minimum size for washing machine fixture

Discussion in 'Canadian Plumbing Code Questions' started by mmmm, Oct 25, 2010.

  1. mmmm

    mmmm New Member

    Messages:
    3
    Location:
    British Columbia, Canada
    Hi,

    I am in a older house with 2x4 construction. We are relocating our washer. I searched and found that the minimum size for the stand pipe is 1 1/2" for Canada. Can I have a 2" stand pipe going into 1 1/2" p trap? The length of the stand pipe is 29".

    Thanks

    Mike
  2. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    What would be the point?

    The only thing that will come from downsizing as you go downstream is problems.
  3. Jerome2877

    Jerome2877 In the Trades

    Messages:
    397
    Location:
    BC
    No you cannot do that by code.
  4. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Not true at all.

    The NPC of Canada doesn't say much about what you can do with a fixture outlet pipe, but only what you can do with a trap and what's downstream of a trap.

    Lots of people put 2" stand pipes in when they remodel because it gives you a bit more volume before the washer backs up if you have old, slow draining pipes.

    I've seen it plenty of times and it's perfectly acceptable on a retro-fit.
  5. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,360
    Location:
    Yakima WA
    Code issues aside, there are a couple of problems you may encounter. Newer washing machines empty water very rapidly and a 1-1/2" drain is too small to handle it. As noted in a previous answer, the 2" standpipe will give you a small amount of extra space, but may or may not be enough. A pretty basic principle in drain plumbing is that you never reduce the size going away from the fixture. It's rather like a funnel with a large top and small outlet. You can pour a bunch of liquid in the top, but it will empty slowly through the small outlet. Keep pouring water in the top, and it will overflow. If your drain pipes are old galvanized pipes, they also can be half clogged with crud which effectively makes the pipe even smaller.
Similar Threads: minimum size
Forum Title Date
Canadian Plumbing Code Questions minimum drain pipe size for a lav Mar 31, 2013
Canadian Plumbing Code Questions Drain size for washer in Canada Aug 26, 2013
Canadian Plumbing Code Questions I need to know the vent size for a 2 inch shower pipe drain Oct 7, 2010
Canadian Plumbing Code Questions pipe size /max length of run for kitchen, Canada Code Aug 7, 2010

Share This Page