How a kitchen exhaust fire happens
A flare-up on the cooktop is normal. Flame reaches the canopy. In a clean system, the filters act as a barrier, and what gets through is hot air moving through a clean duct to a clean fan.
In a loaded system, the filters are saturated and offer no barrier. Flame passes through into a plenum coated in grease, then into a duct lined with it. The grease ignites and the duct becomes a chimney carrying fire above the ceiling, through the roof space, to the fan. By the time anyone in the kitchen knows, the fire is somewhere nobody can reach with an extinguisher.
This is the mechanism insurers know intimately, because it is behind a large share of the commercial kitchen fires they pay for.
What insurers ask
At renewal, commercial property and business insurance questionnaires for hospitality venues commonly ask about kitchen exhaust maintenance: whether it is cleaned, how often, by whom, and whether records are kept. Some ask specifically about compliance with AS 1851.
The answers affect the premium and the terms. Some policies include a condition requiring exhaust systems to be maintained at a stated interval, and a condition is not a suggestion. It is a term of the cover.
What happens after a fire
An investigator looks at the cause and at whether the policy conditions were met. Two things get asked immediately: where did the fire start, and when was the exhaust last cleaned.
If the fire started in the exhaust and the venue can produce dated, photographed reports showing the system was cleaned on a reasonable schedule, the claim proceeds on the basis that the operator did what a reasonable operator does.
If the venue cannot produce records, or the records show the system had not been cleaned for years, the insurer has grounds to question whether a policy condition was breached or whether the operator failed to take reasonable care. That can reduce or void a claim, and on a fire that has closed the business it is the difference between rebuilding and not.
This is the part that makes the report worth more than the clean.
What "reasonable" looks like
There is no single figure, but insurers and the standard converge on the same idea: an interval appropriate to the cooking, a professional clean of the whole system including duct and fan, and a documented record. A venue on a sensible documented schedule is reasonable. A venue that wiped the canopy and kept no records is not.
Working out the right interval
Landlord insurance
Property owners carry their own cover, and a landlord's insurer takes an interest in tenant fire risk. Some landlords write exhaust maintenance into the lease specifically because their insurer requires them to, and ask tenants for the reports so they can produce them at their own renewal. A tenant who cannot supply them creates a problem for the landlord as well as themselves.
Reducing the risk beyond cleaning
- Baffle filters rather than mesh, because they act as a flame barrier
- Filters cleaned weekly in-house so they can do that job
- Fire suppression over high-risk equipment where the building requires or the insurer prefers it
- Access panels in the duct so it can actually be cleaned
- Staff trained on flare-up response, which is not to throw water at a grease fire
- The maintenance record kept where it can be found in thirty seconds
Check your own policy before you rely on this
This page describes insurance practice in general terms as at September 2026. Policies differ, and what your insurer requires is set out in your policy documents and renewal questionnaire.
Read your policy for any condition relating to kitchen exhaust maintenance, and ask your broker or insurer directly what they require. AS 1851 is published by Standards Australia at standards.org.au. Building fire safety in Queensland is administered by Queensland Fire Department.
We are not insurers, brokers or lawyers. Nothing here is advice about your cover or a claim. If you have had a fire, speak to your insurer and get your own advice.