Soil stack as common vent.

[Duplex]

Hi all. I'm new here and have a question. I'm remodeling a duplex. The 3 inch soil stack is straight vertical. It's a two storey. There's a total of 10 dfu on it. From the top down, second floor, lav, then WC. Ground floor lav, kitchen sink on shared trap arm. And last is washer standpipe. All the drain arms are properly sized. The longest trap arm is the upper lav at about 24 inches. Everything else is closer. At thus point there's no issues. Would some type of dry vent be needed from the lower floor, to up past the highest fixture? Or is the 3 inch stack sufficient. I'm re doing drywall and it's exposed. Thanks.

 

[Sylvan]

Vent lower floors until your 4" above the flood level of the highest fixture and then connect to the 3" vent

 

[Sponsor]

 

[Duplex]

Vent lower floors until your 4" above the flood level of the highest fixture and then connect to the 3" vent

That's what I was thinking, yes.

 

[Duplex]

I'm just not sure how to interpret the code on this. Seems 3 inch stack is fine for the dfu totals. It's just the multi storey part that's unclear to me. I'm thinking the positive pressure in front of the WC draining would have more of an effect than negative pressure behind.

 

[Weekend Handyman]

I am not a pro.

I could be wrong, but Under the Plumbing Code Of Canada I think you would not be allowed to use the stack for a wet vent for anything down stream of the top floor toilet.

Check out this video series on wet venting based on PCC. This guy seems to be a plumbing instructors at one of the trade schools.