During a recent site review, we observed a grease exhaust duct installation that can only be described as grossly incompetent.

Standard HVAC access panels were installed directly into an NFPA 96 grease duct. This is not a grey area. It is not a judgment call. It is a clear code violation and a fundamental failure to understand how grease exhaust systems work.

Why This Installation Is Unacceptable

Grease ducts are fire containment systems. They are designed to withstand internal grease fires without allowing flame spread to the structure. NFPA 96 requires these ducts to remain grease-tight, fire-resistance-rated, and listed as a complete system.

Standard HVAC access panels:

  • Are not fire-rated

  • Are not grease-tight

  • Are not listed for grease duct applications

  • Compromise the integrity of the duct

Installing them on a grease duct defeats the entire purpose of the system.

Below is a photo of a properly installed access panel with our engineered detail compliant with NFPA-96:

This Is Not a Minor Mistake

This is not a missed detail or a cosmetic deficiency. It demonstrates a complete lack of understanding of:

  • NFPA 96

  • Commercial kitchen exhaust systems

  • Basic fire protection principles

Errors like this introduce a serious life safety hazard and place the building owner, contractor, and design professionals at risk. Any contractor working on grease exhaust systems should know this. If they don’t, they should not be installing them.

The Bottom Line

Grease exhaust systems are not general HVAC work.

They require:

  • Listed grease duct access doors or built to section 7.4.3

  • Fire-rated, grease-tight construction

  • Strict adherence to NFPA 96

Applying residential or comfort-HVAC practices to grease ducts is unacceptable and dangerous. This installation would not pass review by any competent authority having jurisdiction—and it should be rejected and corrected immediately.

James Hicks P. Eng.
Evolve Mechanical Solutions
236.777.3487

#NFPA96 #GreaseDuct #FireLifeSafety #MechanicalEngineering #KnowTheCode #KitchenExhaust