Air Admittance Valves: Modern Alternatives to Roof Vents
For decades, traditional plumbing systems have relied on roof vents to balance air pressure and keep wastewater flowing smoothly. But what happens when punching a hole in the roof isn’t practical—or when you’re remodeling a space that wasn’t originally plumbed for a full vent system? That’s where Air Admittance Valves (AAVs) come in.
At Brown Plumbing & Heating, we’re seeing more homeowners in Billings and Laurel consider these compact, code-compliant devices for everything from kitchen islands to basement bathrooms. Here’s what you need to know about AAVs and whether they’re right for your plumbing setup.
What Is an Air Admittance Valve?
An Air Admittance Valve is a one-way mechanical device installed on drain lines. It allows air into the plumbing system when negative pressure develops—such as when a toilet is flushed or a sink drains—but it closes tightly afterward to prevent sewer gases from escaping into your home.
Think of it as a “breather” for your pipes, without the need to extend a vent pipe through the roof.
Why Consider an AAV?
Montana homes often face layout or climate challenges that make traditional venting complicated. Whether you’re building a new addition, finishing a basement, or installing a sink in an island, AAVs offer several benefits:
Fewer roof penetrations – Reduces the risk of leaks and simplifies roof design
Easier retrofits – Ideal for remodels where adding a full vent stack is costly or impossible
Code-approved – Recognized in the International Plumbing Code (IPC) with proper placement
Discreet – Installed under sinks or behind walls, often out of sight
Where AAVs Work Best
In Billings and Laurel homes, we commonly install AAVs in:
Kitchen islands (no nearby wall for a vent pipe)
Basement bathrooms
Detached garages or workshops
Remodeled areas where extending vent piping isn’t feasible
AAVs must be placed above the fixture’s flood level rim and in accessible locations for maintenance. Proper installation is crucial—these valves are not a DIY shortcut but a strategic solution when used correctly.
Are They Safe and Reliable?
Yes, when professionally installed. Modern AAVs are built with long-lasting materials and internal seals designed to open and close precisely when needed. They typically last 20+ years and require little maintenance. However, they don’t replace all venting needs—homes still need at least one full vent to the outside for overall system pressure balance.
At Brown Plumbing & Heating, we ensure AAVs are used in the right applications and meet Montana code requirements. We’ve seen too many poorly placed valves lead to sewer smells or drainage issues—something no homeowner wants to deal with.
Know When to Use (and Not Use) AAVs
Use AAVs when:
You’re remodeling or adding a fixture far from existing vents
Running vent lines through the roof is expensive or structurally difficult
You need a discreet solution without compromising plumbing function
Avoid AAVs when:
Your local code doesn’t allow them in specific applications
You lack proper venting altogether
They’d be hidden in inaccessible areas without an access panel
Ask the Local Experts
Air Admittance Valves can be a smart, space-saving solution for modern homes, but only when used correctly. If you’re unsure whether your project qualifies, or if your current system is underperforming, give us a call.
📞 Brown Plumbing & Heating proudly serves Billings and Laurel with expert plumbing advice and installations. Visit https://brownplbg.com or call (406) 656-8585 to schedule a plumbing consultation today.
Read Next: Understanding Your Home’s DWV System (Drain-Waste-Vent)