Living in or near an Area of Outstanding Natural Beauty (AONB) comes with the privilege of being surrounded by protected natural landscapes, but it also means more restrictions when it comes to home improvements.

While permitted development (PD) rights still apply in AONBs, they are more limited than in other areas to preserve the natural character.

This guide explains the key rules for household development under PD in an AONB and outlines which works might require planning permission.‍

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What is an AONB?

An Area of Outstanding Natural Beauty (AONB) is a designated landscape in the United Kingdom that is protected for its exceptional natural beauty and environmental significance.

Distinct from National Parks, these areas encompass a variety of landscapes, from coastlines and moorlands to rolling hills and valleys, and are home to important wildlife habitats.

The national bodies that represent AONBs in the UK are: Natural England, NatureScot, Natural Resources Wales, and the Northern Ireland Environment Agency.

There are 46 AONBs in total and the National Association for Areas of Outstanding Natural Beauty (NAAONB) represents the interests of all AONBs in the UK.

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The Kent Downs, an Area of Outstanding Natural Beauty.

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Permitted Development in an AONB

PD rights do apply in AONBs, but they come with additional restrictions compared to other areas. Some key points to consider include:

Domestic Extensions

• Side extensions are not allowed under PD rights in an AONB.
• Two-storey extensions are not permitted.
• Rear extensions are limited to 4 metres for detached houses and 3 metres for other dwellings.
• Extensions must not exceed the height of the existing house.
• Materials used should be similar in appearance to the existing house.

Outbuildings and Garden Rooms

• They must be single storey and "incidental to the enjoyment of the dwellinghouse".
• There is a maximum height of 4 metres for a dual-pitched roof, or 3 metres for other roof types.
• If within 2 metres of a boundary, there’s a maximum height of 2.5 metres, regardless of the roof profile.
• The total area of an outbuilding more than 20 metres from the house must not exceed 10 square metres.
• The total area of the outbuildings must not exceed 50% of the total area of the curtilage.
• Outbuildings cannot be built forward of the principal elevation of the original house.

Change of Use

• Class Q permitted development rights (converting agricultural buildings to dwellings) are not available in an AONB.

Sustainable heating

• Solar panels and heat pumps are generally allowed under PD rights in an AONB.

PD rights vary slightly across the UK, so check the specific guidance for your country.

Note that PD rights in relation to alterations and extensions only apply to houses. Flats, maisonettes and other properties are exempt. If you live in a listed building, you may need listed building consent to alter your home.

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In an AONB, converting agricultural buildings to dwellings requires planning permission. Photo by Clementine Blakemore Architects.

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Additional Restrictions

Before continuing under PD, check whether there are any additional restrictions in your local area. AONBs are classified "article 2(3) land," which means they have special protected status.

Local Planning Authorities (LPAs) can use Article 4 directions to remove specific PD rights in AONBs if they feel it is necessary to protect the area's character.

You can check if there’s an Article 4 direction on your land through your local authority’s planning website.

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Minor Works Requiring Planning Permission

In AONBs, certain minor works that would usually fall under PD may require planning permission.

Some examples include:

• Any extension higher than a single storey.
• Alterations to roofs, including the installation of dormer windows.
• Changes to the external cladding.

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Planning Permission vs Permitted Development in an AONB

Development in AONBs that falls outside of PD rights is controlled by local planning authorities who typically have specific policies and guidelines for AONBs. During a planning application they will consult with:

• The AONB management team
• Relevant national bodies
• The local community

At the end of the consultation process, the LPA has the final say on proposals.

In contrast, PD developments do not undergo this same level of scrutiny and are assessed based on the guidelines in the General Permitted Development Order (GPDO).

As a result, PD offers a much more streamlined planning process.

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New-build homes in an AONB need to be of exceptional design quality. Project by Oliver Leech Architects. Photo by Jim Stephenson.

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Apply for a Lawful Development Certificate

Even if you are confident that your development falls under PD rights, it's advisable to apply for a Lawful Development Certificate (LDC). This provides peace of mind by confirming that your proposal meets PD guidelines. It’s also useful for mortgage lenders and potential future buyers.

The fee for an LDC is half the cost of a full planning application, and a decision is usually made within eight weeks.

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READ: How Much Does Planning Permission Cost in the UK?

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Permitted Development AONB Checklist

If you're considering building under permitted development in an AONB:

• Check with your local planning authority before starting any work, as PD rights may be restricted.
• Familiarise yourself with PD guidelines specific to your area.
• Apply for a Lawful Development Certificate for added assurance.

AONBs are protected for their natural beauty, with strict planning controls to prevent low quality development. It's essential to seek professional advice or consult your local planning authority before embarking on any development project within an AONB.

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The information provided in this article is intended for general guidance and educational purposes only. For specific expert advice on your project, consult a skilled residential architect featured on Designs in Detail.

About the Author

Aron Coates is an architect with over two decades of experience, working on projects ranging from historic building restoration to contemporary home design.

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