A kitchen extraction system can look complete on installation day yet still create problems at handover. A canopy that is too small, a poorly positioned discharge point, inaccessible ductwork or a fan selected without allowing for resistance can all lead to rework. This commercial kitchen ventilation compliance guide sets out the areas that need to be considered before fabrication, installation and commissioning.
The aim is not simply to fit a canopy above the cooking line. A compliant system needs to capture heat, grease-laden air, steam and combustion by-products at source, move them through suitable ductwork and discharge them safely. Each part affects the next, so the specification should be treated as one system rather than a collection of separate products.
Start with the cooking equipment and layout
The extraction requirement is driven by what sits beneath the canopy. A light-duty electric cooking line does not place the same demand on a system as a bank of gas appliances, chargrills, fryers or solid-fuel equipment. Heat load, grease production, appliance position and the way staff work around the equipment all influence canopy size and extraction design.
The canopy must provide enough overhang to capture the rising thermal plume rather than allowing it to spill into the kitchen. This is particularly relevant at the front and ends of a cooking line. An island arrangement normally needs more careful consideration than a wall-mounted line because air can enter from all sides and interfere with capture.
Do not specify canopy length from the appliance width alone. Consider splashbacks, end panels, gaps between appliances and whether the cooking line may change later. A canopy that just matches the current equipment can become restrictive as soon as an extra fryer or griddle is added.
Use DW172 as the kitchen ventilation benchmark
For commercial kitchen ventilation projects, DW172 is the principal industry guidance covering ventilation systems for kitchens. It addresses canopy design, air movement, grease filtration, ductwork, access, discharge and cleaning. It is not a shortcut to a one-size-fits-all specification, but it gives designers, installers and operators a recognised framework for making sound decisions.
A practical DW172-led approach starts with effective capture. The canopy, filters, fan and duct route must work together. Increasing fan capacity alone does not solve poor capture caused by an undersized canopy, excessive cross-draughts or an unsuitable appliance layout.
Make-up air also needs consideration. Extraction removes air from the kitchen, and replacement air must be allowed back in without creating uncomfortable draughts or pushing contaminated air away from the canopy. Where a kitchen feels excessively negative, doors become difficult to open or smoke escapes at the front of the cooking line, the issue may be air balance rather than extraction rate alone.
Choose the right canopy construction
Stainless steel is the normal material for commercial kitchen canopies because it is hygienic, durable and straightforward to clean. Material grade and thickness should suit the environment, installation and budget.
For many standard commercial applications, 430-grade stainless steel at 0.7 mm thickness is a sensible, cost-conscious option. Where corrosion resistance is a greater concern, or where the specification calls for it, 304-grade stainless steel can be supplied as a made-to-order alternative. The right choice depends on the site conditions, cleaning regime and the client’s required finish, not simply the headline material price.
Fabrication quality matters as much as sheet grade. Smooth welds, properly formed edges and rigid folded construction make a canopy easier to maintain and better suited to daily commercial use. Bespoke fabrication is often worthwhile where there are restricted ceiling heights, non-standard wall returns, existing services or an awkward cooking layout.
Ductwork needs to be designed for cleaning
Grease is not only a filter issue. Once grease-laden air enters the ductwork, the duct system must be capable of being cleaned properly throughout its working life. This means considering access doors, direction changes, branch arrangements and the position of fans from the start.
DW144 is the relevant standard for ductwork manufacture and installation. For kitchen extract, well-made ducting with suitably formed joints, appropriate supports and accessible cleaning points is preferable to an improvised route that cannot be inspected or maintained. Spiral duct and fittings can be appropriate for certain sections, while fabricated ductwork may be better suited to larger dimensions or more complex arrangements.
Keep the route as direct as the building allows. Every elbow, transition, branch and length of duct adds resistance. A complicated route can require a different fan selection and will usually increase the importance of access provision. It may also create surfaces where grease can collect if the system is not properly designed and maintained.
Access panels should not be treated as an afterthought. They need to be positioned where a competent cleaning contractor can actually reach them. An access door behind a fixed ceiling, above permanent joinery or in an area with no safe working access offers little practical value.
Pay attention to the discharge point
The final discharge location is one of the most common sources of planning, environmental health and neighbour complaints. Extract air must not be directed towards opening windows, air intake points, pedestrian areas or neighbouring properties where odour, grease or noise could cause a nuisance.
The correct discharge arrangement depends on the building, surrounding occupiers, local authority expectations and the type of cooking. In some cases, discharge at high level may be needed. In others, additional odour control may be considered as part of the overall design. The key point is to resolve the route and termination early, before ductwork and external fittings are ordered.
A vent cap or external termination is not just a finishing item. It must suit the duct size, protect the system from weather ingress and allow air to leave without creating unnecessary resistance. Poorly selected external fittings can undermine an otherwise well-specified extraction system.
Select filters, fans and controls as one package
Baffle filters are commonly used within commercial kitchen canopies to remove grease particles before air enters the duct system. They need to fit correctly, be removable for regular cleaning and be appropriate for the expected cooking load. Filters reduce grease carry-over, but they do not remove the need for duct cleaning.
The extraction fan must be selected against the real system resistance, not just the desired airflow figure. Duct length, bends, filters, silencers, external grilles and any treatment equipment all affect the duty the fan must overcome. An underspecified fan may run but fail to achieve suitable capture. An oversized fan can introduce unnecessary noise, energy use and make-up air problems.
Speed control can be useful where the cooking load changes through the day. However, reducing fan speed must not compromise capture during busy service. Controls should support practical operation, not encourage staff to turn extraction down below an effective level because of noise or draughts.
For projects requiring S&P fans and compatible speed controllers, using correctly matched equipment helps simplify selection and installation. The final choice should still be based on the complete system duty and the site layout.
Plan for fire safety and maintenance from day one
Kitchen extract systems handle grease, heat and contaminants, so maintenance is a compliance issue rather than a cosmetic task. Filters need a documented cleaning routine, canopy surfaces require regular degreasing, and ductwork must be cleaned at intervals appropriate to the cooking activity.
The interval depends on use. A kitchen operating long hours with heavy grease production will need more frequent attention than a lightly used daytime operation. Keeping records of filter cleaning, duct cleaning, inspections and remedial works provides evidence that the system is being managed responsibly.
Fire safety also relies on keeping the system free from excessive grease accumulation and ensuring that any associated fire suppression or fire-rated requirements are coordinated with the kitchen design. The extraction contractor, kitchen supplier, mechanical designer and fire specialist should not work in isolation where the project is complex.
Avoid common specification shortcuts
The quickest way to create a difficult installation is to buy components separately without confirming that they work together. A canopy may be correctly sized, but the wrong duct diameter, restrictive fitting or unsuitable fan can still leave the kitchen with poor extraction.
Another frequent mistake is assuming a standard product will suit every site. Standard sizes are useful where the layout is straightforward and lead time matters. A made-to-measure canopy, bespoke duct transition or custom stainless steel detail is often the more economical choice once site alterations and installer time are considered.
Before placing an order, confirm the cooking equipment schedule, canopy dimensions, ceiling height, duct route, access requirements, fan location, electrical arrangement and discharge point. This reduces changes on site and gives every contractor a clearer scope of work.
A well-planned extraction system is easier to install, easier to clean and less likely to become a source of complaints. For kitchens across England and Wales, working with a manufacturer that can supply standard equipment or fabricate to the actual site dimensions gives the project team more control before problems are built in.