How Often Should Kitchen Extracts Be Cleaned? TR19 Frequency Explained

What Is TR19 Grease?

TR19 Grease is the industry standard for kitchen extract system cleanliness, published by the Building Engineering Services Association (BESA). It defines acceptable levels of grease accumulation, cleaning methods, verification techniques, and — critically — how often systems must be cleaned based on their usage level.

If you operate a commercial kitchen in the UK, compliance with TR19 Grease is not optional. It is referenced by insurers, environmental health officers, and fire safety enforcement bodies as the benchmark for whether your kitchen extract system is being maintained properly.

The TR19 Cleaning Frequency Matrix

TR19 Grease categorises kitchen extract systems by their level of usage and prescribes a cleaning frequency for each. Here is how it breaks down:

High Usage - Every 3 Months

• Kitchens operating 12-16 hours per day
• 7 days per week cooking
• Heavy frying, grilling, wok cooking
• Fast food restaurants, busy takeaways, high-volume restaurant kitchens
• Example: a fryer-heavy takeaway cooking 14 hours a day, 7 days a week needs quarterly cleaning

Medium Usage - Every 6 Months

• Kitchens operating 6-12 hours per day
• 5-6 days per week cooking
• Mixed cooking methods with moderate grease production
• Most restaurant kitchens, pub restaurants, hotel kitchens
• Example: a pub kitchen cooking 8 hours a day, 6 days a week needs cleaning every 6 months

Low Usage - Every 12 Months

• Kitchens operating less than 6 hours per day
• Occasional or light cooking only
• Limited frying, mostly preparation and reheating
• Staff canteens, day nurseries, some hotel breakfast-only kitchens

How Is Compliance Verified?

Cleaning alone is not enough. TR19 Grease requires measured verification that the system has been cleaned to an acceptable standard. We use a wet-film thickness gauge (WFTG) to take readings before and after cleaning:

• Pre-clean reading — measures the thickness of grease deposit on ductwork walls in microns. High readings (200+ microns) indicate heavy accumulation requiring urgent cleaning.
• Post-clean reading — should be below 50 microns for most systems. This confirms the cleaning has removed grease to an acceptable level.
• Grease rating — systems are rated A (low) through D (very high) before and after cleaning. A post-clean rating of A is the target.

These readings are documented in your compliance report and certificate, providing evidence of compliance for insurers, environmental health, and fire safety officers.

What Are the Risks of Non-Compliance?

• Fire risk — grease-laden extract ductwork is one of the most common causes of commercial kitchen fires. A grease deposit of just 1mm can ignite and spread fire through the entire duct run.
• Insurance invalidation — most commercial property and business interruption insurance policies require evidence of TR19-compliant cleaning. If you cannot produce a certificate when making a claim, it will be rejected.
• Environmental health enforcement — local authority environmental health officers can issue improvement notices and, in serious cases, close kitchens that fail to maintain extract systems.
• Legal liability — if a fire spreads through uncleaned ductwork and causes injury or death, the responsible person can face criminal prosecution under the Regulatory Reform (Fire Safety) Order 2005.

What Does a Compliant Clean Involve?

Our team cleans every accessible surface of the extract system:

• Canopy and canopy filters
• Ductwork (as far as accessible — access panels are fitted where needed)
• Fan unit and fan blades
• Grease trap and drainage
• Before and after photographic evidence at every location
• Wet-film thickness gauge readings documented
• TR19 Grease compliance certificate issued on completion

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