Toilet distance from main stack? (Canada)

Discussion in 'Canadian Plumbing Code Questions' started by K-Rod, Dec 12, 2011.

  1. K-Rod

    K-Rod New Member

    Messages:
    3
    Location:
    Saskatoon, SK
    Hey Folks, I've been browsing around here for a while and there seems to be lots of great advice so I thought I'd jump in with a question.

    I'm planning a basement reno and I was wondering what (if anything) the code says about how far a toilet can be from the main stack. I've just drawn up a quick sketch and it looks like the ideal place for the toilet is about 10 ft from the 3" main vertical stack. It dissapears under the slab and I'm not sure what direction it goes from there, so for planning purposes right now I'm just assuming I have to get within a foot of the vertical part. (obviously I would confirm this before building anything)

    anyway the green lines are my first rough guess at where the new drains would be placed. Am I in a realistic ballpark here? or is it just too far from the stack? There is a cleanout at the base of the stack oriented at about the 10 o'clock position looking straight down. Would this suggest the sewer line would run back towards kindof the bottom right of the sketch? Which would mean I'd have to re-think my drain situation.

    Attached Files:

    Last edited: Dec 12, 2011
  2. Terry

    Terry Administrator Staff Member

    Messages:
    14,754
    Location:
    Bothell, Washington
    It depends on your local plumbing code.
    The UPC plumbing code requires a vent within fix feet.
    If a lav or shower is close, you can use that to "wet vent" if the pipe is 2" or larger.

    If the stack in your picture is serving as the waste stack for the upstairs plumbing, then it can't be used as a vent. You will need to run a separate vent up through the roof.

    Venting on trap arms
    1.5", 42"
    2.0", 60"
    3.0", 72"
    Last edited: Dec 16, 2011
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,802
    Location:
    New England
    Also, the drain pipe must slope nominally 1/4" per foot, so, once you start with the trap from the shower or the toilet elbow which will lower the pipe some below the slab, then you must maintain that slope to where you can then attach it to the main drain line. So, it also depends on how deep that existing drain line goes before it turns horizontal to go out to the sewer. Worst case, you may need to pump it from a new basin, but hopefully not.
  4. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,236
    Location:
    Land of Cheese
    If the existing stack is a drain for fixtures on the floor above, you will need a separate vent regardless.

    Chances are the the vertical stack turns horizontal right under the slab, so by the time you figure in pitch, you may need to connect elsewhere.
  5. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    First thing will be to determine where the horizontal drain to the sewer is. If you're not in an urban area (and even if you are, but things get messier there), likelyhood is that it goes generally towards the main street in front of your house. It might not go straight there, if there are other drains coming in, floor drains, etc, but it will usually go that direction. However, it can do anything... in renovating my row house, we discovered that my stack comes down right at the front wall (where I'd assume it would have a wye to turn the stack out to the street, and pull in the floor drains off the back of the wye), goes towards the back of the house about 6 feet, picks up the floor drains, then goes out the side of the house and ties into a giant terra cotta pipe going down the side of my house. 9"... they call this thing the Pittsburgh 9, apparently almost nobody else used it... but I digress...

    That was a weird situation. Look around your basement, see what else goes into the slab, and where the drain could go. This will not be definitive, but you can get an idea. Open up your cleanout and shine a flashlight down there, see if you can see an elbow at the bottom, and which direction it turns. This may require a small mirror stuck down in there to see. Beware of a Wye at the bottom, where the drain could be going one of two directions.

    If you have a good look down there, see if you can get an idea of how far below the slab the pipe is. Often its only a couple inches below the slab surface to the top of the pipe. If it happens to go over right past your bathroom group, that might be ok (as it should be at least 2 1/2" lower by then), but if not, you're probably out of luck.

    You might have to look into a mascerating toilet or similar system, or rearrange your basement to get the bathroom closer to the stack so you can tie in. You could also look into a rear discharge toilet, if you can hide the pipe in a false wall between the bathroom and the stack. This will handle the toilet and the lav, but if that 2" line shown at the top is for a shower, you'll still have the same problem there... the drain will likely be too low to be able to tie it in.
  6. K-Rod

    K-Rod New Member

    Messages:
    3
    Location:
    Saskatoon, SK
    The more I think about it the more I need to make certain where the main runs under the slab. Seems I can work everything backwards from there rather easily. That will be this weekends project.

    Thanks everybody. I'll probably post back with some more diagrams when I get the location figured.
  7. K-Rod

    K-Rod New Member

    Messages:
    3
    Location:
    Saskatoon, SK
    So what do you guys think of this?

    I had about 10 ft of 12ga 2 wire in the garage, and borrowed a metal detector from work. I opened up the cleanout and ran the wire as far as I could into my under slab main pipe, and swiped the floor with the metal detector. Picked up a faint signal but it's something. I'm fairly certain I've got a good idea where my main pipe is now under the slab, for about 10 ft anyway, but thats all I need.

    I'm thinking of doing something in this configuration. the one picture is the top view of what I'm going to bury under the slab. and the other pic is the iso of the way I'm figuring I can vent it. In the iso, the green represents 3", red is 2" and blue is 1-1/2". I was thinking I could even use 2" instead of 1-1/2" except for the sink connection. I'm not really sure of where I've connected the sink to the 3" though because it's downstream of the toilet. I've got a vent there though so I think that covers that, and the toilet and sink would share a 2" vent. I will tie them together and run it into the main vertical stack above where the upstairs fixtures tie in.

    I thought about swapping the sink and toilet positions so that the toilet is always downstream of the shower and sink, but then it would have to make a bit of a crazy bend.

    What do you folks think? on the right track here? Basement sketch 3.JPG basement sketch 2.JPG
    Last edited: Dec 15, 2011
  8. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    How sure are you that you found the Kleenex(tm) wire (we're not allowed to use that other name), and not something else in the slab? You want to be pretty sure you know where the stack is before planning out too much.

    It seems like you could fairly easily vent all 3 fixtures if you needed to. I always vent every fixture, but I know there are legal ways to share a vent. I won't comment on that, as I'm not very experienced with it.

    Can an entire bathroom group share a 2" vent? I think that might be ok, but not sure. I don't remember the fixture units off hand... I usually have at most 2 things (shower and lav typically) on one vent before it ties back to the stack, but again, not sure what the requirements are, I just try to be overly safe in my layouts. You will need to get that vent(s?) up to at least 6" above the flood rim of the highest fixture entering the stack before tying it in, or run it up through the roof separately.

    Its hard to see much else in the rough sketch, but seems like it could work, given the right fittings, etc. Keep in mind that venting rules are a bit different in a basement... stricter about when you can go horizontal, etc.
  9. mikeplummer

    mikeplummer Plumber

    Messages:
    190
    Location:
    Ontario, Canada
    old thread so i won't go into great detail.... a toilet drain can go 1m vertical AND 4m horizontal before vent connection, beyond vent connection it is a matter of maintaining proper pipe grading until connection at building drain....

    a bathroom group can be vented using a 2 " wet vent. the wet vent must transition from wet vent to dry through a continous vent, the secondary vented fixture can connect to this 2" wet vent and not require its own separate vent, providing it meets other required vent requirements (135 deg change direction, 1.7m trap arm (1.5"pipe), etc etc)
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