Remodel: kitchen island sink vented with an AAV under the cabinet, bathroom group vented with an AAV in the attic sitting on the branch under the blown insulation, and the old roof vent was capped because 'we don't need it now.' Inspector's coming.

Multiple code violations. Expect a hard fail.

1. Kitchen Island AAV (IPC 916.1 / UPC 906.1 / IRC P3114.1): AAVs are prohibited on kitchen island sinks. The horizontal offset creates siphonage risk that AAVs cannot reliably break. You need a loop vent (IRC P3114.3) or a waste stack vent (IRC P3114.2) routed up inside the island cabinet and back down.

1. Attic AAV Buried in Insulation (IPC 917.3 / UPC 906.7 / IRC P3114.8): AAVs must be accessible and located in a space allowing free air circulation. Buried under blown insulation blocks airflow, traps heat (killing the diaphragm), and makes inspection/maintenance impossible. It must be in an accessible attic space or a vented soffit/chase with an access panel.

1. Capped Roof Vent (IPC 903.1 / UPC 904.1 / IRC P3103.1): Every building requires at least one vent terminal extending to open air. AAVs are supplemental devices, not a total replacement for the stack vent. Capping the only roof penetration eliminates the primary relief for positive pressure and sewer gas escape. You must re-open or install a new through-roof vent for the main stack.

Fix: Re-pipe the island with a loop vent. Relocate the bathroom AAV to an accessible, insulated enclosure (or use a through-roof vent). Uncap/install a 3" min. roof vent for the main stack.

Multiple code violations will likely fail inspection. Here’s what’s wrong, per the International Residential Code (IRC 2021/2024) and IPC (International Plumbing Code):

1. Kitchen island sink AAV under cabinet → IRC P3114.1 / IPC 903.2: AAVs (Air Admittance Valves) are permitted only where venting to the outdoors is impractical. → IRC P3114.2 / IPC 903.2.1: AAVs must be installed at least 4 inches above the flood level rim of the highest fixture they serve. → Under-cabinet installation typically places the AAV below the sink drain — violates minimum height requirement. → Failure: AAV too low → risk of siphoning trap seals → sewer gas entry.

1. Bathroom group AAV in attic on branch under blown insulation → IRC P3114.3 / IPC 903.3: AAVs must be accessible for inspection, maintenance, and replacement. → Buried under blown insulation = not accessible → violates accessibility requirement. → IRC P3114.4 / IPC 903.4: AAVs must be installed in a location where temperatures are between 32°F and 140°F — attic insulation can trap heat/cold, risking AAV failure. → Failure: Not accessible + potential environmental exposure → AAV may malfunction undetected.

1. Old roof vent capped → IRC P3105.1 / IPC 903.1: Every plumbing vent system must terminate outdoors via a stack vent or AAV only if permitted. → Capping the main roof vent eliminates the primary vent path — even if AAVs are used, they are supplements, not replacements for the main vent stack unless the entire system is designed as an AAV-only system (which is rare and requires engineering). → Failure: No outdoor vent termination → system relies solely on AAVs → violates the principle that AAVs cannot replace the main vent stack unless specifically allowed by local amendment (uncommon). AAVs are for individual fixture or branch venting when outdoor venting is impossible — not for wholesale system replacement.

Inspector will fail:

• AAVs installed too low (kitchen)
• AAVs inaccessible (bathroom attic)
• Main vent capped without approved AAV-only system design
• Likely outcome: All AAVs must be removed or relocated; main roof vent must be reopened and extended to code (typically 6" above roof, 10' from openings, etc.).

Recommendation: Hire a licensed plumber to re-vent properly — AAVs have limits, and this setup ignores core venting principles. Do not attempt to “fix” with more AAVs. Word count: 298