Planning to extend your home can feel overwhelming, especially when you're trying to understand whether you need planning permission. The good news is that many single storey extensions fall under permitted development rights, meaning you can proceed without a formal planning application. However, there are specific limits and conditions you need to be aware of before breaking ground.
Understanding Permitted Development Rights for Extensions
Permitted development rights allow homeowners to make certain improvements without needing planning permission. For single storey rear extensions, you can typically extend up to 4 metres for a detached house or 3 metres for a semi-detached or terraced property. These limits increase to 8 metres and 6 metres respectively if you follow the Larger Home Extension scheme, which requires you to notify your neighbours first.
However, these rights come with important caveats. The extension cannot exceed 4 metres in height, and if it's within 2 metres of a boundary, the maximum height drops to 3 metres. The extension also cannot cover more than half of the land around the original house, and it must not extend beyond the side of the original property.
When You Definitely Need Planning Permission
Certain circumstances automatically require a planning application, regardless of your extension's size. If your property is a listed building, you'll need both planning permission and listed building consent for virtually any alterations. Similarly, if you live in a conservation area, national park, or Area of Outstanding Natural Beauty, permitted development rights are more restricted.
Front extensions almost always require planning permission, as do two-storey extensions that don't meet strict criteria. If you've already extended your property in the past, you may have used up your permitted development allowance. These rights apply to the property as a whole since 1948, not per owner, so previous extensions count against your limit.
Flats and maisonettes have virtually no permitted development rights for extensions, meaning you'll need to submit a planning application for any significant building work.
The Neighbour Notification Scheme
If you're planning a larger single storey extension under the extended permitted development rules, you must use the neighbour notification scheme. This involves submitting details to your local planning authority, who then notify your immediate neighbours. Your neighbours have 21 days to raise objections, and the council has 42 days to make a decision on whether prior approval is needed.
During this period, the council will only consider impacts like loss of light or overlooking windows. They cannot object based on design preferences or property values. If no objections are raised, or if the council doesn't respond within 42 days, you can proceed. Be aware that this process costs around £100 and adds roughly six weeks to your project timeline.
Building Regulations Still Apply
This is crucial: even if you don't need planning permission, you always need Building Regulations approval. These regulations ensure your extension is structurally sound, energy efficient, and safe. Building control will check foundations, damp-proofing, insulation, ventilation, and electrical work.
You can either apply directly to your local authority's building control department or use an approved inspector. Most builders are familiar with the process and can guide you through it, but the responsibility ultimately lies with you as the homeowner. Failing to get Building Regulations approval can make your property difficult to sell and may result in expensive remedial work later.
Getting Professional Advice and Quotes
Before committing to any extension, it's worth getting a pre-application consultation with your local planning authority. This typically costs £50-£100 and provides written advice on whether your plans are likely to succeed. It's money well spent if you're uncertain about your situation.
When selecting a builder, it's sensible to obtain at least three detailed quotes to compare not just prices but also timelines, materials, and what's included. A good builder will help you understand whether planning permission or prior approval is needed for your specific project, and many will handle the Building Regulations application as part of their service.
Ask potential builders about their experience with similar extensions and request references from recent projects. Check whether they're registered with trade associations like the Federation of Master Builders or have relevant insurance. Remember that the cheapest quote isn't always the best value – look for builders who communicate clearly and demonstrate a thorough understanding of building regulations and local planning requirements.