What TR19 Grease is
TR19 is published by the Building Engineering Services Association (BESA). The original document covered all ventilation hygiene. In 2019 BESA split the kitchen fire-risk content into its own specification, TR19 Grease, and the general ventilation content later became TR19 Air. The two are separate documents with separate tests and separate certificates. If a contractor offers you a "TR19 clean" for a kitchen, the document you want named on the paperwork is TR19 Grease.
TR19 Grease is not law. It is the recognised benchmark. BESA states that the specification and the Vent Hygiene Register are recognised by London Fire Brigade, by the RISCAuthority, the insurer-funded fire research body, and by many insurers. In practice that means a fire officer, a loss adjuster or a landlord's surveyor will ask for evidence of cleaning to TR19 Grease and will judge your system against its numbers.
The legal duty behind it
The Regulatory Reform (Fire Safety) Order 2005 applies to every non-domestic premises in England and Wales. It places duties on the responsible person, normally the employer, the occupier or the person in control of the building. Two of those duties matter here. The responsible person must carry out and keep up a suitable fire risk assessment. The responsible person must also make sure that the premises and any equipment provided for safety are subject to a suitable system of maintenance and kept in good repair.
A grease-laden extract system fails both tests. Fire risk assessments for commercial kitchens routinely list the extract system as a significant hazard, and enforcement officers expect the assessment to say how that hazard is controlled. Cleaning to TR19 Grease, with a written report, is the control they expect to see.
How much grease is too much
TR19 Grease works in microns of deposit measured on the internal surfaces of the duct. The measurement is taken with a wet film thickness gauge, a calibrated comb pressed into the deposit at each test point. BESA and the specialist contractors who work to the specification quote three figures.
- The mean deposit across the system must stay below 200 microns between cleans.
- Any single point at 500 microns or above needs immediate local cleaning.
- A completed clean should bring the system down below 50 microns on average.
The pre-clean readings are as important as the post-clean ones. They show how quickly grease builds in your kitchen and they drive the recommended interval for the next visit.
Cleaning frequency by hours of use
TR19 Grease sets minimum intervals based on how many hours a day the kitchen cooks.
| Usage | Daily cooking hours | Minimum interval |
|---|---|---|
| Heavy | 12 to 16 hours | Every 3 months |
| Moderate | 6 to 12 hours | Every 6 months |
| Light | 2 to 6 hours | Every 12 months |
Treat these as floors, not targets. A charcoal grill or a bank of fryers running eight hours a day can lay down grease faster than a moderate rating suggests. If the pre-clean readings on your last report were close to 200 microns, the interval should come down. Some fire and rescue guidance goes further than the BESA table and suggests monthly attention for the heaviest kitchens.
What a compliant clean involves
A TR19 Grease clean is not a wipe of the canopy. The specification covers the whole extract path from the filters to the discharge point.
- A pre-clean survey with photographs and wet film readings at each access point.
- Removal and degreasing of baffle or mesh filters.
- Manual scraping and degreasing of the canopy, plenum and collection trays.
- Cleaning of every reachable duct run through the access panels, using scrapers, rotary brushes and degreaser as the deposit demands.
- Cleaning of the extract fan impeller, casing and any attenuator or flexible connection.
- Post-clean photographs from the same positions as the pre-clean set and repeat wet film readings.
Access is the usual limiting factor. Ductwork installed to the DW172 design specification should have panels along the run and at every change of direction. Older systems often do not. A competent contractor will say where panels are missing, fit them where the client agrees, and record any section that could not be reached. A report claiming a full clean on a duct with no access panels is not credible.
What the report and certificate must contain
The post-clean verification report is the document your insurer and the fire service will read. A compliant one includes:
- A yes or no statement on whether the whole system was cleaned, with reasons and locations for any part that was not.
- Before and after photographs at each access point, taken from matching positions, with more images on long runs.
- Wet film thickness readings in microns at every test point, pre-clean and post-clean, and the mean average.
- A schematic or as-installed drawing showing the canopy, plenum, duct route, fan and every access point.
- The cleaning date or dates, the client and site details, and the name and signature of the technician.
- A recommended next clean date based on the measured grease rate and the hours-of-use category.
- The contractor's insurance details.
Contractors on the BESA Vent Hygiene Register also upload the report to the register, which issues the client a notification certificate for a full or partial clean. Ask whether your contractor's clean will be registered.
Two warning signs of a poor report: a single composite "before" photograph rather than one per access point, and a generic statement of compliance with no micron readings.
The insurance angle
BESA cites London Fire Brigade data showing a kitchen extract ductwork fire in Greater London on average every nine days. Insurers price that risk, and some policies name TR19 and require cleaning at the intervals it sets. Others rely on a general condition that the insured complies with statutory duties, which pulls the Fire Safety Order in by the back door. Either way, a fire that starts in an uncleaned duct invites a dispute over the claim. Keep every report for the life of the policy.
Who is liable: landlord, tenant or operator
The lease normally makes the tenant responsible for cleaning the extract system it uses. The landlord does not escape liability by writing that clause. Where the duct passes through common parts or serves more than one unit, the landlord or managing agent is usually a responsible person too. Many landlords require a TR19 Grease report at lease start, at set intervals and at lease end before a deposit is released.
How Commercial Cleaning London arranges it
We survey the system, agree a written specification that names TR19 Grease, the access points, the sections to be cleaned and the test points, then appoint a TR19 Grease specialist and schedule the work outside service hours. The specialist's post-clean verification report, in the format described above with photographs and micron readings, comes to you with a recommended date for the next clean. Where access panels are missing we quote for them before the clean rather than reporting an incomplete job afterwards.