While enjoying a glass of wine during a recent tasting, I happened to notice several issues with a nearby commercial kitchen exhaust fan installation. Even from a casual vantage point, the deficiencies were clear—each carrying implications for safety, performance, and code compliance.

First, the exhaust fan lacks proper seismic restraint, a requirement in many jurisdictions to prevent equipment displacement during seismic activity. Without this protection, the fan could shift or detach, causing both structural damage, system failure and worse falling on an occupant.

Clearance issues were also identified. The fan termination is required to be a minimum of 40 inches away from the roof line (and 60 inches if the roof is combustible) to prevent grease-laden vapours from collecting on building surfaces.

NFPA 96 Section: 7.8.2.1(8)(b): Upblast fans must discharge at least 40 inches away from any roof surface.

NFPA 96 Section: 7.8.2.1(2): A minimum of 1.5 m (5 ft) of horizontal clearance from the outlet (fan housing) to any combustible structure

Additionally, the ductwork and kitchen exhaust fan must remain at least 18 inches from combustible construction. In the current configuration, these distances appear insufficient.

NFPA 96 Section: 7.8.2.1(8)(a): Where the fan attaches to the ductwork, the ductwork is a minimum of 0.46 m (18 in.) away from any roof surface, as shown in Figure 7.8.2.1.

The grease duct was never painted, leaving the exterior metal fully exposed to weather. As a result, corrosion has begun to form—an early indicator of long-term deterioration. Unprotected grease ducts mounted outdoors must be properly coated to prevent rust, maintain durability, and comply with NFPA 96 requirements for exterior duct construction and protection.

NFPA 96 Section: 7.6.4 All ducts shall be protected on the exterior by paint or other suitable weather-protective coating.

Neglecting this step shortens the service life of the system and increases the risk of failure in the future.

Addressing these deficiencies not only ensures compliance with NFPA 96 and local building codes but also protects the building, its occupants, and the long-term performance of the kitchen exhaust system.

James Hicks P. Eng.
Evolve Mechanical Solutions
236.777.3487

#MechanicalEngineering #HVAC #KitchenExhaust #NFPA96 #BuildingSafety #CodeCompliance #GreaseDuct #CommercialKitchens #EngineeringInsights #FireProtection