My understanding is that the IRC allows Air Admittance Valves (AAV’s) at island sinks or other appropriate places. I also understand that the UPC is silent on the use of AAV’s. Therefore, if my local AHJ has adopted the UPC then it may or may not allow an AAV to be used. Is this correct?

The way I understand it, it doesn’t matter what either one say. It only matters what your local AHJ wants to say about it. I suggest you give him/her a call. Then you will know what their standing is on the subject. I have found that my local AHJ will not except the black colored ones but will except the white plastic ones. The black ones are 1/2 the price at Home Depot.

The UPC does not recognize the use of AAV’s as an approved means to vent fixtures, however, they do allow for “island vents” (high loop).

Loop Venting… Again I suggest checking with your local AHJ. I had two different inspectors in the same city… one approved the high loop the other would not. Both were for the same house.

The first inspection failed not because of my work, but because my boss insisted I use 1-1/2" PVC for the direct drain for the laundry machine when I said it had to be 2" PVC. That inspector approved the AAV. The inspector for the reinspection said he would not have approved the AAV that it had to be an Island Loop, but he was not there to check that. I had asked the first inspector about doing an Island Loop… he said that they were no longer an approved form of venting.

The Local AHJ’s don’t even know what is approved and what is not! I still say a phone call is cheaper than having to pay for two inspections and the wasted plumbing parts. Not to forget the lost day wages at your day job.