The Audit That Found Years of Missed Cleaning

How the audit was carried out, step by step

A credible audit follows the method set out in BESA's TR19 Grease specification, the recognised UK standard for fire risk management of grease in kitchen extract systems. It is not a visual glance at the canopy - it is a measured, photographed, documented survey of the whole route from hood to fan to discharge.

1. Mapped the full system first. We drew the complete extract route - canopy, filters, riser, every horizontal and vertical duct, the fan and the final discharge. You cannot certify a system you have not mapped, and the sections most likely to be missed are the ones a quick job never records.
2. Checked access provision against the standard. TR19 Grease expects access panels roughly every two metres and at every bend and junction, sized as large as the duct safely allows up to 460mm x 610mm. This system had panels at the canopy and almost nowhere else, which was the first clue that long stretches had never truly been touched.
3. Measured grease deposits objectively. Using Deposit Thickness Test and Wet Film Thickness Test readings, we recorded grease depth at fixed points along the run rather than trusting a look and a wipe. The standard sets a mean average of 200 microns as the trigger for cleaning, and a single reading above 500 microns as cause for immediate localised cleaning.
4. Photographed from matched positions. Every reading was paired with a photograph taken from a repeatable position, so before and after images line up exactly. This is what turns a claim into evidence, and it is precisely what the missing historical records never contained.
5. Compared the findings against the paperwork. We set the measured deposits beside the dated certificates and the stated cleaning frequency. A heavy-use kitchen running twelve to sixteen hours a day should be cleaned around every three months under TR19 Grease, and the readings were wildly inconsistent with a system cleaned that often.
6. Graded the risk and flagged inaccessible runs. Where deposits sat well beyond threshold, we graded the section and noted every length that could not be reached at all. The standard is clear that any area left uncleaned must be documented on a schematic and the responsible person advised of it in writing.
7. Issued a verification report and a remediation plan. The audit closed with a written report, the measured readings, the paired photographs and a costed plan to install access and clean the system back below 50 microns average. That report is the document that stands up to an insurer or a fire officer, not a one-line certificate.

Why years of cleaning had genuinely been missed

The uncomfortable finding was not that the previous cleaners had been dishonest. It was that they had cleaned what they could open - the canopy and the first metre or two of duct - and issued a certificate for the system as a whole. Everything beyond the last access panel had been left to accumulate. With no panels along the horizontal run and none at the bends, the grease in those sections had been growing steadily through every one of those tidy-looking visits.

That pattern is common because the risk is invisible from the kitchen floor. A canopy that looks clean, filters that are changed, and a fan that still pulls air all suggest a healthy system. The danger lives in the concealed ductwork, where warm grease-laden air deposits a flammable film that thickens month after month. Around 70% of commercial kitchen fires are linked to build-up in extract systems, and it is the hidden runs, not the visible canopy, that carry the risk. This is exactly the kind of exposure that takes years to show up - quietly compounding until an audit or an incident forces it into the open.

There is a commercial sting alongside the fire risk. Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person for the premises must assess and control fire hazards, and grease in the extract system is squarely one of them. Many commercial property and liability policies also carry a warranty on extract cleaning frequency - sometimes stricter than TR19 itself - and a certificate that does not reflect the real state of the ducts offers no protection at all if it is challenged after a fire.

The lesson for anyone reviewing their own file is to look past the certificate to the evidence behind it. Ask what was measured, where the access panels are, and whether before and after photographs exist for the concealed runs. If a quote comes in noticeably cheaper than the rest, ask what it leaves out - the same corners that create a missed-cleaning history often start with a price that only ever covered the easy metre of duct. It is worth knowing the red flags in a cheap cleaning quote before you accept one.