Key points
- BESA TR19 Grease is the industry specification for cleaning grease extract systems in commercial kitchens. It is published by the Building Engineering Services Association.
- Minimum cleaning intervals depend on daily cooking hours: roughly 3 months for heavy use, 6 months for moderate and 12 months for light.
- Grease deposits are measured. An average above 200 microns means the system needs cleaning, and a clean should bring surfaces below 50 microns.
- The legal driver is the Regulatory Reform (Fire Safety) Order 2005. The commercial driver is your insurer.
- A clean is only as good as its report. Keep the photos, measurements and certificate for every visit.
What TR19 Grease is
TR19 is a family of guides from BESA on the internal cleanliness of ventilation systems. The kitchen extract part, TR19 Grease, deals specifically with grease-laden systems over cooking appliances. It sets out how to assess a system, how often to clean it, how to measure grease and how to report the results.
A kitchen extract system is more than the canopy you can see. It includes the canopy and its grease filters, the plenum behind them, the ductwork running through the building, any fire dampers, and the extract fan and discharge. Grease that gets past the filters condenses on the inside of the ductwork. Over time, that layer becomes fuel.
TR19 Grease asks for the whole system to be cleaned, not just the parts that are easy to reach. That is why access panels matter. A system without enough access cannot be cleaned or inspected properly, and the contractor should say so in their report.
Why it matters: fire risk and the law
Kitchen extract fires are hard to fight. Grease in a duct can ignite from a flare-up on the cooking line and spread through concealed spaces to other floors or neighbouring units.
TR19 Grease is not law. The legal duty comes from the Regulatory Reform (Fire Safety) Order 2005. The responsible person must assess fire risks, take general fire precautions and keep equipment maintained in efficient working order. A greasy extract is an obvious fire risk, so a fire risk assessment for a commercial kitchen should cover extract cleaning. Fire and rescue authorities, when inspecting, may ask how you control that risk.
TR19 Grease is the recognised benchmark for showing that you do. If something goes wrong, being able to show regular cleaning to a published specification is far stronger than saying the filters were washed.
How often to clean
TR19 Grease sets minimum cleaning intervals based on how many hours a day the kitchen cooks. These are starting points. The specification is clear that measured grease levels should drive cleaning, so a system that fills up faster than expected needs cleaning sooner.
| Usage level | Typical daily cooking hours | Minimum cleaning 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 |
Cooking style matters too. Kitchens doing a lot of frying, chargrilling or wok cooking produce more airborne grease than a café that mostly reheats and bakes. Solid fuel appliances, such as wood-fired pizza ovens, bring their own risks from soot and sparks, and may need separate arrangements.
Count the hours the cooking appliances are in use, including prep before service and any late kitchen. A site that opens for eight hours but cooks for fourteen is a heavy-use kitchen.
Measuring grease: the 200 and 50 micron figures
TR19 Grease uses measurement, not just appearance, to judge cleanliness. The main method is the deposit thickness test, where the technician uses a comb-style gauge to measure the depth of grease at points along the system.
- Before cleaning: if the average deposit is above 200 microns, the system needs cleaning.
- After cleaning: surfaces should measure below 50 microns to show the clean was effective.
A micron is a thousandth of a millimetre, so 200 microns is 0.2 mm. That is a thin film, which is the point: by the time grease is visibly thick, the system is well overdue.
Measurements are also how intervals get adjusted. If a three-monthly system is consistently well under 200 microns at the next visit, the data supports that interval. If it is over, the interval is too long.
What a post-clean report should include
The report is your evidence. Insurers, landlords and fire inspectors will judge your extract by it. A TR19 Grease report should typically include:
- Before and after photographs, taken from the same positions.
- Grease thickness measurements before and after, with locations.
- A schematic or drawing of the system showing what was inspected and cleaned.
- Notes of any areas that could not be accessed, and why.
- Defects found, such as damaged ductwork, missing access panels or faulty fire dampers.
- A certificate with the date, site address and technician details.
- A recommended date for the next clean.
The most important line in a report is often "areas not cleaned". If a section of duct was inaccessible, the certificate does not cover it. Ask for access panels to be fitted and schedule a follow-up clean.
What insurers expect
Many commercial insurers make kitchen extract cleaning a policy condition. Wording varies, but it often requires cleaning by a competent contractor to TR19 Grease at a stated minimum frequency, with records kept. Some ask to see certificates at renewal.
If a fire starts in or spreads through the extract and you cannot show the system was cleaned as the policy required, the insurer may reduce or refuse the claim. Read the exact wording in your policy and match your cleaning schedule to it, not just to the minimums in the table above.
Questions to ask a contractor
- Do you clean the full system, including ductwork and fan, to TR19 Grease?
- Will you measure grease deposits before and after, and include the readings in the report?
- How will you deal with sections you cannot reach, and will you recommend access panels?
- Can you work outside trading hours, and how will you protect the kitchen during the clean?
- Will you check fire dampers in the extract ductwork and report on their condition?
When choosing a contractor, ask whether they work to TR19 Grease, what their technicians' training is, and to see a sample report. Membership of a recognised ventilation hygiene scheme is a useful sign, but check what it covers.
Between cleans: filters and daily care
A specialist deep clean every few months does not replace daily care. Kitchen staff should:
- Clean or swap canopy grease filters on a set routine. In busy kitchens this is often daily or several times a week.
- Wipe down canopy surfaces and empty grease collection troughs.
- Report fan noise, poor extraction or grease dripping from the canopy.
- Never run cooking appliances with filters missing.
Extract performance also affects gas safety. Where gas appliances are interlocked with the ventilation, a failing fan can shut down the cooking line. See our guide to gas safety in commercial kitchens, and the wider commercial kitchen compliance checklist.
Fabric FM can hold each site's extract cleaning as a planned task with the right interval, store the TR19 report against the system, and turn access issues or defects into follow-up jobs. It is in early access now; see our planned preventative maintenance software page.
This guide is general information, not legal advice. Check the current regulations and guidance, or speak to a competent person, for your premises.
