Permitted development for agricultural buildings: Part 6

Part 6 of Schedule 2 to the General Permitted Development Order 2015 lets farmers put up buildings and form tracks without a full planning application, provided the holding is large enough and the work is reasonably necessary for agriculture. The thresholds do the heavy lifting: units of five hectares or more use Class A, smaller units down to 0.4 hectares use the narrower Class B, and anything below 0.4 hectares has no Part 6 rights at all. Most disputes about part 6 agricultural permitted development come down to unit size, the 1,000 square metre ground area cap, or a building that was never really for farming.

The classes and the unit size thresholds

Part 6 divides agricultural rights by the size of the agricultural unit, measured as the whole holding rather than the field in which the building will stand.

Class A applies to units of five hectares or more and allows the erection, extension or alteration of a building, and works such as excavations and the deposit of waste, where reasonably necessary for the purposes of agriculture within that unit. Class B applies to units of at least 0.4 hectares but less than five hectares and is much tighter: extension or alteration of an existing agricultural building and the provision or replacement of plant or machinery, with no right to erect a new building. Separate classes in Part 6 deal with mineral working for agricultural purposes on the holding and with forestry buildings and private ways.

Units under 0.4 hectares fall outside Part 6 entirely. Smallholdings, paddocks and pony fields regularly sit below that line, and the owner who assumes a field shelter is permitted has no right to rely on.

Floor area, height and siting limits

The limits are cumulative across the unit and they are where schemes fail.

A protected building means, broadly, a permanent building normally occupied by people, with exceptions for buildings on the same holding. The 400 metre rule is the one that catches diversification: a new livestock shed sited for operational convenience near the farmhouse of a neighbouring property has no Part 6 cover.

Note that the 1,000 square metre figure applies to the ground area of the building together with other buildings erected under the class within the relevant period, so a sequence of smaller sheds can exhaust the allowance. Count what has already gone up before designing the next one.

Class B has its own ceiling: the ground area of the building as extended must not exceed 1,000 square metres, the cubic content must not increase by more than ten per cent, and the height must not exceed that of the original building. An extension beyond ten per cent falls outside the class and needs a different route.

Prior notification and what it covers

Part 6 is a prior notification regime, not a free hand. Where the development is the erection of a building, a significant extension or alteration to one, the formation or alteration of a private way, or an excavation or deposit of waste, the developer must first apply to the local planning authority for a determination as to whether prior approval will be required.

The application gives the siting, design and external appearance for a building, or the siting and means of construction for a private way, with a site plan and the relevant fee. The authority then either confirms that approval is not required or requires approval and determines those limited matters. Procedure and timescales sit in the Order and in the Development Management Procedure Order 2015, so read the current paragraph before committing to a start date.

What the authority cannot do at this stage is reopen the principle. Siting, design and appearance are in scope. Whether a farm needs the building is not, provided the agricultural purposes test is met. That narrow scope is the value of the route, and it is why authorities scrutinise the purposes test instead.

The agricultural purposes test

The work must be reasonably necessary for the purposes of agriculture within the unit. Three failure modes recur.

A building designed for a non-agricultural use from the outset, such as a shed laid out with offices, a reception and customer parking for a farm shop. A building on a unit with no real agricultural activity, where the holding was assembled recently and the enterprise exists mainly on paper. And a building out of all proportion to the enterprise, where the stated purpose is storage of a crop the unit does not produce in that quantity.

Authorities test this with a farm business case: cropping records, livestock numbers, movement records, accounts and machinery schedules. Prepare that material rather than waiting to be asked, because a weak purposes case leads to the determination being challenged and to enforcement later. The biodiversity gain condition that now attaches to most permissions does not apply to Part 6 development, which is one of the quieter advantages of using the right properly.

Excluded operations and designated land

Part 6 does not authorise a dwelling, and it does not authorise the keeping of livestock as a non-agricultural activity such as a commercial equestrian or livery business. Equestrian use beyond grazing is not agriculture, and that single point accounts for a large share of rural enforcement.

On designated land the rights are restricted. In National Parks, the Broads, National Landscapes, conservation areas and World Heritage Sites, additional controls apply and some operations lose permitted development status altogether. An Article 4 direction can remove the rights anywhere.

Check the designations before design, using the national datasets rather than local memory. Our note on air source heat pumps and permitted development limits shows the same pattern of designation-based restriction in a different class.

Conditions on roads and excavations

Two conditions are easy to overlook. Where a private way is formed or altered, the authority can control siting and means of construction, and a visibility splay onto a classified road will usually involve the highway authority separately under the Highways Act 1980.

Waste deposits and excavations carry their own conditions about the material used and the restoration of the land, and the deposit of waste other than material from the unit itself is outside the class. Importing inert fill to level a field is a common breach, and it often brings in environmental permitting as well as planning.

Where a building erected under Part 6 is later used for something else, the use is a separate matter. A building put up under Part 6 is also subject to a requirement to remove it and restore the land if the agricultural use ceases within a set period after construction, so keep the dates.

Where a full application is unavoidable

Apply for planning permission where the unit is under 0.4 hectares, where the building exceeds 1,000 square metres or the height limits, where the siting breaches the 25 metre or 400 metre rules, where the use is equestrian or commercial, or where the purpose is diversification rather than agriculture.

A full application needs a design and access statement on most sites, landscape and ecology evidence where the setting demands it, and a Planning Statement that makes the agricultural or diversification case openly. Browse the full index of report types to see which of those a rural scheme usually attracts.

This is general guidance, not legal advice, and only a lawful development certificate confirms formally that works are lawful. 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.