How much does a make-up air unit cost to install in a Toronto home with a range hood?

A make-up air unit costs $2,000 to $5,000 installed in a Toronto home, and it becomes a mandatory requirement under the Ontario Building Code whenever your total exhaust capacity exceeds 75 litres per second (approximately 159 CFM). In practical terms, if you are installing a kitchen range hood rated at 400 CFM or higher — which includes most professional-style range hoods popular in GTA kitchen renovations — you need a make-up air system.

The make-up air unit replaces the air that your range hood exhausts from the home. Without it, a powerful range hood creates significant negative pressure inside the house, which causes several serious problems. The most dangerous is backdrafting — negative pressure can reverse the flow in gas furnace, water heater, and fireplace flues, pulling carbon monoxide into your living space instead of venting it outside. This is not a theoretical risk in Toronto's tight housing stock; it is a real and potentially deadly hazard, especially in newer energy-efficient homes and older homes that have had air sealing upgrades.

The cost breakdown for a typical GTA make-up air installation includes the unit itself ($800 to $2,000 depending on capacity and whether it includes tempering), ductwork to bring outdoor air into the home ($500 to $1,500 depending on run length), electrical connections for the interlock and controls ($300 to $600, requiring an ESA-Licensed Electrical Contractor), and labour for installation and commissioning ($500 to $1,200). If the incoming air needs to be tempered — heated in winter before entering the home — the unit requires either an electric or hydronic heating element, which pushes toward the higher end of the price range.

Tempering is essential in Toronto's climate. Bringing in -20 degree Celsius outdoor air directly into your kitchen during a January cold snap is not acceptable. A tempered make-up air unit pre-heats incoming air to a comfortable level before distributing it into the home. Some units integrate with your existing furnace ductwork, while standalone units have their own dedicated supply point. Your contractor should recommend the appropriate approach based on your home's layout and existing HVAC system.

The make-up air system must be interlocked with the range hood so it only operates when the exhaust fan is running. This interlock is a code requirement and ensures that the make-up air system does not bring in outdoor air unnecessarily, which would waste energy. The interlock can be a simple pressure switch, a current-sensing relay on the range hood circuit, or a wired connection between the hood's control board and the make-up air unit.

Many GTA homeowners discover the make-up air requirement mid-renovation and are frustrated by the added cost. The reality is that this requirement exists for a critical safety reason, and skipping it is not an option. A building inspector will flag it, your gas technician should flag it during the next furnace service, and — most importantly — running a high-CFM range hood without make-up air in a GTA home with gas appliances creates a genuine carbon monoxide risk.

Need help finding a contractor for your make-up air installation? Toronto Ductwork can match you with experienced professionals through the Toronto Construction Network.