Arbour House - nimtim Architects; Photo credit - Elyse Kennedy
To avoid this stress, we have written this concise guide setting out to help you through the permitted development process so you can plan your project with confidence.
Or skip to the relevant section below, as required.
What are permitted development rights?
Which properties have permitted development rights?
Permitted development rules for single storey extensions
Permitted development rules for side extensions
Permitted development rules for two storey extensions
Permitted development rules for roof dormer extensions
Permitted development rules for entrance porches
Permitted development rules for outbuildings
Advantages and disadvantages of Permitted Development
Types of permitted development application
How much does a permitted development application cost?
How long does a permitted development application take?
How long does permitted development last?
Other considerations before you build
Gallery House - Studio Octopi Architecture - Loft extension - Photo Credit - Julien Lanoo
Distinct from local authority planning policy, Permitted Development rights were introduced by parliament to allow householders (and businesses) to carry out many common building projects without the need for planning permission.
Permitted development rights are defined within General Permitted Development Orders (GPDO). There are separate GPDOs forEngland, Scotland, Wales and Northern Ireland. While similar in many aspects, there are differences in how each works.
Here you'll find the technical guidance for England, Scotland, Wales, Northern Ireland
Permitted development rights only apply to houses. and are excluded from multiple occupancy houses, houses formed under permitted development (for example a converted shop), and houses with legal restrictions where the title deeds contain constraints that restrict development. Check with a solicitor if you think this may apply to you.
Rights are restricted on houses built on designated land – conservation areas, National Parks, areas of Outstanding Natural Beauty, the Broads, and World Heritage Sites – which means certain types of work may require planning permission.
Permitted development rights do not apply to flats and maisonettes.
Works to a listed building that fall under permitted development will require listed building consent which means permitted development rights are largely irrelevant.
Leaf House - Szczepaniak Astridge - Loft extension - Photo Credit - Edmund Sumner
Under permitted development rules new extensions are to be measured from the ‘original house’, meaning the house as it was first built or as it stood on 01 July 1948.
The purpose of this wording is to prevent the overdevelopment of sites through incremental expansion over an extended period of time. This means that if you already have an existing extension on your house and are looking to extend out further, you measure from the wall the existing extension is built off - not from the extension itself.
For example, if you live in a Victorian terrace house which has an existing extension built after 01 July 1948 and you want to replace it with a larger extension, the depth of the new extension will be measured from the back wall of the Victorian structure not the back wall of the existing extension.
However, if the existing extension was built before 01 July 1948, it would qualify as an original part of the house - in this instance, you would measure from the back wall of the existing extension.
If you are seeking to extend a newer property which has been extended by its previous owners, any replacement extension will be measured from the part which was first built, not the extension.
In addition to the above, new extensions cannot exceed 50% of the land around the original house. Any extensions built after 01 July 1948 will contribute to your site allocation and need to be deducted from the final calculation.
Matchbox House - Archmongers - Loft extension - Photo Credit - French & Tye
Single storey rear extensions must not exceed:
In Northern Ireland, a single storey rear extension must be at least 3.5m from the rear boundary if the house backs onto a road.
In England, larger extension rights apply. Single storey extensions can project up to 8 metres for a council before work can start on site. More on this below.
Additional rules to note:
Side extensions must not exceed:
Other rules to note:
The rules for two storey extensions are as follows:
Additional rules to note:
Roof dormers are limited to:
Other rules to note:
The erection of a porch outside an external door of a house is not permitted if:
The main rules outbuildings, which includes garages and garden rooms, are as follows:
Other rules to note:
Local authorities will assess the application against permitted development rights, rather than local planning policy. This is advantageous because permitted development rights are much less subjective and clearly set out what is permissible.
Permitted development rights often allow you to build developments that would otherwise be refused by a local planning policy.
As there is less subjectivity in assessing permitted development applications, it gives you more confidence to plan the next stages of your project.
Applications for permitted development are simple and quick to prepare, and are normally determined within 8 weeks.
Permitted development can result in sub-standard builds. As the rights are largely orientated towards size and volume rather than design, extensions built under permitted development can be visually unattractive. Therefore, a design-led approach is needed to ensure good-quality development.
External materials need to be similar to your existing house, which limits scope for expression. A skilled architect, however, can interpret ‘similar’ in many creative ways.
In some situations, you can achieve a better extension by apply for planning permission. For example, there may be local precedent for a ground floor ‘wrap around’ extension which are not permitted under permitted development. It is always advisable to carry out a planning search of your local area at the beginning of your project to work out the best planning route.
Lawful development certificates confirm the work is lawful on the date the certificate is issued, whereas planning permission lasts 3 years. If work has not commenced and permitted development rights change in away that results in the design contravening the new rights, then technically the design is no longer lawful. Unlikely, but worth noting.
You do not need to seek local authority approval for building work that falls under permitted development, but you may wish to seek confirmation that it meets guidelines before you start building on site. This will not only give you peace of mind but also prove to buyers that your works were built legally should you decide to sell your property in the future.
There are two main types of application relevant to home improvement works: Lawful Development Certificate for a Proposed Use and Prior Approval: Larger Home Extension.
To confirm if your proposals meet permitted development guidelines, you can apply for a Lawful Development Certificate. Here, plans are assessed against predefined design criteria and are deemed either ‘lawful’ or ‘unlawful’.
If your application is considered lawful, you can continue with confidence knowing your plans are compliant.
If your application is deemed unlawful, the council will identify which aspects of the design are noncompliant. You can then revise the plans to suit planning officer comments, appeal to the Secretary of State, or apply for planning permission.
If you decide to revise the plans, you can resubmit for a second time free of charge. A third application will be charged at the normal fee.
If you are seeking to build a larger extension in England, you will need to apply for Prior Approval: Larger Home Extension before starting work on site.
Here, the council evaluates the impact of your proposals on surrounding properties and consults with neighbours. The maximum permitted size limit is only possible if there are no valid objections.
If the council deems your proposals ‘do not require prior approval’, it means they are permissible, and you are free to build. If your plans ‘require prior approval’, it means you will need to modify your plans or apply for planning permission.
Prior approval only confirms whether the size and scale of your proposals are acceptable. Following a successful prior approval application, you can then apply for a Lawful Development Certificate to confirm all permitted development guidance is met.
A certificate of lawful development application costs £103 in England, £101 inScotland, and £115 in Wales. Equivalent to 50% of the equivalent fee for planning permission.
An application for Prior Approval: Larger Home Extension costs £96 (England only).
When applying online through the Planning Portal, a service charge fee of £28(including VAT) is added to the above.
For more information on understanding planning stage project costs, see the article below.
How much does planning permission cost?
Unlike an application for planning permission, which requires a planning officer to evaluate the proposals against local planning policies, a lawful development certificate involves a simple tick-box exercise to check if the proposals meet permitted development guidelines.
As a result, lawful development certificate applications are normally processed within 8 weeks of validation. Applications for prior approval take a similar length of time.
Unlike planning approvals, there is no statutory time limit attached to permitted development decisions.
A successful Lawful Development Certificate simply confirms proposals are lawful on the date it was issued. If building work has not commenced and permitted development rights change in a way that results in the design contravening the new rights, then technically the proposals are no longer lawful. Highly unlikely, but worth noting.
Even if your extension does not require planning permission you will need to seek other statutory approvals before you start on site.
Building regulation approval is distinct from planning-related matters, including permitted development, and ensures building work is safe for habitation and meets current technical standards.
Simple house extensions can be built under a Building Notice where both the plans and building work are approved as your project progresses on site.
If the design of your extension is complicated, or you want peace of mind that your plans meet the required standards, apply for a Full Plans application to get the design signed off beforehand.
If you are building close to a boundary, you may need to form a party wall agreement with your neighbour(s) before starting work on site. A simple agreement can take a few days to resolve. However, if a neighbour dissents to the work, it can take a lot longer.
Having a broad understanding of the Party Wall Act will help you plan your project. Appointing professionals - such as an architect, structural engineer and party wall surveyor - will ensure your project runs smoothly. They will produce drawings and calculations to demonstrate your proposals meet building legislation and obtain the necessary approvals to allow building work to take place.
About the author: Aron Coates is an architect with over two decades of experience, encompassing projects ranging from the restoration of historic buildings to the design of contemporary homes.
The information provided in this article is intended for general guidance and educational purposes only. At Designs in Detail, we advise you appoint a skilled residential architect to provide specific expert advice for your project.
