Part 6 Class A: agricultural buildings on larger units

Agricultural building permitted development on a holding of 5 hectares or more runs through Class A of Part 6 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015. It allows buildings, extensions, alterations, excavations and engineering operations that are reasonably necessary for agriculture within that unit, subject to a ground area limit of 1,000 m², a height limit of 12 metres, and a prior approval procedure that gives the council 28 days to ask for details of siting, design and external appearance.

It is not a right to build whatever the farm needs. The limits are specific, and three of them catch schemes after the slab has been poured.

The unit, and what counts towards five hectares

The right applies to agricultural land comprised in an agricultural unit of 5 hectares or more. The unit is the land occupied as a unit for agriculture, which excludes the farmhouse and its garden.

Tenure is not the test. Land held under a farm business tenancy or a grazing licence can form part of the unit if it is occupied with the rest for agricultural purposes, and land you own but have let out to a separate business is not part of your unit. Where a holding is fragmented, the arithmetic is the total area occupied as one unit, not the largest field.

There is a trap for scattered holdings. The right does not permit development on a separate parcel of land of less than 1 hectare that forms part of the unit. So a detached half hectare paddock three miles from the main block gets nothing under Class A, however large the rest of the holding is.

Ground area, height and the 90 metre rule

The ground area limit is 1,000 m², and it is not measured on the new building alone. The area covered by the proposed building is taken together with the ground area of any other buildings within 90 metres that were erected or extended under this class within the preceding two years.

That is the limit most often misread. A grain store put up two summers ago sits inside the calculation for the new machinery shed 60 metres away, and the two together must stay within the figure.

Height is capped at 12 metres, reduced to 3 metres where any part of the development is within 3 kilometres of the perimeter of an aerodrome. Check the aerodrome position before the portal frame is specified, because licensed and unlicensed airfields both count and the reduced limit rules out most modern agricultural buildings.

Reasonably necessary for the purposes of agriculture

The works must be reasonably necessary for agriculture within that unit, and agriculture carries the statutory meaning in section 336 of the Town and Country Planning Act 1990: horticulture, fruit growing, seed growing, dairy farming, breeding and keeping livestock, grazing land, market gardens and nursery grounds, among others.

Two things fall outside it more often than owners expect. Equestrian use other than the grazing of horses is not agriculture, so a building for a livery or a riding school is not covered. And storage or processing of produce brought in from other holdings is not agriculture within that unit, which is the point that defeats a good number of farm shop and packing shed proposals.

The test is about need, so the council can ask what the building is for and how the enterprise justifies it. A building specified for a herd the holding does not have, and cannot support, is vulnerable. Keep the herd numbers, cropping records and the reason for the new capacity on file before you notify.

Prior approval, and the 28 days

For most Class A development, including any new building, a significant extension or alteration, a private way, an excavation or a deposit of waste, the developer must first apply to the council for a determination as to whether its prior approval will be required.

The application states the proposed development, includes a plan showing the site, and is accompanied by the fee. Then one of three things happens. The council says prior approval is not required, and you may build. The council says prior approval is required and gives or refuses it on the stated matters, which for a building are siting, design and external appearance. Or the council says nothing within 28 days of receipt, in which case the development may proceed in accordance with the details submitted.

Two practical points follow. Submit drawings good enough to live with, because the silence route locks you into exactly what you sent. And start on time: the development must be begun within the period the Order specifies, so a notification obtained and then left for years is not a banked permission.

On National Parks, National Landscapes and other protected land the procedure is tighter still, and our note on article 2(3) land and permitted development in protected areas sets out how the restrictions stack up.

Distances from protected buildings and roads

Two separation distances sit in the limits, and both are measured from the building rather than from the boundary.

No part of the development may be within 25 metres of a metalled part of a trunk road or classified road. And a building for accommodating livestock, or for storing slurry or sewage sludge, cannot be erected, extended or altered under this class within 400 metres of the curtilage of a protected building.

Protected building has a defined meaning: a permanent building normally occupied by people, excluding a building within the agricultural unit and excluding one occupied by a person employed in agriculture on that unit. So the neighbour's cottage counts. The stockman's house on the holding does not.

The 400 metre rule is absolute for those uses. There is no prior approval route around it, and the answer for a livestock building inside that radius is a planning application with an odour and amenity case, not a notification.

Conditions that follow the building

Class A buildings come with conditions attached to the use. The building must be used for the purposes of agriculture within the unit, and where the unit ceases to be used for agriculture within a defined period after the building is substantially completed, the council can require its removal or the reinstatement of the land.

That has consequences for anyone planning a later conversion. A building erected under agricultural permitted development cannot simply become a dwelling. The residential conversion route under Class Q of Part 3 has its own qualifying dates and tests, including how long the building has been in agricultural use, so putting up a barn with a conversion in mind is a decade-long plan rather than a two year one.

Extensions to other kinds of building follow different rules again, and the industrial and warehouse equivalent is covered in Part 7 Class H.

What to send with the notification

Councils see a lot of thin Part 6 notifications. A good one contains the site location plan with the unit outlined and its area stated, a block plan showing the 90 metre radius and every building put up under the class in the last two years, elevations and sections with the height dimensioned, a short note on the agricultural need with enterprise figures, and confirmation of the distances to the nearest classified road and protected building.

Where the siting raises landscape or heritage questions, add the reasoning rather than waiting to be asked. A short Planning Statement covering need, siting alternatives and materials turns a contested determination into a straightforward one, and it is the same document you would need if the notification fails and a full application follows. You can see the wider set of supporting documents a rural application tends to need.

This is general guidance, not legal advice. A lawful development certificate is the only formal way to confirm that works are lawful, so 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.