Design for rebuilt stack - does it meet code?

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Calgary, AB
Hi folks. I am renovating a bungalow and I have removed the old 3” cast iron stack various piping on the main floor. I am going to rebuild the stack using 3” ABS. There is also a 2” drain into the basement floor that I will be using for a couple of fixtures.

I’ve taken a shot at designing the stack and venting requirements. I would like to get some advice/corrections on my design to make sure everything is up to Canadian code (and will work!). I have replumbed a reno house before with the help of an old pro. This time around I’m trying to do the plumbing myself as long as I have some expert advice on the design.

The stack will be in a wall that divides the main floor bathroom and laundry room. (I am also planning for a washer in the basement so there will be two in all, it’s a long story…).

The main floor bathroom will have toilet, sink and a tub/shower combo. The tub/shower will have a 1.5” vent pipe that runs up a wall and into the attic where it will manifold into the main stack.

The main floor laundry room will have a washer and a laundry sink. This laundry sink will be back-to-back with the bathroom sink and using a 2” drain pipe running to the stack, I think these can direct vent on the stack as their traps will be 5’ or less away.

The other fixture on the main floor is the kitchen sink (plus dishwasher). These are about 17’ from the main stack so I will have a 1.5” vent that runs up an exterior wall and then horizontally through the attic till it meets up with the stack. I am thinking I need a 2” drain pipe to run to the main stack from this because of the distance — but I’ll use 1.5” if the experts on here say that’s enough.

See the attached diagrams.

My design for the fittings from highest on the stack to lowest, is:

1. 3x3x1.5 sanitary tee to tie in vent lines from main floor tub and kitchen sink. This is in the attic.

2. 3x3x1.5 double sanitary tee to tie in vent lines from basement bathroom sink & basement tub, and from and basement washer & utility sink. (Basement bathroom sink drains into an existing 2” waste pipe in the basement floor. Main floor tub will also drain into this using a 2x2x1.5 wye.)

3. 3x3x2 sanitary tee to drain back-to-back main floor sinks (bathroom & laundry). (These direct vent on the main stack.)

4. 3x3x2 sanitary tee to drain main floor washer. (This direct vents on the stack.)

5. 3x3x3 sanitary tee for main floor toilet. (This direct vents on the stack.)

6. 3x3x2 sanitary tee for main floor kitchen sink (and DW). Trap is about 17’ from main stack, so is vented through attic to main stack.

7. 3x3x2 sanitary tee for basement washing machine and utility sink. This drain pipe will have a separate vent pipe that manifolds to main stack above all fixtures (42” above finished floor).

8. 3x3x3 wye with test plug to serve as cleanout.


  • stack design Feb 21.pdf
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Just an amateur but here is my take after a look:

It's a little hard to read being on multiple pages and don't see overall view. Some descriptions don't seem to match so not sure what is what. Don't know if it is a bad description or wrong choice. It is easier to have one drawing where fixtures, vents, and drains are in one place. Try one drawing per floor but complete.

It seems you have way too many connections to main stack. Vents can be combined. Drains can be combined. Can't tell what you can't change because don't know what old plumbing is staying and what is new and can be changed.

Basement washer should have vent before sink to not siphon sink.

Toilet needs a vent. Usually 2" and lots of times a wet vent from sink/tub.

Is there only one toilet in the house? None in basement bathroom?

Don't see vent for main floor washer.
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