Phoenix Journal · Ductwork
A compliance certificate is only as strong as the evidence sitting behind it. We explain what turns a kitchen extract certificate into a document that actually holds up when your insurer, a fire officer or a court starts asking questions.
Compliance & evidence
A certificate is not the achievement - it is the receipt. What matters is whether the work behind it can be defended long after the van has driven away.
When you hold a kitchen extract cleaning certificate, it feels like the job is closed. In reality the certificate is a summary. It asserts that, on a given date, your extraction system was cleaned to a recognised standard - almost always BESA's TR19 Grease specification, published in 2019 as the standalone benchmark for managing fire risk from grease in commercial kitchen ductwork. The certificate is the headline. The legal weight lives in the pages, photographs and measurements underneath it.
Think about who reads the document and when. Your insurer files it and never looks at it again - until there is a claim. A fire officer glances at it during a routine visit and studies it closely after an incident. An environmental health officer may ask to see it as part of a broader hygiene inspection. In every case the certificate is being used to answer one question: did the responsible person take reasonable, evidenced steps to control a known risk? A single sheet of paper with a logo on it does not answer that question. A verified record does.
So the honest way to read any certificate is to ask what it is standing on. Was the whole system opened up and cleaned, or only the parts that were easy to reach? Were grease levels measured after cleaning, or simply declared clean by eye? Were photographs taken from fixed positions so a third party can see the before and after? If those foundations are missing, the certificate still exists - it just cannot carry any weight when it is finally put under load.
Strictly speaking, the law does not name the certificate. What it names is the duty. Under the Regulatory Reform (Fire Safety) Order 2005 - the order that governs fire safety in almost all non-domestic premises across England and Wales - the responsible person must assess fire risk, put suitable measures in place and keep the premises maintained so those measures stay effective. Grease build-up inside extract ductwork is a well documented fire risk, so keeping that ductwork clean is squarely within your legal duties, whether or not anyone ever prints a certificate.
That is where the certificate earns its role. It is not the legal obligation itself - it is the evidence that you met the obligation. If a fire starts and spreads through neglected ductwork, investigators will ask what you did to control the risk. A TR19 Grease certificate, backed by verification, is how you demonstrate due diligence. Without it, you are relying on memory and assertion, which is a poor position to be in when an enforcement notice or an uninsured loss is on the table. The order also allows for unlimited fines and, in the most serious cases, imprisonment, so the stakes are not abstract.
There is a second reader whose requirements are effectively binding even though they are not statutory - your insurer. Most commercial property and business interruption policies now carry conditions requiring extract systems to be cleaned to a recognised standard at appropriate intervals. Those conditions do not appear in an act of parliament, but breach them and your cover can be reduced or refused. In practice, then, a valid certificate is close to mandatory: the law makes the duty, and your policy makes the proof a condition of paying out.
Because they were never verified in the first place. This is the single biggest reason a certificate that looked reassuring on the wall turns out to be worthless when it matters. TR19 Grease does not treat cleaning as complete simply because a technician says so. It requires post-clean verification - objective measurement proving the grease has actually been removed.
The measurement is a Deposit Thickness Test, sometimes carried out as a Wet Film Thickness Test. Readings are taken at set points throughout the system, and the mean grease deposit after cleaning should sit below 50 microns. That number is the spine of the whole document. A certificate that states a system is clean but records no post-clean readings is an opinion; a certificate that shows a mean below 50 microns across defined test points is evidence. For ongoing management the standard treats a mean of around 200 microns as the point at which fire risk climbs, with any single localised reading above 500 microns demanding immediate attention - so the figures on your report have real meaning, not decoration.
Post-fire scrutiny then attacks the gaps. Investigators and loss adjusters look for the parts of the system that were declared clean but never actually reached - the runs behind fixed panels, the vertical risers, the sections above ceilings where no access hatch was fitted. If your certificate claims a whole-system clean but the report shows access was limited to the canopy and the first metre of duct, the document contradicts itself. A certificate that overstates coverage is worse than an honest one that flags what could not be reached, because the overstatement is what a claim is refused on.
The other common failure is anonymity of proof. Strong reports carry before and after photographs taken from identical, labelled positions, a schematic showing where access panels sit and where readings were taken, and the qualification details of the technician who did the work. Weak reports carry a stock photo and a signature. If you have ever wondered why your compliance certificate is being questioned by your insurer, the answer almost always lives in this gap between what was claimed and what was recorded.
Start by treating the certificate as the end of a chain of evidence, not a standalone product. Before work begins, agree what a full clean means for your specific system - every accessible run, riser and plenum, with new access panels fitted where the ductwork cannot otherwise be reached. A system that has never had adequate access will never produce a whole-system certificate until that access is created, and that is a conversation to have up front rather than after a fire.
Then insist on verification you can hand to a third party without explanation. Your report should include mean post-clean deposit readings against the 50 micron benchmark, before and after photographs from fixed positions, a plan showing panel and test locations, and the details of the qualified technician. Check, too, that the contractor is properly accredited - membership of a recognised ventilation hygiene scheme and technicians holding the BESA Grease Hygiene Technician qualification are what turn a claim of competence into a checkable fact. Finally, keep every certificate and report together as a continuous history, because a pattern of maintained cleaning over years is far more persuasive than a single recent visit.
Get those elements in place and the certificate stops being a hopeful piece of paper and becomes a defensible record - one that answers the insurer's question, satisfies the fire officer and demonstrates the due diligence the law expects. That is the whole point of the exercise. A certificate is not there to make you feel finished; it is there to protect you on the worst day your kitchen ever has.
Questions
Not by itself. The Regulatory Reform (Fire Safety) Order 2005 places a duty on the responsible person to control fire risk, and the certificate is evidence that you met that duty rather than the duty itself. To satisfy scrutiny it needs to be backed by verification - post-clean grease readings, photographs from fixed positions and an accurate record of what was actually cleaned. A certificate with none of that behind it proves very little.
Post-clean verification under TR19 Grease should demonstrate a mean grease deposit below 50 microns across defined test points, measured with a Deposit Thickness Test or Wet Film Thickness Test. For ongoing management, a mean approaching 200 microns signals rising fire risk and any single reading above 500 microns needs immediate localised cleaning. A certificate that records no readings at all cannot really be called verified.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.