Air-admittance valve (AAV): when is it allowed?
Understand that an AAV is not a universal replacement for outdoor venting: location, accessibility, freezing and system configuration matter.
VERT / GREEN
Identify the fixture and vent path before opening a wall.
JAUNE / YELLOW
An AAV may be allowed in certain situations under the locally adopted code, but must remain accessible and be installed per manufacturer.
ROUGE / RED
Hidden/inaccessible AAV, freezing location, plenum or a plan to eliminate all outdoor vents: have the design reviewed.
Quick triage
What the professional checks
The plumber confirms whether the case is permitted, sizing, height, accessibility, freezing, manufacturer instructions and required outdoor vents.
Official sources
Checked 2026-08-23
V28
Finish and service details to verify
V28 connects small details that become costly once finishes are closed.