Noise assessment or extraction statement: which a fit out needs
Fitting out a restaurant or takeaway usually attracts two separate documents: a noise assessment for the plant and an extraction statement for the odour. They overlap on the fan and nowhere else.
A noise impact assessment measures whether the sound from your plant is acceptable at the nearest home, judged against the background sound level. A ventilation and extraction statement describes how cooking odour is captured, cleaned and discharged, and where the flue terminates. If you are opening a restaurant, a takeaway or a café with a commercial kitchen above or beside residential accommodation, expect the council to ask for both, because the environmental health officer is answering two different questions.
Applicants often submit one and assume it covers the other. It does not, and a validation officer who has seen the same mistake fifty times will return the application.
What each document is actually for
The noise assessment is an acoustics report. Its job is to establish the existing background sound level at the nearest noise sensitive receptor, predict the sound from the proposed plant at that receptor, and compare the two.
The extraction statement is a ventilation design document. Its job is to show the kitchen's extract rate, the filtration and abatement fitted, the route of the ductwork through the building, the discharge point and the arrangements for cleaning and maintenance.
They meet at one place only. The extract fan is plant, so its sound output belongs in the noise assessment, and its position on the elevation belongs in the extraction statement. Everything else is separate.
The standards each is judged against
| Question | Document | Method |
|---|---|---|
| Is the plant too loud | Noise impact assessment | BS 4142:2014+A1:2019 rating level against measured background |
| Will neighbours smell cooking | Ventilation and extraction statement | Defra guidance on odour and noise from commercial kitchen exhaust systems |
| Is the internal environment acceptable | Noise assessment, where residential is above | BS 8233:2014 internal noise guideline values |
| Will the flue be seen | Design and elevations | Development plan design policy, heritage policy where relevant |
Under BS 4142 the assessor measures the background sound level, usually as an LA90 over representative periods including the latest hour you intend to operate. The specific sound level from the plant is predicted, character corrections are added for tones, impulses or intermittency, and the resulting rating level is compared with the background. A rating level around 10 dB above background indicates a significant adverse impact, around 5 dB an adverse one, and a level at or below background a low impact. Context then modifies the conclusion.
For odour, the Defra guidance sets out a risk based approach: assess the sensitivity of the receptors, the type of cooking and the separation distance, then specify abatement to match. Deep frying next to a first floor bedroom window is a different problem from a sandwich counter.
Where the fan appears in both
Manufacturers publish sound power data for their units, usually in octave bands. The acoustician needs that data sheet, the duct run, the silencer specification and the proposed operating hours. The ventilation designer needs the same fan selected for a duct velocity that actually delivers the extract rate through the filters once they are loaded.
The common failure is a fan selected for the duct pressure and then, after the acoustic report is written, swapped for a larger one because the original could not overcome the resistance of a carbon filter. The noise assessment is then wrong. Fix the sequence: size the extraction system first, select the fan, then assess the noise from the fan you are actually buying.
Anti-vibration mounts, flexible connections and a lined discharge cowl are routine and inexpensive at installation stage. Retrofitting them after a complaint costs several times more and happens with the shop trading.
Drawings each one needs
The noise assessment needs a site plan marking the measurement positions and the nearest receptors, elevations showing plant locations, and a plant schedule with the make, model and sound data of every item, including refrigeration condensers and air conditioning as well as the kitchen extract.
The extraction statement needs a ductwork layout in plan and section, an elevation showing the termination point with a dimension above the ridge or eaves line, a schedule of filtration and abatement, and a maintenance schedule. Defra guidance points towards vertical discharge at high level, clear of the building and of nearby openings, and many councils apply a rule of thumb that the flue terminates at least a metre above the ridge of the building and of neighbouring roofs. Check the current guidance and the council's own supplementary planning document rather than relying on the rule of thumb.
Where the building is listed or in a conservation area the flue becomes a heritage matter as well, and the route may need to run internally. That decision changes the duct sizing, so make it early.
Conditions you should expect
Councils rarely refuse a well evidenced kitchen scheme. They condition it. Typical conditions cover:
- A maximum rating level, often expressed as plant sound not exceeding the background level at the nearest residential façade.
- Installation of the extraction system in accordance with the approved details before the use begins.
- A maintenance and filter replacement schedule, with records kept and made available on request.
- Restricted opening hours and restricted delivery and waste collection hours.
- Grease trap and waste storage arrangements.
Read these carefully before you sign a lease. A condition capping plant sound at background level is demanding on a quiet suburban street, and it binds the operator, not the landlord. Where the fit out involves structural work, the construction management plan and the traffic arrangements become a separate discussion.
Sequencing them for a fast determination
Order of work that tends to produce an eight week determination rather than a six month one.
First, confirm the use class. A restaurant or café falls within Class E(b) of the Use Classes Order, while a hot food takeaway is sui generis, and that distinction decides whether you need planning permission for the change of use at all.
Second, appoint the ventilation designer and get the extract rate and duct route fixed. Third, give the acoustician the final plant schedule and commission background measurements at the right time of day, which for a late opening premises means measuring late.
Fourth, draft the two documents together so the fan data matches. Fifth, send the package to the environmental health officer through pre-application advice before you submit. An officer who has already seen the flue drawing rarely objects to it later.
A worked illustrative example. A ground floor unit in a parade with flats above proposes a 12 seat takeaway with a single deep fryer and a combi oven. The extract rate drives a 400 mm duct, run internally to a discharge a metre above the ridge at the rear. Odour risk is assessed as medium, so grease filtration plus a carbon cell is specified with a six monthly replacement schedule. The fan is mounted on anti-vibration mounts with an attenuator, and the predicted rating level sits at the background level at the nearest bedroom window. That package answers both questions in one submission.
You can draft both documents from the same set of site answers. Browse the 66 report types to see what each one contains, and check PlanScope pricing if you want to edit and version the drafts before your acoustician reviews them. You can start from your postcode on the PlanScope home page.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. 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
Do I need both a noise assessment and an extraction statement?
For a commercial kitchen near residential accommodation, usually yes. The noise assessment deals with sound from plant at the nearest neighbour, and the extraction statement deals with odour capture, abatement and the discharge point. Some councils accept a combined document for a small unit, so check the local validation list before you commission anything.
What standard is used for plant noise in a planning application?
BS 4142:2014+A1:2019 is the usual method for sound of an industrial or commercial nature, including kitchen extract fans, refrigeration and air conditioning. The assessor measures the background sound level, predicts the specific sound level from the plant, applies character corrections and compares the rating level with the background. Context is then taken into account before a conclusion is drawn.
How high does a kitchen extract flue have to terminate?
There is no single statutory height. Defra guidance points to vertical discharge at high level, clear of the building and of nearby openings, and many councils expect the flue to terminate above the ridge line of the building and of neighbouring roofs. Check the council's own supplementary planning document, because local expectations vary.
Is a takeaway the same use class as a restaurant?
No. A restaurant or café sits in Class E(b) of the Use Classes Order, while a hot food takeaway is sui generis and sits outside the class system. Moving from one to the other is a material change of use needing planning permission, and it usually brings the odour, noise and litter arguments with it.
When should background noise measurements be taken?
During the periods when the plant will run, including the quietest of them. For a premises open until 23:00 the assessor should measure the late evening background, because that is when the plant sound stands out most against a lower background level. Daytime measurements alone will understate the impact and invite an objection.
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.