Offset Sink Venting

[Cgrothaus3]

I am currently working on renovating back to back bathrooms in which the vanity drains are offset by approx. 16” on either side of the wall. Is it allowable for both drains to connect into the same waste line and share the same vent as pictured? Or will the offset drain need a separate vent run and tied in above flood rim level? Any advice is appreciated!

 

[wwhitney]

Not as shown--the right hand sink needs to be vented before its trap arm turns down. You can't have a vertical offset before the vent. [Plus a combo like you have for the right hand sink to connect to the stack doesn't allow for venting, it would need to be a san-tee.]

But you could, for example, use a san-tee with side inlet to allow both trap arms to connect to the stack at the same elevation. Or you can stick with the stack connections you have if you use a separate san-tee for the right hand sink and run a separate dry vent up to at least 6" above the flood rim before turning horizontal to connect to the existing vent.

Cheers, Wayne

 

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[Terry]

It looks like 1.5" to the two lavs. I normally have to run 2" until I split them off.
I have plumbed like below when I've encountered 1.5", still not code but does work very well in practice.

And when you have 2" to work with.