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Kitchen extraction - cleaning intervals
There is no single right answer to how often a kitchen extract should be cleaned - and the recognised guidance does not pretend there is. Instead it bands kitchens by how much they cook, because that, not the calendar, is what decides how fast grease builds to a fire risk.
The short answer
The TR19 Grease guidance sets kitchen extract cleaning frequency by how heavily a kitchen cooks, banding usage into light, moderate and heavy. The more hours of cooking and the more grease produced, the shorter the recommended interval - because grease accumulation, which creates the fire risk, is driven by cooking volume. A heavy-use kitchen needs cleaning far more often than a light-use one, and matching the interval to the band is how the risk is kept controlled rather than left to guesswork.
The principle
The logic behind the TR19 Grease intervals is a simple chain. The fire risk in a kitchen extract comes from grease building up in the ductwork and fan. That grease is produced by cooking - especially frying and grilling - so the more a kitchen cooks, the faster grease accumulates, and the sooner it reaches a level that carries real fire risk. Cleaning frequency therefore has to follow cooking volume, because that is what determines how quickly the danger builds back up after each clean.
This is why a single universal interval would be wrong for almost everyone. A quiet cafe and a high-volume fast-food kitchen produce grease at completely different rates, so cleaning them on the same schedule would leave one over-serviced and the other dangerously under-serviced. The guidance solves this by banding kitchens by usage and setting the interval to match - a risk-based approach that ties the cleaning to the actual grease production rather than to an arbitrary calendar figure.
The bands
The guidance groups kitchens into three broad usage bands. Light use covers kitchens cooking for relatively few hours a day - the sort of operation doing light or occasional cooking, which produces grease slowly and needs the least frequent cleaning. Heavy use is the opposite end: kitchens cooking for long hours, often continuously, doing large volumes of frying and grilling, which load the system with grease fastest and need cleaning most often. Moderate use sits between the two, for kitchens with substantial but not round-the-clock cooking.
The bands work by hours of cooking per day as a proxy for grease production - roughly, a light-use kitchen runs a few hours, a moderate one a good part of the day, and a heavy one long or continuous hours. The recommended cleaning interval shortens as you move up the bands, so heavy-use kitchens are cleaned on a much tighter cycle than light-use ones. The point of the banding is to give each kitchen an interval proportionate to its own grease production, rather than one figure stretched across all of them.
Placing your kitchen
Applying the bands means placing your kitchen honestly, and the temptation is always to under-rate it. What matters is the real cooking pattern - the hours the equipment is genuinely in use and the amount of grease-producing cooking done - not an optimistic self-image. A kitchen that runs busy lunch and dinner services with a lot of frying is heavier use than its operator might like to think, and placing it too low means cleaning too rarely and letting grease build past a safe level between cleans.
The type of cooking matters as much as the hours. Heavy frying, grilling and char-cooking throw far more grease into the extract than, say, boiling or steaming, so two kitchens open the same hours can sit in different bands depending on what they cook. Getting the placement right - by honest assessment of hours and cooking type - is what makes the interval genuinely protective. An accurate band gives an interval that keeps grease controlled; a flattering one gives a schedule that quietly lets the risk grow.
Interval is a floor, not a ceiling
The banding gives a recommended interval, but it is best treated as a baseline that specific conditions can shorten rather than an absolute permission to wait. If a system fouls faster than expected - because of the particular cooking, a long or awkward duct run that traps grease, or heavier use than the band assumed - it may need cleaning more often than the nominal interval. The interval is there to be met or bettered, not stretched, and the real test is whether grease is being kept below a fire-risk level.
This is why inspection alongside the interval is sound practice. Checking the actual grease build-up confirms whether the chosen interval is keeping the system clean enough, and flags when a kitchen has been placed too low or is fouling faster than its band suggests. The band sets a sensible starting frequency; the condition of the system tells you whether it is enough. Used together, they keep the cleaning genuinely matched to the risk rather than to a number that may not fit this particular kitchen.
The takeaway
The TR19 Grease intervals answer how often to clean a kitchen extract by banding kitchens into light, moderate and heavy use and shortening the interval as cooking volume rises. It is a risk-based approach, because grease production - driven by how much and what a kitchen cooks - is what determines how fast the fire risk rebuilds after each clean. A heavy-use kitchen needs cleaning far more often than a light one, and the band is how that is set proportionately.
Getting the benefit means placing your kitchen honestly by its real hours and cooking type, treating the interval as a floor that fouling conditions can shorten, and checking the actual grease build-up to confirm the interval is enough. Done that way, the banding turns the vague question of frequency into a concrete, defensible cleaning cycle matched to your kitchen's real risk - which is exactly what it is designed to do.
Questions
By cooking volume, not the calendar. The TR19 Grease guidance bands kitchens into light, moderate and heavy use and shortens the recommended cleaning interval as usage rises - because grease production, which creates the fire risk, follows how much a kitchen cooks.
Broadly, hours of cooking per day as a proxy for grease production - light use is a few cooking hours, moderate is much of the day, and heavy is long or continuous cooking. Heavy-use kitchens produce grease fastest and need cleaning most often.
Because kitchens produce grease at completely different rates. A quiet cafe and a high-volume fast-food kitchen on the same schedule would leave one over-serviced and the other dangerously under-serviced - so the interval has to follow actual cooking volume.
By honestly assessing your real cooking pattern - the hours equipment is genuinely in use and the amount of grease-producing cooking like frying and grilling. The type of cooking matters as much as the hours; heavy frying puts a kitchen higher up the bands.
It is best treated as a baseline that conditions can shorten, not stretch. A system that fouls faster - through the cooking type, an awkward duct run or heavier use than assumed - may need cleaning more often. The real test is keeping grease below a fire-risk level.
Yes. Inspecting the actual grease build-up confirms whether the chosen interval is keeping the system clean enough and flags if the kitchen was placed too low. The band sets the starting frequency; the condition tells you whether it is enough.
We place your kitchen honestly in the TR19 use bands and clean on an interval matched to your real cooking volume - keeping grease genuinely under control.
