Common Myths About Makeup Air Systems Debunked

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Safety

February 27

This article was originally published in May 2019 and has been updated to reflect current information.

Radon is a natural gas that can seep into homes, but misconceptions about how it enters, how dangerous it is, and how it can be managed are widespread. The root cause of these myths is a lack of awareness. Our radon mitigation experts are here to clear up some of the most common misconceptions about radon and offer guidance to homeowners in Canada.

At Fantech, we’re focused on designing ventilation solutions for modern homes. With my background in airflow dynamics and energy efficiency, I led the development of our latest makeup air system, built for today’s energy-efficient, tightly sealed homes. In this article, I’ll debunk common myths about makeup air systems and explain why they’re essential in tightly built homes.
Alec Dunn
Senior Design and Manufacturing Engineer

Myth #1: Makeup Air Systems Are Only Necessary in Large Homes

Radon is responsible for approximately 3,000 lung cancer deaths annually in Canada. Many people believe that if they haven't had issues with radon in the past, they’re safe. However, radon exposure accumulates over time, and long-term exposure significantly increases the risk of lung cancer, particularly for people who smoke or have other respiratory conditions.

Myth #2: Exhaust Fans Alone Are Enough

Many homeowners and builders assume that any exhaust system will address ventilation needs. However, in spaces like kitchens with high airflow exhaust systems, the removal of large air volumes can create an imbalance. In tightly sealed homes, this imbalance leads to negative pressure, drawing unconditioned outdoor air inside through unintended gaps and openings.

Exhaust fans alone do not ensure balanced airflow. The makeup air system works specifically with kitchen hood liners or kitchen exhaust systems to replace air removed during operation. This ensures the home remains balanced, preventing drafts, backdrafting, and poor indoor air quality. These systems are essential when exhausting more than 400 CFM (according to the IRC M1503), a common scenario with high-powered kitchen range hoods. However, any amount of unwanted negative pressure can be offset with this system to keep the home’s environment operating smoothly.

Myth #3: Makeup Air Systems Are Expensive and Complicated to Install

The perception that makeup air systems are costly and complex to install is another common myth. Modern makeup air systems, such as unitary solutions designed to replace large amounts of air, are engineered to be easy to install and require only a single penetration to the exterior of the home. This simplicity not only reduces labor costs but also speeds up installation time.

Furthermore, these systems don't condition the air, which keeps the overall costs down. However, for homes in colder climates, heater accessories are available to temper the incoming air. This optional heater can be integrated into the system to ensure that cold outdoor air doesn't reduce comfort during the winter months. This flexibility allows HVAC contractors to customize installations based on regional climate needs without adding unnecessary complexity.

Myth #4: Makeup Air Systems Aren't Needed in Tight Homes

Some believe only tight homes with basements are susceptible to radon. In reality, all homes—old, new, drafty, insulated, with or without basements—are at risk.

Radon comes from uranium breakdown in soil. Any home built on soil has the potential for infiltration.

New-construction homes are also at risk. Although building codes in nine U.S. states require radon-resistant new construction (RRNC), compliance varies widely. In Canada, provincial building codes also differ. For example:

Ontario requires radon mitigation measures in areas with high radon potential, per the Ontario Building Code.
British Columbia includes provisions for radon-resistant construction in certain regions.
In Quebec, building code updates emphasize radon risk assessments and preventive measures.

Without standardized enforcement, new homes in both Canada and the U.S. may lack adequate radon protection.

Myth #5: Makeup Air Systems Are Only About Air Quality

While the primary function of a makeup air system is to replace exhausted air and maintain balanced indoor pressure, their benefits go beyond just improving air quality. Makeup air systems also help prevent issues like backdrafting, which can cause harmful gases like carbon monoxide to enter the living space.

In homes with powerful exhaust systems, makeup air systems stabilize the home’s pressure. Although these systems don’t condition the air, the optional heater accessory can be used in colder climates to warm incoming air, ensuring that the introduction of outdoor air doesn't affect comfort. This makes makeup air systems essential for maintaining a comfortable, efficient, and safe environment in all climates.

The Importance of Makeup Air Systems in Modern Homes

Misunderstandings that surround makeup air systems can lead to critical oversights in residential construction and renovation projects. With homes becoming more airtight and energy-efficient, the need for balanced ventilation is as important as ever. By dispelling these myths, you can make informed decisions that improve the comfort, safety, and efficiency of their homes.

Incorporating a makeup air system into your residential design isn’t just about meeting code requirements—it’s about creating a balanced and comfortable living space. Whether you're working on a new build or a renovation, understanding the role of makeup air systems will help you deliver superior results for your clients or your own home.