Daily Code Talk #71IMC 508 - Commercial Kitchen Makeup Air

Commercial kitchen exhaust is not solved by fan CFM alone. The replacement air has to support hood capture, pressure balance, comfort, and startup.

Permit Proof Chain

01SourceIdentify contaminant, appliance, process, or exhaust category.
02Capture / RouteShow hood or pickup, duct material, access, and routing.
03DischargeConfirm termination, separation, make-up air, and controls.
04Safety InterfaceCoordinate fire alarm, suppression, AHJ, or specialty review when required.

Commercial kitchen exhaust removes a large amount of air from the building. That air has to be replaced. If the design only focuses on the hood exhaust fan and ignores makeup air, the kitchen may look complete on a schedule but fail in operation.

The field issue is pressure. When exhaust pulls air out faster than the building can replace it, the kitchen can become too negative. That can reduce hood capture, pull odors into dining areas or adjacent tenant spaces, make doors hard to open, interfere with appliance operation, and create comfort complaints for staff.

Makeup air also has to be delivered in a way that helps the hood instead of fighting it. Air dumped at the wrong location or velocity can disturb the cooking plume and reduce capture. Air that is too hot, too cold, or poorly distributed can make the kitchen technically functional but miserable to work in.

**Drawing Review Checklist** - Confirm hood exhaust airflow and makeup air airflow are coordinated. - Check where makeup air enters relative to the hood, cooking line, doors, dining area, and transfer paths. - Review pressure relationships between the kitchen, dining area, corridors, restrooms, and adjacent tenant spaces. - Confirm whether the design relies on dedicated makeup air, transfer air, outdoor-air units, or a combination. - Check whether the makeup air system is tempered enough for staff comfort and hood performance.

Submittal And Startup Checks

Hood, exhaust fan, and makeup air unit selections should be reviewed together. Air balance reports should verify both exhaust and replacement air. Controls should prove that makeup air operates when the hood exhaust operates. Field testing should confirm capture, comfort, door pressure, and odor control during real kitchen operation.

Common Review Risk

The common mistake is treating makeup air as a late equipment add-on. By then, the architectural layout, ceiling space, shaft routing, hood selection, and exterior openings may already be locked in. That turns a coordination item into a redesign problem.

Owner / Architect / Contractor Takeaway

For commercial kitchens, ask one question early: where does the replacement air come from, and will it help the hood work? If that question is unanswered, the project has operating risk before construction starts.

Masterbuild QA Lens

Review kitchen exhaust and makeup air as one system: appliance lineup, hood selection, grease duct route, fan discharge, fire suppression interface, replacement air path, pressure balance, temperature impact, and startup sequence. The hood can be sized correctly and still fail if the replacement air is wrong.

When To Escalate

Escalate when the kitchen is in a high-rise, mixed-use, tight-envelope, or restaurant build-out with limited exterior openings, long duct routes, large exhaust volumes, or no clear path for tempered makeup air. This is not a basic fan schedule review.

MasterBuild CTA

MasterBuild can review commercial kitchen exhaust and makeup air coordination before permit, bid, or construction so owners and project teams catch pressure, routing, comfort, and startup risks early.

PE-led project support

Need this applied to a live project?

Masterbuild Consulting helps owners, architects, GCs, and project teams turn code questions into permit-ready MEP decisions before review comments, field changes, or inspection issues cost more time.

Daily Code Talk uses the 2024 IMC as model-code education. Verify the adopted code, local amendments, project scope, listings, manufacturer instructions, and AHJ path before project use.

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