What is TR19? BESA ventilation hygiene guidance explained

TR19 — formally Internal Cleanliness of Ventilation Systems — is a technical specification published by BESA. It is the most widely referenced ventilation hygiene guidance document in the UK and is treated by the industry, insurers and many building operators as the benchmark for ductwork cleanliness.

It is important to be clear about its status. TR19 is industry guidance and recognised good practice. It is not itself a statutory regulation, and a TR19-aligned clean is not a legal certification. Where building operators have duties under workplace, fire safety or food hygiene legislation, TR19 is the practical reference used to demonstrate that the ventilation system is being managed to a recognised standard.

The guidance is split into two main strands. The general TR19 specification covers supply and general extract ductwork in offices, schools, healthcare, hotels and other commercial buildings. TR19 Grease is the dedicated specification for kitchen extract systems, where the dominant risk is grease accumulation in canopies, plenums, ductwork and discharge points.

TR19 Grease introduces the concept of measured grease deposit thickness and inspection-led cleaning frequencies driven by how heavily the kitchen is used. We cover that in more detail on our TR19 duct cleaning page.

A TR19-aligned ventilation hygiene project typically follows a recognised sequence: a pre-clean inspection and condition report, installation of suitable access where it is missing, mechanical cleaning of the ductwork internals, cleaning of associated components (grilles, dampers, fans, coils, plenums) and a post-clean verification with photographs and a written report.

The post-clean report — sometimes called a Post Cleaning Verification (PCV) — is the document FMs and insurers rely on as evidence. It records what was cleaned, the methods used, the access points worked from, before-and-after photography and any items that remained out of scope.

Facilities managers, landlords, managing agents, hospitality operators, healthcare estates teams and insurers all use TR19 as a reference point. Insurance policies for commercial kitchens, in particular, frequently reference TR19 Grease and ask for evidence of inspection and cleaning at suitable intervals.

Building operators are not always asked to deliver TR19 in name, but they are usually asked to demonstrate that ventilation hygiene is being managed — and TR19 is the practical reference used to define what "managed" looks like.

TR19 promotes an inspection-led, condition-based approach rather than a fixed interval for every building. Indicative starting points exist (for example for kitchen extract systems used heavily, moderately or lightly), but the recommended frequency for any specific system is driven by an inspection that measures actual contamination levels.

For a practical walk-through of how to evidence this in a building, see our TR19 compliance guide.

TR19 does not certify a building or its operator. It does not replace statutory duties under fire safety, workplace health and safety or food hygiene legislation. And no contractor — including us — should describe a clean as making a building "TR19 certified". The correct framing is that the works were carried out in line with TR19 / TR19 Grease and documented accordingly.