Planning Permission for House Extensions

Do you need planning permission for an extension?

Planning permission is a necessary legal requirement for a range of construction projects in the UK, including house extensions. Planning permission is required to ensure that the proposed development is appropriate for its intended use, and that it complies with local planning policies and regulations. In this blog post, we will explore planning permission for house extensions in the UK and provide a comprehensive guide to help you understand the process and requirements.

House extensions are a popular way to add space and value to a property, but they are also subject to certain restrictions and regulations. It’s important for homeowners to understand these regulations and seek the necessary planning permission before beginning construction. Failure to obtain planning permission can result in costly fines and legal action.

We will cover the types of planning permission required for house extensions, the process for obtaining planning permission, permitted development rights, common issues and challenges that you may face, and provide some final thoughts and advice for those considering a house extension.

House extension under construction

Understanding Planning Permission

Planning permission is a legal requirement that applies to a wide range of construction projects in the UK, including house extensions. It is the process of obtaining approval from the local planning authority (LPA) for a proposed development, which ensures that it complies with local planning policies and regulations.

There are two types of planning permission that may be required for a house extension: full planning permission and householder planning permission.

Full planning permission applies to major developments, such as new buildings or substantial extensions, and involves a more detailed application process. Householder planning permission is required for smaller-scale projects, such as house extensions and minor alterations, and involves a simpler application process.

To obtain planning permission for a house extension, the extension project must meet certain criteria and provide detailed plans and specifications for the proposed development. These criteria may include factors such as the impact on the local area, the size and design of the proposed extension, and any potential impact on neighbouring properties.

The application process for planning permission typically involves the submission of detailed plans and specifications to the local council, along with an application fee. The LPA will then review the application and consider factors such as the impact on the local area, the design and materials used, and any objections or comments from neighbours and other interested parties.

If the application is approved, the homeowner will receive a planning permission notice, which sets out the conditions of the permission, such as any restrictions on the design or use of the extension. If the application is refused, you can appeal the decision or make changes to the proposal and resubmit the application.

Discussing planning application

Planning Permission Process for House Extensions

The process for obtaining planning permission for a house extension can be broken down into several steps.

While the exact process can vary depending on the location and nature of the proposed development, the following steps provide a general overview of what you can expect:

1. Determine if planning permission is required: Check with the local planning authority (LPA) to determine if planning permission is required for the proposed extension. You can also consult the government’s Planning Portal for guidance on planning permission requirements.

2. Consult with a planning consultant: Depending on the nature and size of the project you may wish to consult with a planning consultant to ensure that the plans meet local planning policies and regulations, and can also help to address any concerns or objections raised by the LPA or neighbouring properties.

3. Prepare and submit an application: Prepare and submit an application for planning permission to the local planning authority. The application should include detailed plans and specifications for the proposed extension, along with any other relevant information requested by the LPA. An application fee will also be required.

4. Wait for a decision: The LPA will review the application and consider factors such as the impact on the local area, the design and materials used, and any objections or comments from neighbours and other interested parties. This process can take several weeks or even months, depending on the complexity of the application and the workload of the local planning office.

5. Receive a decision: If the application is approved, you will receive a planning permission notice, which sets out the conditions of the permission, such as any restrictions on the design or use of the extension. If the application is refused, you can appeal the decision or make changes to the proposal and resubmit the application.

6. Commence construction: Once planning permission has been obtained, the homeowner can commence construction of the extension. It is important to ensure that the construction adheres to the plans and conditions set out in the planning permission notice.

It is important to note that failure to obtain planning permission for a house extension can result in costly fines and legal action. You should also be aware that there may be additional permits or approvals required, such as building regulations approval, before construction can begin.

House extension and renovation in progress

Requirements for a House Extension Planning Application 

Some of the documents required for a planning application include, but are not limited to:

  • Completed application form – This is usually filled in online via the planning portal.
  • Ownership certificates and notices / Agricultural holdings certificate  – This is usually filled in online via the planning portal.
  • Appropriate Fee – This is payed for via the Planning Portal
  • Location plan
  • Design and Access statement
  • Existing and proposed elevations
  • Existing and proposed floor plans including roof plans
  • Existing and proposed sections
  • Surface water drainage assessment – This is required if the existing house or garden are at risk of flooding. 
  • Tree Survey/Arboricultural Implications – This is required if there are any trees near to the proposed extension. 
  • Heritage statement – If the house is near a listed building or a conservation area, a simple heritage statement may be required by the Local Authority. 
  • Other documents may be requested following the submission. 
drawing plans for planning permission

​Permitted Development Rights

In some cases, you may not need to obtain planning permission for the proposed house extension. This is because you may have “permitted development rights”, which allow certain types of development to be carried out without the need for planning permission.

Permitted development rights apply to a wide range of construction projects, including house extensions, loft conversions, and certain types of outbuildings. However, the specific rules and regulations around permitted development can vary depending on the location and nature of the proposed development.

We will explore permitted development rights in more detail in a separate article. 

It is important to note that even if the proposed house extension meets the criteria for permitted development rights, they may still need to obtain other permits or approvals, such as building regulations approval.

Planning Permission for House Extensions

Pre-Application Advice

For more complicated applications, local authorities recommend a pre-application submission. This is a confidential consultation with the Local Planning Authority (LPA) to discuss the application. The negatives of this is that the process comes at a cost, usually based on the size of the proposal and that it is not binding for the LPA. You can get positive feedback on an application at pre-application stage and it can be refused once submitted for a full planning application.

The positives of this type of application is that you can begin dialoguing with the LPA at a much earlier stage. This can help put together a more specialised design team, know exactly what extra documentation will be needed and it can also save time in the Planning Permission application process as you are submitting a proposal which the LPA has already seen and in theory approves of.

Planning permission meeting for house extension

Common Issues and Challenges

While the planning permission process for house extensions can be straightforward in some cases, there are a number of common issues and challenges that you may encounter. These include:

1. Planning constraints: You may face planning constraints due to the location of their property, such as being in a conservation area, national park, or area of outstanding natural beauty. These areas may have stricter planning regulations and may require additional permits or approvals before any development work can be carried out.

2. Design and aesthetics: The design and aesthetics of the proposed house extension may be a concern for the local planning authority. You should consider the impact that the extension may have on the surrounding area, such as the appearance of the property from the street or the effect on nearby properties.

3. Neighbour objections: Neighbours may object to the proposed house extension, either due to the design, the impact on the surrounding area, or concerns about privacy and light. In some cases, these objections may result in the planning application being denied or delayed.

4. Building regulations: The project may need to comply with building regulations, which set out the technical standards for construction work. These regulations cover areas such as fire safety, ventilation, insulation, and structural stability, and must be adhered to regardless of whether planning permission is required.

5. Cost: Planning permission and building works can be expensive, and this should be considered before beginning the planning permission process. This may include the cost of the application, the cost of professional advice, and the cost of the construction work itself.

rear house extension

Some Common House Extension Planning Questions

 

Do you need building regulations for an extension?

Most extensions will require approval under the Building Regulations. You will likely require approval if work is being carried out on any of (but not limited to) the following areas in the house extension plan:

  • Doors and windows
  • Drainage
  • Electrics
  • External walls
  • Kitchens
  • Bathrooms
  • Internal walls
  • Roofs

 

Do you need to consider Part O for a house extension?

Approved document Part O applies to new residential buildings, and there is no reference to extensions of existing dwellings. 

However, it is still recommended to be mindful of some of the main requirements of Part O. 

Reasonable provision must be made in respect of a dwelling to limit unwanted solar gains in summer, and provide adequate means to remove heat from the indoor environment.

To limit solar gains, Part O sets out requirements for the maximum glazing area of the building, along with shading provisions for buildings in high risk locations. 

Strategies mentioned in Part O for reducing overheating risk and limiting solar gains include shutters, external blinds, overhangs and awnings. 

Glazing design should consider size, orientation, g-value and depth of window reveal. 

Other considerations include the placement of balconies and other shading provided by adjacent buildings, structures or landscaping.

The removal of excess heat can be achieved by any of the following means:

  • opening windows (particularly effective with cross ventilation)
  • ventilation louvres in external walls
  • a mechanical ventilation system
  • a mechanical cooling system

 

What is a lawful development certificate?

A lawful development certificate (LDC) can be considered where it is in question whether the house extension project falls under permitted development rights or not. For peace of mind, an application for a lawful development certificate can be made. This can be useful if small works are carried out on the property that did not require planning permission, but you would like to prove the development was lawful – especially if you decide to sell the property later. 

 

What if the house is in a conservation area?

These are areas designated as being of special architectural or historic interest, the character or appearance of which it is desirable to preserve or enhance. The Planning (Listed Building and Conservation Areas) Act 1990 creates special requirements for areas designated as conservation areas. Conservation area controls apply in addition to normal planning legislation.

Any desktop research done on a site should reveal if a building is within a conservation area. This information is usually found on a council’s website within the Local Plan and Planning Policy documents or in the form of a policy map.

Small changes to a building that would otherwise fall under permitted development rights such as adding an extension, installing dormer windows or satellite dishes may not be permitted in conservation areas without planning permission. Cutting down or lopping trees is also restricted in these areas as the local authority may consider whether the tree contributes to the character of the conservation area. Any proposed developments must also preserve or enhance the special architectural or historic character of the conservation area. This is not so relevant if the extension is at the rear but any side extensions or those visible from the street must preserve or enhance the character. 

 

Do I need planning permission for a side or rear extension?

Many side and rear extensions are built without planning permission as they fall under permitted development rights. The permitted development rights have various criteria that specifies whether or not the extension is lawful without planning permission. A single storey rear extension will often be acceptable under permitted development as long as it falls under the stipulated dimensions. 

We will cover permitted development requirements in more detail in a separate article. 

 

Do permitted development rules apply to all house extensions?

Permitted development rights do not apply to flats, maisonettes, listed houses and home located in conservation areas, or areas of outstanding natural beauty – in these instances a full planning application would be required. 

 

Do I need planning permission for a single storey extension?

A single storey extension to the rear will often be acceptable under permitted development as long as it falls under the stipulated dimensions. Two storey extensions will require planning permission if they are on designated land, ie, conservation areas, areas of outstanding natural beauty, world heritage sites, or the property is listed. Other factors considered are roof pitch, ridge height, maximum height, along with other specific limitations.

The planning portal provides in depth information on all types of extensions, and whether planning permission is required including:

  • one storey extension
  • two storey extension
  • side extension
  • terraced house
  • detached house
  • semi detached house
  • and more…
Completed House Extension

Conclusion

In summary, the planning permission process for house extensions in the UK can be complex and requires careful consideration and planning. It is an essential step in ensuring that any development work is carried out safely, legally, and in a way that is considerate to the surrounding area and community.

Author

Written by Emma Walshaw, Architectural Technologist and founder of First In Architecture and Detail Library. Emma has written a number of books about construction and architectural detailing.

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4 Comments

  1. Hi Emma,

    I just read this document and found it very useful for my projects in practice.

    And I am sure I will be referring to it.

    Well done and thank you.

    Reply
    • Hi Gordon

      Many thanks for your kind words and for being a FIA reader, we hope our content has been helpful in your projects! 🙂

      Best wishes,
      FIA team

      Reply
  2. Yes, a god and clear read, and I really liked that you pointed out the advantages of “considering” Part O (Overheating) in extensions.

    Reply
    • Many thanks John, we are glad to hear you found the article useful 🙂

      Best wishes,
      FIA team

      Reply

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