Grease, fire and the compliance gap
A commercial kitchen fire doesn’t always start at the hob. Grease accumulation in extract ductwork is a significant and frequently underestimated fire risk, one that can spread rapidly and silently through a building’s ventilation system before anyone realises the danger. Gary Nicholls, Managing Director of Swift Fire Compliance and co-author of BESA TR19® Grease, explains how contractors and dutyholders can ensure compliance and safety.
It may seem like cooking vapours simply disappear into kitchen extract systems, but unseen inside ductwork, they deposit layer upon layer of fats, oils, grease (FOG) and other combustible residues. It’s estimated that around 25% of commercial kitchen fires are linked to poorly maintained extract systems, a figure that should give every dutyholder pause for thought.
Clear guidance exists in the form of TR19® Grease, yet compliance remains inconsistent across the industry. Failure to ensure regular cleaning can invalidate buildings insurance while indicating a lack of legal compliance with the Regulatory Reform (Fire Safety) Order. During my work as an expert witness in legal disputes, I have seen cases where insurers have refused to pay out millions of pounds in claims where compliance cannot be proven.
TR19® Grease
TR19® Grease is the specification from the Building Engineering Services Association (BESA) that sets the UK industry standard for the cleaning and maintenance of kitchen extract ventilation systems, primarily as a fire risk management measure. It covers the entire extract system and requires cleaning to bare metal, with post-clean grease thickness verified using precision tools, such as a wet film thickness gauge.
Cleaning frequencies are determined by cooking volume and type, ranging from every three months for heavy use kitchens such as fast-food operations, to every six months for moderate use and annually for light use kitchens. Grease levels must not exceed a mean average of 200 microns between scheduled cleans and frequencies should be reviewed regularly to confirm that threshold is being maintained.
Verify compliance
The Vent Hygiene Register (VHR) exists to verify that kitchen extract cleaning works are compliant with TR19® Grease and to provide auditable evidence. Registered contractors must provide a post-clean verification report together with before and after photographic evidence of system condition. A BESCA certificate of compliance is generated that provides evidence of compliance, protects contractors against future liability and supports predictive maintenance.
Train for competence
Two BESA-accredited courses underpin competency in this sector:
• Grease Hygiene Operative (GHO) course – this course covers safe working practices, the principles of extract systems, preparing the work location, selecting the correct tools and equipment and applying the correct cleaning methods and techniques to meet TR19® Grease requirements.
• Grease Hygiene Technician (GHT) course – designed for those in supervisory or managerial roles, training covers risk assessments and method statements, pre- and post-clean testing and reporting and the installation of access panels to industry standards. Completion of the GHT qualification is mandatory for technicians signing off kitchen extract cleans under the VHR scheme.
Best practice for contractors and facilities managers
• Review cleaning frequencies regularly — cooking volume and menu type can change. The frequency of cleaning must reflect current operational demands, not historic assumptions
• Verify grease levels quantitatively — use a wet film thickness gauge before and after every clean. Visual inspection alone does not satisfy TR19® Grease
• Ensure full system coverage — compliance applies to the entire extract system, including canopy filters, ductwork, fans and fire dampers, not just the most accessible sections
• Use VHR-registered contractors only — unregistered contractors cannot issue BESCA certificates, leaving dutyholders exposed in the event of a claim or inspection
• Document everything, without exception — maintain TR19® compliant reports with photographic evidence, pre- and post-clean readings and a record of any inaccessible areas
• Position and confirm TR19® compliance is being evidenced
The clean alone is not enough
TR19® Grease and the VHR certification pathway have set a high standard for kitchen extract cleaning, providing a robust and independently verified framework for good practice and compliance. The emphasis, however, is not just on good cleaning, but on maintaining the golden thread of documented evidence that demonstrates due diligence in the event of a fire, an insurance claim or an enforcement inspection.
I would strongly encourage contractors and dutyholders to undertake the relevant training and continue to support a culture of competence, compliance and safety in ventilation hygiene.
