Size matters—at least it does if you’re thinking about planning and permitted development rights.
Under the rules, it’s possible for many building projects to go ahead without the need for full planning permission.
This guide explains how to navigate the rules and get your project moving.
Understanding Permitted Development Rights
Permitted development rights make some extensions to your property possible without submitting a full planning application. But there are limitations based on footprint, height, and location.
Find out if your project meets the rules.
Single-Storey Rear Extensions
If you have a detached house, you can extend up to four metres without planning permission. With prior approval, this can increase up to eight metres.
For a semi-detached or terraced house, extensions up to three metres are allowed without planning permission. With prior approval, this can extend to six metres.
Note: Prior approval involves notifying your local planning authority and may require neighbour consultation. If objections arise, the extension may not proceed under permitted development.
The team at SEH BAC are skilled in successfully negotiating these projects and are always happy to discuss how we can help you get the extension you want. Learn more about our home extensions.
Double-Storey Rear Extensions
Double-storey rear extensions face more restrictions under permitted development:
- They must not extend more than three metres from the original rear wall.
- The extension should be at least seven metres from the rear boundary.
- The roof pitch must match the existing house, and upper-floor windows on side elevations must be obscure-glazed.
Side Extensions
Side extensions under permitted development must:
- Be single-storey.
- Not exceed four metres in height.
- Be no wider than half the width of the original house.
Height and Boundary Restrictions
Regardless of extension type: The maximum height is four metres. If the extension is within two metres of a boundary, the eaves height must not exceed three metres.
Conservation Areas and Article 4 Directions
Properties in conservation areas or subject to Article 4 directions have stricter controls:
- Permitted development rights may be limited or removed.
- Side extensions may not be permitted
- Even small extensions might require full planning permission.
Always get in touch with SEH BAC first to discuss your options and ensure your plans align with current regulations.
If you live in a conservation area, our experience with planning rules and bespoke conservatory designs and modern extensions can help bring your ideas to life while staying compliant.
Other Considerations
- Materials: The extension should use materials similar in appearance to the existing house.
- Land Coverage: Extensions must not cover more than 50% of the land around the original house.
- Listed Buildings: If your property is listed, you’ll need listed building consent for any extension.
Conclusion
Understanding permitted development rights can save you time, stress, and unnecessary costs when extending your home. But it’s crucial to ensure your project fully complies with current planning and building regulations to avoid delays or enforcement issues.
At SEH BAC, we take the stress out of the process by guiding you from start to finish. Whether you’re extending a standard property or one in a sensitive area, our expert team can handle everything—from initial guidance to submitting applications and managing all the paperwork.
With our help, your extension project is much more likely to proceed smoothly, giving you complete peace of mind.
Please note: This guide is based on information available as of June 2025. Planning regulations are subject to change, so we recommend speaking to our team here to discuss your project in detail before moving forward.
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