Rooftop and inline exhaust fan cleaning

A commercial kitchen exhaust fan is the powered component at the top of the exhaust system that pulls grease-laden vapour out of the kitchen, up the duct, and into the outside air. The fan sits on a rooftop curb in most restaurant builds, but it can also live inline in the duct run in older buildings or in basement-kitchen installations. Wherever it lives, the fan is the only mechanical, moving part in the whole exhaust system, which means it is the one component that can fail mid-service and shut down the kitchen.

Every fan service we perform covers the housing interior, the blade pack itself, the motor and the belt-drive assembly, the bearings on both shaft ends, the hinge or curb hardware, the fan-house gasket, and the section of duct that runs immediately below the fan curb. We treat the fan as a single mechanical unit and document every component on the certificate, not just the surfaces that happen to be greasy.

A rooftop exhaust fan has two pieces of hardware that the operator never sees but that determine how cleanly the fan runs between service visits. The first is the fan-house gasket — the rubberized seal that sits between the fan housing and the rooftop curb. When the gasket is intact, every droplet of grease that condenses on the fan-house interior is trapped and runs back down the duct. When the gasket fails, those droplets escape between the housing and the curb and run down the exterior of the duct, eventually staining the ceiling of the kitchen below.

The second is the hinge kit — the pivot hardware that lets the fan-house tilt open on one edge so a technician can reach the blade pack without unbolting the entire housing. NFPA 96 effectively assumes a hinge kit is present. Modern fans ship with one factory-installed. Older fans on existing rooftops often have no hinge kit, which forces every cleaning to unbolt the housing, lift it off, set it aside, and reassemble at the end — an extra forty-five minutes of labour per visit. Ontario Hood Cleaning installs hinge kits at cost on the first visit to any fan that does not have one, because the labour saved across the next two cleanings pays for the part.

NFPA 96 does not publish a fan-specific frequency separate from the rest of the exhaust system. Whatever cleaning frequency the cooking type triggers — monthly for solid-fuel, quarterly for high-volume, semi-annually for moderate-volume, annually for low-volume — applies to the fan on the same calendar. In practice, the fan tends to need attention sooner than the schedule suggests if the kitchen runs char-broiling, wok cooking, or any cuisine that produces high volumes of airborne grease.

Rooftop conditions also tighten the interval. Fans on roofs that are exposed to weather, ice, or low ambient temperatures during the Ontario winter accumulate condensate inside the housing that mixes with grease and forms a thicker deposit faster than a temperature-controlled inline fan would. Operators in any of those situations are usually moved one frequency tier tighter — from semi-annual to quarterly, or quarterly to bi-monthly — by their insurance carrier or brand auditor regardless of what NFPA 96 strictly requires.

The exhaust fan is the component an operator never sees. It lives on the roof, behind a curb, behind a hinged housing, behind a blade pack. A competitor who quotes on a per-hood basis can finish the hood, polish the canopy, sign a certificate, and never set foot on the roof. The fan keeps spinning, the kitchen passes its next inspection on the strength of the hood interior alone, and six months later the fan-house gasket fails or a bearing seizes during dinner service.

Every Ontario Hood Cleaning visit includes climbing to the fan and pulling the blade pack regardless of whether the operator booked a full-system cleaning or a standalone hood service. The fan is photographed before and after, the hinge kit and gasket are documented, and the result lands on the same signed certificate that covers the canopy and plenum. That is the operational baseline. There is no extra line item, and there is no scenario where the fan is left unopened.

Every fan service ends with three documents. The first is the signed NFPA 96 compliance certificate, which records the property, the date, the surfaces actually cleaned on the fan and the duct take-off underneath it, and the chemicals used. The certificate is signed in ink by the crew chief and handed to the operator before our crew leaves the rooftop.

The second is the before-and-after photo report, emailed within 24 hours. The report covers the fan-house interior, the blade pack, the duct take-off under the curb, and the surrounding rooftop work zone. The third is the belt-and-bearing inspection log, which records the condition of every mechanical component and flags anything that should be replaced before the next service visit. Operators receive the inspection log even if no items were flagged, so the inspection-binder file has a continuous mechanical history of the fan across multiple service visits.