Kitchen Extraction and Fire-Safety Cleaning Schedules

Every commercial kitchen with a gas or high-heat cooking line builds up a layer of grease inside its extract ductwork, and that layer is fuel for a fire that travels above your ceilings where nobody can reach it. Cleaning it out on a schedule is not optional housekeeping — it is a fire-safety control the law expects you to manage, your insurer expects you to document, and a fire officer will ask to see certificates for. This guide sets out the cleaning schedules that actually apply: the TR19 Grease intervals by cooking hours (3, 6 or 12 months), the 200-micron measured trigger that overrides the calendar, the Regulatory Reform (Fire Safety) Order 2005 duty that sits underneath all of it, how ductwork access panels decide whether a clean is even possible, and exactly what to keep in your records so that after an incident your paperwork works for you and not against you.

Extraction cleaning is the compliance job most operators under-do until an insurer or a fire officer forces the issue — usually because the grease that matters is out of sight. You can see the filters going brown, but the duct run above the ceiling, the fan on the roof and the plenum behind the canopy are hidden, and out of sight becomes out of schedule. This guide is about turning that hidden system into a managed one: a written cleaning schedule matched to how hard you actually cook, a competent contractor certifying the work, and a records file that proves it. Get those three things right and the fire risk drops, the insurance position strengthens, and the awkward inspection becomes a five-minute file check.

This guide is for operators, kitchen managers, landlords and facilities teams responsible for a commercial kitchen — whether you are setting a schedule for the first time, inheriting a site with no records, or being asked by an insurer to prove your cleaning regime. It is an educational compliance guide: Craven Cooling supplies and services the cooking equipment that sits under the canopy and generates the grease load, and our servicing team keeps that equipment maintained; for the specialist duct cleaning itself you engage a competent ventilation-hygiene contractor, and this guide tells you exactly what to demand of them.

1. Why Grease in the Duct Is a Fire Risk, Not a Cleaning Job

It helps to reframe extraction cleaning from a hygiene task into what it actually is: fire-load management. The canopy filters catch the heavy grease, but a meaningful fraction passes through as fine aerosol and condenses on every internal surface downstream — the plenum behind the filters, the duct walls, every bend and riser, the impeller of the extract fan, and the discharge cowl on the roof. Over weeks and months that film thickens into a continuous coating of combustible residue lining the one part of the building specifically designed to carry hot air and flame away from the cooking line.

The danger is the combination: an ignition source (a flare-up on the chargrill, a chip-pan flash, a burner fault) meeting a fuel path (the grease layer) inside a spread route (the duct passing through ceilings, voids and compartment walls). A canopy fire that would be a contained incident in a clean system becomes, in a loaded one, a fire that runs the full length of the extract before anyone in the kitchen realises where it has gone. This is precisely why extraction cleaning has its own industry specification and sits under fire-safety law rather than food-hygiene rules — it is managed as a fire control, and the schedule is the control.

2. TR19 Grease Cleaning Intervals by Cooking Hours

TR19 Grease is the UK building-engineering industry’s specification for cleaning grease-laden extract systems — the standard your contractor should certify against and the one your insurer means when they write “TR19” into a policy. Its headline output is a set of indicative cleaning intervals keyed to how many hours a day you cook, because cooking hours are the crude proxy for how fast grease accumulates.

Read these as starting points, not guarantees. The usage bands assume a broadly typical menu; two kitchens cooking the same hours can load their ducts at very different rates. A café frying breakfast for three hours can generate more grease than a lunch-only bistro doing gentle pan work over six, and a wood-fired pizzeria’s soot-and-grease mix behaves differently again. The honest way to set your interval is to start from the band that matches your hours, then let the first one or two cleans’ measurements tell you whether you need to go more or less often. The contractor’s deposit readings, not the catalogue band, are your real schedule.

3. The 200-Micron Test and What a Real Clean Includes

The intervals are indicative because TR19 Grease’s actual measure is not time — it is grease-layer thickness. A competent contractor uses a wet film thickness gauge at defined points through the system, and when the mean deposit reaches 200 microns — a fifth of a millimetre — the system requires cleaning, whether that took your chargrill three months or your café eighteen. The measurement is what converts “we clean twice a year” from a hopeful statement into an evidenced compliance position, and it is why the pre- and post-clean readings belong in your records.

Just as important is scope. A cheap “clean” that does the canopy face, swaps the filters and reaches a metre into the duct leaves the bulk of the fire load exactly where it was — and it produces a certificate that looks reassuring right up until a loss adjuster reads the small print. A proper TR19 Grease clean addresses the whole grease-bearing system.

When you commission a clean, ask three questions before you book: which specification will you certify against, what is included from canopy to discharge, and how will you evidence areas you can’t reach? A contractor who answers “TR19 Grease, full system, photographs and a schematic of exclusions” is selling you compliance. A quote that is markedly cheaper than the rest is almost always cheaper because it is doing less of the system — and the part it skips is the part that burns.

4. The Fire Safety Order 2005 — the Legal Duty Underneath

Cleaning schedules are industry practice; the legal obligation they satisfy is the Regulatory Reform (Fire Safety) Order 2005, the fire-safety law for virtually all non-domestic premises in England and Wales. It replaced fire certificates with a self-assessment regime built around one figure: the responsible person — usually the employer or whoever controls the premises — who must carry out and maintain a suitable and sufficient fire risk assessment and keep the resulting fire precautions in place.

The Order never mentions “extraction”. It doesn’t have to. The fire risk assessment must identify significant fire hazards and the people at risk, and a grease extract system is an ignition point, a fuel load and a spread route rolled into one — so an assessment for a catering premises that says nothing about the duct’s condition, its cleaning regime and its route through the building is not suitable and sufficient. That is the legal hook: your TR19 Grease cleaning schedule is one of the “general fire precautions” the Order requires you to maintain, and your certificates are the evidence you are maintaining it. Enforcement sits with the local fire and rescue authority, which can inspect, serve enforcement and prohibition notices — up to closing the kitchen — and prosecute, with serious breaches carrying unlimited fines.

Three practical moves discharge the duty cleanly: name the responsible person in writing; commission a fire risk assessment that explicitly covers the extract system and review it whenever the cooking line or building changes; and treat the cleaning schedule as a maintained control with a paper trail, not a favour you do the building when someone remembers. In leased premises, settle in writing who controls the duct that runs through the landlord’s voids carrying the operator’s grease — the unwritten split is the one that unravels after an incident.

5. Access Panels — No Access, No Clean, No Compliance

The single most common reason a kitchen cannot achieve a compliant clean is not budget or laziness — it is that the duct was never built to be cleaned. TR19 Grease and the underlying design practice call for inspection and access hatches at regular intervals along the whole run, at every bend and riser, so a contractor can physically reach and mechanically clean the internal surface end to end. Where those panels are missing, the contractor cleans as far as they can reach from each open end and formally excludes the rest — and that excluded middle stays coated in grease indefinitely, a permanent fire load with a certificate that quietly admits it was never touched.

6. Insurance and the Real Cost of Getting It Wrong

Insurers underwrite commercial kitchens on the assumption that the extract system is cleaned to TR19 Grease by a competent contractor, and most policies now say so — as a condition or warranty requiring cleaning at usage-appropriate intervals, documented. After a fire the loss adjuster’s opening requests are entirely predictable: the fire risk assessment, the gas safety records, and the duct cleaning certificates with their photographic reports. An operator who can produce a consistent run of TR19 Grease certificates matching their usage band is negotiating from strength. One who can’t is negotiating from underneath, and a reduced or refused settlement on a kitchen fire is frequently a business-ending event.

Two points that quietly matter. First, tell your insurer what you actually cook: a policy priced for a “restaurant” that is really a high-volume fried-chicken operation on annual cleaning is a misrepresentation problem stacked on top of a fire problem, and both surface at claim time. Second, when the cooking line changes, the change ripples through your extract load, your cleaning frequency, your fire risk assessment and your premium at once — make the calls before the equipment lands, not after the incident.

7. Choosing a Competent Contractor

Extraction cleaning is unregulated as a trade, which means the quality range is enormous — from specialists who measure, photograph and certify to a specification, down to a van with a pressure washer and a template certificate. Because the certificate is worthless if the work behind it wasn’t done, vetting the contractor is part of the compliance job, not an afterthought.

• ✓
  They certify to TR19 Grease by name
  Not “deep clean” or “steam clean” — the certificate should name the specification, because that is the word your insurer and fire officer recognise.
• ✓
  They measure deposit before and after
  Wet film gauge readings at defined points, on the report. Measurement is the difference between compliance and a hopeful guess.
• ✓
  They photograph pre- and post-clean at defined locations
  Time-stamped images of the same points before and after are the evidence a loss adjuster actually looks at.
• ✓
  They provide a schematic of inaccessible areas
  An honest contractor tells you what they couldn’t reach and recommends the access panels to fix it — rather than quietly certifying the whole system as done.
• ✓
  They carry appropriate insurance and can evidence competence
  Working at height, in voids and on roofs. Ask for their own liability cover and evidence of trained, competent operatives.
• ✓
  The quote covers the whole system, in writing
  Canopy, plenum, filters, full duct run, fan and discharge — itemised. A quote that is vague on scope is vague because the scope is small.

8. Your Cleaning Records File — What to Keep, Forever

Extraction fire safety comes down, in the end, to a folder. One place — physical or digital — holding the documents that answer the fire officer, the insurer and the landlord in a single flick through. Keep it current, keep everything, and never discard old certificates: the value is in the unbroken run of history that proves a regime rather than a one-off tidy-up.

Extraction cleaning is one part of the wider ventilation and compliance picture. Pair this guide with the commercial kitchen extraction regulations guide for DW/172 design and gas interlocks, the dark-kitchen prep equipment guide for the high-volume lines that load ducts hardest, the commercial kitchen fit-out guide, and the first aid and compliance checklist.

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