No, not every vent. Under the 2024 IPC and IRC that Phoenix has adopted, a vent may end through the roof or through a sidewall, and many branch vents can end at an air admittance valve. But every house still needs at least one vent that reaches the open air outside, and a wall exit has strict placement limits.
What does the code actually require?
It requires a way out, and it gives you a short list of approved ways. IPC Section 903.1 says the vent pipe shall terminate by extending to the outdoors through the roof or the side wall, using one of four methods in Sections 903.1.1 through 903.1.4. The IRC says nearly the same thing in Section P3103.1: vents terminating outdoors go through the roof or a sidewall.
So the four outdoor options are:
- 1Roof extension, the familiar pipe sticking up through the shingles or tile. The IRC sets it at least 6 inches above the roof, or 6 inches above expected snow, whichever is greater.
- 2Roof used by people, like a rooftop deck. Both codes require at least 7 feet above that roof.
- 3Covered roof extension, where a solar panel or decorative shroud sits over the pipe. The IRC and IPC allow it as low as 2 inches above a sloped roof, with an open area at least as big as the pipe and protection against birds and rodents.
- 4Sidewall terminal, which exits through an outside wall.
Our page on how high a vent must rise above the roof goes deeper on the roof options and window clearances.
When can a vent go out through a wall?
When it can meet three placement limits, and that's harder than it sounds on a typical lot. IPC 903.1.4 says vent terminals extending through the wall shall terminate not less than 10 feet from the lot line and 10 feet above the highest adjacent grade within 10 feet horizontally of the vent terminal. The IRC version, P3103.1.4, carries the same 10-foot numbers.
Both codes add two more rules:
- Not under a vented soffit. The IPC says vent terminals shall not terminate under the overhang of a structure with soffit vents. Plenty of Valley homes have soffit vents in the eaves, which rules out the easy spot under the overhang.
- Screened against critters. The terminal must be protected so birds and rodents can't get in or block it.
The general location rule still applies too. IPC 903.5 bars an open vent terminal directly beneath any door, openable window or air intake, and keeps it 10 feet away horizontally unless it sits 3 feet or more above the top of that opening.
Put those together on a single-story ranch house in a subdivision and you see the problem. Ten feet above grade is roughly at or above the eave line. Ten feet from the lot line rules out the side yard on many lots. That's why sidewall vents show up more on two-story walls and commercial buildings than on Valley tract homes.
Can an air admittance valve replace the roof vent?
For most branch vents, yes. For the whole house, no. An AAV is a one-way valve that lets air into the drain when water flows and closes to keep sewer gas in. The IPC permits individual, branch and circuit vents to end at an individual or branch-type AAV, and lets stack vents end at a stack-type AAV, within limits.
The catch is written into both codes. IPC 918.7 says that within each plumbing system, not less than one stack vent or vent stack shall extend outdoors to the open air. IRC P3114.7 says the same. So AAVs can handle an island sink or a remodeled bathroom far from the stack, but at least one pipe still has to reach outside.
The IPC also sets placement rules for AAVs, including at least 4 inches above the branch drain for individual and branch types, access for service, and a spot where air can reach the valve. It bars them in supply or return air plenums. Our pages on what an air admittance valve is and whether AAVs are allowed in Arizona cover the details, including the important wrinkle below.
Which code applies to your Phoenix project?
It depends on which code the plans are drawn to, so check before you design around a wall vent or an AAV. Phoenix's administrative code, Section 101.4.3, says the provisions of the Uniform Plumbing Code or International Plumbing Code, as amended, apply to plumbing systems. The city's code history sheet lists the 2024 International Residential Code among the codes adopted effective August 1, 2025, by Ordinance G-7397. We checked Phoenix's 2024 IPC amendments and found no changes to the Chapter 9 vent terminal sections.
The Uniform Plumbing Code works differently. It has no AAV section, as our AAV page explains, and its own vent terminal section. If your plans follow the UPC, confirm the vent route with the designer or the city before you count on a wall exit. Other Valley cities adopt their own codes and amendments, so don't carry Phoenix's answer to Mesa or Scottsdale without checking.
What does this mean for a remodel?
Plan the vent before you plan the cabinets. Moving a sink to an island, adding a bathroom in a garage conversion, or building a casita usually means a new vent. The usual choices are:
- Tie into an existing vent in the wall or attic, if one is close enough.
- Run a new pipe up through the roof, which means a roof penetration and flashing that has to be watertight.
- Use an AAV for the branch, if your code path allows it and the house already has a vent to open air.
- Exit a sidewall, only if the lot and wall can meet the 10-foot rules.
Adding or rerouting drains and vents is generally permit work, as our page on what plumbing work needs a permit in Phoenix explains, and a plan that fails inspection costs more time than one drawn right. If you're adding or moving fixtures, our residential plumbing team can lay out a vent path that passes the code your plans use. For a fixture move that's already underway, see moving a toilet, sink or shower.