Make-up air refers to the replacement air that is brought into a building to compensate for air that is exhausted by ventilation systems or other processes. In a well-designed building, make-up air ensures that there is a balanced airflow, maintaining indoor air quality and comfort while preventing negative pressure conditions.

The primary purpose of make-up air is to replace the air that is exhausted from the building by mechanical ventilation systems, kitchen hoods, bathroom exhaust fans, clothes dryers, and other appliances. Without adequate make-up air, excessive negative pressure can develop within the building, which can cause a range of issues such as discomfort for occupants, inefficient operation of exhaust systems, and even back-drafting of combustion appliances.

Make-up air systems are often equipped with controls to regulate the flow of air based on factors such as occupancy levels, indoor air quality, temperature, and humidity. This helps optimize energy efficiency while ensuring adequate ventilation and comfort for building occupants.

Whether or not make-up air is required for your kitchen depends greatly on the size of your home, how air-tight it is, the power of your range hood and if you have a gas range or any other combustible appliances. If you have a gas range and/or your range hood is higher than 600 CFM then in a lot of cases make-up air is required. In some cases, anything over 400 CFM will require make-up air.

We recommend getting a professional opinion from someone in the HVAC industry if you are not sure if you need make-up air or not. We also recommend researching your local building codes as some cities require make-up air for any range hood that meets a certain CFM threshold.