower head. I understand the concerns that some may have. However, it would seem to me that if it has worked OK for 25 years it should not be a problem.
  5. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,335
    Location:
    Yakima WA
    As I understand the reasoning behind the 2" drain requirement is this lessens the chance of a clog which would result in an overflow. In my opinion, your drain falls in the grandfather clause, so I would leave it. New shower heads are supposed to be limited in gpm, so there is little chance of a problem. We got along with 1-1/2" shower drains for many years and mostly without problem.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,933
    Location:
    New England
    Code allows it in Canada, and there are millions of places with shower drains that size. It is much better to have a larger one, but people are generally happy with what they have. The reasoning for the larger drain is to ensure if you accidentally stand on the drain or drop the washcloth, you might notice it before it overflows the shower curb. It is also necessary if you have a high flow or multiple showerheads. Showerheads meeting current codes are pretty low-flow, much less than those of old which helps, too. Most tubs are 1.5", and many are used as showers, but they can hold a LOT more volume than a typical shower before overflow, AND they have a secondary, overflow path down the drain that usually works.
  7. mikeplummer

    mikeplummer Plumber

    Messages:
    190
    Location:
    Ontario, Canada
    1-1/2" is allowed in the OBC...with 1 shower head, and is common practice in Ontario
  8. Footman_75

    Footman_75 Renovating

    Messages:
    36
    Location:
    Ontario, Canada
    1) Thanks to all for the input.

    2) Other option is to tie shower drain to toilet drain using a 3x3x2 low heel, or 3x3x2 side inlet. (See image below.) If I understand correctly, this complicates matters, as it will require a vent for the new shower drain (pls correct me if I am wrong). Further, the only feasible way to vent the shower drain would likely incur a downhill slope. Note that slopes are not to scale in the image.

    That said, the existing vent was formerly an LV drain and presently has no fixtures upstream from this diagram. So, worst case, backed-up shower vent would drain down the old LV drain. Still, it's ugly and likely not code. Pls comment on any other concerns over this option.

    Thanks again. Feedback is greatly appreciated.

    Drain 2.jpg
  9. Terry

    Terry Administrator Staff Member

    Messages:
    14,929
    Location:
    Bothell, Washington
    You can't vent using a down hill slope.
    If the shower vent was tied into a lav waste and vent, that would work. The lav would wet vent the shower. The lav piping needs to be 2" for it to work as a vent. And it has to grade up, not down.
    The drawing above wouldn't pass anywhere.

    If you go with a 1.5" shower drain and vent, you can't wet vent it.
    Last edited: Jul 13, 2012
  10. Footman_75

    Footman_75 Renovating

    Messages:
    36
    Location:
    Ontario, Canada
    Thanks Terry.
  11. mikeplummer

    mikeplummer Plumber

    Messages:
    190
    Location:
    Ontario, Canada
    from your drawing, why not keep the new vent (yellow) sloped properly and tie into old lav vent above floor, or above FLR of lav if its still to be used for lav
  12. Footman_75

    Footman_75 Renovating

    Messages:
    36
    Location:
    Ontario, Canada
    @mikeplummer

    Exactly what I was thinking. Trick will be making all this happen between joists. Right now, am planning for yellow vent to go right instead of left, through a joist bridge, then up a wall cavity about 8" away. From there, clear run to attic.

    I will follow up with diagram.
  13. Footman_75

    Footman_75 Renovating

    Messages:
    36
    Location:
    Ontario, Canada
    ITEM A: Yellow vent drops into 2" shower drain from the top
    ITEM B: Run is 45 deg to shower drain

    Does this eliminate horizontal venting?

    Drain 3.jpg

    Drain 4.jpg
    Last edited: Jul 13, 2012
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