The guide serves facilities managers, HVAC contractors, compliance officers and others responsible for maintaining building ventilation systems.
Developed to enhance hygiene, fire safety, and system performance, TR 19® addresses risks associated with dust, debris, and grease buildup in ventilation systems. Its guidance helps building owners, facilities managers, and contractors meet legal obligations and align with best practices.
TR 19® is not just a set of cleaning instructions. It is a comprehensive framework for compliance, supporting traceability, accountability, and consistent hygiene standards across the building services industry.
Poor ventilation hygiene poses multiple risks to buildings and occupants. Dust and debris within ductwork can restrict airflow, reduce energy efficiency, and compromise indoor air quality. In healthcare, food preparation, or educational environments, this can have serious consequences for health and well-being.
In kitchen extract systems, grease deposits present an even greater hazard due to their flammability. Without regular cleaning and inspection, these systems can become a significant fire risk. Insurance data shows that extract duct fires remain a leading cause of commercial kitchen damage.
Regulators, insurers, and fire safety professionals all recognise that unclean ductwork can contribute to building fires and system failures. That is why following TR19® cleaning intervals and inspection procedures is considered essential.
Learn more about kitchen extract system cleaning
TR 19® sets out precise, practical requirements for inspecting and cleaning internal ductwork in both general ventilation and grease extract systems. These requirements support consistent hygiene standards, reduce fire risk and improve indoor air quality.
The first step is a visual inspection of the ductwork to assess its condition and determine whether cleaning is required. TR19 defines minimum inspection frequencies based on the type of system, the level of risk, and the frequency of system use. The guide provides a standard for ventilation duct inspections that facilities teams can follow.
Cleanliness is measured using specific criteria. In a deposit thickness test (DTT), the assessor examines a representative sample of internal surfaces to determine the buildup of grease or dust. TR19® provides threshold levels for when cleaning is required and supports the adoption of ductwork cleaning verification methods.
Photographic evidence is also a crucial component of the TR19 process. Inspectors take before-and-after photos to document the system's condition and verify that cleaning meets the required standard. When cleaning occurs, TR19 outlines the expected methods and equipment that teams should follow. It also details how to ensure access to all parts of the duct system, including advice on the design and placement of access panels.
Explore best practices for duct cleaning methods
TR 19® plays a critical role in ensuring the cleanliness and safety of kitchen extract systems, which are among the highest-risk components in a building's ventilation network. Cooking processes continuously release grease and oil vapours that reach and affect these systems.
TR 19® sets out precise requirements for how often to clean commercial kitchen extract ducts, depending on usage levels. Grease deposits are measured using a DTT, with a maximum permitted buildup of 200 microns.
In commercial buildings beyond the kitchen, TR19® also applies to general supply and extract systems. These are essential for maintaining indoor air quality in offices, healthcare environments, and public buildings.
See how TR 19® supports indoor air quality management
Compliance with TR 19® delivers significant safety, legal, and commercial benefits. As a recognised industry standard, it helps building owners and contractors meet their responsibilities while reducing risk and increasing assurance across ventilation systems.
One of the most immediate benefits is improved fire safety. By following TR 19® cleaning schedules and verification procedures, businesses reduce the chance of ignition and limit the spread of fire through ductwork systems.
Insurance providers increasingly expect building owners to maintain ventilation systems to a recognised standard and provide evidence of compliance. TR19® is widely referenced in inspections and post-incident investigations. Legal compliance is also a key benefit, particularly in regulated sectors.
Beyond compliance, TR 19® supports reputational and operational advantages. Buildings with clean, well-maintained ventilation systems tend to experience fewer system failures and enjoy better indoor air quality.
Industry professionals across the UK widely recognise TR19® as the gold standard for ventilation hygiene. It combines practical cleaning guidance with regulatory awareness and best practice.
Unlike generic cleaning checklists, TR19 guides professionals on how to inspect, clean, and maintain ventilation systems based on risk level, system type, and building use.
Its emphasis on detailed record keeping and verification supports the principles of the Building Safety Act and the Golden Thread.
It also serves as a unifying standard across multiple disciplines. Contractors, designers, cleaning specialists, and insurers can all refer to TR19® for consistent expectations.
In an industry where performance, safety, and compliance must go hand in hand, TR19® provides the tools and confidence to deliver safe, efficient, and maintainable systems.
TR 19® is the UK's recognised industry standard for the internal cleanliness of ventilation systems. Published by BESA (the Building Engineering Services Association), it provides comprehensive guidance on inspecting, cleaning, and maintaining ductwork in both general ventilation and kitchen extract systems. The standard is widely referenced by insurers, fire safety officers, and regulatory bodies as the benchmark for ventilation hygiene compliance.
TR 19® applies to anyone responsible for ventilation system maintenance, including facilities managers in commercial buildings, building owners and landlords, HVAC contractors and cleaning specialists, compliance officers in regulated sectors (healthcare, hospitality, education), fire safety managers, and insurance risk assessors. If you're responsible for a commercial or public building with mechanical ventilation, TR 19® provides the framework to meet your legal and safety obligations.
Cleaning frequency depends on the system type and usage. For kitchen extract systems: heavy use (12-16 hours/day) every 3 months, moderate use (6-12 hours/day) every 6 months, light use (2-6 hours/day) every 12 months. General air systems follow a risk-based approach with annual baseline inspections. Cleaning is scheduled based on deposit thickness test (DTT) results. High-risk environments like hospitals or labs may require more frequent inspection. The standard emphasises regular inspection over rigid schedules, allowing you to clean based on actual system condition.
A Deposit Thickness Test (DTT) is a measurement technique used to assess contamination levels inside ductwork. An inspector examines representative sections of internal duct surfaces and measures the thickness of dust or grease deposits, typically in microns. For kitchen extract systems, TR 19® sets a maximum grease deposit threshold of 200 microns. If deposits exceed this level, cleaning is required. The DTT provides objective, measurable evidence of system cleanliness and is a key component of TR 19® compliance documentation.
Yes, significantly. Many insurance providers now require evidence of TR 19® compliance for commercial kitchen coverage and request cleaning certificates and inspection reports during renewals. Insurers may reduce premiums for buildings with documented compliance, and can deny fire damage claims if the lack of maintenance contributed to the incident. TR 19® documentation demonstrates due diligence and helps protect your coverage. Insurers increasingly expect building owners to maintain ventilation systems to this recognised standard, particularly for kitchen extract systems where fire risk is highest.
TR 19® requires comprehensive record-keeping. After each inspection or cleaning, you need: before and after photographs taken from identical positions, Deposit Thickness Test (DTT) results, a written inspection report identifying areas of concern, a hygiene certificate with date, location, and technician details, system drawings showing areas inspected or cleaned, and notes on any access limitations. For ongoing compliance, maintain a maintenance log with all inspection and cleaning dates, contractor certificates and qualifications, and correspondence with insurers or regulatory bodies. This documentation supports Building Safety Act requirements and creates an auditable compliance trail.
This depends on several factors. You may need specialists if the system includes high-level or difficult-to-access ductwork, kitchen extract systems require grease removal, your team lacks TR 19® training or appropriate equipment, your insurance policy requires certified contractors, or the system serves high-risk environments like hospitals or food production. In-house cleaning may be suitable for basic inspections of accessible general ventilation, simple maintenance in low-risk environments, or pre-inspection preparation work. Most organisations use TR 19® trained contractors who can provide proper documentation, insurance coverage, and verification that meets industry standards. The Vent Hygiene Register (VHR) lists qualified contractors.
Non-compliance can result in serious consequences. Legal consequences include breach of the Regulatory Reform (Fire Safety) Order, enforcement notices or prosecution, and personal liability under the Building Safety Act. Financial impact includes insurance claim denials, increased premiums or coverage refusal, fire damage costs (kitchen duct fires commonly exceed £100,000), system replacement from poor maintenance, and legal costs with potential fines. Operational disruption includes forced closures during emergency cleans, equipment failures from contamination, tenant complaints about air quality, and reputational damage. Regular TR 19® compliance is far less expensive and disruptive than dealing with these consequences.
TR 19® itself is not legislation, but it's the recognised industry standard for meeting legal obligations under the Regulatory Reform (Fire Safety) Order 2005, which requires fire risk assessment and mitigation, the Health and Safety at Work Act 1974, which mandates safe working environments, the Building Safety Act 2022, which requires building safety and maintenance records, and the Food Safety Act 1990, which sets cleanliness requirements for food premises. Courts, insurers, and regulators reference TR 19® as the expected standard of care. If you don't follow it and an incident occurs, you may struggle to prove you met your duty of care.
The complete TR 19® guide is available from BESA Publications. The document includes detailed cleaning methodologies, inspection frequency tables, access panel requirements, verification procedures, documentation templates, and case studies with practical examples. Download TR 19® from BESA Publications. BESA also offers training courses, webinars, and technical support to help you implement TR 19® effectively in your facilities.
Whether you manage commercial kitchens, healthcare facilities, or large commercial buildings, TR19® offers the recognised benchmark for ventilation system cleanliness, safety, and compliance.
To access the complete guidance, cleaning procedures, and verification methods set out in the latest version of TR19®, download the official document from BESA Publications.
Download the TR19® Internal Cleanliness Guide
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