Permitted development extension

Last updated: March 2024 | 3 min read

Embarking on a home extension? Explore our insights on permitted development rights to see if you need planning permission. We also cover how to maintain good relationships with neighbours and understand fencing regulations, ensuring your extension is legally compliant and neighbour-friendly.

Understanding permitted development for home extensions

Key principles of permitted development rights

Defining the scope of permitted development

Permitted development rights allow you to extend your home without the need for full planning permission. These rights are subject to certain conditions and limits, ensuring developments are in harmony with their surroundings.

In the UK, these rights form part of national policy frameworks but can be modified or withdrawn by local authorities.

Single storey rear extension under permitted development

Designated land and impact on rear extensions

On designated lands, including national parks and conservation areas, permitted development rights are more restricted. If your property is in these areas, single storey rear extensions may require planning permission, or face stricter limits on size and design.

Listed buildings and permitted development implications

For listed buildings, permitted development rights are limited. Extensions or alterations to such properties usually require both planning permission and listed building consent, reflecting the need to preserve their historic character.

Dealing with highways and permitted materials

Extensions close to highways must consider visibility and access issues. Materials used in the extension should match or complement the existing house, maintaining aesthetic cohesion in the neighbourhood.

Height and depth limits for a single storey rear extension

Single storey rear extensions must adhere to height and depth restrictions. The maximum height allowed is four meters, and the extension must not extend beyond the rear wall of the original house by more than eight meters for detached houses, or six meters for other houses.

Expanding your home: Two storey rear extensions and beyond

Criteria for two storey rear extensions under permitted development

Two storey extensions bring a new dimension to residential expansions. Your extension must remain within a certain distance of the original house's rear boundary. The materials used should match the existing house, maintaining the visual consistency of the property.

Furthermore, any upper-floor window in a side elevation must be obscure-glazed, and non-opening if less than 1.7 meters above the floor level. These requirements ensure privacy and minimize light pollution for your neighbours.

Assessing the impact on neighbouring properties

Evaluating the potential impact on neighbours is a key step. The Neighbour Consultation Scheme comes into play here. This scheme allows neighbours to voice any concerns about your proposed development. It’s a vital process for maintaining good relations and ensuring your project aligns with community interests.

Maximising space while adhering to restrictions

Many homeowners aspire to maximize their living space. To do this within permitted development rules, one must understand the limitations. For instance, two storey extensions must not exceed three meters beyond the rear wall of the original house. Additionally, roof pitch must, as far as practicable, mimic that of the existing house. These constraints guide the design, ensuring it complements the existing structure and surroundings.

Strategies to navigate permitted development restrictions

Using the neighbour consultation scheme effectively

The Neighbour Consultation Scheme serves as a tool for homeowners planning a single storey rear extension. It requires you to inform adjoining neighbours about your proposed development.

This consultation is a prerequisite for projects extending beyond a specified depth. Your neighbours have 21 days to raise concerns. If objections arise, the local authority evaluates the impact on the amenity of adjoining properties. No objections mean you can proceed under permitted development rights.

Securing a lawful development certificate for peace of mind

Step-by-step process to obtain a lawful development certificate

Applying for a Lawful Development Certificate (LDC) is a proactive step to ensure your extension project complies with permitted development rules. Start by submitting detailed plans of your proposed extension to the local authority, including measurements and materials.

The local authority's assessment focuses on whether your project fits within permitted development criteria. Obtaining an LDC, though not mandatory, is advisable as it officially confirms the lawfulness of the work, a valuable asset if you later decide to sell your property.

Financial considerations for your extension project

Estimating the cost of a rear extension

Cost estimation for a rear extension requires considering several factors. The size and complexity of the extension, chosen materials, and geographical location influence the overall cost. For a single storey extension, typical costs per square metre vary widely.

Remember, additional expenses such as professional fees for architects or surveyors, and potential VAT, add to the final cost. It's advisable to obtain multiple quotes for a realistic budget framework.

Exploring funding options for your extension

Several funding options exist for financing your extension project. Savings are the most straightforward method, ensuring no additional debt. If savings are insufficient, a home improvement loan or remortgaging can provide the necessary funds.

Each option has its merits and drawbacks, such as interest rates and repayment terms, so thorough research and financial advice are recommended before making a decision.

Practical advice for managing local authority interactions

Understanding the prior approval process

Prior approval plays a pivotal role in permitted development extensions, especially for larger projects. This process involves notifying your local planning authority of your planned extension. It's less rigorous than a full planning application, yet it remains essential.

The authority evaluates potential impacts, such as on neighbouring properties or the broader environment. You submit a written description, including dimensions and information on the materials used. This clarity helps prevent later disputes or misunderstandings.

Engaging with your local planning authority

Effective communication with your local planning authority is the key to a smooth prior approval process. Start by understanding their specific requirements. Each authority may have unique guidelines or preferences.

Early engagement, preferably in person or via a detailed written query, helps align your plans with their expectations. Be prepared to adjust your plans based on their feedback. This proactive approach fosters a cooperative relationship, which is invaluable for resolving any issues that may arise during your project.


What size extension is allowed under permitted development?

You're likely wondering about the size limits for extensions under permitted development. For a rear extension on a detached house, the depth limit is 8 meters. In semi-detached houses or other house types, this limit is 6 meters.

Single-storey extensions must not exceed 4 meters in height. Two storey rear extensions, however, should not extend beyond 3 meters from the original house's rear wall. Always remember, if your property is on designated land or a conservation area, these rules can vary.

How to ensure your extension complies with permitted development?

Ensuring compliance with permitted development for your house extension involves a few critical steps. Firstly, check if your property is on designated land, including conservation areas, world heritage sites, or areas of outstanding natural beauty, as different rules may apply. Your extension should not cover more than half of the land around the original house, and materials used should be similar in appearance to the existing house.

Additionally, side extensions must not exceed 4 meters in height and should not be closer to the road than the principal elevation of the original house. Acquiring lawful development certificates can offer you peace of mind by confirming that your extension complies with these regulations.

What happens if you extend beyond permitted development limits?

If your extension exceeds the limits of permitted development, you're stepping into territory where planning permission becomes necessary. Failing to apply for planning permission for a larger extension could result in enforcement action from your local planning authority. This could mean having to modify or even demolish the extension.

If you're considering a larger or more ambitious project, such as a two storey rear extension or a wraparound extension, it's advisable to consult your local authority or a planning professional beforehand. They can guide you on whether your project needs planning permission and help you through the application process.

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