Three routes for a new farm building
Agricultural buildings have their own permitted development rights in Part 6 of the General Permitted Development Order. Depending on the size of your holding and what you want to build, a new building will follow one of three routes:
- Prior notification (Part 6 Class A)On agricultural units of 5 hectares or more, buildings, extensions and excavations reasonably necessary for agriculture on the unit are permitted, but you must first apply to the council to decide whether it needs to approve the siting, design and external appearance.
- Smaller holdings (Part 6 Class B)On units of 0.4 to 5 hectares, the rights are narrower and mainly cover extending or altering existing agricultural buildings. Below 0.4 hectares, there are no Part 6 rights.
- Full planning permissionNeeded where the building falls outside the limits, is not reasonably necessary for agriculture, or is for another use such as equestrian, storage or a business.
The Class A limits
The Order sets firm limits. A building cannot rely on Class A if:
- SizeIts ground area would exceed 1,500 square metres, or 1,000 square metres for works or structures to house livestock.
- HeightAny part would exceed 12 metres, or 3 metres within 3 kilometres of the perimeter of an aerodrome.
- RoadsAny part would be within 25 metres of the metalled part of a trunk or classified road.
- Livestock and slurry near neighboursA building or excavation for livestock, slurry or sewage sludge would be within 400 metres of the curtilage of a protected building, such as a neighbour's house. There is a narrow exception for livestock housing where no other suitable building is available.
- Small parcelsIt would be on a separate parcel of the unit of less than 1 hectare.
- Non-agricultural designIt would be a dwelling, or a building not designed for agricultural purposes.
- Recent conversionsA new building under Class A(a) is not permitted where Class Q or Class S conversions have taken place on the unit in the previous 10 years.
How prior notification works
Before starting, you apply to the council with a description of the development, the materials and a site plan, and pay the fee. The council then has 28 days. You can build if it says prior approval is not required, if it grants approval, or if 28 days pass without a decision. If it decides prior approval is required, you must display a site notice, and the council will assess siting, design and external appearance.
The works must be carried out within 5 years. If the agricultural use stops within 10 years of completion and no other planning permission is granted within 3 years, the building must be removed and the land restored.
Why notifications get refused
- Not reasonably necessaryThe building must be justified by the farming on that unit. Councils ask for the size of the holding, the livestock or crops, existing buildings and what the new building will be used for.
- SitingIsolated sites away from the farmstead, on skylines or in open views attract objections. Grouping with existing buildings is the strongest approach.
- DesignDomestic features, such as large windows, residential doors or rooflights, suggest the building is not really agricultural.
- Missing informationVague descriptions and no evidence of the farming need are the most common problems.
Reservoirs, slurry stores and other works
Excavations and engineering operations reasonably necessary for agriculture, such as irrigation reservoirs, tracks and hardstanding, can also fall under Class A, with prior notification in many cases. Large raised reservoirs of 25,000 cubic metres or more must also be registered under the Reservoirs Act 1975. Slurry stores and livestock buildings must respect the 400 metre rule.
National policy supports this kind of investment. Policy E4 of the National Planning Policy Framework (August 2026) supports development to maintain and enhance farm viability and support domestic food production, and in the Green Belt, buildings for agriculture are not inappropriate (Policy GB7).
Plan the order of your projects
The rights interact. New buildings under Class A can rule out Class Q barn conversions on the unit for 10 years, and recent Class Q or Class S conversions block new Class A buildings. If you are thinking about both a new barn and converting an old one, decide the sequence before you notify.
Local planning advice
Herefordshire · Gloucestershire · Worcestershire · Test Valley
Frequently asked questions
Do I need planning permission for an agricultural building?
Not always. On units of 5 hectares or more, buildings reasonably necessary for agriculture can use Part 6 Class A permitted development, subject to prior notification and limits on size, height and location. Larger or non-agricultural buildings need planning permission.
How big can a farm building be without planning permission?
Up to 1,500 square metres of ground area under Class A, or 1,000 square metres for livestock buildings, and no more than 12 metres high (3 metres within 3 kilometres of an aerodrome).
How long does an agricultural prior notification take?
The council has 28 days. If it does not respond within 28 days, you can proceed in line with the details submitted.
Can I build a livestock building near houses?
Not under permitted development if it would be within 400 metres of the curtilage of a protected building, such as a neighbour's house, except in narrow circumstances. A planning application is usually needed.
Can I use an agricultural building for horses or storage?
Not under Part 6. Keeping horses for recreation is not agriculture, and non-agricultural storage is a different use. These need planning permission, or a change of use under Class R where it applies.
This guide is general information for applications in England and is not advice on your specific project. Requirements differ in Wales, Scotland and Northern Ireland, and every council publishes its own local validation list, so always check the detail with your local planning authority.