Do You Need Planning Permission for a House Extension in the UK?

Planning permission — two words that strike fear into many homeowners. But the reality is, most rear and side extensions in the UK don't need it at all, thanks to permitted development rights. However, get it wrong and you could face enforcement action or difficulties selling your home. Here's what you need to know.

What Are Permitted Development Rights?

Permitted development (PD) rights are a national set of rules that allow you to extend your home without applying for planning permission, provided you stay within certain limits. They were designed to make minor home improvements faster and cheaper to deliver.

Under PD, most detached and semi-detached houses in England can extend to the rear by up to 4 metres (single storey) or 3 metres (double storey) without a planning application. For terraced houses, these limits are 3 metres and 3 metres respectively.

When Do You Need Full Planning Permission?

You will need to apply for planning permission if any of the following apply:

• Your home is in a conservation area, AONB (Area of Outstanding Natural Beauty), or National Park
• Your property is a listed building
• The extension exceeds PD size limits
• The extension would cover more than 50% of the curtilage (land around your home)
• Your local council has removed PD rights via an Article 4 Direction
• You live in a flat or maisonette (PD rights don't apply)
• Your home was built under a permitted development condition restricting further extension

The Neighbour Consultation Scheme

For larger single-storey rear extensions (beyond 4m for detached, 3m for others) under the Larger Home Extension Scheme, you must notify your local planning authority. Neighbours are consulted and can object. This is called prior approval — not full planning permission, but a formal process.

Do You Need a Certificate of Lawful Development?

Even if your extension falls within PD rights, it's strongly recommended to apply for a Lawful Development Certificate (LDC) from your council. This costs around £103 in England and provides legal proof that the work was lawful. Estate agents and solicitors will ask for this when you sell.

How to Apply for Full Planning Permission

1. Appoint an architect to produce planning drawings (typically £1,500–£3,500)
2. Submit your application via the Planning Portal (planningportal.co.uk)
3. Pay the fee: currently £206 for most householder applications in England
4. Your council has 8 weeks to make a decision
5. If approved, conditions may apply — read them carefully
6. Building regulations approval is still required separately

Building Regulations: Always Required

Even if you don't need planning permission, all extensions require building regulations approval. This covers structural integrity, fire safety, insulation, drainage, and electrics. Your builder should submit a Building Notice or Full Plans application before work begins.

Common Planning Mistakes to Avoid

• Starting work before checking with your council
• Assuming PD rights apply to your property without confirming
• Ignoring party wall obligations if building near a shared boundary
• Not getting an LDC — this could cause problems at sale