Understanding Permitted Development Rear Extensions: A Comprehensive Guide

Permitted development rights are a set of regulations that grant automatic planning permission for certain types of development. These rights are intended to simplify the planning process for small-scale extensions and modifications, helping homeowners improve their properties without planning permission. This guide provides an overview of the rules and regulations governing permitted development rear extensions.

What is a Permitted Development Rear Extension (Permitted Development Rights)?

A permitted development rear extension is a type of home improvement project that allows homeowners to extend the rear of their property without the need to apply for planning permission. This is possible under the UK's permitted development rights, which grant automatic planning consent for certain types of developments, provided they meet specific criteria and limitations.

Permitted development rights offer a streamlined way for homeowners in the UK to extend their properties. By understanding and adhering to the specific criteria, homeowners can avoid the need for formal planning permission and enhance their living space efficiently.

Do I Need Planning Permission? Benefits of a Permitted Development Rear Extension

What are the advantages of building a rear extension under permitted development?

Time and Cost Savings: Avoid the lengthy and costly process of obtaining formal planning permission.

Increased Living Space: Enhance your home with additional space tailored to your needs.

Improved Property Value: Extensions can increase the overall value of your property.

Regulations and Guidelines for Permitted Development Rear Extensions

To qualify as permitted development, rear extensions must adhere to several specific criteria. What are the permitted development rules?

Rear Extension Rules: Size Limits

  • Terraced or Semi-Detached House Extensions: An extension cannot exceed 3 metres from the original rear wall. After getting prior approval from the relevant Local Planning Authority regarding proposed development (by submitting a planning application), you can proceed with a larger home extension (with a depth up to 6m).
  • Detached Houses: New home extension can extend beyond the rear wall of the original property up to 4 metres.
  • Single Storey Extensions: Maximum height of 4 metres and 2 metres from the property boundary. 
  • Two Storey Extensions: Maximum height of 7 metres and depth of 3 metres, and must be at least 7 metres from the rear boundary line. Remember: the maximum eaves and ridge height can't be higher than your house. If the extension is within 2 metres of a boundary wall, the height of eaves must be no more than 3 metres.

House Extension Plans: Location

  • Must not extend beyond the principal elevation or a side elevation fronting a highway.
  • Must not cover more than half the area of land around the original house.

Rear House Extension Without Planning Permission: Height Restrictions

  • Single-storey rear extensions have a maximum height of 4 metres.
  • Two-storey rear extensions cannot exceed the height of the highest part of the roof of the existing house.

Materials

  • The materials used must be similar in appearance to those of the existing house.

Windows and Rooflights

  • Upper-floor windows on the side elevation must be obscure-glazed and non-opening unless the opening part is more than 1.7 metres above the floor.
  • Rooflights must not project more than 150mm beyond the plane of the existing roof slope.

Adding a Rear Extension in Designated Areas

  • In conservation areas, national parks, and Areas of Outstanding Natural Beauty (AONB), permitted development rights are more restricted. You can't build a side extension nor add it to your prior build rear extension.
  • If the property is listed, permitted development rights do not apply, and full planning permission is required.

Steps to Plan and Execute a Permitted Development Rear Extension

Step 1: Understand Permitted Development Rights

Before you begin, it's crucial to understand the specific criteria for permitted development rear extensions. These include size limits, location restrictions, height restrictions, and material requirements. Ensure your project falls within these guidelines to qualify as permitted development.

Step 2: Building Without Planning Permission: Verify Eligibility

Check Property Status:

  • Confirm your property is not in a designated area with restricted permitted development rights, such as a conservation area, national park, or Area of Outstanding Natural Beauty (AONB).
  • Ensure your property is not a listed building, as listed buildings do not benefit from permitted development rights.

Assess Previous Extensions: Consider any previous extensions, as permitted development rights are cumulative. The total extension area, including past projects, must not exceed permitted development limits.

Step 3: Draw Detailed Plans

Engage a Professional: Hire an architect or a professional draughtsman to create detailed plans of your proposed extension. This ensures accuracy and compliance with regulations.

Include Key Details:

  • Ensure plans show the size, height, and materials of the extension.
  • Include the relationship to existing structures and the distance from boundaries.

Step 4: Apply for a Lawful Development Certificate (Optional)

Prepare Application: Complete an application for a Lawful Development Certificate (LDC) through your local planning authority. This is optional but highly recommended for legal confirmation that your extension meets permitted development criteria.


Submit Plans and Documents: Include detailed plans and any supporting documents with your application.

Await Decision: The local planning authority will review your application and issue the certificate if your extension is compliant.

Step 5: Notify Neighbours (Larger Home Extension Scheme)

Neighbour Consultation Scheme: If your extension is larger than the standard permitted size (up to 6 metres for terraced/semi-detached houses and 8 metres for detached houses), notify your local planning authority under the Neighbour Consultation Scheme.

Local Authority Notification: The local authority will inform your neighbours and allow them to raise any objections.

Address Objections: If objections are raised, the local authority will consider them and may require modifications to your plans.

Step 6: Prepare for Construction

Hire a Contractor: Obtain quotes and hire a reputable contractor experienced in residential extensions.

Set a Timeline: Work with your contractor to establish a realistic timeline for the project.

Arrange Financing: Ensure you have the necessary funds in place to cover all project costs.

Step 7: Begin to Build an Extension

Site Preparation: Clear the area where the extension will be built and make any necessary preparations.

Construction: Monitor the construction process to ensure it follows the approved plans and meets all building regulations.

Regular Inspections: Schedule regular inspections with your contractor to address any issues promptly.

Step 8: Complete and Inspect

Final Inspection: Once construction is complete, conduct a final inspection to ensure all work meets the required standards.

Building Control Sign-Off: If necessary, have your local building control officer sign off on the completed extension to confirm it complies with building regulations.

Obtain Completion Certificate: Request a completion certificate from building control as evidence that the extension meets all necessary standards.