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Duct cleaning - frequency
There is no single answer - the interval is set by how hard the kitchen works. Here is how TR19 Grease turns your cooking hours into a cleaning schedule, and why the hidden ductwork drives the timing.
The short answer
TR19 Grease, the benchmark most insurers and fire risk assessors work to, sets kitchen extract cleaning frequency by daily cooking hours: broadly every three months for heavy use, every six months for moderate use, and every twelve months for light use. The right figure for your kitchen comes from measuring the grease that has actually built up, not from a calendar guess.
The rule of thumb
TR19 Grease groups kitchens by how many hours a day the extract system runs over hot cooking. A takeaway or hotel kitchen frying from breakfast to late evening is a different fire risk from a village hall used a few hours a week, and the standard reflects that.
The widely used guidance runs like this: heavy use, around 12 to 16 hours of cooking a day, points to cleaning roughly every three months. Moderate use, around 6 to 12 hours, points to every six months. Light use, around 2 to 6 hours, points to every twelve months. These are starting points - the actual interval is confirmed by what the system looks like inside.
Why it is measured, not guessed
TR19 Grease does not just count hours - it looks at deposit. A technician takes readings of grease thickness at set points across the system, before and after cleaning, so the result is recorded rather than assumed. If a kitchen on a nominal six-month cycle is caking up faster than expected - a change of menu, a new fryer, longer trading - the readings show it, and the interval is shortened.
This is the part a canopy wipe-down can never answer. The grease that sets the risk is inside the concealed horizontal runs, up the vertical risers and on the extract fan - out of sight. Only opening and measuring the full run tells you honestly when it next needs doing.
Why the interval matters
Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person for a premises must assess and control fire risk. A grease-laden extract duct is one of the most serious risks in any catering building, because a flare-up on the cookline can travel the ductwork through concealed voids and spread fire between floors.
Most commercial insurance policies for premises with a kitchen now require TR19 Grease cleaning at a stated frequency, backed by certification. Let the interval slip and a fire claim can be reduced or refused - an expensive gap to find out about after the event. Keeping to the right frequency, with a dated certificate each time, is how you show the duty is being met.
Dry and laundry ductwork
Kitchen extract is the fire-risk case, but it is not the only ductwork that needs a schedule. Dry supply and general ventilation ductwork fills with dust and debris that throttles airflow and spreads contamination; it is assessed on build-up and air-quality need rather than grease thickness. Laundry and tumble-dryer ducting packs with lint - one of the most flammable build-ups in any building - and is common in hotels, care homes and gyms.
For each of these we survey what has actually accumulated and agree a sensible interval, so the whole building is on a plan rather than only the parts that are obvious.
Questions
Under TR19 Grease the interval is set by daily cooking hours: broadly every three months for heavy use, six months for moderate use and twelve months for light use. The exact figure is confirmed by measuring grease thickness inside the system.
It is risk-based. A competent cleaner assesses your cooking hours and takes grease-depth readings across the system, then recommends an interval. Your insurer or fire risk assessor may also specify a minimum frequency in your policy or assessment.
No. Cleaning the canopy and filters leaves the concealed ductwork - the horizontal runs, risers and extract fan - untouched, and that is where the fire risk sits. TR19 Grease covers the whole system, measured, not just the visible parts.
The grease keeps building, the fire risk rises, and your certification lapses - which can mean an insurer reduces or refuses a fire claim. Environmental health and fire officers can also act on an obviously neglected system.
Each clean is recorded with a dated certificate, before-and-after grease-depth readings, photographs of each section and an access report for your fire logbook.
We work across the whole of the UK. Call 07961 915018 or send your location through the contact form and we will confirm and quote.
We will survey the full run, measure it and set an honest cleaning frequency for how your kitchen actually works.
