1/2 bath & laundry remodel.

[DIYluke]

Good afternoon.
I was hoping for a bit of clarity on a drain venting question.
I have three fixtures sharing the same main horizontal drain but are connected to it with two different vertical stacks. They also share the same vent through the roof.
Is it acceptable that the vent leave the first fixture (kitchen sink) and pitches up away from the sink for about half the run, then turns down and pitches towards the other fixtures (washing machine/utility sink) vent pipe? That pipe then goes up through the roof.
In this scenario any liquid in the vent will gravity drain, but some of the kitchen sinks vent "liquid" may end up in the laundry room drain.
I only ask because I'm looking at IPC 905.2 and maybe I'm being too literal in its interpretation by thinking the vent pipe can only drain back to the fixture it serves.
Thanks in advance.

 

[Terry]

I have plumbed kitchen sinks using the Island Vent and AAV's.
I think using an AAV is much easier on a kitchen than what it takes to do a proper Island Vent.

You will note in this drawing that some of the fittings are different than what has been pictured.

 

[Sponsor]

 

[DIYluke]

Terry,
Thanks for the response. The picture helps.
Were you showing me that the sink vent rises then falls and then rises again?
Is it safe to say I can run a vent up or down as long as it gravity drains back to the drain of the house, if not the drain of that fixture?

 

[Terry]

The vent does loop down to the drain below. In this case it has a foot vent that goes up a wall with a cleanout that isn't show.
Any kitchen sink should have a cleanout accessible and the foot vent in a wall needs a cleanout.

It depends on the inspector, but in a case like this I've been leaning toward the AAV. It's much simpler.

 

[DIYluke]

I understand the AAV, and I see how much simpler it would be in that application.
In mine, most of the venting is existing. The issue is getting the vent from the kitchen to the laundry over a newly added structural beam.
I've attached a photo with the all the related drains and vents. The red dot I added is the beam I have to get over.
Does this drawing look like an acceptable instalation?