Toilet vent advice

[mmax]

I am roughing in for a new 1/2 bathroom and am having trouble with venting the toilet. See the attached photo. The vent for this bathroom and a laundry room above is to the left of the toilet. I would like to have the closet bend go to the right under the toilet to stay in the joist bay all the way to the basement wall below where it will turn and connect to the stack. I can go out the back of the toilet and vent up the wall behind the toilet, but I would 1) like to avoid cutting through the joist, and 2) there is currently an HVAC supply duct filling up most of that joist bay.

Is there another way I can make this work? I am under the 2018 UPC. And advice is appreciated. Thanks

 

[wwhitney]

Yes, you can wet vent the toilet using the sink drain by sending it into the joist bay with the toilet fixture drain and connecting them with a horizontal wye.

Which plumbing code are you under? If it's the UPC, then the sink drain and vent would need to be upsized to 2" (the trap arm can be 1.5"). If you are under the IPC, then it can all be 1.5".

Cheers, Wayne

 

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[Jeff H Young]

UPC 2 inch just put a combi on the 3 inch line to the w/c and run to your lav and vent 2 inch the whole way