AAV on exterior of new build

I’ve never seen an AAV inset on an exterior wall for a bathroom sink, especially on new construction. I’m located in Florida where FBC P3103.1.4 states:

“Vent terminals extending through the wall shall terminate not closer than 10 feet from a lot line and not less than 10 feet above the highest grade elevation within 10 feet in any direction horizontally of the vent terminal”

This seems like a clear violation, except the FBC defines a vent terminal as:

“a pipe or other conduit composed of factory-made components, containing a passageway for conveying combustion products and air to the atmosphere, listed and labeled for use with a specific type or class of appliance.”

Sewer gases aren’t considered combustion products, to my knowledge (unless we’re talking about post-TacoBell events, i suppose).

I guess this is one of those “this seems wrong, but I don’t know why” episodes. Hoping someone could help out.

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Isn’t it sucking air into the system rather than conveying air to the atmosphere?


I was once told by a Plumber that if it’s installed in a non-conditioned area, there is the potential for the valve to freeze in the closed position, not that you would have to worry about that so much in Florida.

If it’s lower than 10’ above grade per the regulation you mentioned, which it appears to be, call it out as improper installation and let the builder prove otherwise.


Good point. Wasn’t even considering that

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Guess I found another reason it’s wrong. I’ve discovered the venting issue is actually secondary to the FBC that requires AAVs to be installed in accordance with manufacturer’s instructions. Looks like Kevin was right!


Yep…it “admits” the air into the pipe :wink:

You can check out anytime you like but you can never leave.


That is odd. I am also in Fl, and I have never seen an AAV at the exterior. They are designed to be used indoors, thats the whole point… :man_shrugging:

You said it was for a bathroom sink? It should just be inside the cabinet.


That makes no sense. In good time the rubber will deteriorate in the sun, and the AVV will do something other than intended (not good).

And I’ll bet the wall is sealed, if anything, with caulk that will go bad over time.

Looks like a patch, even on a new build. So likely somebody screwed up and did not run the vent to the roof. The roof run defects I find are usually cutting too much framing, neglecting air sealing or fire sealing.

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Im thinking they did this because they used a pedestal sink, so there was no cabinet to hide it under. Apparently this is easier then taking a plumbing stack straight up. the window above that area doesnt even open, so theres no reason i can see why they did it this way.

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This was likely a retroactive cure for a sink that was not vented. They hacked into the wall and added the vent from the exterior. Look at that cut-out? Was that done with a chain saw?


Also, that vent is wet. Rain, sprinklers or condensate?

Lol, probably!

I had just shut off the sprinklers in that area.

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