Reports for an agricultural building on a small holding

On an agricultural unit of five hectares or more you can usually put up a building of up to 1,000m² under Part 6 of the General Permitted Development Order, subject to a prior notification. Below five hectares you cannot erect a new building under those rights at all, and the route becomes a full planning application. That threshold decides which reports you need, so measure the holding before you do anything else.

The five hectare line is the whole of the answer for a lot of small holdings, and it surprises people every year.

Part 6 prior notification and the five hectare threshold

Schedule 2 Part 6 splits agricultural permitted development in two. Class A covers units of five hectares or more and allows the erection, extension or alteration of a building reasonably necessary for the purposes of agriculture within the unit. Class B covers units between 0.4 and five hectares and is far narrower, permitting extension or alteration of an existing agricultural building, private ways, excavations and similar works, but not a new building.

Class A carries real limits. The ground area covered by the development must not exceed 1,000m². The height is capped, with a lower cap close to an aerodrome. Nothing may be built within 25m of the metalled surface of a trunk or classified road. And the parcel must not be a separate parcel of less than one hectare.

Where the proposal is the erection, extension or alteration of a building, or the formation or alteration of a private way, you must first apply to the authority for a determination as to whether its prior approval is required for the siting, design and external appearance of the building. The authority has 28 days. You may proceed once it tells you prior approval is not required, once it grants prior approval, or once 28 days pass with no response, and the development must be completed within five years.

Additional restrictions apply on designated land such as National Parks, National Landscapes and conservation areas, so read Part 6 in full rather than relying on a summary.

Proving the agricultural need for the building

The words "reasonably necessary for the purposes of agriculture within the unit" do a lot of work, and authorities test them.

What satisfies an officer is a short functional statement setting out the holding: its area, its tenure, the enterprise, stock numbers or cropped area, the existing buildings and their capacity, and why the new building is needed for that enterprise on that unit. Attach the land registry plan, the holding number and the stocking records.

What fails is a general assertion of storage need on a holding with three empty barns, or a building sized for a business that does not yet exist. Authorities also look hard at buildings that appear designed for future conversion to a dwelling, and a domestic-looking window arrangement in a notification drawing invites that suspicion.

Horses are the recurring trap. Keeping and grazing horses is agriculture only where the animals are grazing for food. Livery, riding schools, competition yards and stabling are not agriculture, and a building for them needs a full application.

Siting, landscape and the 400 metre restriction

Two siting rules bite hardest on small holdings.

The first is the 400m restriction. A building designed for accommodating livestock, or a structure for storing slurry or sewage sludge, cannot be erected within 400m of the curtilage of a protected building under Part 6. A protected building is broadly a permanent building normally occupied by people, with exceptions for buildings on the same agricultural unit and certain others. On a compact holding near a village edge, the 400m circle can eliminate every sensible position.

The second is the prior approval discretion itself. Where the authority does require prior approval, the matters it may consider are siting, design and external appearance, which in practice means the position in the landscape, the roof colour, the cladding and the relationship to existing farm buildings.

That is where a short landscape appraisal earns its keep. Photographs from three or four public viewpoints, a note on the existing group of buildings, and a materials schedule using dark recessive finishes answer most objections before they are made. On a site in or near a National Landscape, a fuller Landscape and Visual Impact Assessment may be proportionate, though on a single agricultural building it usually is not.

Access, track construction and highway safety

A new building generates vehicle movements, and Part 6 includes private ways as notifiable development.

Where the access onto the public road is being altered or used more intensively, the highway authority will look at visibility splays derived from recorded speeds, at whether an articulated feed lorry or a livestock transporter can enter and leave in forward gear, and at the surfacing of the first stretch inside the gate so that mud is not carried onto the road. A short Transport Statement covering those three points is usually all that is needed.

Track construction brings surface water with it. A new hardcore track on clay sheds water that used to soak away, and if it discharges onto the lane the highway authority objects. Interception, a swale along one side and a discharge point away from the road are the usual answers.

Where a vehicle crossing over a verge or footway is being formed or altered, separate consent is needed from the highway authority under the Highways Act 1980.

Slurry, manure storage and water pollution rules

This is the part that catches holdings out, because it sits outside planning entirely and is enforced separately.

Check whether the holding is in a nitrate vulnerable zone, because the required storage capacity changes and the building you notify may need to be larger than you planned. Notify the environmental regulator in advance of using a new or substantially altered slurry store, within the period the regulations require.

And keep the two regimes separate in your head. A prior approval from the council says nothing about whether the store complies with the pollution rules, and compliance with the pollution rules says nothing about whether you needed planning permission.

Ecology and the loss of field margins

Permitted development is outside the biodiversity net gain regime, so a Part 6 notification does not carry a 10 per cent gain requirement. Protected species law applies regardless.

Barn owls are the common issue. They nest in open-sided barns and in old stone buildings, and a scheme that alters or replaces such a building without a survey risks a criminal offence under the Wildlife and Countryside Act 1981. Bats in roof voids of older buildings raise the same problem, and both require a suitably licensed ecologist rather than a general adviser.

A Preliminary Ecological Appraisal is proportionate where an existing building is being altered or demolished, where hedgerow or scrub is being cleared for the footprint or the track, or where the holding sits next to a designated site.

Field margins and hedgerows have their own protection. Removing a countryside hedgerow needs a removal notice under the Hedgerows Regulations 1997 unless an exemption applies, and taking a margin out of an agri-environment agreement can breach the agreement even where planning has no view.

An illustrative example

A 6.8 hectare holding with a small suckler herd, applying to erect a 420m² general purpose building for fodder and machinery. The unit is above five hectares so Class A is available. The proposed position is 310m from a neighbouring cottage, which is fine because the building is not for livestock or slurry. The prior notification includes a one-page functional statement with stocking records, siting and elevation drawings, a materials note specifying dark olive profiled sheeting, four viewpoint photographs and a short access note. The authority confirms prior approval is not required within 28 days. This example is illustrative rather than drawn from a specific case.

Where a full application is required instead

Seven situations push you out of Part 6 and into a full application.

1. The agricultural unit is under five hectares and a new building is proposed.
2. The ground area exceeds 1,000m².
3. The building is for livestock or slurry storage and sits within 400m of a protected building.
4. The use is not agriculture, including equestrian, livery, contracting, storage for a non-farming business or a farm shop.
5. The building is within 25m of the metalled surface of a trunk or classified road.
6. Designated land restrictions in Part 6 remove the right.
7. The holding has already used the 1,000m² allowance within the relevant period.

A full application brings a Planning Statement, a design and access statement where required, and whichever technical documents the constraints generate. It also brings biodiversity net gain into play, since the exemption for permitted development no longer applies.

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.