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Permitted Development: All You Need to Know

Single-storey extension added under Permitted Development
(Image credit: Jody Stewart)

Not all changes or improvements to your home need permission from the planning department. There are many that you can carry out with implied consent, known as Permitted Development. It is well worth being aware of these rights, and recent changes to the rules, if you want to make any significant home improvements. It could save you time and money!

What is Permitted Development?

Permitted Development (PD) grants rights to enable homeowners to undertake certain types of work without the need to apply for planning permission. There are many innovative opportunities whereby PD rights can bring significant benefits to anyone who wants to undertake a project to improve their existing home or is looking to maximise the potential of a new investment.

To take advantage of PD you need to fully understand what is involved and the criteria — as well as stay up to date with all the latest changes.

This implied consent of Permitted Development is granted in the form of General Development Planning Orders (GDPOs) which apply separately to England, Wales, Scotland and Northern Ireland.

Do double check with your local authority or get confirmation from a qualified surveyor that your proposed works are classed as Permitted Development before you begin. It may be beneficial to submit a prior notification application.

If you need to apply for planning permission, check out our complete guide to what the process involves.

Do I Have Permitted Development Rights?

Most likely yes, but there are a few things to bear in mind. Unfortunately, the slate is not wiped clean when you buy a home — any space added by past owners since 1948 counts towards your Permitted Development allocation.

If your house is located in a Designated Area, such as a National Park, Area of Outstanding Natural Beauty or Conservation Area then your Permitted Development rights may be restricted or removed under what is known as an Article 4 direction. This is where rights have been removed in the interest of maintaining the character of the local area. This could also be the case if your property is listed.

Alternatively, if you’re planning to self build a replacement dwelling and your proposed new home is bigger than the existing house on site, then your Permitted Development rights are likely to be restricted or even removed on condition of granting planning permission.

Natalie Davies and Mark Hills were able to convert a barn on their property and link it to their existing home under PD rights

Natalie Davies and Mark Hills were able to convert a barn on their property and link it to their existing home under PD rights, though they did receive a Lawful Development Certificate from their local authority to ensure that there could be no further redress (Image credit: Dave Burton)

Remember than all Permitted Development requirements apply to the dwelling as it was originally built, or as it stood on 1st July 1948.

PD Rights do not apply to flats or maisonettes due to the impact that any alterations could have on neighbouring properties.

Changes to Permitted Development Rights in 2019

All planning legislation changes, and Permitted Development and Prior Notification is no exception. Revisions stem fro the relaxation of regulations in 2012 which encouraged development and helped to take the pressure off planning departments processing applications.

One of the key changes in the May 2019 regulations is that the new order makes it clear that the regulations make permanent the right to build larger rear single-storey extensions under Class A. This means it is now possible to build the larger extensions subject to the prior approval process without fear of their previously temporary provision expiring.

Types of Permitted Development Rights

Householder PD rights fall into different categories depending on the work being planned. These are:

This allows a householder to build a single-storey side extension up to half the width of the existing dwelling; a single-storey rear extension up to 4m in length for a detached dwelling and 3m long for a semi or a terrace house; and, in certain circumstances, 3m two-storey rear extensions.

The changes that took effect on 30 May 2019 now make permanent the decision that larger single-storey rear extensions of up to 8m (6m for semi or terrace) are permissible under Class A — but do require prior notification (see ‘Lawful Development Certificates are key’).

This allows for rear dormers and hip-to-gable extensions as long as the additional volume created does not exceed 50m3 (40m3 for semis and terraced homes).

This allows for an outbuilding to be erected within a residential curtilage as long as it is sited behind the principal (often the front) elevation, does not cover more than 50% of the curtilage and is not more than 3m in height (4m for a dual-pitched roof; 2.5m where within 2m of a boundary).

There are also specific regulations relating to Hard Surfaces (Class F), Chimneys & Flues (Class G) and Microwave antennas (Class H).

Is Prior Notification the Same as Permitted Development?

Prior notification is a form of Permitted Development whereby the local planning authority must be notified of the details prior to development taking place. Although prior notification is a form of PD, the process is a lot more involved and the local planning authority (LPA) has a lot more say in comparison with a PD application.

Terraced London home remodeled with a hip-to-gable loft conversion achievable under PD rights

This remodel of a terrace London home designed by Selencky///Parsons had a two-stage plan: a two-storey extension that fell outside the remit of PD, and a hip-to-gable loft extension that was achievable under PD rights (Image credit: Siobhan Doran c/o Selenky///Parsons)

With a PD application, the regulations are explicit and it is normally pretty clear cut as to whether a proposed scheme complied with the regulations or not. However, under a prior notification application, the LPA often has the opportunity to determine whether they consider the proposal to constitute conversion as opposed to rebuilding, whether the materials used are appropriate, whether the proposal would be broadly in line with the objectives of the National Planning Policy Framework, and whether there might be other associated impacts such as contamination, noise, flooding etc.

However, these rules do allow for a number of projects to be completed without planning permission.

For householders, single storey, rear residential extensions can be built up to 8m in depth (6m for a semi or terrace) provided that boundary neighbours are first informed. If no objections are received (or any objections received are not considered to have planning merit) and the LPA is satisfied that there are no significant adverse impacts arising from flooding, highways or contamination, a Lawful Development Certificate is issued.

Prior notification can also be used to change the use of non-residential buildings to residential purposes. It can be used to change buildings from one commercial use to another, too.

A1 (shops), A2 (professional and financial services) and A5 (hot food takeaways) may be converted to residential (up to 150m²). The LPA may consider the design of the associated physical development to ensure it complies with the Local Plan and the potential impact of the loss of the A1/A2 use on the economic health of the town centre.

Agricultural buildings may be converted to residential (up to 450m²), as long as the building is structurally capable of being converted without requiring engineering work and providing access can be achieved. Up to five dwellings may be created up to a maximum floorspace of 465m², of which three may be ‘large’ (>100m²). This change of use is subject to prior approval being sought in respect of:

  • transport and highways impacts
  • noise impact
  • contamination risks
  • flooding risks
  • location or siting
  • the design or external appearance of the building

B1c (light industrial) and B8 (storage) buildings may be converted to residential as long as the gross floor space of the existing building does not exceed 500m². Again, the LPA may assess the highways, contamination, flooding and economic impacts and risks associated with the proposal.

Permitted Development and Lawful Development Certificates

In theory, if a proposal constitutes Permitted Development and is fully compliant with the regulations, no application is required.

However, if you’re not going down the prior notification process, it is extremely advisable to apply for a Certificate of Lawful Proposed Use or Development, otherwise known as a Lawful Development Certificate (LDC), to ensure that your proposal complies with the regulations and that you will not be faced with difficulties post construction.

If, once an extension or outbuilding etc. is constructed, the LPA determines that the proposal does not comply with PD regulations then you may be faced with enforcement action, which would normally result in a request for a retrospective application. Should permission be refused there is a real likelihood that any extensions or associated works would be required to be demolished. As such, confirmation in the form of the LDC is highly recommended.

The legislation is not the easiest to interpret, so take a look at the Planning Portal which is a useful resource in helping to find out what is covered within these rights. There is an option to select England or Wales, so depending on where your property is you can select the appropriate country for the relevant regulations.

Single-storey extension added under Permitted Development

An old conservatory was knocked down and a single-storey extension to the rear of the house was added under Permitted Development (Image credit: Jody Stewart)

How Big Can an Extension be Under Permitted Development?

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Under the rules, the ‘original’ (as it stood in or prior to 1948) rear wall of a detached home can be extended (subject to the neighbour consultation scheme) by up to 8m in depth with a single storey extension; this is reduced to 6m if you live in a semi or terrace. If your proposed new extension will be within 2m of a boundary, then the eaves height is limited to 3m under Permitted Development. Otherwise, a single storey rear extensions must be no higher than 4m.

If you hope to build a two storey extension (no higher than the house), this can project up to 3m from the original rear wall, so long as it is at least 7m from the rear boundary. It’s also important to note that no extension can project beyond or be added to what is deemed to be the front of the house or an elevation which affronts the highway. And a side extension can not make up more than half your house’s width.

Furthermore, with the exception of conservatories, new extensions must be built of materials ‘similar in appearance’ and with the same roof pitch as the main house. So while Permitted Development rights are beneficial, there’s a lot to consider before starting work.

Permitted Development Rules for Extensions

  • You can extend a detached dwelling by 8m to the rear if it’s single storey or 3m if it’s double
  • Semi-detached and terraced homes can be extended up to 6m to the rear of the property if single storey
  • There are height restrictions but they boil down to a single storey extension not being higher than 4m in height to the ridge and the eaves, and ridge heights of any extension not being higher than the existing property
  • Two storey extensions must not be closer than 7m to the rear boundary
  • It must be built in the same or similar material to the existing dwelling
  • Extensions must not go forward of the building line of the original dwelling
  • Side extensions must be single storey, maximum height of 4m and a width no more than half of the original building
  • In Designated Areas side extensions require planning permission and all rear extensions must be single storey
  • An extension must not result in more than half the garden being covered
  • You can only do it once and the original building is either as it was on 1st July 1948 or when it was built. In Northern Ireland it is as it was built or as it was on 1st October 1973

Could I Both Extend My Home and Convert My Loft Under Permitted Development?

In the past, volume limitations were applied to the entire house — so if you extended, you were unlikely to be able to convert your loft under Permitted Development rights as well. The good news is that the latter has now been separated out, allowing you to undertake both without one restricting the other.

Editor's Note: Homebuilding.co.uk partners with the UK's best loft conversion specialists to match your requirements with their services. Simply answer a few questions on what you need from your loft conversion and we’ll put you in touch with a suitable partner.

So, you can also convert your loft into a bedroom or extra living space by up to 50m³ in a detached house, or by 40m³ within any other home. Flush rooflights or those which do not project further than 150mm are permitted, but you will need permission to add a dormer window on any roof elevation which faces the highway.

However, you cannot cover more than 50% of the land around your house with extensions (including extensions by previous owners), and you have to include any outbuildings when calculating this coverage. Sheds and other outbuildings count in this calculation.

What Improvements Can I Make Within Permitted Development?

The scope of your Permitted Development rights are varied and cover both internal and external works, but there are strict design criteria that need to be adhered to. If your project falls outside of the set criteria, then it is likely you will need to submit a planning application.

Some home improvements that you can make under Permitted Development include:

  • Building a porch
  • Internal alterations
  • Convert and occupy the loft space
  • Installing microgeneration equipment such as solar panels (apart from wind turbines)
  • Installing satellite dishes and erecting antenna
  • Adding rooflights or dormer windows
  • Extending the back of your home

(MORESee 20 home improvements you can make under Permitted Development)

Are Outbuildings Covered by Permitted Development?

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  • You can construct all sorts of outbuildings for the use and enjoyment of the home so long as they do not cover more than 50% of the garden space. In Scotland this is reduced to 30%
  • In Wales and Northern Ireland any outbuildings closer to the house than 5m count as extensions. In Scotland any outbuildings larger than 4m² and closer to the dwelling than 5m count as extensions
  • Outbuildings must be single storey with a maximum ridge height of 4m for a pitched roof or 3m for any other kind of roof. The eaves height must be no more than 2.5 metres
  • If the outbuilding is closer to the boundary than 2m it shall be no higher than 2.5m
  • No outbuilding can be forward of the original dwelling. In Wales and Northern Ireland the same applies unless the resulting building would be more than 20m from the road

Can I Convert an Existing Building Under Permitted Development?

Under Permitted Development, existing buildings – such as offices, barns and other agricultural buildings – can be converted into homes.

In March 2013 a new system was introduced to allow the conversion of barns into dwellings. Permission would still be required via the prior approvals process, but it created potential for more conversion opportunities than before. Read more here.

In an attempt to release inner-city land for housing, the next change in Permitted Development was an announcement in May 2013 to allow offices to be converted to residential. This was set to expire in 2016, but in October 2015 it was declared that these rights would be made permanent.

Permitted Development for Balconies and Driveways

  • Balconies, verandas and raised platforms (above 300mm) do not fall under Permitted Development rights
  • You will also now need planning permission to construct a drive from non-porous materials such as tarmac. But you can construct a new drive of porous materials, or non-porous if provision for drainage is provided on the property, under Permitted Development

For more details on the rules see the Planning Portal.