Thinking about extending your home but worried about planning permission? It might not be as complicated as it seems. This guide simplifies the process, helping you understand when planning permission is required and exploring your options.
At CB Building Services, we don’t just build beautiful extensions; we guide homeowners in Cambridgeshire and Hertfordshire through every stage of the project (though this guide can be for anyone in the UK). We manage the paperwork and permissions so you can focus on the exciting parts.
What is Planning Permission?
In simple terms, planning permission is the approval you need from your local council before you can start certain building work on your property. The system is in place to make sure that new developments are appropriate for their location, won’t negatively affect neighbours and are in keeping with local architectural styles.
Many home extensions don’t actually require a full planning application. Instead, they fall under what’s known as ‘Permitted Development Rights’. This is a set of government-approved rules that allow you to extend your home without needing to apply for planning permission, as long as your project meets specific criteria.
Understanding whether your project falls under Permitted Development is the first step in a smooth and successful build.
When is Planning Permission Not Required? (Permitted Development)
Permitted Development Rights cover many common home extension projects. While the rules are detailed, they offer a clear path for homeowners looking to add space. Here’s a simple breakdown for some of the most popular extension types.
Single-Storey Rear Extensions
This is one of the most common projects we undertake. A single-storey extension at the back of your house is often covered by Permitted Development if it meets these conditions:
- It doesn’t extend more than 3 metres from the rear wall of an emi-detached or terraced house, or 4 metres for a detached house. (Note: These limits can be extended to 8m and 6m respectively under the ‘Larger Home Extension Scheme’, but this requires a different notification process).
- The height of the extension does not exceed 4 metres.
- The materials used are similar in appearance to the existing house.
Double-Storey Rear Extensions
Adding a second floor to your extension requires a bit more consideration, but can still fall under Permitted Development.
- The extension cannot extend beyond the rear wall by more than 3 metres.
- It must be at least 7 metres away from the rear boundary.
- The roof pitch should match the existing house as closely as possible.
- No windows on the side elevations of the upper floor should overlook neighbouring properties.
Side Extensions
A side extension is a fantastic way to add width to your home, often creating space for a utility room or a wider kitchen.
- It must be single-storey only.
- Its width cannot be more than half the width of the original house.
- The height is limited to 4 metres.
Loft Conversions
Converting your loft is one of the most effective ways to add a room without extending your home’s footprint. Most loft conversions are considered Permitted Development.
- The additional roof space created cannot exceed 40 cubic metres for terraced houses or 50 cubic metres for detached and semi-detached houses.
- The extension cannot be higher than the highest part of your existing roof.
- Dormer windows are not allowed on the front-facing roof slope.
When Will You Definitely Need Planning Permission?
While Permitted Development covers a lot of ground, there are certain situations where a full planning application is unavoidable.
- Flats and Maisonettes: Permitted Development Rights do not apply to these property types.
- Listed Buildings: Any alteration to a listed building requires Listed Building Consent, which is a separate and more detailed process.
- Conservation Areas: If your home is in a Conservation Area, National Park, or an Area of Outstanding Natural Beauty (AONB), your Permitted Development Rights will be more restricted. For example, side extensions are generally not allowed.
- Large-Scale Projects: If your proposed extension exceeds the size limits mentioned above, you will need to apply for planning permission.
- Building Forward: Any extension that comes forward of the principal elevation (the front of your house) will require planning permission. Porches are a specific exception to this, with their own set of rules.
Our Approach: Making It Simple for You
Navigating these rules is part of our job. At CB Building Services, we manage the entire process, so you don’t have to become a planning expert overnight.
Here’s how we help:
- Initial Consultation: We start by discussing your vision. We listen to what you want to achieve with the space, which helps us advise on the best route forward.
- Feasibility Check: Our team assesses your property and plans against the local council’s policies and Permitted Development criteria. We can quickly tell you what’s likely to be possible.
- Design and Drawings: We produce detailed architectural drawings that are needed for any application, whether it’s for a Certificate of Lawfulness (to confirm your project is Permitted Development) or a full planning application.
- Application Management: We handle all the paperwork and act as the agent on your behalf, liaising directly with the local planning authority. This saves you time and removes the stress of dealing with official correspondence.
Your Next Steps
The planning system is there to ensure quality development, not to stop you from improving your home. With the right guidance, it’s a manageable part of the journey. The key is to work with experienced professionals who understand the local landscape.
As TrustMark Approved contractors and members of the Federation of Master Builders, our reputation is built on trust and quality. We take pride in creating beautiful, functional spaces that families across Cambridgeshire and Hertfordshire love to live in.
Ready to explore your home’s potential? Contact CB Building Services today for a consultation. Let’s talk about your ideas and create a clear plan to turn your vision into a reality, starting with getting the right permissions in place.