Air Admittance Valves

I’ve been running into these plumbing vent valves a lot recently, the kind that do not require roof penetration, and I’m curious to know from some more seasoned inspectors what they think of them. Are these kind of venting valves okay under a kitchen sink or in the attic?

Here’s a good picture of them.


They are a mechanical valve and, therefore, subject to failure. Check your local codes to see if they are allowed. IRC says they’re okay, UPC does not recognize them.

Jeff, you bring up a good point here.

Maine does not allow Mechanical vents as of last year. How would we address the fact of it’s existance in dwellings before the Code change?

Since we are not Code Officers, how does it get addressed in the report?

Could we look at it as a Safety issue?
Point out that it is no longer accepted by the Building Plumbing Code and needs to be upgraded?

What are your thoughts on that subject?


Marcel :slight_smile:

CA does not allow them, although some local jurisdictions do. Here is one of my standards when I see these. You might be able to modify it for your state.

I think it’s a bit of a stretch to call it as a “safety” issue, unless they are not functioning.

Thanks Jeff, that was a lot of help.

Marcel :slight_smile: :smiley:

Just ran into my first AAV in an attic this week on a 3 inch vent set me back on my heels for a moment used to seeing them on sinks not in the attics here; darn Plumbers connot find a good one any more all they want to do is take short cuts. Maybe we should all turn the clocks back and start using outhouses again???

It may be worthy to add the smell (rotten eggs) of hydrogen sulfide, or “sewer gas” to your list of odors.

One of the problems with hydrogen sulfide is that, after a few whiffs, it will deaden the olfactory nerves (sense of smell) and while still being in high concentrations, it becomes odorless.

Hydrogen sulfide effects are also cumulative and, repeated exposures even to small levels, have been known to cause neurological damage.

The nose not always knows.:wink:

I might just do that. Thanks James. . .

It is not unusual that you should be seeing air admittance valves on plumbing vents in Oklahoma since Oklahoma has adopted the International Plumbing Code and the plumbing provisions of the International Residential Code statewide.

Both the IPC and IRC plumbing provisions allow air admittance valves on all vents except for pneumatic sewage ejectors, except on the required one 3" vent that penetrates the roof as a main vent, and where local codes restrict or forbid AAV use.

AAVs are also allowed in Maine jurisdictions and elsewhere that have adopted the IPC and IRC plumbing provisions.

To see which ICC Codes, if any your state or municipal jurisidction have adopted, click the state on the ICC map link here:

How much you wanna bet that valve was installed post contruction after some moron completed the roof without the penetration?:roll: May not be the plumbers fault!

I will bet anything you have to loose.
The home was a 100 years in age and had been gutted in 1995 with a new bathroom installed in the original part of the home the plumber just did not want to cut a hole in the roof. Would of been very easy in that location of the roof that is why they started making hole saws and sawzalls???

Back to Codes

StateIPCIRCUPCNSPC****Approval Status

as of 8/ 2006


AlaskaXNot approved



CaliforniaXPartial approval







HawaiiXNot approved

IdahoXNot approved

IllinoisNot approved


IowaXNot approved

KansasX****XPartial approval

KentuckyNot approved

LouisianaNot approved

MaineX****XPartial approval

MarylandXApproved appendix “E”
2005 edition

MassachusettsNot approved


MinnesotaNot Approved


MissouriXPartial approval

MontanaXNot approved

NebraskaX****XNot approved

NevadaXPartial approval

New HampshireXApproved

New JerseyXApproved appendix “E”
2005 edition

New MexicoXNot approved

New YorkX****XApproved except NYC

North CarolinaX****XApproved

North DakotaXNot approved



OregonXNot approved

PennsylvaniaX****XApproved except

Rhode IslandX****XApproved

South CarolinaX****XApproved

South DakotaXPartial approval


TexasXXXPartial approval




WashingtonXPartial approval

West VirginiaX****XApproved


WyomingX****XNot approved

IPC=Internatinal Plumbing Code IRC=International Residential Code****UPC=Uniform Plumbing Code NSPC=National Standard Plumbing Code

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Right, Marcel

AAVs are*** permitted*** in Maine jurisdictions but ONLY where they are approved by Code…

Both Studor (only one such manufacturer of AAVs) and the ICC Plumbing Codes acknowledge this…

Whether or not AAVs can be used in Maine depends entirely on the municipality involved.

AAVs IMO are great for older homes, but do have their draw backs due to failure, but if that’s the only way to vent a sink what are you going to do?

I point them out and educate my client on their limitations and put that into the report. I see nothing wrong with them, I have one in my house.