Commercial kitchen extraction regulations in the UK

The short answer

A commercial kitchen in the UK needs mechanical extraction that removes cooking fumes at source, brings in enough fresh make-up air to replace what it extracts, and is built from non-combustible materials that can be cleaned. If you cook with gas, the gas supply has to be interlocked with the ventilation so the gas cannot run unless the fans are running. Outside the building, the flue usually needs planning permission, and the council will judge it on odour and noise.

No single regulation covers all of this. The duties come from health and safety law, gas safety law, food hygiene law, the Building Regulations and the planning system, with industry standards filling in the design detail.

The laws that apply

What HSE expects from the system

HSE's Catering Information Sheet 10, Ventilation in catering kitchens, is the guidance environmental health officers and HSE inspectors work from. It sets out the objectives of an effective kitchen ventilation system:

• Remove cooking fumes at source, at the appliance.
• Remove excess hot air and bring in cool, clean air, so staff are not working in heat stress.
• Avoid draughts strong enough to cause discomfort.
• Provide enough air for complete combustion, and prevent carbon monoxide building up.
• Be easy to clean, so fat does not build up and air inlets do not block.
• Run quietly and without vibration.

The sheet asks for a canopy over every appliance that produces fumes and heat, as close to the source as the work allows, with uniform airflow sized to the appliances underneath. The extraction rate should be worked out from the appliance manufacturers' data and the air change rates the kitchen needs. Where there is no canopy, for example in a ventilated ceiling, a competent ventilation engineer should calculate the rates.

Make-up air is not optional

Every cubic metre of air the canopy extracts has to be replaced. In a small kitchen that can come naturally through grilles in walls, doors or windows. Larger kitchens need a mechanical supply with a fan and filter. HSE is specific about where it comes from: fresh air from outside, not from waste stores or smoking areas, and never in a way that upsets the flues of gas appliances. A kitchen that is short of make-up air pulls combustion products back into the room, which is how carbon monoxide builds up.

Ductwork and filters

Ductwork has to be non-combustible and designed so dirt, grease and condensation do not collect. It needs access panels for regular cleaning, and grease filters must be easy to take out for cleaning or replacement. Local freestanding fans do not count as make-up air. HSE notes they disturb the airflow into the canopy and add tripping and electrical hazards.

Gas interlocks

A gas interlock stops the gas supply to the cooking line unless the extraction is proven to be running. If the fans fail or are switched off, the gas shuts off before combustion products can build up. HSE's guidance links this to the Gas Safety (Installation and Use) Regulations 1998: where extraction acts as the flue for flued appliances, an interlock connecting the airflow to the gas supply is required. For other installations, HSE asks for a competent person to assess the need based on the risks of the appliances in use.

The industry standard for the installation of gas catering appliances, BS 6173, sets out the interlock arrangement in detail, and IGEM/UP/19 gives the supporting guidance. In practice that means a Gas Safe registered engineer with the right commercial catering categories installs the gas side and commissions the interlock. Any overrides that bypass the interlock defeat its whole purpose.

Design standards: DW/172 and TR19

Two documents from the Building Engineering Services Association (BESA) shape most UK kitchen extract systems:

• DW/172, the specification for kitchen ventilation systems, covers canopy design, extract rates, grease filtration, ductwork construction and fire safety. Council planning conditions for restaurants often reference it directly.
• TR19 Grease sets out how often kitchen extract ductwork should be cleaned and how cleanliness is measured. The interval depends on how many hours a day the kitchen cooks: a busy kitchen needs cleaning far more often than one that cooks for a few hours. Many insurers will not pay out after a duct fire without TR19 cleaning records.

Planning permission, odour and noise

A flue running up the outside of a building, a louvre in an external wall or a fan on the roof changes how the building looks. That usually makes it development that needs planning permission. The council's environmental health team will also look at two things:

• Odour. Many councils assess this with the 2018 EMAQ+ guidance on controlling odour and noise from commercial kitchen exhaust systems, which replaced the withdrawn 2005 Defra guidance in practice. It scores the risk from how well the discharge disperses, how close the neighbours are, how big the kitchen is and the type of cooking. A higher score means more odour control: higher-grade filtration, carbon filters, electrostatic precipitators or ozone systems.
• Discharge height. High-level discharge is often required so fumes clear neighbouring buildings. HSE's guidance warns against rain caps and anything that pushes the discharge downwards, because they cause down-draughts and fumes re-entering the building.
• Noise. Fans and motors running late at night next to homes are a common source of complaints, so councils usually ask for a noise assessment and set limits by condition.

Changing a unit's use can also need permission in its own right. A restaurant falls within Use Class E, but a hot food takeaway is sui generis, so turning a shop into a takeaway needs planning permission even before the flue is considered.

Getting it right on a fit-out

Extraction is the item that most often delays a restaurant opening, because it touches planning, gas, fire, structure and every trade that needs ceiling space. What makes the difference:

1. Fix the menu and the cooking line first. HSE expects the caterer to tell the designer the maximum demand, the equipment, the menu, the number of meals and the number of staff. Charcoal grills and tandoors are a different design problem from a pizza oven.
2. Check the duct route before signing the lease. If there is no realistic way to run a flue to roof level, or the landlord will not allow one, the unit may not work as a kitchen at all.
3. Put in the planning application early. Odour and noise reports take time, and permission often comes with conditions that change the specification.
4. Coordinate the ceiling void. Ductwork, canopy supports, fire dampers, lighting and the sprinkler or suppression system all compete for the same space.
5. Commission and record. Keep the design criteria, commissioning results, interlock test and cleaning schedule. HSE recommends keeping those records, and insurers and environmental health will ask for them.

Common questions

Do I need a gas interlock in a commercial kitchen?

Where mechanical extraction serves as the flue for flued gas appliances, yes: HSE guidance ties the requirement to the Gas Safety (Installation and Use) Regulations 1998. In other gas kitchens a competent person should assess the need, and the installation standard BS 6173 sets out when interlocking is required. Treat it as standard on any new gas cooking line.

How often does kitchen extract ductwork need cleaning?

BESA's TR19 Grease sets the interval by how many hours a day the kitchen cooks, so a heavily used kitchen needs cleaning far more often. Your insurer may set its own requirement. Check the policy wording.

Can I use a recirculating hood instead of ducting outside?

For light cooking, some kitchens use recirculation units that filter grease and odour and return the air to the room. They do not remove heat or moisture the way an external extract does, and they are not a substitute where gas appliances need flueing. Whether one is acceptable depends on the cooking, so confirm it with environmental health before you buy.

Who signs off a commercial kitchen extraction system?

There is no single sign-off. Building control covers any building work, the planning authority covers the external parts and any odour and noise conditions, a Gas Safe engineer commissions the gas installation and interlock, and environmental health inspects the kitchen under food hygiene and health and safety law.

Sources

• Ventilation in catering kitchens, Catering Information Sheet 10 (HSE)
• Gas safety in catering and hospitality, Catering Information Sheet 23 (HSE)
• Building Engineering Services Association: DW/172 and TR19 Grease
• Gas Safety (Installation and Use) Regulations 1998 (legislation.gov.uk)