AAV venting basements sink on drain connected to upstairs sink that uses AAV

[elockwood]

Hi,

I'm adding a basement kitchenette below our main floor kitchen. The main floor kitchen sink is AAV vented and there is a 2in drain connected to the sink and dishwasher as seen in the photo below. I'm getting confused on the code (I'm in WA state) around AAV on two floors. I've seen that AAVs "can't vent multiple fixtures when the fixtures are on different floors." However, does adding a separate AAV to the downstairs sink solve this issue? And does the downstairs sink AAV need to be above flood level of the upstairs sink ( I could run it up into the upstairs sink cabinet)? I've attached a plumbing diagram of what I think would work. Thanks for any advice!

 

[Breplum]

The flood protection provided on an AAV would NOT be adequate since they are just a rubber diaphragm and tiny spring.

 

[Sponsor]

 

[elockwood]

The flood protection provided on an AAV would NOT be adequate since they are just a rubber diaphragm and tiny spring.

What would you recommend instead? Run a new vent to the roof to vent both the sinks?

 

[Tuttles Revenge]

Washington Residential code allows AAV. Some jurisdictions in WA have banned them in certain applications. In Bellevue we can't use them in commercial applications and in residential, they are limited to islands only.

Multiple fixtures on the same floor level, can be served by a single AAV provided that the AAV be placed a minimum 6" above the flood level of the highest fixture being served.

In your instance, if the stack from above is connected to a vent through the roof, then your sink in the basement can be vented with an AAV located 4" above the branch drain / trap arm of the fixture. IE under the counter top accessible via an access panel inside your cabinet.

2018 WASHINGTON STATE RESIDENTIAL CODE | ICC DIGITAL CODES

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.

codes.iccsafe.org

 

[elockwood]

Washington Residential code allows AAV. Some jurisdictions in WA have banned them in certain applications. In Bellevue we can't use them in commercial applications and in residential, they are limited to islands only.

Multiple fixtures on the same floor level, can be served by a single AAV provided that the AAV be placed a minimum 6" above the flood level of the highest fixture being served.

In your instance, if the stack from above is connected to a vent through the roof, then your sink in the basement can be vented with an AAV located 4" above the branch drain / trap arm of the fixture. IE under the counter top accessible via an access panel inside your cabinet.

2018 WASHINGTON STATE RESIDENTIAL CODE | ICC DIGITAL CODES

ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.

codes.iccsafe.org

Thanks for the information. The upstairs sink is not roof vented, it only has an AAV and there is a window directly above the sink that makes running a roof vent a bit of a challenge. But maybe that is the better approach, add a new vent to the upstairs sink either through the roof or through the wall possibly to make for less in wall work? And then use an AAV only on the basement sink tied to the 2in existing drain.

 

[Tuttles Revenge]

The manufactures requirement for installation of AAV is that the branch that is AAV vented be connected to a stack that is itself vented to atmosphere. Its been a while that I read through all of Studors install instructions, but I doubt that changed. It was a big part of IAPMO / UPC allowing AAV's in the 90s.

Studor sued IAPMO King County and forced them to allow AAV by the Alternate installation method of the code.

 

[Jeff H Young]

I dont see how the OPs drawing could overflow the basement any more so with an AAV than a regular vent I think overflowing has nothing to do with it. p3114.3 might be related to why it cant have an AAV in basement. Or manufacture requirements