Learn · Building Science
Make-Up Air Systems
When big exhaust fans steal air from your house, make-up air puts the pressure — and the comfort — back in balance.
By Billy Gregus, Owner · Last updated July 2026
The Short Answer
Make-up air is outdoor air intentionally supplied to replace air that powerful exhaust equipment removes. Without it, range hoods, dryers, and commercial kitchen fans can depressurize the building, pull from the garage or attic, backdraft combustion appliances, and drag humidity through every crack. Designing make-up air is premium work most residential HVAC companies never touch.
The problem make-up air solves
Air that leaves the building has to be replaced. If you do not provide a clean path, the house pulls replacement air through the easiest leaks — often the worst ones. That can mean garage fumes, attic dust, and humid outdoor air arriving in all the wrong places.
High-CFM kitchen hoods are the classic residential trigger. Light commercial kitchens and process exhaust create the same physics at larger scale.
When to ask about make-up air
- A new high-CFM range hood or commercial-style kitchen.
- Doors that are hard to open when the hood runs.
- Odors from the garage appearing when exhaust fans are on.
- Combustion appliances (water heater, furnace) sharing the same building envelope.
- Restaurants and food-service spaces with large exhaust loads.
How Integrity designs it
We look at exhaust CFM, building tightness, existing HVAC capacity, and whether the make-up air should be tempered, filtered, or interlocked with the hood. That is analytical, whole-system work — the kind our engineering-minded team is built for — not a random duct stuck through the wall.
In Florida, raw outdoor make-up air is a humidity load. Sometimes the right answer includes tempering, dedicated dehumidification, or coordinating with an ERV strategy so comfort does not collapse the first humid afternoon.
Failure modes
- Undersized make-up air that still leaves the building negative.
- Unconditioned outdoor air dumped on occupants or on a struggling AC coil.
- No interlock — hood runs, make-up air does not.
- Ignoring code and combustion safety on shared envelopes.
Premium building-science work is what separates a comfort plan from a parts swap. Integrity's engineering-minded team diagnoses Winter Haven homes from every angle — envelope, ducts, humidity, and fresh air — then designs the fix.
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Common Questions Answered
Is make-up air the same as an ERV?
No. An ERV is balanced ventilation for everyday fresh air. Make-up air specifically replaces large exhaust volumes, often intermittently with a kitchen hood. Some projects use both for different jobs.
Do all homes need make-up air?
No. Modest bath fans in a typical home usually do not. Large range hoods, tight envelopes, and commercial exhaust are when make-up air becomes a real design requirement.
Can Integrity handle light commercial make-up air?
Yes. Our commercial HVAC and refrigeration work already lives in kitchens and process spaces where exhaust and make-up air have to be engineered together — not improvised.
Ready for a Straight Answer From a Local Team? No Pressure.
Talk to a real Integrity technician about your system — same-day appointments across Central Florida.