What the fan does and why it fails
The fan sits at the end of the duct run, usually on the roof, sometimes inline in a ceiling space or plant room. It is the only thing in the system that actively moves air. Everything else is passive.
Grease that gets past the filters and through the duct arrives at the fan and coats the impeller blades. As the coating builds, three things happen. The blades lose their aerodynamic shape and move less air. The impeller goes out of balance, so the fan vibrates and the bearings wear. And the fan housing fills with grease, which is a fuel load sitting next to a motor.
The kitchen notices this as extraction that has quietly got worse: smoke lingering, heat building, a fan that sounds louder than it used to.
What a fan clean involves
- Isolation. Power to the fan isolated and tagged before anyone opens it.
- Access. Roof reached safely. This is the part that varies most between venues.
- Cowl and housing opened. Photographed before anything is touched.
- Impeller degreased. Blades scraped and degreased individually. Balance matters, so cleaning has to be even.
- Housing and discharge cleaned. Including the base where grease pools and the discharge cowl.
- Inspection. Bearings, mounts, belt if there is one, corrosion, and the roof around the fan where grease has been discharged.
- Reassembled, tested and photographed.
Roof access decides the price
A fan on a single storey roof reached by a fixed ladder is routine. A fan on a three storey roof with no fixed access, or one inside a plant room that needs a key from building management, or one on a shopping centre roof with its own induction and permit requirements, is a different job.
This is the single biggest reason fan cleaning quotes vary between venues, and it is worth telling the contractor what the access situation is before they price it.
Coastal corrosion
Rooftop fans within a few kilometres of the ocean corrode faster than anywhere else, and grease makes it worse by holding salt against the metal. On the Sunshine Coast that describes most of Mooloolaba, Caloundra, Coolum and Noosa.
A fan housing that has never been opened can be in far worse condition than the canopy below suggests: rusted through, mounts failing, impeller pitted. The fan clean is often the first time anyone finds out. It gets recorded on the report because a failing fan is a defect, not a cleaning problem.
Grease on the roof
A fan discharging grease-laden air over years leaves a pool of grease on the roof around it. It damages membranes, attracts pests, and in heavy rain runs into gutters and stormwater. Some contractors include roof cleanup around the fan; many do not. Worth asking, and worth checking the roof yourself if you have access, because building owners are increasingly being asked about it.
Check the current requirements before you rely on this
This page describes kitchen exhaust cleaning standards and practice as they stood in September 2026. Standards are revised, and what applies to a particular venue depends on its equipment, its building, its council and its insurer.
AS 1851 is published by Standards Australia at standards.org.au. Food premises requirements in Queensland sit under the Food Act 2006 and are administered by your council, Sunshine Coast Council at sunshinecoast.qld.gov.au or Noosa Council at noosa.qld.gov.au. Building fire safety is administered by Queensland Fire Department. Where anything here differs from those sources, they are right and we are not.
We are not fire engineers, council officers or insurers. For what applies to your venue, speak to your council's environmental health team, your insurer or a fire safety adviser.