Agricultural buildings on holdings of 5 hectares or more

Class A of Part 6 of the General Permitted Development Order lets you put up an agricultural building on a holding of 5 hectares or more without planning permission, provided the building is reasonably necessary for agriculture on that unit and stays inside a set of numerical limits. Below 5 hectares, and down to 0.4 hectares, a much narrower right in Class B applies and new buildings are not part of it.

Two things decide most Part 6 cases: whether the unit qualifies, and whether the building is actually for agriculture. The dimensions are usually the easy part.

The unit has to qualify before the building does

The right applies to agricultural land comprised in an agricultural unit of 5 hectares or more. That is the whole unit, not the field the building sits in, and the unit is the land occupied for agricultural purposes as a single holding.

Two traps follow. First, development is not permitted on a separate parcel of land less than 1 hectare in area, so an isolated outlying field cannot host the building even if the holding as a whole is large enough. Second, land that has been let out, sold off or taken out of agricultural use shrinks the unit, and a holding that was 6 hectares a decade ago may not be now.

Measure the unit as it stands and record the measurement. A plan showing the holding, its ownership or tenancy and its area is the first item in the file.

Reasonably necessary for the purposes of agriculture

The building must be reasonably necessary for agriculture within that unit. Agriculture has a statutory definition in section 336 of the Town and Country Planning Act 1990, covering horticulture, fruit growing, seed growing, dairy farming, livestock breeding and keeping, grazing land, market gardens and nursery grounds, among other things.

What fails the test is instructive. Buildings for storing machinery used for contracting work off the holding. Buildings for a farm shop selling bought-in goods. Buildings for equestrian use, because keeping horses for riding is not agriculture even though grazing them is. Buildings sized for a scale of production the holding does not support.

Councils test this by asking what the holding produces, what equipment it runs and why the existing buildings are inadequate. Answer those three questions in the submission and most enquiries stop there.

Ground area, height and the limits that bite

The ground area covered by the building must not exceed 1,000 square metres. That figure is calculated cumulatively: other buildings erected on the unit within 90 metres in the preceding two years count towards it, which prevents a large shed being built as three smaller ones in sequence.

Height is limited to 12 metres generally, and to 3 metres where any part of the building is within 3 kilometres of the perimeter of an aerodrome. The aerodrome limit catches people out on land near small airfields as well as near commercial airports, so check before designing a grain store.

The right does not permit the erection, extension or alteration of a dwelling, and it does not permit a building or structure that is not designed for agricultural purposes. A steel portal frame with roller shutters is agricultural. The same frame with domestic windows, a first floor and a bathroom is not.

Where an existing building is being extended or altered, the Order treats the works as significant, and so requiring notification, once they pass a threshold defined by reference to an increase in cubic content or in height over the original.

Distance from roads and from protected buildings

Two separation distances do most of the refusing.

No part of the development may be within 25 metres of a metalled part of a trunk road or a classified road. Measure from the metalled surface, not from the boundary or the verge.

Buildings for accommodating livestock, and structures for storing slurry or sewage sludge, must not be within 400 metres of the curtilage of a protected building. A protected building is broadly a permanent building normally occupied by people, excluding buildings on the same agricultural unit. On a holding with cottages sold off along the lane, that 400 metre radius can sterilise most of the farmyard.

Check both distances on a scaled plan before the steelwork is ordered. They are absolute, and there is no discretion to relax them.

The prior notification procedure and the 28 days

Where the development consists of the erection of a building, an extension or alteration above that threshold, or the formation or alteration of a private way, or certain excavations and deposits, the developer must first apply to the local planning authority for a determination as to whether prior approval is required.

For a building, the matters are the siting, design and external appearance. For a private way, the siting and means of construction. The authority cannot refuse because it dislikes the agricultural justification; it can only address those listed matters, and it may decide prior approval is not required at all.

Development must not begin before the expiry of 28 days from the application, unless the authority notifies sooner that prior approval is not required. If prior approval is required, wait for the decision. If the authority does nothing within the 28 days, the development may proceed in accordance with the details submitted.

Diarise the date the application was received and keep the receipt. Our explanation of how the prior approval procedure actually works covers the mechanics across the different classes.

The application itself is short: a written description, a plan of the site, the siting and design details and the fee. Submit a properly dimensioned elevation rather than a manufacturer's brochure, because a vague submission invites a request for further information that restarts the clock in practice if not in law.

What the right does not cover

Permitted development under Part 6 is not a general exemption. Other consents run in parallel.

If the site is in Flood Zone 2 or 3, the flood position still matters for the works themselves and for any later application, and a Flood Risk Assessment may be needed. If the building is within the curtilage of a listed building, listed building consent is a separate requirement and the right may not apply at all. Building regulations approval, environmental permitting for slurry storage, and highways consent for a new access onto a public road are all separate again.

Article 4 directions can withdraw Part 6 rights in sensitive areas, and additional conditions apply on National Park and other designated land. Check the council's published list before designing.

Buildings put up under Part 6 also carry a condition about what happens if the land ceases to be used for agriculture within ten years, which is worth reading if the long-term plan involves a change of use. A conversion later on is a different question with its own rules, and our note on Class Q sets out what that route requires.

Evidencing a genuine agricultural unit

Keep a file from the start. Useful evidence includes the holding number and Rural Payments Agency registration, tenancy agreements or title plans showing the extent of the unit, cropping and livestock records, purchase invoices for feed, fertiliser or seed, accounts showing agricultural turnover, and photographs of the existing buildings showing why they are inadequate.

Where an authority challenges the agricultural purpose after construction, that file is the defence. Where it challenges beforehand, a short Planning Statement setting out the holding, the enterprise and the need for the building usually resolves it without a formal dispute.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. A lawful development certificate is the only formal way to confirm that works are lawful.

Enter your postcode on PlanScope to see which supporting documents a farm building or later conversion is likely to need. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.