Commercial Kitchen Extraction Regulations Explained: The Complete UK Guide (2026)
Commercial kitchen extraction sits under four overlapping frameworks that most operators only half know: DW/172, the industry design specification for kitchen ventilation systems; TR19 Grease, the industry specification for cleaning grease from extract ductwork on defined intervals; the Regulatory Reform (Fire Safety) Order 2005, which makes the “responsible person” legally accountable for fire risk in the ductwork; and the Gas Safety (Installation and Use) Regulations 1998, which drive the interlock between your gas supply and your extraction fan. Get any one of them wrong and the consequences stack: a grease-loaded duct is the classic hidden fire path, an unserviced interlock can shut down your whole cooking line, and an insurer presented with a duct fire and no cleaning certificates can walk away from the claim. This guide explains each framework in plain trade English — what it covers, what it demands, what it costs, and what to keep on file.
- DW/172 is the industry specification for the design and installation of kitchen ventilation — canopy sizing and overhang, extract rates, duct materials, access panels for cleaning, and make-up air. It is not a statute, but it is the benchmark that building control, fire risk assessors and insurers measure your system against.
- TR19 Grease is the industry specification for cleaning grease extract systems. Indicative intervals: heavy use (12–16 hours cooking per day) — every 3 months; moderate use (6–12 hours/day) — every 6 months; light use (2–6 hours/day) — every 12 months.
- The 200-micron trigger: TR19 Grease works to measured grease deposit thickness — when the mean deposit across the system reaches 200 microns, the system needs cleaning, whatever the calendar says.
- The Regulatory Reform (Fire Safety) Order 2005 makes a named “responsible person” legally accountable for fire safety in the premises — and your fire risk assessment must cover the extract ductwork, the single most common hidden fire spread route in hospitality buildings.
- The Gas Safety (Installation and Use) Regulations 1998 require gas catering equipment to be installed and maintained safely by Gas Safe registered engineers — and in a commercial kitchen with mechanical extraction, the accepted way of demonstrating safe operation is a gas interlock that cuts the gas if the extract fan is not running.
- Canopy sizing basics: the canopy should overhang the cooking equipment by roughly 250–300mm on all open sides, with extract rates calculated from the equipment beneath it — heavier duty cooking (chargrills, fryers, woks) demands substantially higher airflow than boiling pans and ovens.
- Insurance: most commercial kitchen policies now require TR19 Grease-compliant cleaning by a verifiable contractor, with certificates and photographic reports. After a duct fire, missing certificates are one of the most common grounds for a disputed or reduced claim.
- Budget figures: professional duct cleaning typically runs £500–£1,500+ per visit depending on system size and access; a gas interlock installation £600–£1,200; annual extraction servicing (fans, filters, belts, controls) £300–£600. All + VAT.
Extraction is the part of the kitchen nobody sees and everybody depends on. The canopy and ductwork remove heat, steam, combustion products and — critically — airborne grease, which condenses on every internal surface of the duct from the filters to the roof fan. That grease layer is fuel. A flare-up on the chargrill pulled into a loaded duct becomes a fire travelling inside a steel tube, above your ceiling, past your fire compartmentation, with nothing between it and the rest of the building. This is why extraction has its own body of rules, and why those rules concentrate on two things: designing systems that can be cleaned, and proving they actually are cleaned.
This guide is for operators, kitchen managers, landlords and facilities teams who need to understand what applies to them — whether you’re fitting out a new site, inheriting an old system, or being asked awkward questions by an insurer. It is an educational compliance guide: Craven Cooling supplies the cooking equipment that sits under the canopy, and our servicing team keeps that equipment maintained; for ductwork design and specialist duct cleaning you’ll engage ventilation contractors, and this guide tells you exactly what to ask them for.
Table of Contents
- 1. Why Extraction Has Its Own Rulebook
- 2. DW/172 — The Design Specification
- 3. TR19 Grease — Cleaning Intervals and Certification
- 4. The Fire Safety Order 2005 — Who Is Responsible
- 5. Gas Safety Regulations 1998 and Interlocks
- 6. Canopy Sizing Basics
- 7. Insurance Implications
- 8. Your Compliance File — What to Keep
- Frequently Asked Questions
- Related Buying Guides
1. Why Extraction Has Its Own Rulebook
A commercial extraction system does four jobs at once: it removes heat and steam so the kitchen stays workable; it removes combustion products from gas appliances so the air stays breathable; it captures airborne grease at the canopy filters so the duct loads slowly rather than quickly; and it maintains airflow so gas appliances burn cleanly and safely. Each of those jobs has a failure mode serious enough to attract regulation — fire in the duct, carbon monoxide in the kitchen, and appliances starved of the ventilation they were designed for.
The framework splits cleanly into two industry specifications and two statutory instruments. DW/172 and TR19 Grease are specifications published by the building engineering services industry — not law in themselves, but they define what “competent design” and “adequate cleaning” mean in practice, and fire authorities, environmental health and insurers all use them as the yardstick. The Regulatory Reform (Fire Safety) Order 2005 and the Gas Safety (Installation and Use) Regulations 1998 are law, and they are the instruments through which extraction failures actually get enforced.
2. DW/172 — The Design Specification for Kitchen Ventilation
DW/172 is the UK building engineering services industry’s specification for kitchen ventilation systems. If you are fitting out a new kitchen, refurbishing an old one, or changing the cooking line under an existing canopy, DW/172 is the document your ventilation designer should be working to — and the document building control and your fire risk assessor will expect the installation to reflect. Its core requirements, in operator terms:
Canopy Design
Capture the plume- Overhang of ~250–300mm beyond equipment on open sides
- Sized to the cooking line beneath, not the room
- Grease filters angled and drained, removable for washing
- Mounting height set so the plume is captured, not dodged
Extract Rates
Match airflow to duty- Airflow calculated from the equipment schedule
- Chargrills, fryers and woks demand the highest rates
- Ovens and boiling pans sit lower on the scale
- Change the cooking line = recheck the airflow
Ductwork & Access
Build it cleanable- Rigid metal duct, sealed joints, adequate velocity
- Access panels at regular intervals along the run
- Every bend and riser reachable for cleaning
- No access = no TR19 clean = permanent non-compliance
Make-Up Air
Replace what you extract- Extracted air must be replaced, ideally ~85% supplied mechanically
- Prevents doors slamming, draughts and starved combustion
- Undersupplied kitchens pull air through every gap in the building
- A common failing in converted and older premises
The clause that matters most to an existing operator is access. A duct without access panels cannot be cleaned to TR19 Grease — contractors reach a few metres from each end and exclude the rest from the certificate, and that exclusion zone stays dirty forever. Before taking on any site, ask one question: “can every metre of this extract run be physically reached for cleaning?” Retrofitting access panels costs hundreds; discovering mid-claim that 60% of your duct was never cleanable costs everything.
3. TR19 Grease — Cleaning Intervals, the 200-Micron Test and Certification
TR19 Grease is the industry specification dedicated to the cleaning of grease-laden extract systems — the standard your duct cleaning contractor should certify against, and the certificate your insurer means when they ask for “TR19”. It answers three questions: how often, how verified, and how documented.
| Usage level | Cooking hours per day | Indicative cleaning interval | Typical operations |
|---|---|---|---|
| Heavy | 12–16 hours | Every 3 months | Hotels, hospitals, all-day dining, fast food, dark kitchens running long shifts |
| Moderate | 6–12 hours | Every 6 months | Most restaurants, gastropubs, school and workplace kitchens |
| Light | 2–6 hours | Every 12 months | Cafés, small pubs with limited menus, function-only kitchens |
The intervals are indicative because the real test is measured deposit. TR19 Grease works to grease layer thickness, measured with a wet film thickness gauge at defined points through the system: when the mean deposit reaches 200 microns — a fifth of a millimetre — the system requires cleaning, whether that takes three months of chargrilling or eighteen months of light café use. A competent contractor measures before and after, and the post-clean report shows the readings. High-grease menus (fried chicken, chargrilled meats, wok cooking) routinely need cleaning faster than the calendar suggests; the measurements, not the diary, are the compliance position.
What a proper TR19 Grease clean includes: the full system — canopy plenum, filters and filter housings, every accessible metre of ductwork, the fan and impeller, and the discharge — not just “canopy and a metre each way”. What proper documentation includes: a certificate naming the specification, pre- and post-clean photographs at defined locations, deposit measurements, a schematic showing any areas that could not be accessed, and recommendations (usually new access panels) for closing those gaps. Keep every report. A run of consistent certificates is the single most persuasive document in your file after a fire, and the schematic of inaccessible sections is your evidenced action plan.
4. The Regulatory Reform (Fire Safety) Order 2005 — Who Carries the Duty
The Regulatory Reform (Fire Safety) Order 2005 is the fire safety law for virtually all non-domestic premises in England and Wales. It abolished fire certificates and replaced them with a self-assessment regime built around one concept: the responsible person — usually the employer, or whoever has control of the premises — who must carry out and maintain a suitable and sufficient fire risk assessment, put general fire precautions in place, and keep them maintained.
The word “extraction” doesn’t appear in the Order. It doesn’t need to. The fire risk assessment must identify fire hazards and the people at risk from them, and a grease extract system is simultaneously an ignition point (flare-ups at the canopy), a fuel load (the deposit layer), and a spread route (a steel tube passing through ceilings, voids and compartment walls). A fire risk assessment for a catering premises that doesn’t address the extract system — its condition, its cleaning regime, its route through the building — is not suitable and sufficient, and fire risk assessors treat it exactly that way. Enforcement sits with the local fire and rescue authority, which can inspect, issue enforcement and prohibition notices — including shutting your kitchen — and prosecute; serious breaches carry unlimited fines and, at the top end, imprisonment.
Practical consequences: 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 TR19 Grease cleaning schedule as one of the general fire precautions the Order requires you to maintain. In leased premises, resolve in writing who controls which parts — landlord-owned ductwork carrying operator-generated grease is the classic split-responsibility trap.
5. Gas Safety Regulations 1998 — Interlocks and the Extraction Connection
The Gas Safety (Installation and Use) Regulations 1998 require gas appliances and installations to be installed, maintained and used safely, with work carried out only by competent (Gas Safe registered) engineers. In a commercial kitchen, gas safety and extraction are inseparable: gas appliances need adequate ventilation to burn cleanly, and a kitchen where the extract fan has failed but the burners are still roaring is accumulating combustion products — including carbon monoxide — in the room where your staff work. The Health and Safety Executive’s guidance on catering gas safety (see hse.gov.uk) treats ventilation as a core element of a safe gas installation.
This is where the gas interlock comes in. An interlock links the gas supply to proof that the extraction system is actually running — typically via airflow or fan-current monitoring — so that if the extract fan stops or airflow falls below design, a solenoid valve closes the gas line to the cooking equipment. Interlocks have been standard practice for new and refurbished commercial kitchen installations for many years, and a Gas Safe engineer inspecting an uninterlocked commercial kitchen with mechanical extraction will typically classify it against current standards and recommend upgrading. Expect £600–£1,200 + VAT installed, depending on the panel and the number of monitored fans.
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Annual gas safety maintenance by a Gas Safe registered engineer Commercial catering appliances, pipework and the interlock itself, serviced and certificated yearly. Keep the reports with your compliance file.
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Interlock tested as part of the routine Kill the fan, confirm the gas drops out. A bypassed or bridged interlock is a serious finding — if an engineer or EHO discovers one, expect the installation to be classified as at risk or dangerous.
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Staff briefed on what the interlock does When the gas “fails” mid-service, the first check is the extract fan. Train the team so nobody’s response to a tripped interlock is to look for a way around it.
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CO alarm as a backstop, not a substitute A carbon monoxide detector in the kitchen is cheap insurance, but it is the last line — the interlock and the maintenance regime are the controls.
6. Canopy Sizing Basics — Enough Hood Over Enough Equipment
You don’t need to be a ventilation engineer to sanity-check a canopy. Three numbers do most of the work:
| Check | Rule of thumb | What failure looks like |
|---|---|---|
| Overhang | Canopy extends ~250–300mm beyond the cooking equipment on all open sides | Steam and smoke curling out past the canopy edge; grease film on the ceiling in front of the hood |
| Duty match | Extract rate calculated from the actual equipment schedule — chargrills, fryers and woks at the top of the scale | A kitchen that was fine with two ovens now hazy since the chargrill arrived; eyes stinging on the line |
| Make-up air | Replacement air supplied to balance extraction — ideally around 85% of extract volume mechanically | Doors that slam or won’t open, whistling gaps, pilot lights blowing out, extraction that underperforms its spec |
The pattern behind most underperforming extraction isn’t a bad fan — it’s mismatch that crept in over the years: a canopy sized for the 2015 menu grilling the 2026 one, make-up air balanced before the refurb sealed the windows, filters washed monthly instead of weekly. Before spending on new plant, have the system surveyed against what’s actually cooking below it — often the fix is filters, balancing and a proper clean rather than capital kit.
7. Insurance Implications — Where the Paperwork Becomes Money
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 in terms — as a policy condition or warranty requiring cleaning at intervals appropriate to usage, with documentation. After a fire, the loss adjuster’s first requests are predictable: the fire risk assessment, the gas safety records, and the duct cleaning certificates with their photographic reports. Operators who can produce a consistent run of TR19 Grease certificates matching their usage level are in a strong position. Operators who can’t are negotiating from underneath.
Two further points. Tell your insurer what you actually cook — a policy priced for a “restaurant” that turns out to be a high-volume fried chicken operation on annual cleaning is a misrepresentation problem as well as a fire problem. And when the cooking line changes, the change flows through extract rates, cleaning frequency, the fire risk assessment and the premium at once: make the phone calls before the equipment lands.
8. Your Compliance File — What to Keep, Forever
Extraction compliance is ultimately a documentation discipline. One folder — physical or digital — with these contents, kept current, answers the fire officer, the EHO, the landlord and the loss adjuster:
Design/installation records for the ventilation system (ideally referencing DW/172), a schematic of the duct route through the building, and the locations of all access panels. If you inherited the site with nothing, have a survey produce this — it’s the foundation of everything else.
Every clean: certificate, pre/post photographs, deposit measurements, inaccessible-area schematic, and the remedial recommendations with your evidence of acting on them. Never discard old ones — the run of history is the proof of regime.
Current version, explicitly addressing the extract system, with the named responsible person and the review log. Reviewed after any change to equipment, menu intensity or building layout.
Annual maintenance records from the Gas Safe registered engineer, interlock test results, and any remedial work. The engineer’s registration number should appear on every document.
Filter washing frequency, canopy wipe-downs, visual duct checks — dated and initialled. The professional cleans handle the duct; the daily discipline at the canopy is what stretches the interval and shows a working culture.
The cooking line under the canopy needs maintaining too — burners burning clean, thermostats accurate, seals sound. Craven Cooling’s servicing team covers the catering equipment side, with records that slot straight into this file.
UK commercial kitchen extraction compliance stacks four frameworks. DW/172 is the industry design specification — canopy overhang of roughly 250–300mm beyond the cooking line, extract rates matched to the equipment schedule, cleanable ductwork with access panels, and balanced make-up air. TR19 Grease is the industry cleaning specification — indicative intervals of 3 months for heavy use (12–16 cooking hours/day), 6 months for moderate (6–12 hours) and 12 months for light (2–6 hours), with a 200-micron mean grease deposit as the measured trigger, and certification that includes photographs, readings and an inaccessible-areas schematic. The Regulatory Reform (Fire Safety) Order 2005 makes a named responsible person legally accountable, and a fire risk assessment that ignores the extract duct is not suitable and sufficient. The Gas Safety (Installation and Use) Regulations 1998 require Gas Safe engineers and drive the gas interlock that cuts supply when extraction fails. Insurers expect the whole stack documented — after a duct fire, missing TR19 certificates are a common route to a disputed claim. Budget roughly £2,780 + VAT a year for a moderate-use site. Craven Cooling supplies and services the cooking equipment under the canopy — Swansea showroom, 2-year parts warranty: 01792 732702, sales@cravencooling.co.uk.
