Venting kitchen sink in window wall

[wabba]

Helping some friends with a kitchen remodel. Sink is moving to a first floor exterior wall centered under an 8' window. If I snake over to the side of the window and head up the outside wall with a vent, assuming I can get past the rim boards (and it's only 2x4 framing), it then runs into the middle of a second floor window.

The good news is the new sink location has a 6' high crawlspace, and the main 4in drain line runs directly underneath it right on the crawlspace floor - so I have a ton of working room.

Couple options I was thinking of and not sure if either is allowed or not - run an island loop scenario (does this need to be in cabinet, or can it be buried in-wall with cleanout accessible?) and could run a vent line across the crawlspace to tie into vent stack which is probably 20 feet away.

Second option is an AAV, but not clear if it needs to be above the flood line or just the drain line:

Options? I like the idea of the island/bow loop scenario because there is no AAV involved, but not sure how acceptable that technically is. Unincorporated pierce county, WA state.

 

[Terry]

You can use an AAV in Washington. Many of the new homes are using them on kitchen sinks.
The picture above on the left? Someone should have either removed the vent through the roof, or wyed it into the drain. Rainfall will be getting that wall wet.

 

[Sponsor]

 

[wabba]

You can use an AAV in Washington. Many of the new homes are using them on kitchen sinks.
The picture above on the left? Someone should have either removed the vent through the roof, or wyed it into the drain. Rainfall will be getting that wall wet.

That LH photo was in-progress off another site before they removed the old vent and fixed the framing. Sounds like a vote of confidence in the AAV; does it need to be (or preferred to be) above the flood line of the fixture if configured like the LH photo (does that qualify as a stack vent) or just the trap arm (as in RH photo). Would one method be preferred over the other?

 

[Terry]

It would be hard to install an AAV over flood level in a kitchen. They do like them at least 4" above the trap arm.