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permitted development

Planning: What is Permitted Development?

There are many types of building works which do not require planning permission.  These are called “permitted development rights”.  These are a form of general planning permission granted not by local planning authorities but instead by parliament.

However, flats and maisonettes often do not benefit from permitted development rights in the same way as houses.  Likewise, commercial properties have different permitted development rights which will not be discussed in this article.

What Types of Works Are Permitted Development?

Listed below are some of the different types of residential work which can be carried-out under permitted development.  In addition, a brief description of the limitations has been included to outline what is possible under permitted development. 

Roof Extensions

  • Max height must not exceed existing roof
  • Max increase in loft volume 50m³ for detached or semi-detached
  • Max increase in loft volume 40m³ for terrace

Single Storey Rear Extensions

  • Max height 4m (3m if within 2m of boundary)
  • Max depth of 4m (8m until May 2019) for detached
  • Max depth of 3m (6m until May 2019) for semi-detached or terrace
  • Extension must not exceed 50% garden

Two Storey Rear Extensions

  • Max height must not exceed existing house
  • Max height 3m if within 2m of boundary
  • Max depth 3m
  • Side windows much be above 1.7m and obscure glazed

Side Extensions

  • Max height 4m
  • Single storey only
  • Max width must not exceed 50% of house

Change of Use

  • Class A1 (Retail) changed to C3 (Dwelling up to 150m²)
  • Class B8 (Storage & Distribution) changed to C3 (Dwelling)
  • Class C4 (HMO) changed to C3 (Dwelling)
  • Class C3 (Dwelling) changed to C4 (HMO)


  • Max roof height 4m (2.5m if within 2m of boundary)
  • Max eaves height 2.5m


The above details are correct at the time of writing. However, permitted development changes frequently so if you have any questions regarding a potential project, please feel free to contact us.

It is worth noting that multiple permitted development rights can be use for the same project.  Below are some examples of what can be done under permitted development:

permitted development two extensions   permitted development two extensions and loft   permitted development rear extension


When Does Permitted Development Not Apply?

In many areas of the country permitted development rights are restricted.  These areas are known as “designated areas” and include the following:

  • Conservation Areas
  • Areas of Outstanding Natural Beauty
  • National Parks
  • World Heritage Site

Properties located in designated areas will require planning even for projects which would fall under permitted development in other areas.

Similarly, it is important to check that the local planning authority has not removed specific permitted development rights for the area in which a property is located.  This is known as an “article 4” direction and is usually made when the character of an area of recognised importance would be threatened.

If you are unsure as to whether your property is located in a designated area or is subject to an article 4 direction, we would recommend contacting your Local Planning Authority.


How to get a Certificate of Lawful Development?

Whilst the permitted development rights are clearly set-out, there are subtle details which are open to interpretation and local planning authorities do not always interpret the guidelines in the same way.  Therefore, we always advise our clients to obtain a Certificate of Lawful Development before carrying-out works.  At the time of writing a certificate costs just £96 and gives peace of mind against costly planning enforcement action from the local authority.

In order to obtain a Certificate of Lawful Development you’ll first need to have drawings drafted including the critical dimension of the project.  These drawings can then be submitted to your local planning authority.  For further information on our drafting & planning services, please feel free to contact us.


Temporary Changes to Permitted Development

A temporary increase has been implemented for house extensions falling under permitted development.  For detached properties the depth of a rear extension has increased from 4m to 8m.  Similarly, rear extensions for terrace houses has increased from 3m to 6m.  However, in order to take advantage of this increase additional conditions must be satisfied:

  1. Prior approval must be given before carrying-out the works.  Once received, the local planning authority will notify neighbours for their comment.  Issues such as light or privacy will be taken into consideration


  1. The works must be completed by 30th May 2019


For further information on permitted development you can refer to the planning portal which provides a wealth of up-to-date advice.