Ventilation and extraction statement for a hot food unit
A ventilation and extraction statement specifies the kit rather than predicting the effect. Here is what environmental health officers expect to see in it.
A ventilation and extraction statement for planning is a design document. It tells the council what equipment is being installed, where the duct runs, where it discharges and how it will be kept working, and it is judged on whether an environmental health officer could write a condition from it without asking you a single question.
That is the difference between this and an odour assessment. One predicts the effect. The other specifies the kit. Applications for hot food uses usually need both, and they have to describe the same system.
What the statement has to contain
Six things, and officers look for them in roughly this order: the proposed use and cooking methods, the extraction system schematic, the duct route and termination, the filtration train, the fan specification with acoustic data, and the maintenance regime.
Cooking method drives everything downstream. Charcoal grilling, deep frying and tandoor ovens produce far more grease and odour than a unit reheating pre-prepared food, so state the menu type and the appliance schedule rather than describing the use as "restaurant". An officer who cannot tell what is being cooked will assume the worst case.
Duct route and termination height
The duct should be taken vertically to discharge above the roof, and the working rule most councils in England apply, following Defra's guidance on commercial kitchen exhaust systems, is a termination at least 1 m above the ridge of the building. Discharge should be vertical and at high velocity, commonly around 15 m/s, with no cowl or cap that pushes the plume back down towards windows.
Three details cause most of the refusals.
- A termination at eaves or first-floor level because the applicant could not obtain access through the upper floors.
- A discharge point within a few metres of an opening window, a balcony or an air intake serving another occupier.
- A horizontal outlet through the rear wall, which councils treat as unacceptable next to residential accommodation almost without exception.
Show the route on an elevation drawing and a section, with dimensions to the ridge and to the nearest neighbouring openings. If the duct crosses a demise you do not control, say how you have secured the right to install it, because a permission you cannot implement is worth nothing.
The filtration train
Filtration works in stages and each stage does a different job.
| Stage | Purpose |
|---|---|
| Coarse grease filters at the canopy | Remove bulk grease, protect everything downstream |
| Fine filtration or electrostatic precipitation | Capture fine particulate and grease aerosol |
| Ultraviolet or ozone treatment | Break down odorous compounds in the air stream |
| Activated carbon | Adsorb residual odour before discharge |
Not every unit needs every stage. A small café serving toasted sandwiches does not need carbon. A fried chicken unit under flats will almost always need it, and the officer will expect the carbon to be sized against the airflow rather than specified as a single line in a quotation.
Give the make, model and rating for each stage, and give the design airflow in litres per second or cubic metres per second. Vague specifications get conditioned in terms you will not like.
Fan noise and the acoustic information
Kitchen extract fans run during evening and night hours, which is when background sound levels are lowest. Environmental health will want the sound power level of the fan from manufacturer data, the predicted level at the nearest noise-sensitive window, and the attenuation being provided.
Anti-vibration mounts and a flexible connection at the fan are standard where the unit is fixed to a structure shared with residential accommodation. Where the fan sits on a flat roof close to bedroom windows, expect a request for an acoustic enclosure and a full Noise Impact Assessment rather than a manufacturer's data sheet. In a building that also contains flats, check separately whether the scheme raises fire safety questions that need a Fire Statement or a Fire Safety Strategy, since ductwork passing through compartment walls is a building safety matter as well as a planning one.
Drawings and schedules the officer expects
A statement without drawings gets returned. The bundle that gets through validation normally has a kitchen layout plan showing canopy positions and the fan location, a rear or side elevation showing the full duct route with the termination dimensioned, a section through the building, and a system schematic listing the stages in order.
Add a short appliance schedule and a filter schedule with replacement intervals. The schedules are what turn into the maintenance condition, so writing them yourself is the easiest way to keep the condition proportionate.
Maintenance, conditions and records
Filtration only works while it is maintained. Grease-laden ductwork is a fire risk as well as an odour source, and cleaning to a recognised ductwork hygiene standard is what insurers and environmental health both look for.
Set out cleaning and filter replacement frequencies by stage, say who is responsible, and commit to keeping records on the premises for inspection. Typical conditions require the system to be installed before the use starts, maintained in accordance with the approved details, and operated with records available on request. Some councils add a restriction on the hours the extract may run.
If you offer a written maintenance regime up front, the condition is usually drafted around it. If you do not, the council writes its own.
Retrofit in a listed or terraced building
This is where schemes fail on heritage grounds rather than technical ones.
Fixing a duct to the external elevation of a listed building needs listed building consent as well as planning permission, and consent for a duct on a principal elevation is rarely given. Internal routes through a chimney flue or a service riser are sometimes acceptable, though they raise questions about the loss of historic fabric and about fire compartmentation. Get a conservation officer's view before you spend money on a design.
In a conservation area, a duct on a rear elevation that is not publicly visible is a far easier proposition than one on a side elevation facing a street. In a terrace, the practical obstacle is usually ownership: the riser has to pass through flats or a neighbouring demise, and the freeholder's consent is a private law matter the council will not resolve for you.
An illustrative example. A former shop converted to a hot food takeaway in a Victorian terrace, with two flats above in separate ownership, proposes a rear duct terminating 1 m above the ridge with grease filters, an electrostatic stage and carbon, discharging vertically at 15 m/s. The planning issue is the duct's appearance on the rear elevation. The deliverability issue is the flat owners' consent for the fixings. The example is illustrative only.
A Ventilation and Extraction Statement and an Odour Assessment usually travel together on a hot food application, and you can see what else a change of use is likely to need before you commission drawings. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval, and for specialist technical reports qualified professional input may be required.
This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.
Frequently asked questions
How high should a kitchen extract duct terminate?
The working rule most English councils apply, following Defra guidance on commercial kitchen exhaust systems, is a vertical discharge at least one metre above the ridge of the building. Discharge velocity is normally around 15 metres per second with no cowl. Lower terminations are sometimes accepted where separation distances are generous and abatement is strong.
Do I need both an odour assessment and an extraction statement?
Hot food applications close to housing usually need both. The odour assessment predicts the effect at receptors using the FIDOL factors, while the extraction statement specifies the equipment, the duct route and the maintenance regime. They must describe the same system, so prepare them together rather than commissioning them from different suppliers months apart.
Is activated carbon always required?
No. A café producing little grease or odour will not need it. A unit deep frying or char grilling below residential accommodation will, and the carbon should be sized against the design airflow rather than quoted as a single line item. Carbon also needs replacing on a stated interval, which councils usually condition.
Does a duct on a listed building need separate consent?
Yes. Fixing an extract duct to a listed building needs listed building consent alongside planning permission, and consent on a principal elevation is rarely granted. Internal routes through existing flues or risers are sometimes acceptable but raise questions about loss of historic fabric. Take a conservation officer's view before paying for a design.
What conditions are usually attached to an extraction system?
Typical conditions require the system to be installed and operating before the use begins, maintained in accordance with the approved details, and supported by maintenance records available for inspection. Some councils restrict the hours the extract may run or require a specified filter replacement interval. Offering your own maintenance schedule usually keeps the condition proportionate.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.