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The Differences Between Planning Permission and Permitted Development

Planning Permission

Having a comprehensive understanding of the difference between planning permission and permitted development plays an important role in determining what kind of extensions you can build.

In some cases, permitted development will achieve more space, and in other cases applying for planning permission might be the best route to bring your ideas to life.

To help you decide which option might work best, we have created the comprehensive guide below which include some of our most frequently asked questions.

1. What is permitted development?

Homeowners can carry out certain works to their homes without applying for planning permission. In these circumstances, different terminology would be used, such as ‘permitted development’ or ‘permitted development rights’.

Full details of this legislation and the various sections highlighting what is permitted can be found in a publication referred to as the General Permitted Development Order (GPDO) by clicking here.

This document grants permission for certain types of development to be carried out without planning permission provided the relevant qualifying criteria, conditions and restrictions are adhered to.

2. When does permitted development apply?

When it comes to residential extensions, many different types qualify for permitted development. The scope is varied and covers both internal and external works, but there are strict design criteria that need to be adhered to.

Concerning the question, ‘When does permitted development apply?’ it’s a case of first deciding what sort of extension you would like to build. Once you have an idea of how you would like to extend your home, we would then suggest discussing those ideas with a local architect or planning consultant, as they will have a very good idea of how best to help you move forward to develop your ideas into an incredible design.

The General Permitted Development Order is quite a long and technical document that can be difficult to absorb. To help understand all the various permitted development rights, we have highlighted below the most popular types of extensions coupled with a summary of the rules they must conform to, to be considered as permitted developments.

3. Permitted development criteria for:

3.1. All extensions

  • Only 50% of the area of land around your original house can be covered by an extension or other building
  • An extension cannot be taller than the highest part of the existing roof
  • Where the extension comes within two metres of the boundary, the height at the eaves cannot exceed three metres
  • Extensions cannot be built forward of the ‘principal elevation’ (usually considered to be the front of your house)
  • In conservation areas or areas of outstanding natural beauty (AONB), works cannot include cladding the exterior of your house
  • The materials used on any works to the outside of your house must be of a similar appearance to those of the existing house.

3.2. Loft extensions

  • The increase in the volume of your proposed roof extension should not exceed 40 cubic metres for terraced houses, or 50 cubic metres otherwise
  • It must not go above the height of the existing roof
  • It cannot extend towards the front roof slope
  • Any new side facing widows must be obscure-glazed
  • If a rear dormer window is proposed, it should be set back at least 20cm from the original eaves
  • No part of the roof extension should overhang the outer face of the wall of the original house.

3.3. Single storey rear extensions

  • If you own a detached house, the rear extension cannot extend beyond the original rear wall of the house by more than 4m. This is slightly reduced for terraced and semi-detached houses to 3m.
  • If you live within a conservation area and work is subject to ‘prior approval’, the depth limit for single-storey rear extensions is increased to eight metres if a detached house, or six metres for any other house.
  • The overall height of a single-storey rear extension cannot exceed four metres.

3.4. Single-storey side extensions

  • Cannot exceed four metres in height
  • Can only be up to half the width of the original house
  • Side extensions in conservation areas are not considered permitted developments.

3.5. Two-storey extensions

  • A two-storey rear extension should not extend beyond the rear wall of the original house more than three metres. There should also be a gap of 7m or more from the rear wall of the two-storey rear extension and boundary fence
  • The proposed pitch of the roof should match that of the original house
  • If any proposed windows are below 1.7m floor height, they should be obscure glazed and fixed shut
  • Two storey rear extensions do not apply if your house is located within a conservation area.

4. How can I check whether the extension falls within permitted development rights?

There are several very useful permitted development guides for householders available online.

The planning portal has a number of mini-guides related to the most popular types of extension by clicking here.

The government has also released a very easy to understand technical guidance document which includes lots of illustrations showing what is or is not considered to be permitted development: Technical Guidance.

5. Restrictions – When does permitted development not apply?

Permitted development rights only apply to houses. The following do not fall within the permitted development criteria:

  • Flats or maisonettes
  • Converted houses or houses created through the use of ‘permitted development’ rights for changes of use or a new house
  • Areas where there may be a planning condition, Article 4 Direction or other restriction that limits or removes ‘permitted development’ rights.

6. Changes to permitted developments in 2020

In 2020, there was a change to permitted development rights, allowing a homeowner to build larger rooftop extensions. You may now add up to two additional storeys where the existing house consists of two or more storeys, or one additional storey where the property consists of one single storey or a bungalow.

That being said, although construction under the new permitted development rights does not require planning permission, you are required to apply for prior approval. Prior approval involves making a formal submission to your local planning authority, seeking confirmation that your proposed extension is acceptable before work can commence.

Important note: we have worked on a large number of applications of this type and would always advise that you first consult with a structural engineer so that they can confirm that your existing foundations and structure can take the weight of an additional storey or two.

7. Differences between permitted development and planning permission

The main difference between permitted development and planning permission is that permitted development involves works that do not require planning permission. This means that householders are not necessarily required to apply for consent before works start on site (unless prior approval is required). All works which fall outside the scope of permitted development would require planning permission, requested via a formal householder planning application. This should be made and approved prior to the work commencing on site.

It is worth noting that, although you may not be required to submit a formal application for permitted development, we would always advise that you apply for a Certificate of Lawful Development. Your architect will prepare and submit a full set of existing and proposed plans to your local planning authority and they will then issue a certificate confirming your proposed extension does indeed fall within permitted development rights. This avoids any queries later on.

In terms of application fees, a Certificate of Lawful Development costs approx. £100.00 whilst the local authority fee for a householder planning application is approximately £230.00.

8. What is planning permission?

Planning permission essentially involves the householder asking the local authority if they can carry out certain building work that might otherwise be considered inappropriate development. In the UK, parliament has given the responsibility of determining planning applications to your local authority. Planning permission is usually required where:

  • The works fall outside of permitted development
  • You wish to build something new on your land
  • You wish to make an alteration to your property
  • You wish to change the use of your property.

9. When would I gain more space through permitted development rather than planning permission?

This is a question we are asked a lot and the answer is that every situation is very different and it depends on specific circumstances on site. The most common scenario where you can achieve far more space through permitted development is when it comes to loft extensions. The majority of loft extensions in the UK are built using permitted development rights. This is because the main restriction is one of volume (which rarely applies to planning applications). Terraced houses can add up to 40 cubic meters of space while semi-detached and detached houses can add up to 50 cubic meters of space. Below is an example of what a typical loft extension to a semi-detached house would look like achieved with permitted development.

3D image of a loft extension

As you can see from the above drawing, the house now benefits from a hip-to-gable as well as a full width rear dormer window, thus creating a huge amount of usable internal space within the loft.  When it comes to planning policies for loft extensions, all local planning criteria will differ slightly but as a general rule of thumb, hip-to-gable extensions will not conform to planning policy and rear dormer window planning policies will usually state that they should be half the width and depth of the roof slope. This would create a far smaller usable space within the loft. So in this example, when it comes to loft extensions, a homeowner would achieve far more space through permitted development than they would if they applied for planning permission.

10. When would I gain more space by applying for planning permission rather than permitted development?

As mentioned above, when it comes to extensions, local planning policies differ slightly between boroughs. The most common type of extension we are asked about is the single-storey extension which wraps around both the side and rear of the house, an example of which is shown below.

If someone wanted to go down the permitted development route the above design would be deemed unlawful and not considered to fall within permitted development. This is because the rear extension extends beyond the side wall of the original house and the side extension would be greater than half the width of the original house.

While it may not be allowed under the terms of permitted development, depending on the site, specific circumstances and policies, we have designed and obtained planning permission for a huge number of wrap-around extensions in the past. This is not to say that such designs always meet the relevant local planning policies but in some cases, going down the planning permission route would have a greater chance of success when compared to permitted development.

Plan showing wrap-around ground floor extension

11. Frequently Asked Questions

11.1. Can I have a permitted development extension without planning permission?

Yes you can. The permitted development and planning permission processes operate independently of one another. Which one will achieve the most space or create the most usable space for you will depend on what kind of new spaces and extensions you would like.

11.2. Do you need planning permission for permitted development?

No, you don’t. The polices governing permitted development can be found within the General Permitted Development Order (GPDO). Unlike planning polices whose interpretation can be subjective, the GPDO is more black and white. Projects which meet the relevant permitted development criteria are considered to be ‘lawful’ (not requiring planning permission) and projects which do not meet the relevant criteria would be considered ‘unlawful’ (requiring planning permission).

11.3. Can we use planning permission and permitted development at the same time?

This depends on the circumstance. For example, if you were to obtain planning permission for a single storey rear extension and also obtained a certificate of lawful development for a front porch at the same time, they could be built at the same time because they are all independent of one another.

However, there are cases where homeowners might obtain planning permission for a two-storey rear extension as well as a certificate of lawful development for a loft conversion simultaneously. That being said, if the roof of the proposed two storey extension was cited in the same location as the approved rear dormer window, they could not be built at the same time. The reason is that you would have built neither set of approved plans because they both touch one another. In this case you would have to choose which one to implement.


The difference between planning permission and permitted development is mainly one of process, legislation and assessment.

One is not necessarily better than the other, as it all hinges on what ideas you have for your dream home.

If you have any questions you would like answered about your specific ideas, please feel free to call one of our experienced in house planning consultants anytime.

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