Planning Permission vs Permitted Development: A Beginner's Guide

In this guide we’ll be covering the essentials of the planning process for residential properties in the UK. If you need more detail on specific requirements, you can find more information via the Planning Portal.

What’s the difference between planning permission and permitted development?

Planning Permission is formal approval from your local planning authority that you can carry out building work on your property. 

Permitted Development rights allow you to extend or renovate your home without the need to apply for planning permission, if the project falls under certain criteria. You will still need to apply to your local planning authority in most cases. 

With our Detailed Design service, we guide you through the whole process, creating detailed architectural drawings and then submitting either a Householder Planning Application or a Lawful Development Application. 

Both options can take up to 6-8 weeks to be processed by your local planning department. You would then need to obtain Building Control drawings and submit a Building Control application before starting the work.

What am I allowed to build under permitted development?

Extensions:

Permitted development rights allow you to extend your property if no more than 50% of the original land is used for extensions or a structure of any kind (this includes fixed structures in the garden such as garages, outbuildings, garden rooms, summer houses etc.). You will also need to ensure that the works are in keeping with the original property (for example, you may need to use similar materials to the existing house or match the pitch of the roof with the existing). For more information on the specific requirements for your property and your local area, we recommend discussing your project with your local planning authority who will be able to advise you. 

To build a single storey extension under permitted development, your project will need to meet the following criteria:

• Up to 6m to the rear for semi-detached and terraced properties.

• Up to 8m to the rear for detached properties.

• The depth of a rear extension must not come within 7m of the rear property boundary.

• The width of a rear extension must not exceed the side of the house.

• A side extension must be no more than half of the existing width of the house.

• The height must be no more than 4m. (If any part of the roof is within 2m of your neighbour’s boundary this must be no more than 3m high).

Note: Any wraparound extension will require planning permission.

Double storey extensions are only allowed to be built to the rear of the property under permitted development. Any double storey side or front extension would require planning permission. You can extend out no further than 3m for semi-detached and terraced properties (4m for detached). The height of the roof must not exceed the height of the original roof and any part within 2m of your neighbour’s boundary must not exceed 3m.

Loft Conversions:

The additional volume of a proposed loft conversion must not exceed 50 cubic metres for detached and semi-detached properties (and 40 cubic metres for terraced) to be considered permitted development.

Skylights (such as Velux roof windows) can be used on the front of the roof under permitted development as long as they do not protrude the roof surface beyond 15cm. However, if you would like to add any extension to the front of the roof, such as dormers, this will require planning permission.

Internally, the staircase to the loft must also have at least 2m clearance for head height.

Whilst balconies would require planning permission, Juliet balconies (with no platform exceeding the house) are considered permitted development.

Front Porch:

Whilst any extension to the front of a property requires planning permission, you are able to build a small porch within permitted development rights. This porch must not exceed a footprint of 3 square metres and be no taller than 3m. It is also required to be at least 2m away from any boundaries or roads.

Garden Rooms / Outbuildings:

An outbuilding is a permanent structure within your property boundary that is not attached to the main house. This could be a garage, summer house, garden room etc. These can be built under permitted development as long as they do not exceed the front wall of your house and are within the following dimensions:

• No larger than 50% of the footprint of the original house (when it was built or as it stood on 1st July 1948).

• Up to 3m high for most roof types (up to 4m for a dual pitched roof).

• Any part of the roof within 2m of your neighbour’s boundary must be no higher than 3m.

Any outbuilding built under permitted development cannot be used as sleeping accommodation. 

What are the limitations?

There are different regulations to consider for certain types of properties and permitted development may not apply. You can find more information on which properties would be excluded on the Planning Portal or by speaking with your local planning authority.

As a rough guide, permitted development rights do not apply to the following cases:

• Properties in conservation areas, areas of outstanding natural beauty, world heritage sites, national parks etc. 

• Listed buildings (you will need listed building consent).

• If the property has already been extended previously, using the allowance of space under permitted development. The total size of all previous and proposed extensions to the original building (unless extended before 1st July 1948) cannot exceed the current permitted development rights. 

• Flats and maisonettes.

Where we come in...

If you’re not sure if your project meets the criteria for permitted development, our designers can help you visualise your early stage ideas in 3D and tell you if you will be able to build under permitted development or if you are likely to need planning permission. We can even give you a ballpark cost estimate for the building work too. 

Once you’re happy with your concept design, we can guide you through the rest of the planning process, creating detailed plans and even submitting the application on your behalf. 

For more information and to save on your plans, check out our Concept + Detailed bundle.