Phoenix Journal · Ductwork
There is no law that names ductwork and tells you to clean it - but fire safety duties, your insurance conditions and TR19 Grease all mean a dirty extract system can leave you dangerously exposed. Here is what the rules really ask of you.
Case postmortem
A busy takeaway had a small fire in the extract canopy one evening, put it out in minutes, and reopened the next morning thinking they had got away with it - then the insurer refused the claim.
The blaze itself was almost boring. A flare-up on the range caught grease that had built up inside the canopy plenum, ran along the first metre of ductwork, and scorched the ceiling void before the staff knocked it down with an extinguisher. Nobody was hurt. The damage bill, once the smoke, the void and the lost trade were added up, came to a little over £40,000.
The owner assumed the buildings policy would cover it. It did not. The loss adjuster asked one question - when was the extract system last cleaned to a recognised standard, and where was the certificate? There was no certificate. There was a handwritten note from a window cleaner who had "wiped down the filters" eight months earlier. The claim was declined, and the owner was left personally out of pocket for a fire that a routine clean would very likely have prevented.
It is a common story, and it turns on a question people ask far too late - are you actually legally required to clean your ductwork?
There is no clause in UK law that names ductwork and tells you to clean it every so many months. If you go looking for one, you will not find it, and plenty of operators take that as permission to do nothing. That is the trap.
What the law does is place broad duties on you, and grease-laden ductwork is one of the clearest ways to breach them. The Regulatory Reform (Fire Safety) Order 2005 makes a "responsible person" - usually the employer, owner or occupier - legally accountable for managing fire risk on the premises, including taking general fire precautions to reduce the risk of fire and the spread of fire. A duct lined with combustible grease running through a ceiling void is a textbook route for fire to spread, so leaving it uncleaned sits squarely inside what the Order expects you to control.
Alongside it, the Health & Safety at Work etc. Act 1974 requires you to keep the workplace safe for staff and anyone affected by your work. And your insurance policy - which is a contract, not guidance - will almost always carry a condition requiring the extract system to be cleaned and maintained to a recognised standard, with evidence to prove it.
The standard everyone points to
The document that fills the gap between vague legal duty and practical action is TR19® Grease, the specification for fire risk management of grease extract systems published by the Building Engineering Services Association (BESA). It is not itself a statute. But fire services, environmental health officers, loss adjusters and insurers have all adopted it as the benchmark, which means that in practice it is the yardstick you will be measured against when something goes wrong.
TR19® Grease sets a measurable target - grease deposits controlled to a mean average of no more than 200 microns between scheduled cleans, roughly half the thickness of a business card. Anywhere reading 500 microns or more needs immediate spot cleaning. Those figures are checked with a Deposit Thickness Test or Wet Film Thickness Test at points along the system, and the results are what a proper clean is signed off against.
Pulling the fire apart afterwards, the failures were not exotic. They were the ordinary ones that catch out most kitchens that have never had a proper look inside their ductwork.
None of this was bad luck. Each point was a small decision to treat the extract system as cosmetic rather than as a fire safety asset, and the fire simply added them up.
Getting compliant is not complicated, and it is a great deal cheaper than an uninsured fire. Here is the order we would work through with any operator starting from scratch.
One thing worth saying plainly - compliance almost never means ripping systems out. Grease is a cleaning problem, not usually a replacement one, and a well-run maintenance regime keeps existing ductwork serviceable for years. We have written more on why cleaning beats replacing ductwork if you are weighing up the cost either way.
The tidy answer is this. You are not required to clean your ductwork by a law that says so in those words. You are required to manage fire risk, keep your workplace safe, and honour your insurance conditions - and for a commercial kitchen, a clean, certified extract system is the single most reliable way to show you have done all three. Treat the certificate as the goal, and the legal question answers itself.
Questions
No single law names ductwork and tells you to clean it, so strictly speaking there is no standalone duct-cleaning statute. However, the Regulatory Reform (Fire Safety) Order 2005 and the Health & Safety at Work etc. Act 1974 both place duties on you to manage fire risk and keep the workplace safe, and grease-laden ductwork is one of the clearest ways to breach them. In practice, keeping the system clean and certified to TR19 Grease is how you demonstrate you have met those duties.
TR19 Grease is the specification for fire risk management of grease extract systems, published by the Building Engineering Services Association (BESA). It is guidance rather than legislation, but fire services, environmental health officers, insurers and loss adjusters have all adopted it as the recognised benchmark. That means if you have a fire or a claim, TR19 Grease is the standard your system will be judged against.
TR19 Grease gives indicative intervals based on daily running hours - roughly every three months for heavy use of twelve to sixteen hours a day, every six months for moderate use, and every twelve months for light use. These are only a starting point, not a fixed rule. The real interval should come from a risk assessment that measures grease deposit thickness, keeping the mean below 200 microns between cleans.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.