Quick Answer

What Is an AONB?

An Area of Outstanding Natural Beauty (AONB) is a landscape designation for areas of countryside in England, Wales, and Northern Ireland that have significant landscape value. There are 34 AONBs in England, covering around 18% of the country. Well-known examples include the Cotswolds, the Chilterns, the High Weald, the Surrey Hills, and the Peak District fringes.

In 2023, the Levelling Up and Regeneration Act renamed AONBs to “National Landscapes” — though many areas still use the AONB name and both terms refer to the same designation. National Parks are a separate, stronger designation with their own National Park Authority.

PD Restrictions in AONBs

What Is Still Permitted Development

Despite the restrictions, the following works remain permitted development in AONBs:

• Rear extensions: Single-storey rear extensions up to 4m (detached) or 3m (other houses) remain PD — the restriction on the larger home extension scheme means the maximum doesn’t increase beyond these limits
• Two-storey rear extensions: Up to 3m deep, subject to normal conditions
• Loft conversions: Rear dormers and hip-to-gable conversions remain PD (50m³ for detached/semi, 40m³ for terraced)
• Outbuildings: Garden offices, sheds, and outbuildings under Part 1 Class E remain PD
• Porches: Porches under Part 1 Class D remain PD

Applying for Planning Permission in an AONB

When PD rights don’t apply in an AONB, you need a planning application. Applications within AONBs are assessed with particular regard to the impact on the natural beauty and character of the landscape. The relevant policy test is in the NPPF: great weight should be given to conserving and enhancing landscape and scenic beauty in AONBs, and development that would have an adverse effect on the designated area should be refused.

In practice, planning applications for modest house extensions within AONBs are often approved where the design is sympathetic to the local vernacular — traditional materials, appropriate massing, and a design that doesn’t jar with the character of the area. Councils are more likely to refuse applications that introduce materials or forms inconsistent with the local building traditions.