Grain stores and the Part 6 siting and design notification

A grain store on a holding of 5 hectares or more usually does not need planning permission. It needs a grain store prior notification: an application to the local planning authority for a determination of whether it wishes to approve the siting, design and external appearance of the building. The right comes from Class A of Part 6 of Schedule 2 to the General Permitted Development Order 2015, and the notification is the step that catches people out, because building without it makes an otherwise lawful store unlawful.

The authority cannot refuse the building on the ground that it does not like the idea. Its powers under the notification are limited to siting, design and external appearance. What it can do is take those matters seriously, and on a prominent ridge in a National Landscape it will.

Which buildings the right covers

Class A permits works on agricultural land within an agricultural unit of 5 hectares or more, where the works are reasonably necessary for the purposes of agriculture within that unit. That includes the erection, extension or alteration of a building, and it includes excavation and engineering operations such as a new private way or a slurry store.

What it does not cover:

• A dwelling of any kind, including an agricultural worker's house.
• A building, structure or works not designed for agricultural purposes. A machinery store that is really a commercial workshop is outside the right.
• Development on a separate parcel of the unit smaller than 1 hectare.
• Excavations or engineering operations on or under a site of archaeological interest.

The functional test is the one that gets forgotten. "Reasonably necessary for the purposes of agriculture within that unit" means within your unit, so a store built principally to take contract grain from neighbouring farms is not covered, and neither is a building erected in anticipation of a diversification scheme. Where the real purpose is commercial, the honest route is a full application, and the arguments for that sit alongside those for workshops and offices on a farm.

The limits that apply to Class A

The ground area limit is cumulative in a way that surprises people. Where another building has been put up on the same unit within the previous two years and sits within 90m of the proposed store, its area counts towards the 1,000 m². Two 600 m² sheds erected 18 months apart at either end of the same yard will not both fit inside the right.

Check the aerodrome distance before designing a store with a high eaves for a grain dryer or an auger tower. Three metres is nothing, and the 3km radius takes in more small airfields than most people realise.

Where 465 square metres comes from

The 465 m² figure belongs to Class B, not Class A. Class B applies to agricultural units of at least 0.4 hectares but less than 5 hectares, and it is a much narrower right: extensions and alterations to existing buildings and some works, with a ground area limit of 465 m² and a cap on how much an existing building may be enlarged.

So the first question on any farm building is the size of the agricultural unit, not the size of the building. Under 0.4 hectares there is no Part 6 right at all and a full application is required. Between 0.4 and 5 hectares you are in Class B territory. At 5 hectares and above you are in Class A.

Get that wrong and everything downstream is wrong, which is why the area of the unit should be calculated and stated in the notification with a plan.

The notification of siting, design and external appearance

Where the development involves the erection, extension or alteration of a building, the formation or alteration of a private way, certain excavations or deposits, or the placing of a tank in waters, you must apply to the authority for a determination as to whether its prior approval is required.

The application is short: a written description of the proposed development and the materials to be used, a plan showing the site, and the developer's contact address, together with the fee. Councils have their own forms and most take it through the national portal.

Send more than the minimum where the setting is sensitive. A site plan showing the store in relation to the existing yard, a simple elevation with the colour finish stated, and a short note on why that position was chosen over the alternatives will often produce a determination that prior approval is not required. On an exposed site a landscape appraisal, or a full Landscape and Visual Impact Assessment where the scale warrants it, saves an argument later.

The 28 day period and what follows

The authority has 28 days from receipt to notify you whether prior approval is required.

1. If it tells you prior approval is not required, you may build in accordance with the details you submitted.
2. If it tells you prior approval is required, you must obtain that approval before starting, and the authority then considers the siting, design and external appearance on their merits.
3. If it does not respond within 28 days, you may proceed in accordance with the details submitted.

Three things follow from that. Do not vary the design afterwards, because the right attaches to what you submitted. Keep the determination letter with the farm records permanently, since it is the evidence that the building is lawful. And note that the development must be carried out within five years of the determination, so an old notification does not authorise a store built a decade later.

The right also carries use conditions. A building erected under Class A must be used for agriculture, and using it for storage of non-agricultural goods, or letting it to a business, is a change of use requiring permission.

Excluded locations and designations

The right is not available everywhere in the same form.

An Article 4 direction can remove or restrict it, and some authorities have made directions covering agricultural buildings in sensitive areas. Additional restrictions apply in National Parks, the Broads, National Landscapes and conservation areas, so check both the current Order and the local position before relying on the general limits.

Separately from Part 6, other consent regimes still apply. Works affecting a listed building or its curtilage need listed building consent. A protected tree needs consent for works. Removing a length of countryside hedgerow to widen an access may need a notification, as set out in our note on the important hedgerow test. A new or altered access onto a classified road needs the highway authority's agreement. And larger intensive livestock proposals can require environmental impact assessment screening, which is a different question from Part 6 entirely.

What to submit with the notification

Keep it to a short pack that answers the authority's questions before they are asked.

• A site location plan and a block plan showing the store, the existing yard buildings, the access and the boundaries.
• A calculation of the agricultural unit area with a plan showing the land in the unit.
• The ground area of the proposed building, plus any building erected within the previous two years within 90m, with dates.
• Elevations and a section with overall height, eaves height and the proposed external materials and colour.
• A short statement of agricultural necessity: the cropping area, current storage capacity, the shortfall and why the store is needed on this unit.
• Screening or planting proposals where the site is visible from a road, a right of way or a settlement.
• Confirmation of distances to any aerodrome, trunk or classified road and, for livestock or slurry, to protected buildings.

Illustrative example: a 210 hectare arable holding proposing a 900 m² grain store with 7m eaves, 60m from the existing yard and 340m from the nearest classified road. A machinery shed of 180 m² was built 14 months earlier, 70m away, so the combined area is 1,080 m² and the right does not cover it. The store is redesigned to 780 m² with a taller centre bay to keep the same tonnage, bringing the total within the limit, and the notification is submitted with a planting scheme along the western boundary.

Where a full application does turn out to be necessary, a Planning Statement setting out the agricultural justification and the landscape response is the document that carries the case.

Enter your postcode on PlanScope to see which documents a farm building proposal is likely to need.

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. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.