What Does Code-Compliant Commercial Kitchen Exhaust Design Take?

Code-compliant kitchen exhaust design selects the right hood type for the cooking equipment, sizes exhaust rates to the appliance lineup, specifies welded grease duct construction with required clearances and cleanouts, provides listed grease-duty exhaust fans, coordinates the fire suppression system with automatic fuel shutoff, and balances the exhaust with dedicated makeup air so the building doesn't run negative. Kitchens are the most code-intensive HVAC design in commercial work because they combine fire risk, grease, high exhaust volumes, and health department scrutiny. Every element — hood, duct, fan, suppression, makeup air — is regulated, and the interfaces between them are where designs fail.

The makeup air design is where kitchen HVAC succeeds or fails as a system. A large kitchen might exhaust 6,000 to 10,000 CFM; that air has to come from somewhere. The design typically provides 80 to 90 percent of it as dedicated tempered makeup air introduced near the kitchen, with the remainder transferring from the dining area to maintain proper pressure relationships — kitchen negative to dining, dining neutral to outdoors. Getting this wrong produces the classic symptoms: exterior doors that won't stay closed, hoods that spill cooking effluent into the dining room, and dining HVAC systems that can't hold temperature because they're fighting uncontrolled infiltration. I model the building air balance explicitly on kitchen projects — it's not a detail to leave to the test-and-balance contractor.

Kitchen exhaust has more code touchpoints than any other commercial HVAC system, so the verification list is long. These are the items that determine whether the kitchen passes inspection and operates safely. My kitchen exhaust checklist.

• Hood classification and sizing: Type I vs Type II correct for the actual equipment lineup
• Grease duct construction: welded seams, clearances or rated enclosures, cleanout access
• Listed grease-duty fan: proper fan type with grease containment and roof termination clearances
• Suppression interlocks: fuel shutoff, makeup air shutdown, and exhaust continuity on activation
• Documented air balance: makeup air quantities, transfer air paths, and pressure relationships shown