Phoenix Journal · Ductwork
A cleaning schedule is only worth anything if it matches how hard your kitchen actually works and leaves you with proof you can hand to an inspector. Here is how to set one up with a contractor so nothing is left to chance.
Duct cleaning · planning your schedule
A cleaning schedule is a promise about how often grease gets removed before it becomes a fire risk, and who is responsible for proving it.
Most kitchen operators know they should have their extract system cleaned. Far fewer have a schedule written down that actually reflects how many hours the range runs, what they cook and what their insurer expects to see. The gap between those two things is where trouble lives - a system that looks fine at the canopy while grease builds quietly along the horizontal duct runs and around the fan.
Setting up a schedule with a contractor is not simply booking a clean and hoping they come back. It is a short, deliberate conversation about frequency, scope and evidence that you settle once and then hold the contractor to. Get it right at the outset and the rest runs itself. Get it vague and you will find out how vague it was at the worst possible moment - a fire risk assessment, an insurance renewal or an actual incident.
The single most important input to a schedule is usage. The recognised UK benchmark is TR19® Grease, the specification published by the Building Engineering Services Association (BESA) for the inspection, cleaning and maintenance of kitchen extract systems. It ties cleaning frequency directly to how many hours a day the kitchen runs, and any contractor worth hiring will open the conversation there.
The headline bands are straightforward. Heavy use - roughly twelve to sixteen hours a day - points to cleaning every three months. Moderate use of six to twelve hours a day points to every six months. Light use of two to six hours a day points to every twelve months. These are minimums, not targets. A pizza oven or a charcoal grill throws off far more grease-laden vapour than a kitchen doing gentle service, so two sites open the same hours can genuinely need different schedules.
A good contractor will not just take your opening times and read off a band. They will ask what you cook, how your ventilation performs and what the ductwork looked like last time. Weak airflow, long duct runs and high-grease menus all pull the interval shorter, because grease accumulates faster than the calendar suggests. This is the same mechanism that makes an underperforming system so expensive to maintain - if you want the detail on that, it is worth understanding how poor ventilation drives up cleaning frequency before you commit to an interval you will later have to shorten.
The practical move is to agree an initial frequency, then let the first one or two cleans confirm or correct it. The verification measurements from those visits tell you whether you guessed right. If the system comes up clean well within the interval, you may be able to stretch it. If grease is already heavy, you tighten it. A schedule set this way is defensible because it is evidence-led rather than a number someone plucked from thin air.
The numbers your schedule turns on
TR19® Grease does not just recommend intervals - it sets a measurable target for how much grease is acceptable between cleans. That figure is what turns a schedule from a vague intention into something you can prove. These are the reference points to hold your contractor to.
The 200 micron figure is the one that matters most. TR19® Grease asks that grease is controlled so it does not exceed a mean average of 200 microns - about half the thickness of a business card - across the system between scheduled cleans. Where a contractor finds deposits of 500 microns or more, that is not something to leave for the next visit; it warrants attention there and then. A schedule that keeps you comfortably under 200 microns is a schedule that is working. One that lets you drift past it is telling you the interval is wrong.
Frequency is half the job. The other half is agreeing exactly what gets cleaned and what you get handed afterwards. Vague scope is where disputes start, because "the extract system" can quietly shrink to mean the canopy and filters while the ductwork and fan - the parts that actually carry the fire risk - go untouched behind panels nobody opened.
Insist that the schedule names the whole system: canopy and plenum, grease filters, the full length of ductwork including horizontal runs and risers, and the extract fan. Then talk about access. TR19® Grease expects the system to be cleaned to a verifiable standard along its whole length, and that is only possible if there are enough access panels to reach every section. If your ductwork is short of panels, agreeing to fit them is part of setting up a proper schedule, not an optional extra. Without access, a contractor can only clean what they can reach and honestly report the rest as inaccessible - which is precisely the note an insurer or fire risk assessor will seize on.
Every clean should leave you with a post-clean verification report: before-and-after photographs, grease depth measurements taken at defined points, a note of anything inaccessible and the date the next clean is due. This is the document that proves compliance under the Regulatory Reform (Fire Safety) Order 2005 and satisfies the condition most commercial insurers now attach to cover. Without it, you have paid for a clean but hold nothing that stands up when it is questioned. It is genuinely worth walking through what a cleaning schedule needs to stand up to inspection so you know the report you are being handed is the report you actually need.
Keep every certificate in one place, dated, and let the next-clean date drive your diary rather than a rough memory of "a while ago". A schedule is a live record, not a one-off receipt. If your contractor manages the reminders, holds the reports and flags when a band needs revisiting, you have the thing every responsible person is really after - continuous, provable control of the grease in your system, with the evidence ready before anyone asks for it.
Questions
There is no single legal interval, but TR19 Grease sets recognised minimums tied to usage: every three months for heavy use of twelve to sixteen hours a day, every six months for moderate use, and every twelve months for light use. What the law does require, under the Regulatory Reform (Fire Safety) Order 2005, is that you control the fire risk grease creates. In practice that means following the TR19 bands and being able to prove it, because your insurer will almost always treat compliance as a condition of cover.
TR19 Grease asks that grease deposits are controlled so they do not exceed a mean average of 200 microns across the system between scheduled cleans - roughly half the thickness of a business card. Staying under that figure is the measurable test of whether your schedule is frequent enough. Where a contractor records 500 microns or more, that area needs immediate spot cleaning rather than waiting for the next visit.
You should receive a post-clean verification report every time. It should include before-and-after photographs, grease depth measurements at defined points, a record of any sections that could not be accessed, and the date the next clean is due. This report is what demonstrates compliance to a fire risk assessor and satisfies your insurance policy, so treat it as the deliverable rather than an afterthought.
TR19 Grease expects the system to be cleaned to a verifiable standard along its whole length, which relies on having enough access panels. If yours are missing, fitting them should be part of setting up the schedule. A contractor can only clean and certify what they can reach, and any inaccessible sections will be flagged in the report - which is exactly the gap an insurer or inspector will question, so it is better closed at the outset.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.