TR19 Duct Cleaning — BESA-Aligned Ventilation Cleanliness in the UK

TR19 is the long-established BESA (Building Engineering Services Association) industry guide that sets out how the internal cleanliness of ventilation ductwork should be assessed and maintained. The guide is widely referenced by landlords, insurers, fire risk assessors and facilities teams as the de-facto UK benchmark for ventilation cleanliness and ductwork hygiene standards.

TR19 covers two main areas: general ventilation ductwork (supply, return, recirculation and non-kitchen extract) and grease-bearing kitchen extract systems, which are addressed by a dedicated specification because of the additional fire-risk considerations involved.

We refer to the TR19 framework professionally — it is industry guidance, not statute. Whether or not it applies to a specific building is generally driven by the building's fire risk assessment, insurance conditions and lease obligations rather than by direct legal duty.

A TR19-aligned clean follows a structured sequence:

1. Pre-clean survey and inspection. The system is walked, photographed and — where required — measured for deposit thickness in representative locations. This establishes the starting cleanliness classification.
2. Method statement and access review. Existing access doors are catalogued and any additional doors needed for a thorough clean are specified and installed to a recognised standard.
3. Mechanical cleaning under HEPA extraction. Internal surfaces are agitated with rotary brushes, whips or compressed air and the released debris is captured by HEPA-filtered negative pressure extraction. AHU internals, fan coils, dampers and terminal devices are cleaned in sequence.
4. Post-clean verification. Photographic evidence and, where applicable, re-measurement of deposit thickness against TR19 acceptance criteria, with a written PCV report.

A defensible TR19 position is not just about the clean itself — it is about being able to show what was cleaned, how it was cleaned and the condition achieved. Every TR19 duct cleaning project we deliver is supported with:

• Pre-clean photographs of representative duct sections
• Deposit thickness measurements where the scope or system type requires it
• Post-clean photographs of the same locations for direct comparison
• A written Post-Clean Verification (PCV) report referencing the TR19 framework
• An access door schedule and a recommended re-inspection interval

That evidence pack is what an insurer, fire risk assessor, incoming tenant or auditor typically expects to see, and it is what we hand over at the end of every project.

Grease-bearing kitchen extract ductwork is treated separately within the TR19 framework because grease build-up is a recognised commercial fire risk. Cleaning frequency for these systems is normally driven by daily hours of cooking and the type of food being prepared, and the clean itself is supported with photographic and, where appropriate, deposit measurement evidence. We deliver kitchen extract cleaning to the same documentation standard as the rest of our TR19 work, including pre-clean condition reports, access door installation and PCV-style sign-off suitable for the building's fire risk file.

TR19 describes cleanliness in measurable terms rather than as a simple pass/fail. After a clean, the system is classified against the framework's acceptance criteria and a sensible re-inspection interval is recommended based on the system type, usage pattern and the deposit accumulation observed at survey. For most commercial buildings this leads to a planned ventilation hygiene cycle — surveyed annually, cleaned on a frequency that matches risk, and re-verified each time.

For a TR19-aligned scope of works, a deposit survey or a planned ventilation hygiene programme, get in touch. Request a quote, book an inspection, or contact us.