When do you need planning permission for an extension?

Last Updated: 7 December 2023

Understanding when you need planning permission for an extension in the UK can be complex. This article aims to simplify these regulations, providing clear guidance for homeowners and builders. We will explore the key situations that require permission and those falling under permitted development. 

Our focus is to demystify the rules, helping you confidently plan your property’s expansion. From small kitchen extensions to larger projects, we’ll cover what you need to know to stay compliant with UK planning laws.

Here’s a summary of the key points as of 2023

Permitted Development Rights

Many extensions can be done under ‘permitted development’ rights, which means they don’t require formal planning permission. This includes certain sizes of extensions for different types of houses. For instance, in England, single-storey extensions to the rear of a house can be 3m deep for terraces and semi-detached homes, or 8m deep for detached houses​​.

Single-Storey Extension Rules

These include limits on the area covered by the extension relative to the original house, restrictions on the materials used, and height limits. For example, an extension cannot exceed four meters in height and must not cover more than half the area of land around the original house​​.

Two-Storey Extension Rules

The rules are more restrictive for two-storey extensions, such as not extending past the back wall of the house by over three meters, and having a maximum eaves height of three meters if within two metres of the boundary. The materials and appearance should be in line with the existing property​​.

Side and Rear Extension Rules

For side extensions, there are height limits and restrictions based on the width relative to the original property. Rear extensions have limitations on how far they can extend beyond the rear wall of the original property​​​​.

Terraced and Semi-Detached House Rules

For these types of properties, the extension rules under permitted development rights allow for extensions up to 3m without needing planning permission. However, rules can vary by council, and certain angles and distances from neighbours must be respected​​.

Detached House Rules

Detached houses have more lenient rules under permitted development, with possible extensions up to 4m or 8m under certain conditions. However, like other types, these are subject to local council guidelines and other considerations​​.

Certificate of Lawful Development

It’s often advisable to apply for this certificate, which proves your project complies with permitted development rights, especially if you plan to sell the property later​​.

Planning Applications

If your extension doesn’t fall under permitted development or if you’re in a conservation area or designated land, you’ll likely need to apply for planning permission. This process can vary by council and is influenced by the Local Plan of the area​​.

Conservation Areas

In conservation areas, there can be specific requirements or preferences regarding the style and materials of the extension. It’s important to understand the specific requirements of your area​​.

Party Wall Act

This may apply if your project is close to neighbouring properties and involves shared walls or boundaries. In such cases, you need to inform affected neighbours of your plans​​.

Do you need planning permission to build a conservatory or an orangery?

Building a conservatory or an orangery often falls under ‘permitted development’ rights, meaning you might not need to apply for planning permission, provided certain conditions and limitations are met. These conditions typically include:

  • Size and Scale: The conservatory or orangery must not cover more than half the area of land around the ‘original house’. The ‘original house’ means as it was first built or as it stood on 1 July 1948 (if it was built before that date).
  • Height Restrictions: The conservatory or orangery should not be higher than the highest part of the roof of the existing house. For a single-storey conservatory, the height should not exceed four metres.
  • Depth Limitations: For rear conservatories or orangeries, there are depth limits – these are generally 3 metres for terraced and semi-detached houses and 4 metres for detached houses.
  • Side Extensions: If the conservatory or orangery is to the side of the house, it should not make up more than half the width of the house.
  • Design and Appearance: The materials used in the construction should be similar in appearance to the existing house.
  • Listed Buildings and Conservation Areas: If your house is a listed building or in a designated area (like a conservation area or an area of outstanding natural beauty), you will likely need to apply for planning permission.
  • Neighbour Consultation Scheme: For larger conservatories or orangeries (under certain dimensions allowed by the extended permitted development rights), you might have to notify your local planning authority and submit to the Neighbour Consultation Scheme.

Do I need building regs approval for my Orangery or Extension?

If you are opening up your existing house to the new extension or Orangery and not having an external grade door between the two rooms you will need building regs approval. You will also need building regs approval if the new room remains separate from the house but does not have the required amount of glass in the frames or roof to be called a conservatory.

Building regs is different to planning as it doesn’t depend on the size, it really depends on how it’s linked to your home. It is not something to be worried about as the process is very simple and we make all of the arrangements on your behalf. The building inspector will want to see the new building at various stages to check the quality of the ground and also see plans of what’s being proposed. 

There will also be a need for energy rating calculations, known as SAP calc’s, to make sure the new extension or Orangery doesn’t detract or worsen the overall performance of the energy efficiency of your home, again this is all taken care of by us prior to the building of your new room. 

By ensuring the build is built on the correct foundations and to the correct specification you are ensuring that you get the maximum enjoyment out of the room all year round and its always best to enlist professionals to make sure this happens.

Do you need planning permission to change your doors or windows?

Changing doors and windows in your home usually don’t require planning permission, especially if you’re replacing them with ones of a similar appearance. However, there are certain situations where planning permission may be required:

  • Listed Buildings: If your home is a listed building, you will almost certainly need to obtain listed building consent for any significant changes, including replacing windows and doors.
  • Conservation Areas: If your property is in a conservation area, there might be specific rules about changing external aspects of your home. It’s advisable to check with your local planning authority.
  • Article 4 Directions: Some areas are subject to Article 4 Directions which restrict certain changes that could usually be performed without planning permission. This might include changing windows and doors.
  • New Openings or Significant Alterations: If you’re creating new window or door openings, or significantly enlarging them, you might need planning permission.
  • Flats and Maisonettes: If you live in a flat or maisonette, different rules apply and you might need planning permission for changes that would not be in a detached, semi-detached, or terraced house.

Always check with your local planning authority if you’re unsure, as regulations can vary and it’s important to be certain before undertaking any work.

At Reddish Joinery, we specialise in creating bespoke windows, doors, conservatories, and orangeries that not only enhance the beauty of your home but also comply with all necessary regulations. Our team is here to assist you every step of the way, from design to installation.
Should you have any queries or require personalised advice for your specific project, please don’t hesitate to get in touch with us. Contact us on 0161 969 7474 or send an email to sales@reddishjoinery.com. Let us help you bring your vision to life with our expertise and bespoke solutions.

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