Do you need planning permission for a single storey extension?

A guide to permitted development rights in 2025

If you’re considering a single-storey extension to improve your home, you may be wondering whether you need planning permission or if your project falls under permitted development rights. These rights are a valuable tool for homeowners, offering the chance to enhance their living spaces without the time and cost of a full planning application. However, understanding the specifics is essential to ensure your project remains compliant.

In this article, we will explore what permitted development rights are, the rules for single-storey extensions, and when planning permission might be required.

What Are Permitted Development Rights?

Permitted development rights are a set of government regulations that allow homeowners to carry out certain types of building work without needing to apply for planning permission. These rights are intended to streamline minor home improvements while maintaining a balance with the character of the surrounding area.

It’s important to note that permitted development rights only apply to houses, flats, and maisonettes. Commercial buildings are excluded. Additionally, if your property is in a conservation area, a National Park, or is a listed building, these rights are often restricted or removed entirely.

The Rules for Single-Storey Extensions

To qualify under permitted development, a single-storey extension must meet specific criteria. These rules are designed to ensure the extension doesn’t negatively impact your neighbours or the character of your property. Here’s what you need to know:

Size and Scale

• Depth: The extension can extend up to 3 metres from the rear wall for semi-detached or terraced houses and up to 4 metres for detached houses. However, under the Neighbour Consultation Scheme, larger extensions up to 6 metres (for semi-detached/terraced) or 8 metres (for detached houses) may be allowed.

• Height: The maximum height of the extension must not exceed 4 metres. Additionally, the eaves height must not be higher than the eaves of the existing house.

Positioning

• Extensions cannot extend beyond the principal elevation (the front) of the property.

• Side extensions are allowed under permitted development but must not exceed half the width of the original house.

Land Coverage

No more than 50% of the land around the original house (as it stood in 1948) can be covered by new additions. This includes other buildings and structures like sheds and garages.

Materials

The materials used for the extension must be similar in appearance to the existing property. This ensures that the new addition blends seamlessly with your home.

Windows and Privacy

Windows on side elevations must be obscure-glazed and non-opening if they are within 1.7 metres of the property boundary.

Exceptions to Permitted Development

Even if your plans seem to meet the above criteria, there are certain situations where permitted development rights may not apply:

• Listed Buildings: Any alterations to listed properties require listed building consent, regardless of size or scope.

• Conservation Areas: In these areas, restrictions often prevent extensions that alter the appearance of the property.

• Article 4 Directions: Local councils can issue Article 4 directions to remove permitted development rights in specific areas.

The Neighbour Consultation Scheme

If you’re considering a larger rear extension that exceeds the standard depth limits but falls within the limits of the Neighbour Consultation Scheme, you’ll need to notify your local planning authority. They will consult your neighbours, giving them the opportunity to raise objections. If no objections are received, or if objections are deemed unfounded, the extension can proceed.

Planning Permission vs. Permitted Development

If your extension does not meet the permitted development criteria, you will need to apply for planning permission. While this can seem daunting, it provides an opportunity to create a more ambitious design tailored to your needs. It’s worth consulting with us to ensure your plans comply with local planning policies and to maximise the potential of your extension.

Why Choose a Single-Storey Extension?

Single-storey extensions are a practical and cost-effective way to add space to your home. Whether you want to create a larger kitchen, a bright and airy dining area, or a dedicated home office, a well-designed extension can transform the way you use your property. With careful planning, it can also enhance the value of your home, making it a sound investment for the future.

How We Can Help

At CWJ Architecture, we have extensive experience in designing single-storey extensions that maximise space, light, and functionality. We can guide you through every stage of the process, from initial concepts and planning advice to detailed drawings and construction oversight. Whether you’re looking to navigate permitted development rules or submit a planning application, I’m here to help.

Get Started Today

If you’re ready to bring your extension ideas to life, get in touch. We would be delighted to discuss your project and help you create a space that works for you and your family.