TR19 is the Building Engineering Services Association (BESA) Guide to Good Practice for the internal cleanliness of ventilation systems. TR19 (general ventilation) and TR19/Grease (kitchen extract) are the UK reference for ductwork hygiene.

Is TR19 a legal requirement?

TR19 is industry guidance, not statute — but Workplace Regulations 1992 (Reg 6), the Regulatory Reform (Fire Safety) Order 2005, and insurance policies effectively require evidence of TR19 compliance. Non-compliance has been cited in commercial kitchen fire prosecutions.

How often should ductwork be cleaned under TR19?

TR19 sets cleaning frequencies by usage: low-use ventilation 24 months, medium-use 12 months, high-use (commercial kitchens) every 3–12 months depending on grease accumulation rate measured by deposit thickness.

TR19 Ductwork Cleaning Standards & Regulations (UK)

What TR19 covers

TR19 — Internal Cleanliness of Ventilation Systems — is published by the Building Engineering Services Association (BESA). It defines methodology for assessing ductwork contamination, cleaning to a verifiable standard, and documenting the result. The current edition references BS EN 15780 (ductwork cleanliness classes).

Two strands: TR19 for general supply, extract and recirculation ventilation; TR19/Grease (formerly TR19 Annex A) for commercial kitchen extract, which carries direct fire-risk weight.

Inspection and cleaning frequencies

TR19 sets baseline frequencies modified by usage and contamination evidence:

Low-use ventilation (intermittent occupancy): inspect 24 months, clean as required
Medium-use (offices, retail, standard commercial): inspect 12 months
High-use (24-hour healthcare, hotels, leisure): inspect 6 months
Kitchen extract — heavy use (12+ hrs/day): every 3 months
Kitchen extract — moderate use: every 6 months
Kitchen extract — light use: every 12 months

Grease deposit thickness above 200 microns triggers immediate cleaning regardless of schedule.

Pre- and post-clean verification

TR19 requires evidence at both ends of the job: pre-clean contamination assessment (deposit gauges, photographs, NADCA wet-film tests for grease) and post-clean verification to BS EN 15780 cleanliness classes — Low, Medium or High depending on the ductwork's role. Reports must include access-point locations, methods used, and a hand-signed engineer declaration.

Legal and insurance weight

TR19 is not statute, but failure to maintain ductwork to a recognised standard breaches:

Workplace Regulations 1992, Reg 6 — duty to provide effective ventilation
Regulatory Reform (Fire Safety) Order 2005 — duty to control fire risk (kitchen extract)
COSHH 2002 — where contamination presents an exposure risk
Insurance terms — most commercial policies require demonstrable TR19/Grease evidence; non-compliance has voided claims after kitchen fires

TR19 Ductwork Cleaning: Standards, Frequencies and Legal Weight

What TR19 covers

Inspection and cleaning frequencies

Pre- and post-clean verification

Legal and insurance weight

Ductwork hygiene survey to TR19 standard

TR19 Ductwork Cleaning: Standards, Frequencies and Legal Weight

What TR19 covers

Inspection and cleaning frequencies

Pre- and post-clean verification

Legal and insurance weight

TR19 in the wider regulatory map

Ductwork hygiene survey to TR19 standard