Maintenance
There is no single interval that suits every kitchen. Here is what decides how often your canopy, ducts, exhaust fan and grease filters need cleaning, and how to build a schedule around it.
· 6 min read
Fire safety
How Grease Build-Up Turns a Kitchen Exhaust Into a Fire Risk
Grease that settles inside canopies, ducts and fans is fuel. Here is how kitchen exhaust fires start and spread, and what fire services and insurers suggest you do about it.
By Apex Commercial Exhaust · · 6 min read
Key takeaways
- Grease residue inside range hoods and ducting is a recognised cause of restaurant fires.
- Fire can travel from the cooking line into the canopy and along ductwork, where it is hard to reach and extinguish.
- Fire services recommend routinely cleaning and inspecting range hoods, ducting, grease fans and filters.
- Insurers publish guidance on cleaning frequency and expect more frequent cleaning for intensive or deep-frying kitchens.
- Cleaning reduces a fuel source; it works alongside fire suppression, extinguishers and safe cooking practices.
Most commercial kitchen fires start at the cooking line. What turns a small flare-up into a serious fire is often the grease that has quietly built up inside the canopy, ducts and exhaust fan. Understanding how that happens is the first step to managing it.
How kitchen exhaust fires start
Cooking releases grease-laden vapour. Filters capture part of it, but some grease settles on canopy surfaces, in the plenum, along ductwork and on fan blades. The Restaurant fire safety guidance published with Fire and Rescue NSW lists the ignition of fatty residues within range hoods and ducting among the most common causes of restaurant fires.
Why exhaust fires are hard to fight
Insurer Chubb’s risk bulletin on commercial kitchens notes that fires often start on a cooking appliance and spread into the exhaust system, travelling along lengths of ductwork where they are difficult to extinguish. Vero’s guidance on cleaning ducts and flues makes a similar point: grease residue can ignite and spread fire quickly through the system.
What fire services and insurers recommend
Read the published guidance
- Fire services: routinely clean and inspect kitchen range hoods, ducting and grease fans, and include grease filters in maintenance.
- Chubb: refers to AS 1851 and suggests hoods, filters and gutters at least monthly and exhaust ductwork at least yearly, more often for intensive use or frequent deep-frying.
- Vero: suggests filters at least weekly and the duct system at least every six months, with heavy-use kitchens needing more frequent cleaning, and recommends a service certificate for each clean.
These are published examples, not a rule for every kitchen. Your obligations depend on your building, your insurer and your system.
Practical steps to reduce the risk
- Keep filters clean and correctly fitted so less grease reaches the ducts.
- Clean the whole system, not just the visible canopy: plenum, ducts and fan too.
- Inspect regularly and adjust cleaning frequency to the grease found.
- Maintain fire protection such as suppression systems, extinguishers and fire blankets.
- Keep records of each clean, including photos and areas that could not be accessed.
Within the agreed scope, Apex cleans all accessible and reachable areas of the kitchen exhaust system and provides before-and-after photos.
Cleaning removes a potential fuel source. It does not remove every fire hazard, and it works alongside fire protection systems and safe cooking practices.
Frequently asked questions
Can grease in the exhaust duct catch fire?
Accumulated grease is combustible and can contribute to fire spread when exposed to an ignition source, which is why inspection and cleaning matter.
Does cleaning the canopy alone reduce fire risk?
It helps, but grease also builds up in the plenum, ducts and fan. A complete clean covers the accessible parts of the whole system.
Do I still need fire suppression if the exhaust is clean?
Yes. Cleaning and fire protection systems do different jobs. Follow your fire safety obligations and your insurer’s requirements.
References & further reading
Government, regulator and Standards sources mentioned in this guide (links checked November 2026; requirements can change, so check the current version):
- Fire and Rescue NSW, NSW Rural Fire Service, ACT Fire Brigade and ACT Rural Fire Service, Restaurant fire safety
- Chubb Insurance Australia, Commercial kitchens fire protection fundamentals (risk bulletin)
- Vero Insurance (AAI Limited), RM Insight: Cleaning of ducts and flues
- Australian Institute of Refrigeration, Air Conditioning and Heating (AIRAH), Commercial Kitchen Exhaust Special Technical Group
- Standards Australia, AS 1851-2012 Routine service of fire protection systems and equipment
Need help with your kitchen exhaust? Apex Commercial Exhaust cleans canopies, exhaust ducts, rooftop fans and grease filters for commercial kitchens across Melbourne and Victoria.
This article is general information only and is not legal, insurance or compliance advice. Requirements for your kitchen depend on your system, building and obligations.
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