How Often Should Commercial Kitchen Extract Systems Be Cleaned?

Why Cleaning Frequency Matters

Commercial kitchen extract systems accumulate grease over time. Left unchecked, this build-up becomes a serious fire hazard and can lead to an extract fan failure prompting a shutdown of cooking operations. Any structural failure to the system can be compounded by the presence of high grease deposits.

Airflow efficiency can also be reduced which generates poor working environments – potentially contributing to an increase in staff sickness.

A failure to sufficiently clean your grease extract system at a suitable frequency also puts your business at risk of failing insurance and hygiene requirements.

The frequency of cleaning depends on several factors: the daily hours of operation, the volume and type of cooking, and the specific requirements of your buildings insurer.

What TR19 Grease Says About Cleaning Frequency

TR19 Grease, published by the Building Engineering Services Association (BESA), is the UK's recognised industry standard for fire risk management of grease accumulation within kitchen extraction systems. Since 2019 it has been a standalone specification, separate from TR19 Air which covers general ventilation hygiene.

TR19 Grease bases cleaning frequency on the daily hours of kitchen operation:

Heavy-use kitchens (12–16 hours per day): every 3 months. Moderate-use kitchens (6–12 hours per day): every 6 months. Light-use kitchens (2–6 hours per day): every 12 months.

These are baseline intervals. Your extract cleaning service provider should also assess your system using a Deposit Thickness Test (DTT) or Wet Film Thickness Test (WFTT). Under TR19 Grease, grease deposits exceeding 200 microns require the entire system to be cleaned, and after cleaning, deposits must measure less than 50 microns across all tested surfaces. TR19 Grease also makes reference of buildings insurance requirements which at all times, should be followed with any caveats taken into account.

Insurance Requirements

Many commercial property insurance policies require evidence of regular extract cleaning to maintain cover. If a fire starts in a poorly maintained extract system and a cleaning regime cannot be evidenced, your claim could be rejected.

Policies may include caveats that state different frequencies for the cleaning of separate components within a grease extract system i.e. a system’s filters, canopy and ductwork may all require varying cleaning schedules.

Some insurers specifically require that a TR19-compliant or LPCB LPS 2084 accredited service provider carries out the work.

Signs Your System Needs Cleaning Now

For a fire to be started and sustained, three essential elements are required (this is commonly known as the fire triangle). Within any commercial kitchen these elements are simultaneously present:

• Fuel – grease deposits
• Source of ignition – cooking equipment
• Oxygen – mechanical ventilation

If at any point you notice a visibly high build-up of grease within your system, it is imperative that you do not wait for your next scheduled service but instead arrange one as soon as practicable.

Warning signs include but are not limited to:

• Visible grease build-up on canopy surfaces or filters.
• Reduced airflow or extraction performance.
• Unpleasant odours persisting in the kitchen.
• Grease dripping from filters, ductwork or fan units.
• Filters that are saturated and are no longer effective.

If you have any reservations about the condition or performance of your system, a survey from a specialist provider like Bright can assess its current state and suggest a suitable cleaning schedule going forward.

Getting It Right

It is important to not treat grease ventilation cleaning as a one-size-fits-all project. A kitchen operating 16 hours a day to provide three meals a day will need far more frequent servicing than one that produces a single meal service several times a week.

Furthermore, each building is unique and provides its own set of challenges. For example, if sections of your system are inaccessible for cleaning as they are obstructed by building fabric or other utilities, you may want to consider a more regular cleaning regime to ensure there is a fire-break maintained within the system, or even retain the services of an HVAC engineering company to review the layout of your system.

It is best practice to engage with your cleaning provider to plan a schedule and any required remedial works.

Remember to make sure you receive the documentation you need for insurance and inspections.