Odour risk assessment for a flat above a takeaway
Where a flat sits directly over a hot food unit, the duct route decides the application. This outline follows the order an environmental health officer reads it in.
An odour risk assessment for a takeaway with residential accommodation directly above it turns on one thing: whether the extract duct can get from the kitchen to a discharge point above the roof without passing through a separate dwelling. Answer that before anything else, because every other part of the assessment depends on it. If the duct has to go up the rear elevation externally, say so on the first drawing. If it has to pass through the flat, expect the application to be refused unless you have the freeholder's agreement and a fire engineered enclosure detail.
A hot food takeaway is a sui generis use in England, taken out of the former A5 class when the Use Classes Order was amended in 2020. That means a change of use to a takeaway needs planning permission whatever the previous use was, and the odour case is usually the part that decides it.
Describing the cooking process and its odour potential
Start with the menu. The assessment cannot be written from a floor plan alone, and an officer reading a generic document will ask for this section again.
State the cooking methods, the appliances, their input rating and the daily hours of use. Chargrilling, deep frying and tandoor cooking sit at the high odour end. Boiling, steaming, baking and reheating of pre-prepared food sit lower. Fish frying, curry spices and grilled meat are the three that generate most of the complaints, and describing them honestly does more for the application than understating them.
Then set out the extract system in plain terms: canopy type and size, grease filtration at the canopy, duct diameter and route, fan type, and the abatement you propose. An Odour Assessment should read as a description of a specific installation rather than a set of principles.
Receptor identification above and beside
List the sensitive receptors with distances and heights, measured from the proposed discharge point rather than from the shop front.
- The flat immediately above, with the position of its openable windows and any roof light.
- Flats and dwellings either side, and anything to the rear across a yard.
- Any first floor residential above adjoining units in the same terrace.
- Outdoor amenity space, including rear yards, balconies and the flat roof of a back addition where it is used.
- Non-residential sensitive uses such as a nursery, dental surgery or a place of worship.
Height matters more than plan distance in a terrace. A window 4 metres above a discharge point is far more exposed than a garden 15 metres away at ground level, and an assessment that ranks receptors by plan distance alone tends to reach the wrong conclusion.
Duct route and the building fabric problem
This is the section that decides the application, so give it a drawing rather than a paragraph.
Four routes come up repeatedly. An external duct on the rear elevation to above ridge level. An internal riser within the demise of the commercial unit, where the building has one. A duct through the flat above, which needs the freeholder's consent and a fire resisting enclosure under Approved Document B. A low level discharge at the rear, which is the option officers refuse.
Where the flat is in separate ownership, the planning application and the leasehold position have to be resolved together. A permission that cannot be implemented because the duct crosses land you do not control is worth very little, and the ownership certificate on the application form has to reflect that reality.
If the unit is in a listed shopfront or a conservation area, the external duct also becomes a heritage question. Our outline for a Heritage Statement for a listed shopfront covers how to present an external service run in that context.
Termination point and discharge velocity
The Defra guidance on the control of odour and noise from commercial kitchen exhaust systems is the document environmental health officers work from, and it points in one direction: discharge high, and discharge fast.
In practice that means terminating at or above ridge level of the building and any building immediately adjoining, clear of openable windows, at an efflux velocity high enough to carry the plume up rather than let it fall back down the elevation. Figures in the region of 10 to 15 metres per second are commonly specified for the discharge. A cowl or a downward facing terminal defeats the whole arrangement, so specify a vertical discharge without a cowl and say so on the drawing.
Two details get missed. The duct needs to clear the flat's openable windows in three dimensions rather than merely rising above them. And a neighbouring building that is taller than yours will create a downwash zone, which is a reason to extend the duct rather than a reason to argue.
Control equipment selection
Match the abatement to the odour risk you set out in the first section, and explain the match. A risk based approach asks how strong the source is and how sensitive and close the receptors are, then sets a level of control from that.
| Odour risk | Typical control package |
|---|---|
| Low | Grease filtration at the canopy and high level discharge |
| Medium | Grease filtration plus carbon filtration, sized for the airflow |
| High | Grease filtration, electrostatic precipitation or ultraviolet treatment, plus carbon, with high level discharge |
A flat directly above a chargrill or a fryer is a high risk arrangement almost by definition, so a proposal at the low end of that table will be questioned. State the carbon bed weight or volume, the design airflow, the expected residence time and the manufacturer's replacement interval. An officer who can see the sizing arithmetic will condition it rather than refuse it.
Noise travels with the extract. The fan, the roof terminal and any refrigeration plant need a separate assessment against the prevailing background, and a Noise Impact Assessment using the BS 4142 method is the normal evidence where plant serves a flat above.
Maintenance regime and records
Abatement that is not maintained stops working within months, and councils know it. Set out the regime as a schedule the council can attach to a condition.
- Grease filter cleaning frequency, with the cleaning method and who does it.
- Carbon replacement interval, tied to hours of operation rather than to the calendar alone.
- Ductwork deep clean frequency and the standard followed.
- Fan and terminal inspection, including the belt and the anti-vibration mounts.
- A written log kept on the premises and made available to the council on request.
The log is the part that protects the operator. Where a complaint leads to an investigation under Part III of the Environmental Protection Act 1990, a maintained record of filter changes is the difference between a conversation and an abatement notice.
What to submit and what to condition
A workable submission for this scenario is short. A ventilation and extraction statement describing the system, the odour risk assessment, a duct route drawing in section and elevation, an appliance schedule, the abatement specification with sizing, a plant noise assessment, and a proposed maintenance schedule. A Ventilation/Extraction Statement draft gives you the structure for the first of those.
Offer the conditions yourself. Approval of the final abatement specification before first use, a noise limit at the nearest residential facade, hours of opening, maintenance in accordance with the submitted schedule, and retention of records. Officers are far more willing to grant permission where the applicant has written the conditions that manage the risk.
For specialist technical reports, qualified professional input may be required, and an odour assessment for a high risk installation above a dwelling is one of them. This article is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Does a hot food takeaway need planning permission in England?
Yes. Hot food takeaways became sui generis when the Use Classes Order was amended in 2020, so they sit outside Class E and outside the flexible changes within it. A change of use to a takeaway therefore needs planning permission whatever the previous use was, and odour, noise and parking are usually the issues that decide it.
Can an extract duct be routed through the flat above the shop?
Only with the consent of whoever owns that flat and a fire resisting enclosure designed to Approved Document B. Most takeaway schemes instead run an external duct up the rear elevation to above ridge level. If you do not control the route, say so on the application form ownership certificate, because a permission you cannot implement has little value.
How high does a kitchen extract duct have to terminate?
There is no single statutory height. Defra guidance on commercial kitchen exhaust systems points to a vertical discharge at or above the ridge of the building and any immediately adjoining building, clear of openable windows, with enough efflux velocity to carry the plume upwards. Councils normally condition the final termination detail before first use.
What odour abatement will the council expect above a flat?
Match it to the cooking. Chargrilling and frying below a dwelling is a high odour risk, which usually means grease filtration at the canopy, then electrostatic precipitation or ultraviolet treatment, then carbon filtration sized for the design airflow, discharging at high level. State the carbon bed size and replacement interval so the council can condition it.
Who should write the odour risk assessment?
For a low risk unit an agent can prepare it from the appliance schedule and the duct drawing. Where a dwelling sits directly above a high odour installation, councils normally expect an author with odour or ventilation experience, and the report carries more weight if the abatement sizing has been checked by the equipment supplier or an acoustics and air quality consultant.
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.