What Is TR19®? Grease Cleaning Requirements Explained

If you run or manage a commercial kitchen, you have almost certainly been told your extract system needs cleaning "to TR19®". TR19® is the industry benchmark for the cleanliness of kitchen extract ductwork in the UK, and understanding it is the difference between a compliant, insurable kitchen and one that could be shut down after a fire. This guide explains, in plain English, what TR19® Grease actually is, who is responsible for it, how often you must clean, and what a genuinely compliant clean looks like.

What is TR19® Grease?

TR19® Grease is a specification published by the Building Engineering Services Association (BESA). It sets out the recognised best practice for assessing and cleaning grease deposits in kitchen extract systems — from the canopy and filters, through the ductwork, to the extract fan and discharge point. It is not a law in itself, but it is the standard that insurers, fire risk assessors and Environmental Health Officers refer to when they ask whether a system has been "properly" cleaned.

The reason grease matters so much is simple: cooking vapours condense inside ductwork as a flammable, sticky film. Left to build up, that grease becomes fuel. A spark from the cooking line or a fault in the fan can turn a routine extract run into a rapidly spreading duct fire. TR19® exists to keep that build-up under control and to prove, with evidence, that it has been dealt with.

Who is responsible for TR19® compliance?

Legal responsibility sits with the "responsible person" as defined by the Regulatory Reform (Fire Safety) Order 2005. In most commercial premises that is the employer, the building owner, or whoever has control of the premises — often the head chef, the site manager or the facilities manager in practice. The responsible person must carry out a fire risk assessment and take reasonable steps to reduce fire risk, and a grease-laden extract system is a well-known, foreseeable hazard that assessment must address.

Crucially, you cannot delegate the legal duty away by hiring a contractor — but you can, and should, use a competent contractor to carry out the work and give you the documentation that proves the duty has been met. That evidence is what protects you if there is ever a fire, an insurance claim or an EHO inspection.

How often should a kitchen extract system be cleaned?

TR19® links cleaning frequency to how heavily the kitchen is used. The more hours the cooking line runs each day, the faster grease accumulates and the more frequently the system must be cleaned. The widely used frequency guidance is summarised below.

These are guide intervals. A busy takeaway frying all day will need cleaning far more often than a light-use staff canteen. If in doubt, a survey and a grease-thickness measurement will tell you where you actually stand rather than relying on the calendar alone. For a fuller breakdown with worked examples, see our guide on how often kitchen extract systems should be cleaned.

Not sure which category your kitchen falls into? A free site survey settles it. See our kitchen extract cleaning service.

What does a compliant TR19® clean include?

A clean is only worth the certificate if it is thorough and verifiable. Wiping down the visible canopy is not TR19® cleaning. A compliant clean covers the full accessible length of the system and produces evidence at every stage. It should include:

• The full accessible ductwork run — canopy, filters, plenum, horizontal and vertical duct, extract fan and discharge, not just the parts you can reach without effort.
• Access panels — fitting additional inspection and access hatches where the ductwork cannot otherwise be reached, so no length is left uncleaned.
• Before and after photographs — documenting the condition of each section so the standard achieved is visible and auditable.
• Wet film thickness testing — measuring residual grease deposit before and after cleaning to demonstrate the system genuinely meets the required standard.
• A post-clean verification report — a written record confirming what was cleaned, the results, any areas of restricted access, and recommendations for the next visit.

Why do certificates and insurance matter?

The certificate and verification report are the whole point of doing the work properly. Most commercial property and business-interruption insurance policies contain conditions requiring the extract system to be cleaned to a recognised standard at appropriate intervals. If a fire occurs and you cannot produce evidence that the system was cleaned to TR19®, an insurer may reduce or refuse the claim — and the responsible person may face enforcement under the Fire Safety Order.

A dated TR19® certificate, backed by before/after photos and wet film thickness readings, is the documentary proof that you have discharged your duty. Keep every report on file; together they form a maintenance history that demonstrates ongoing compliance rather than a one-off tick in a box.

What happens if I don't clean to TR19®?

The consequences stack up. Grease build-up sharply increases the risk of a duct fire that can spread through the building. Insurance cover can be invalidated, leaving you exposed to the full cost of fire damage and lost trade. An EHO or fire officer can serve enforcement or prohibition notices, and in serious cases the responsible person can face prosecution. In short, skipping TR19® cleaning is a false economy — the cost of a compliant clean is a fraction of the cost of a single failed claim.