Phoenix Journal · Ductwork
TR19 Grease is not legislation, yet it carries real legal weight. Here is exactly how the BESA specification connects to UK fire safety law, insurance and what you must be able to prove.
TR19 Grease and the law
TR19 Grease is not a law - it is the industry specification that helps you prove you are meeting laws that genuinely do bind you.
This is the single most misunderstood point in commercial kitchen extract cleaning, so it is worth being precise. TR19 Grease is a technical specification published by BESA, the Building Engineering Services Association, which is the UK trade body for ventilation and building services contractors. Its full title is TR19 Grease - Specification for Fire Risk Management of Grease Accumulation Within Kitchen Extraction Systems. It has existed as a standalone document since 2019, when the grease element was separated out from the older, broader TR19 ductwork guidance.
Because it is a specification and not an Act of Parliament or a Statutory Instrument, no one can be prosecuted for "breaching TR19 Grease" in the way they could be prosecuted for breaching fire safety legislation. What the specification does instead is set out the recognised benchmark for good practice. When a court, an insurer or a fire officer asks whether your extraction system was being managed sensibly, TR19 Grease is the yardstick they reach for. Follow it, keep the paperwork, and you have strong evidence that you took the issue seriously. Ignore it and you are left arguing that your own improvised regime was somehow just as good as the accepted national standard - a difficult position to defend after a fire.
So the honest answer is that TR19 Grease sits one step behind the law. It is the accepted method for discharging duties that are legally binding, which is exactly why it carries so much weight even though it is technically voluntary.
The legal backbone
The specification earns its authority by attaching to real legislation. The principal link is the Regulatory Reform (Fire Safety) Order 2005, which applies to virtually all non-domestic premises in England & Wales. The Order names a "responsible person" - usually the employer, owner or occupier - and places a legal duty on them to carry out a suitable and sufficient fire risk assessment, then take general fire precautions to reduce the risks identified. A grease-laden extract duct running above hot cooking equipment is a textbook ignition and fire-spread hazard, so a competent fire risk assessment cannot ignore it. TR19 Grease is how you demonstrate that this specific risk has been assessed and controlled.
Scotland has its own near-equivalent regime under the Fire (Scotland) Act 2005 and the Fire Safety (Scotland) Regulations 2006, with a comparable duty holder concept, so the practical obligation to manage grease build-up follows you across the border.
Sitting alongside the fire legislation is the Health & Safety at Work etc. Act 1974, which requires you to protect employees and members of the public from foreseeable harm. A kitchen fire that spreads through a dirty duct is a foreseeable harm. Manufacturers' warranty terms and your buildings and business-interruption insurance policies add a further layer, and in practice the insurance requirement is often the one that bites first. If the language of specifications, tests and certificates feels like a foreign vocabulary, our plain-English glossary of TR19 Grease and TR19 Air terms untangles what each document actually governs.
What compliance looks like
The specification is refreshingly practical about evidence. It expects you to clean the whole accessible system - canopy, filters, plenum, riser, horizontal ductwork and the extract fan - to a measurable standard, on a schedule that matches how hard the kitchen works. The recommended minimum frequencies are widely cited as follows:
Frequency alone is not enough, though, and this is where TR19 Grease has become far stricter than the old "clean and hope" approach. Cleaning must be verified by measurement. Technicians take grease thickness readings before and after work, typically using a Deposit Thickness Test (DTT) or a Wet Film Thickness Test (WFTT), and record them across the system. The recognised post-clean target is a mean grease film of less than 50 microns - a micron being one thousandth of a millimetre, so this is a genuinely clean surface rather than a superficial wipe. Readings are also used to flag heavier deposits that demand attention; where sections are running well above the acceptable average, they must be brought back down.
The output that matters legally is the post-clean verification report, complete with before-and-after readings, photographs, a system schematic and a clear statement of what was cleaned and what could not be reached. That report - not a vague invoice saying "duct cleaned" - is the document your insurer and fire officer will want to see. If access hatches are missing and parts of the duct cannot be inspected or cleaned, the specification expects that limitation to be recorded honestly rather than papered over. Because grease is the fuel in almost every serious extract fire, it helps to understand exactly how kitchen grease build-up drives fire risk before you decide how often your own system really needs attention.
The cost of ignoring it
Because TR19 Grease itself is not statute, the consequences of ignoring it arrive indirectly - but they are severe. The first and most common is insurance. Most commercial policies covering premises with a kitchen now expect evidence of regular extract cleaning to the TR19 Grease standard, and many make it an express condition of cover. If a fire occurs and you cannot produce dated verification reports, or the paperwork shows cleaning was overdue, the insurer can reduce or reject the claim - sometimes even where the fire did not start in the duct. For a business already dealing with fire damage, a rejected claim is frequently the blow it does not recover from.
The second consequence is regulatory. Fire and rescue authorities can inspect under the Fire Safety Order and issue enforcement or prohibition notices where fire precautions are inadequate. Serious failures can lead to prosecution of the responsible person, with unlimited fines and, in the gravest cases, imprisonment. A neglected grease-laden extract system is precisely the kind of foreseeable hazard that turns a routine inspection into an enforcement action. Keeping to the specification, and keeping the reports, is what turns all of that from a live risk into a closed one.
Questions
Not directly. TR19 Grease is a BESA specification, not an Act of Parliament, so you cannot be prosecuted for breaching it by name. However, it is the recognised way to prove you are meeting duties that are legally binding, such as the Regulatory Reform (Fire Safety) Order 2005 and the Health & Safety at Work etc. Act 1974. In practice, following it is the safest way to stay on the right side of both the law and your insurer.
Yes. Many commercial policies now make regular TR19 Grease cleaning an express condition of cover. If a fire occurs and you cannot produce dated post-clean verification reports, or they show cleaning was overdue, the insurer can reduce or decline the claim. That can happen even when the fire did not start in the ductwork, which is why keeping the certificates matters as much as doing the clean.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.