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01.03.2024

Understanding Planning Permission for your Building Project

Applying for Planning Permission and understanding how to present your extension, loft conversion or Class Q development can seem like a bit of a minefield. Each Local Authority has their own individual ‘Development Plan’ with varying policies which can be time-consuming to navigate. Based in Devon, our team of architects aim to eliminate any uncertainty by dealing with all aspects of the application. Whilst we can’t guarantee the final result, we use our knowledge and skills to do everything possible to ensure a positive outcome. This can involve anything from producing planning drawings, 3D sun-path modelling, written design statements, obtaining third party reports, producing visibility splays and collating any other supporting information, depending on the nature of the project. So, whether you’re extending your existing property, building your dream home or are planning a larger scale development, read on to find out more about planning permission for your unique project.

Permitted Development


There are many alterations and works to residential properties that can be undertaken without the need for planning consent at all. These are often called ‘Permitted Development’ rights and cover various types of building projects from extensions and loft conversions to external outbuildings and garden rooms. These rights come from a ‘general planning permission’ granted by national legislation set by the government.
Single Storey Extension

An extension or addition to your house is considered a permitted development, providing the following limits & conditions are met:

  • On designated land including National Parks, Areas of Outstanding Natural Beauty, Conservation Areas and World Heritage Sites, cladding of any part of the exterior with stone, artificial stone, pebble dash, render, timber, plastic or tiles is not permitted development.

  • Extensions (including previous extensions) and other buildings must not exceed 50% of the total area of land around the original house. The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Sheds and other outbuildings are included in the 50% limit.

  • Extensions forward of the principal elevation or side elevation of a house and fronting a highway are not permitted development.

  • On designated land, side extensions are not permitted development.

  • Materials used in exterior work must be similar in appearance to those of the exterior of the existing house, except a conservatory.

  • Side extensions must not have a width greater than half the width of the original house.

  • Side extensions are to be single storey with a maximum height of four metres.

  • If the extension is within two metres of a boundary, the maximum eaves height should be no higher than three metres.

  • A single storey rear extension must not extend beyond the rear of the original house by more than 3m if an attached house or by 4m if a detached house.

  • A single storey rear extension must not exceed a height of four metres.

  • The maximum eaves and ridge height of the extension are to be no higher than the existing house.

Double Storey Extension

A two storey extension to your home is considered a permitted development, provided the following limits and conditions are met:

  • On designated land, extensions of more than one storey are not permitted development.

  • Extensions, including previous extensions, and other buildings must not exceed 50% of the total area of land around the original house. The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date).

  • Maximum eaves and ridge height of the extension must be no higher than the existing house. If the extension is within two metres of a boundary, the maximum eaves height should be no higher than three metres to be permitted for development.

  • Extensions of more than one storey must not extend beyond the rear wall of the original house by more than three metres, or be within seven metres of any boundary opposite the rear wall of the house.

  • Roof pitch of extensions higher than one storey must match that of the existing house, as far as is practicable.

  • Materials used in exterior work must be similar in appearance to those of the exterior of the existing house.

  • Any upper-floor window in a wall or roof slope in a side elevation must be obscure-glazed and non-opening unless the parts which can be opened are more than 1.7 metres above the floor of the room in which it is installed.

  • No balconies or verandas are permitted for development.

Class Q Developments

Certain agricultural buildings can be converted into a dwelling (or multiple dwellings) without formal Planning Permission through the use of Class Q permitted development rights. Unlike other Permitted Development rights (i.e. Householder rights) there are multiple hoops to jump through for a Part Q conversion and the project still needs to go to the Local Authority for a Prior Approval Application. It is, however, a fantastic option for getting a dwelling out in the countryside – something that is usually an impossible task. The first point is to check the eligibility of the building versus the Part Q legislation.
Loft Conversions

Converting the loft space within your home is generally considered a permitted development, especially if you aren’t planning on altering or extending the existing roof profile and are simply installing some roof lights or similar. If you are planning to extend or alter the roof itself (e.g. a dormer window), this is also considered a permitted development provided the following limits and conditions are met:

  • Loft extensions are not permitted developments for houses on designated land.

  • To be a permitted development, any additional roof space created by a roof extension must not exceed 40m³ for terraced houses or 50m³ for detached and semi-detached houses.

  • An extension beyond the plane of the existing roof slope of the principal elevation that fronts a highway is not permitted development.

  • Materials are to be similar to that of the existing house.

  • No part of any loft extension is to be higher than the highest part of the existing roof.

  • Verandas, balconies or raised platforms are not permitted development.

  • Any side-facing windows, roof lights on a wall, or roof slope must be obscure glazed and non-opening unless the openable parts are more than 1.7 metres above the floor level of the room in which they are installed.

  • Extensions to the roof, apart from hip to gables, or an enlargement which joins the original roof to the roof of a rear or side extension, are to be set back a minimum of 200mm from the original eaves, as measured along the roof plane.

Front Porch

Adding a porch to any external door of your house is considered a permitted development, not requiring an application for planning permission, provided the following limits and conditions are met:

  • Ground area of the porch, measured externally must not exceed 3 square metres.

  • The highest part of the porch should not exceed 3m.

  • No part of the porch will be within 2m of any boundary that fronts a highway.

Outbuildings

Outbuildings are considered a permitted development, not requiring an application for planning permission, provided all the following conditions are met:

  • On designated land, outbuildings to the side of the house are not a permitted development.

  • Outbuildings are not a permitted development within the grounds of a listed building.

  • In National Parks or Areas of Outstanding Natural Beauty, the total area to be covered by any outbuildings more than 20m from any wall of the house must not exceed 10 square metres.

  • Outwith these areas, outbuildings can be any square meterage providing they still adhere to these conditions in all respects.

  • Outbuildings are not a permitted development forward of the principal elevation of the original house.

  • Outbuildings and other additions must not exceed 50% of the total area of land around the original house. Sheds, other outbuildings & extensions to the original house must be included when calculating this 50% limit.

  • Any new building must not be separate, self-contained, living accommodation.

  • Outbuildings must be single storey with a maximum eaves height of 2.5m and maximum overall height of 4m with a dual pitched roof, or 3m in any other case.

  • If the outbuilding is within 2m of the boundary, it should not exceed 2.5m in height.

  • Balconies and verandas are not a permitted development. Raised platforms such as decking are a permitted development provided they are no higher than 300mm.

  • Containers, such as those used for domestic heating purposes, must not exceed 3,500L capacity to be a permitted development. The other permitted development conditions which apply to outbuildings listed above also apply to containers.


Although not a legal requirement, if your project falls into this category we recommend that confirmation is sought from the local planning authority that planning permission is not required. This is done by applying for a ‘Lawful Development Certificate’ and will confirm that the council agrees with our assessment that the works fall within the permitted development guidelines. It will also ensure that any potential conveyancing issues are avoided in the event of a future sale.

If you are unsure as to whether your own project would benefit from these rights then please get in touch and we would be happy to advise.

Heritage + Listed Buildings


In some cases, you might need to apply for Listed Building Consent for any alterations or building works. If a building is ‘Listed’, it means that there is a special architectural or historic significance to the building and the listing itself brings it under the consideration of the planning system so that it can be protected for future generations. As a general rule, the older a building is, and the fewer the surviving examples of its kind, the more likely it is to be listed.

 

There are three ‘grades’ of listing ranging from the most significant historic value to the least:

 

  • Grade I buildings are of exceptional interest and only 2.5% of listed buildings are Grade I

  • Grade II* buildings are particularly important buildings of more than special interest; 5.8% of listed buildings are Grade II*

  • Grade II buildings are of special interest; 91.7% of all listed buildings are in this class and it is the most likely grade of listing for a home owner.


 

Approval is needed from the Local Planning Authority for any alteration, extension or demolition works which would affect a listed building’s historic character, no matter what grade of listing the property has. In practice, this means that any works to original features beyond minor repair are likely to require listed building consent, as well as new work which would alter the historic floorplan or the building’s setting, such as a modern extension.

 

Seeking Listed Building Consent when required is extremely important as the Local Authority has the power to prosecute anyone who carries out any works without authorisation. The application itself will often require the submission of the application and any details of the proposal as well as any additional items such as a Heritage Statement and Schedule of Works.

Tips from a Chartered Planning Consultant


“The role of your Local Authority Planning Department is to protect and enhance the region’s natural and historic environment and to safeguard its landscape setting. They do this by encouraging high-quality design that doesn’t negatively affect public amenity and represents a positive progression in building development.

 

If you are considering a project that may require planning permission, I recommend that you speak to your architect or planning consultant as early as possible in the process. This will ensure that you have the best chance of achieving a positive outcome.

Base Planning Consultants recognise the skill and expertise that the team at New Space Architecture consistently display when it comes to planning strategy and have enjoyed working alongside them on numerous projects.

 

New Space has a proven track record of success in securing consents for a wide range of projects and an obvious understanding of the planning process ensuring that they are able to develop creative and innovative solutions that meet the needs of their clients. Keep up the good work guys!”

 

Base Planning Consultants

Keegan Ferreday MRTPI

 

If you’re looking for an architectural design and consultancy business to keep your project moving, get in touch with New Space Architecture to discuss your design and development ideas.