How Far Can I Extend Without Planning Permission?

Understanding the Limits and How Prior Approval Can Help

For many homeowners, the idea of extending your house comes with one big question: how far can I go before I need planning permission?

The good news is that under the UK’s Permitted Development Rights, you can often extend your home without submitting a full planning application, as long as your project meets certain size and design criteria. At Kingdom, we guide you through every stage of this process, ensuring your design complies with all requirements before work begins.

1. What Are Permitted Development Rights?

Permitted Development (PD) rights are national rules that allow homeowners to make specific types of improvements or extensions without needing full planning consent. They cover a range of works such as rear, side, and loft extensions, as long as they meet clearly defined limits.

Even if your project falls under PD, you will still need Building Regulations approval to ensure the work meets safety and energy standards.

2. How Far Can You Extend Under Permitted Development?

If your home qualifies for PD, you can typically extend:

• Detached houses: up to 4 metres beyond the rear wall.
• Semi-detached or terraced houses: up to 3 metres beyond the rear wall.
• Side extensions: must be single storey, no higher than 4 metres, and no wider than half the width of the original house.

The extension must be built using materials similar in appearance to the existing property, and the total area of ground covered by extensions must not exceed 50% of the original garden.

If your home is in a Conservation Area, a National Park, or has had PD rights removed, you will need to apply for full planning permission before building.

3. How to Extend Further with Prior Approval

If you want to go beyond the standard PD limits, you may be able to use a process called Prior Approval (also known as the Larger Home Extension Scheme).

With Prior Approval, you can extend up to:

• 8 metres for detached houses.
• 6 metres for semi-detached or terraced houses.

This process still falls within PD but requires formal notification to your local planning authority. The council will notify your neighbours and review the proposal within 42 days. If no objections are raised or the council approves, you can proceed.

The current application fee in England is around £325, which is often much less time-consuming and expensive than submitting a full planning application.

4. When Planning Permission Is Required

You will need full planning permission if:

• The extension exceeds the PD limits for height, depth, or overall volume.
• The work involves a listed building or a property in a Conservation Area.
• The property has already reached its PD allowance through previous extensions.
• The design significantly alters the front of your home or its relationship with the street.

Kingdom will always confirm these details before any design is finalised, ensuring your project starts on solid legal ground.

5. Why It Pays to Get Professional Advice

The planning system can feel complex, but the right guidance makes it straightforward. At Kingdom, our design and build team checks every project against PD limits, local planning policies, and conservation constraints before any drawings are submitted.

We also help you apply for a Lawful Development Certificate, which acts as written proof that your extension met all regulations. This certificate can be invaluable if you sell your home later.

6. Key Takeaway

You can often extend your home further than you think without needing full planning permission. The key is careful design, early checks, and clear documentation.

Kingdom’s experienced team manages all of this for you, so your build can begin confidently and compliantly.

✉️ Need expert help understanding your limits? Want guidance checking PD rules, preparing drawings, or navigating Oxfordshire’s planning process? Get in touch and we’ll map the simplest route to approval.