Since 2009, make up air systems have been mandatory to comply with the International Residential Code if a home uses a kitchen exhaust fan with a capacity of 400cfm or more. The vast majority of northwest homes are installing such hoods today but were not built with makeup air systems. This can be a surprise to many homeowners during their project in terms of both cost and additional work done to the home. A well-informed appliance dealer should advise their client on the necessity for a makeup air system, but it is a detail that can easily fall between the cracks during a renovation. On average a makeup air system can add $2500 to a project but for larger systems or more complicated homes that number could double.
What does a makeup air system do?
A makeup air system prevents depressurization within the home while the exhaust fan is operating. The fan can only remove as much air as is being recirculated into the home. Without the makeup air system, the fan cannot function to its capacity. Depressurization within the home can be dangerous as it can cause back drafting of chimney and appliance vents, resulting in dangerous gases accumulating. The makeup air system is essentially a remotely activated fan that works in conjunction with the kitchen exhaust fan to counteract these risks.
How do I know if I need one?
If you’ve bought a home with an existing fan or a home built after 2009, chances are good that you are already compliant. If you are installing a new exhaust vent with a 400 cubic foot per minute capacity, you most likely will need to add the system. They can be installed by the general contractor himself, an HVAC contractor or mechanical contractor. Kitchen & More uses our mechanical subcontractor to install makeup air systems under our supervision, ensuring the project complies with code and the client is protected.