In England, land in a National Park, an area of outstanding natural beauty, the Broads or a World Heritage Site is Article 2(3) land, where Class A permitted development does not allow an enlargement to extend beyond a side wall of the original house or to be more than one storey and extend beyond the rear wall, so a side conservatory needs planning permission, and the larger single-storey rear extension prior approval route is not available.

What Article 2(3) land means

The Planning Portal defines Article 2(3) designated land as land within a conservation area, an area of outstanding natural beauty, an area specified by the Secretary of State for the enhancement and protection of the natural beauty and amenity of the countryside, the Broads, a National Park or a World Heritage Site. The label matters because the permitted development rights for a house extension, which include most conservatories, carry extra restrictions there. These rules apply in England. Wales, Scotland and Northern Ireland have their own permitted development orders, covered in the guides to conservatories in Wales and conservatories in Scotland.

No side conservatory as permitted development

Paragraph A.2 of Class A sets additional limits for a house on Article 2(3) land. Under the GOV.UK technical guidance, development is not permitted by Class A if the enlarged part of the house would extend beyond a wall forming a side elevation of the original house. The Planning Portal states the practical result: on Article 2(3) designated land all side extensions require householder planning permission. A conservatory built beside a house therefore needs an application even where the same structure would be permitted development outside these areas.

Rear conservatories on designated land

The basic single-storey rear limits apply everywhere in England: an extension cannot extend beyond the rear wall of the original house by more than four metres for a detached house, or three metres for any other house, and cannot exceed four metres in height. The Planning Portal explains that the larger limits of eight metres for a detached house and six metres for any other, subject to prior approval, apply only where the house is not on Article 2(3) designated land or a Site of Special Scientific Interest. A rear conservatory on Article 2(3) land is therefore capped at the four or three metre limits unless full planning permission is granted. The same source notes that the rules count the proposed extension together with any previous extensions, the “total enlargement”. The guide to larger single-storey rear extensions explains the prior approval route that is unavailable here.

More than one storey and cladding

The GOV.UK technical guidance says that on Article 2(3) land an extension from a rear wall is not permitted development if it results in an enlarged part of the house with more than one storey, and the Planning Portal says all rear extensions of more than one storey need householder planning permission there. Cladding is the other trap. Under paragraph A.2, cladding any part of the exterior of the house with stone, artificial stone, pebble dash, render, timber, plastic or tiles is not permitted development on this land, whether the wall is original or new.

Materials and other Class A limits

The ordinary conditions still apply. The technical guidance states the materials condition, requiring exterior work to be of similar appearance to the existing house, and it excludes materials used in the construction of a conservatory. The Planning Portal also lists limits that apply everywhere, including that extensions cannot be higher than the highest part of the existing roof, that eaves height cannot exceed three metres within two metres of a boundary, and that only half of the land around the original house can be covered by extensions and other buildings., as explained in the guide to the 50% garden rule. Conservation areas are also Article 2(3) land, so the guide to conservatories in conservation areas and on listed buildings is relevant to houses in those locations.

FAQs

Can I build a side conservatory in a National Park in England?

Not as permitted development. The Planning Portal states that on Article 2(3) designated land all side extensions require householder planning permission.

Does the eight metre prior approval route apply in an AONB?

No. The Planning Portal says the larger single-storey rear extension limits apply only where the house is not on Article 2(3) designated land or a Site of Special Scientific Interest.

Are conservation areas covered too?

Yes. They are part of the Article 2(3) definition on the Planning Portal, and separate consent rules can apply to listed buildings.

Do the same rules apply in Wales or Scotland?

No. This guide covers England; Wales, Scotland and Northern Ireland have separate permitted development rules.

The bottom line

In England, a conservatory on Article 2(3) land, meaning National Parks, areas of outstanding natural beauty, the Broads, World Heritage Sites and conservation areas, cannot extend beyond a side wall as permitted development, is limited to the four or three metre rear limit without the prior approval route, and cannot include cladding in stone, render, timber, plastic or tiles. Checking designation early avoids a design that needs full planning permission. This is general information, not planning advice; confirm the position with the local planning authority.

Sources

This guide draws on the following primary sources, current as of 25 September 2026:

• Planning Portal, “Planning permission for extensions”
• GOV.UK, “Permitted development rights for householders: technical guidance”

Related guides

Compare Conservatories is an independent guide. We may earn a fee from some links; this never affects what we write. This article is general information, not legal or planning advice on any specific property — always confirm requirements directly with your local planning authority.