Venting Question (With Photos!): Tieing together 3", 2", 1.5" where the 2" is vertical

[RedBird52]

I am so grateful for having access to this forum and all of the information contained within! Thank you everyone for sharing your knowedge with me!

So, I have a super tight bathroom renovation. 1st floor is full bathroom and Laundry. 2nd floor is full bathroom. Before I install this vent combination, wanted to confirm it was viable!

 

[wwhitney]

Is the picture of the first or second floor?

You're going to need to diagram the drains and vents on this floor more fully. But my first reaction is that the 3" pipe segment labeled in red as 3" horizontal vent has no function and should be deleted. If it's not venting an individual fixture, you don't need it. I don't see how it could be venting an individual fixture, and if it were, I would expect that the horizontal segment is below the fixture flood rim, which is disallowed.

Cheers Wayne

 

[Sponsor]

 

[wwhitney]

OK, I see that 248 CMR 10.05(a) does require that you have a minimum 3" vent stack or stack vent. But whether you need the horizontal connection shown would depend on whether there is any other 3" path from the building drain to a roof vent. If you did need it, it seems very odd to me to connect a vent to a branch drain and then go horizontal after so little elevation rise.

Basically, I think we need the big picture of the entire DWV system, at least in block format.

Cheers, Wayne

 

[RedBird52]

Just want to say thanks to Wayne who contributed to this post. Was able to move this forward with all of your help. thank you much!