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Kitchen extract ductwork now has its own specification — TR19 Grease — separating kitchen extract cleaning and compliance from other ventilation ductwork. Gary Nicholls explains the change.

© iStock
© iStock

07 October 2019 | Gary Nicholls

Although we have made progress towards ductwork compliance since the BESA (Building Engineering Services Association) first issued ventilation hygiene guidance in the form initially of TR/17 and then TR/19, there can be little doubt that kitchen extract ductwork cleaning is still overlooked. 

To combat this, BESA has created a standalone specification for kitchen extract ductwork systems, TR19 Grease. This has been created by lifting out section seven of the second edition of the well-established TR/19 document and giving it more prominent status as a specification, rather than guidance on best practice.

This brings kitchen extract compliance into the spotlight and should help to make the importance of compliance more widely understood. Failure to comply with TR19 Grease represents a serious potential fire risk in commercial kitchens.

Grease layer thickness

There is a misconception that only a thick build-up of grease creates a fire risk, but TR19 Grease stipulates that the grease layer must be controlled within an average thickness of no more than 200 microns – half the thickness of the average business card. Anything more than this relatively thin film poses a fire risk. Being inside the ductwork makes it more damaging. In the event of a fire, the grease provides fuel and the ductwork itself becomes a chimney, a means of spreading a fire to become a highly destructive force throughout the building — and to neighbouring properties. 

Preventing fire risk

The only way to minimise this fire risk is regular and complete removal of the grease by a specialist cleaning provider that:

  • Employs competent, fully qualified operatives trained to BESA GHT level; and
  • Is a member of BESA’s Ventilation Hygiene Elite (VHE) scheme as members are fully vetted and able to submit each clean for certification once completed. 


Post-clean certification through BESCA – BESA’s certification arm – is a new initiative under TR19 Grease and will incur a small charge, but this is a small price to pay for a robust audit trail and peace of mind.

Consequences of non-compliance

The ‘Responsible Person’: The Regulatory Reform Fire Safety Order says each property must appoint a ‘responsible person’ to ensure compliance with appropriate fire safety measures. Failure to comply with TR19 exposes the responsible person – often the FM – to possible prosecution for negligence. A conviction can result in a prison sentence. 
Building insurance providers: Non-compliance may result in the insurer refusing to pay out on a claim resulting from a fire. This was already quite commonplace with TR/19 as a guidance document. TR19 Grease carries more weight as a specification so many insurers might, understandably, see failure to comply as a breach of terms and conditions. 

The FM needs to ensure that the entire extraction system is compliant, including the canopy, the fans and the entire length of the ductwork. It has never been more crucial to grant access to the whole system. If we cannot access a system, we cannot remove the grease layer or the fire risk. Unfortunately, there are some barriers to compliance and these must be tackled. 

Noteworthy observations

Kitchen extract ductwork comes under DW172 during its design and construction, which requires installation of access doors to facilitate future maintenance. But it is astounding how many new systems require us to retrofit additional access points at their first clean to make them compliant. Equally alarming is how many are later obscured by solid ceilings or false walls. 

If you have any influence as an FM on kitchen extract systems maintenance, then TR19 Grease compliance should be one of your highest priorities.  

Gary Nicholls is MD of Swiftclean and a member of the panel of experts behind the TR19 Grease specification