Guide
How often should kitchen extract ductwork be cleaned?
Updated
There is no legal cleaning interval for kitchen extract ductwork. There is a usage-based approach in the industry guidance, and there is whatever your insurance policy says, which is often the one that decides it.
The usage-based approach
The TR19 Grease guidance approach ties cleaning frequency to how heavily the kitchen is used, on the sensible basis that a hotel kitchen running all day deposits grease far faster than a village hall used twice a week. The bands widely applied from that approach are set out below. Treat them as guidance and as a starting point for a risk-based decision, not as a rule you have complied with by matching a number.
| Usage | Typical hours of cooking per day | Guidance cleaning frequency |
|---|---|---|
| Heavy use | 12–16 hours | Every 3 months |
| Moderate use | 6–12 hours | Every 6 months |
| Light use | 2–6 hours | Every 12 months |
These bands come from industry guidance, not from legislation, and we have not verified them against the current published edition of TR19 Grease. Confirm the frequency that applies to your kitchen with your contractor, against the current guidance, and against your insurance policy wording before you rely on it. Where those three disagree, the policy wording is usually the one with teeth.
What should push the frequency up
- Cooking style. Heavy frying, char-grilling, wok cooking and solid fuel produce far more grease and particulate than steaming or baking.
- Filtration. Poor or badly maintained canopy filters push grease straight into the duct. Cleaning filters weekly is the cheapest thing you can do for the whole system.
- Duct geometry. Long horizontal runs, multiple bends and low-velocity sections accumulate deposits faster than a short vertical riser.
- Findings from the last clean. If the verification report showed heavy deposits despite being on schedule, the schedule is wrong.
- Any change of use. A menu change or an increase in covers can move you a band without anyone noticing.
Cleaning intervals are not the same as inspection intervals
Between cleans, the sensible regime is to check. Filters weekly, canopy and accessible duct sections monthly, and a proper look at the fan and discharge whenever anyone is up there. This is what tells you the interval you chose is still the right one, and it costs almost nothing compared with discovering a problem when the insurer's surveyor visits.
What the responsible person actually has to do
Under the Regulatory Reform (Fire Safety) Order 2005, article 9 requires the responsible person to make a suitable and sufficient assessment of fire risks. Grease in extract ductwork is one of those risks, so what the law wants is a considered, documented decision about how it is managed, along with evidence that the decision is being carried out. A fixed interval taken from a table without thought is weaker evidence than a slightly different interval that you can explain.