TR19 is the UK building-engineering industry standard for the internal cleanliness of ventilation systems, published by BESA. It is split into TR19 Grease, which controls fire risk in kitchen extract ductwork, and TR19 Air, which covers general ventilation hygiene. It is not a standalone law, but insurers increasingly require documented TR19 compliance.
What is TR19 and what does it cover?
TR19 is BESA's (the Building Engineering Services Association) recognised UK industry standard for the internal cleanliness of ventilation systems, endorsed by the building-engineering community and by British insurers. It was split into two documents: TR19 Grease (2019), addressing kitchen extract fire risk, and TR19 Air, addressing the hygiene of general ventilation systems.
The Grease standard governs the greasy extract path above a commercial kitchen — canopy, filters, plenum and ductwork — where accumulated grease is a fire load. TR19 Air governs the ducts and air handling units that circulate air through a building.
Is TR19 a legal requirement?
TR19 is not itself a statute. However, cleaning to it is how a business demonstrates it has managed a known fire and hygiene risk. According to BESA, insurers increasingly require adherence to TR19 Grease, and non-compliance can lead to a claim being denied after a fire. Documented TR19 compliance demonstrates due diligence — which is why buyers and insurers treat it as effectively mandatory for commercial kitchens.
How often should a kitchen extract system be cleaned?
TR19 Grease is measurement-led rather than calendar-led. Grease deposits must not exceed a mean average of 200 microns between scheduled cleans, and any area found at 500 microns or more requires immediate spot cleaning. The right frequency for your site therefore depends on how heavily the kitchen is used and how quickly grease accumulates — verified by measurement, not assumption.
Who can carry out TR19 cleaning?
TR19 Grease cleaning should be carried out and signed off by a holder of the BESA Grease Hygiene Technician (GHT) qualification. A competent contractor provides the DTT/WFTT evidence and hygiene certificate that your insurer and fire risk assessment will ask to see — a verbal assurance that the ducts "look clean" is not the same as documented TR19 compliance.
Why insurers require TR19 Grease compliance
Uncleaned grease in an extract system is a recognised cause of catastrophic kitchen fires. Because of this, insurers increasingly write TR19 Grease adherence into policy conditions. Where a fire occurs and the system was not cleaned to TR19, an insurer may decline the claim. Keeping the DTT/WFTT reports and hygiene certificates on file is the documentary evidence that protects the policy.