This is general guidance based on standard permitted development rights in England. Rules differ for listed buildings, conservation areas, and properties with Article 4 directions. Always confirm with your local planning authority before starting work.
Do I Need Planning Permission for a Single-Storey Rear Extension in Windsor and Maidenhead?
A single-storey extension built to the rear of your home, typically used to enlarge a kitchen, dining room, or living space. One of the most common home improvement projects in the UK.
Planning in Windsor and Maidenhead
69%
of planning applications granted
93%
decided within the statutory or agreed time
72%
of householder applications decided within 8 weeks
In the year to December 2025, Windsor and Maidenhead decided 1,576 planning applications. 1,008 of these were householder projects such as extensions, loft conversions and outbuildings, of which 70% were granted.
Planning statistics: MHCLG planning application statistics, the year to December 2025. Conservation area and Article 4 data: planning.data.gov.uk, © Historic England / Crown copyright. Open Government Licence v3.0.
Important: Additional Restrictions May Apply in Windsor and Maidenhead
Windsor and Maidenhead has conservation areas. If your property is in a conservation area, some or all permitted development rights may be restricted. For example, you may need planning permission for changes that would normally be permitted, including alterations to the roof, cladding, or extensions visible from a public highway.
Windsor and Maidenhead has Article 4 directions in force. Article 4 directions remove specific permitted development rights in defined areas. If your property is covered by an Article 4 direction, you may need planning permission for work that would normally be permitted. Contact Windsor and Maidenhead planning department to check whether an Article 4 direction applies to your property.
Check with Windsor and Maidenhead planning department before starting work to confirm whether your property is affected by any special designations.
Permitted Development Rules for a Single-Storey Rear Extension
Generally permitted under Part 1, Class A of the GPDO. Standard permitted development allows a maximum projection of 3m (semi-detached or terraced) or 4m (detached). Under the Larger Home Extension scheme (prior approval), this increases to 6m and 8m respectively.
Conditions
- 1Must be to the rear of the original dwelling
- 2Must not extend beyond the rear wall of the original house by more than 3m (semi/terraced) or 4m (detached) under standard PD
- 3Under prior approval (Larger Home Extension), maximum depth increases to 6m (semi/terraced) or 8m (detached)
- 4Materials must be similar in appearance to the existing dwelling
- 5Extension must not be built on land forward of the principal elevation fronting a highway
Size and Dimension Limits
- Maximum height: 4m
- Eaves height: maximum 3m if within 2m of a boundary
- Depth from original rear wall: 3m (semi/terraced) or 4m (detached) under standard PD; 6m or 8m under prior approval
When Permitted Development Does Not Apply
- Must not cover more than half the area of land around the original house (curtilage)
- Does not apply to flats or maisonettes
- Restricted or removed in conservation areas, AONB, National Parks, the Broads, and World Heritage Sites
- Listed building consent required separately for listed buildings
- Article 4 directions may remove these rights locally
What About Building Regulations?
Building regulations approval is likely required
Building Regulations approval is required covering structural stability, foundations, damp proofing, insulation (Part L), ventilation, fire safety, drainage, and electrical work. Building control will inspect at key stages.
Building regulations are separate from planning permission. Even if your project is permitted development, you may still need building regulations approval. Contact Windsor and Maidenhead building control or use an approved inspector.
How to Apply in Windsor and Maidenhead
If you need planning permission for your single-storey rear extension, you can apply through Windsor and Maidenhead's planning department or via the national Planning Portal.
If your project is permitted development and you want written confirmation, you can apply for a Lawful Development Certificate (LDC) from Windsor and Maidenhead. This provides proof that your project does not need planning permission, which can be helpful when selling your property.
What Happens If I Build Without Permission?
Building without permission when it is required can result in an enforcement notice from the council, requiring you to alter or demolish the extension. The council has up to 4 years to take enforcement action for building works. Unauthorised extensions can also cause problems when selling your property, as solicitors will check for planning compliance.
Frequently Asked Questions
Do I need planning permission for a single-storey rear extension in Windsor and Maidenhead?
Does a single-storey rear extension in Windsor and Maidenhead need building regulations?
How do I apply for planning permission in Windsor and Maidenhead?
How long does planning permission take in Windsor and Maidenhead?
What percentage of planning applications does Windsor and Maidenhead approve?
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