What is permitted development? Put simply, it is “a national grant of planning permission which allow certain building works and changes of use to be carried out without having to make a planning application.”

Permitted Development rights can be complicated. The classes of development for which planning permission is granted in England are set out in Schedule 2 of ‘The Town and Country Planning (General Permitted Development) (England) Order 2015’. This schedule is split into 20 parts, with each Part further subdivided into Classes.

In this article we will be discussing Part 1 : Development within the curtilage of a dwellinghouse - commonly referred to as permitted development for householders.

This post will cover :

Alterations to a house (Class A-D)
Separate structures (Class E)
Other classes (Class F-H)

There are other Parts of the schedule that may be relevant to householders. For example Part 2 covers items such as the erection of walls, fences and gates, external painting, charging points for electric vehicles and CCTV.

It is also worth noting that there are some instances in which permitted development rights do not apply, have been withdrawn or are restricted. For example if the house:

Was created using permitted development rights (e.g - change of use)
Is within an area under an Article 4 direction
Is within a Conservation Area
Is listed
Is within a National Park
Is within an Area of Outstanding Natural Beauty
Is within a World Heritage Site
Is within the Norfolk or Suffolk Broads.
Is on a site of special scientific interest

In these cases the requirements may be different and the following information does not apply.

Permitted development rights can be complicated and if you are in any doubt regarding a project you are undertaking, you should seek professional advice. Permitted development rights do not remove the requirement for other approvals that may apply – such as building control.

Alterations to a house

In this section we discuss Classes A-D. These classes deal with alterations to the existing house, rather than the addition of new buildings. The following conditions apply to Classes A-C:

The work cannot include:

Raised platforms over 0.3m - including balconies, terraces and verandas
Chimney, flue or soil vent pipe (see Class G)
Any materials used in exterior work should be a similar appearance to the existing exterior materials.
Any window added to the side of the house (including at roof level) must be obscure glazed and non-opening unless the openable part is more than 1.7m above the floor of the room in which it is situated.

Class A- enlargement, improvement or alteration

Class A provides permitted development rights for the enlargement, improvement or other alteration of a house. The following limits and conditions apply to all extensions permitted under this class:

A maximum of 50% of the land around the original house* can be covered by extensions or other buildings.
No extension can be built to the front of the house.
The extension can’t be higher than the existing house
The eaves of the extension can’t be higher than the existing eaves
If the extension is within 2m of a boundary, the eaves can be a maximum of 3m in height
The work cannot include:
- Microwave antenna (see Class H)
- Any alteration to roof (see Class B and C)

In addition to the constraints set out above, single storey rear extensions can be a maximum of 4m high and can extend a maximum of 3m from the original house. This increases to 4m if the property is detached. Larger extensions, up to 6m or 8m respectively, are possible but require prior approval from the Local Planning Authority.

Rear extensions that are more than one storey must not project more than 3m from the original house* and cannot be within 7m of a boundary. The pitch of the new roof must match that of the existing house, so far as practicable. These conditions apply both to multiple storey extensions and single storey extensions constructed on top of an existing storey.

Side extensions can only be singles storey and a maximum of 4m tall. They must be no greater than ½ the width of the original house. Side extensions are not permitted where the side of the house faces a street.

Class AA- enlargement of a dwelling house by construction of additional storeys

Since late 2020, the introduction of Class AA means the addition of up to two storeys over the principle part of your home is permitted development if it was built between 1948 and 2018 and the total height of the resultant house does not exceed 18m. I know – wild.

In all cases:

An application for prior approval from your local planning authority is required
No structural elements can be visible from the exterior
All works and engineering operations that may be required to strengthen the foundations of the existing house must be within the boundary of the property
The floor to ceiling heights of the new storey(s) can be a maximum of 3m and should not be greater than any of the existing floor to ceiling heights within the house.
The roof pitch of the new development must match the roof pitch of the existing house

In the case of single storey, semi-detached and terraced homes, only one additional storey is permitted. The highest part of this storey can be a maximum of 3.5m higher than the existing roof. If the house is terraced, the new storey can be no more than 3.5m higher than the roof peak of every other house in the row it is situated. If the house is semi-detached, the new storey cannot be more than 3.5m higher than the roof peak of its attached neighbour.

In the case of detached houses, up to two storeys can be added. The maximum height permitted is 3.5m above the highest part of the existing roof if a single storey is to be added and 7m of two storeys are to be added.

Class B - Additions to the roof

Additions to the roof, for example loft conversions, are permitted under Class B; provided the resultant development is not higher than the existing house. Chimneys, parapet walls and other protrusions do not count when considering the existing height.

Extensions should be a minimum of 0.2m away from the eaves and can add a maximum of 40m³ to a terraced house (or 50m³ to detached or semi-detached property)

The additions cannot include any veranda, balcony or raised platform or the installation, alteration or replacement of a chimney, flue or soil vent pipe. Again, any exterior materials used must be similar in appearance to those of the existing house.

Class C – Other alterations to the roof

Class C provides permission for roof alterations that do not involve the enlargement of a house; for example, the installation of rooflights. The installation must protrude no more than 0.15m from the original roof*.

Alterations cannot include the installation of any solar panels (including both thermal and photovoltaic), though these may be permitted under Part 14 of Schedule 2.

Class D - Porches

Class D permits the erection of a porch outside any external door of a house provided:

It has a maximum external area of 3m²
It is a maximum of 3m high
It is not within 2m of any boundary that adjoins the street

Separate structures

Permitted development rights for constructing buildings within the boundary of the property around your house is given under Class E. Class E also allows for the installation of a storage container for domestic heating purposes – however, we will not cover the details of that here.

Development of additional buildings is permitted provided they are for uses “incidental to the enjoyment of” the house. For example:

A garden shed
A hobby room
Structures for keeping animals (provided the animals are for personal enjoyment and not commercial purposes).

Separate self-contained accommodation, or the use of an outbuilding for primary living accommodation, is not an incidental use and is therefore not permitted. Primary living accommodation includes:

Kitchens
Bathrooms
Bedrooms

In addition to the restrictions on use, Class E contains conditions relating to the permitted size. As with some of the Classes described previously, a maximum of 50% of the land around the original house* can be covered by extensions or other buildings and no extension can be built to the front of the house.

The eaves of any building must be a maximum of 2.5m high. The overall maximum height permissible is:

4m for a dual-pitched roof
2.5m if the building is within 2m of the boundary
3m in all other cases

Other Classes

Part 1 contains some additional classes of permitted development related to residential properties which we will not detail but have listed here for completeness:

Class F - hard surfaces

Class G- chimneys and flues

Class H - microwave antenna

Final Word

The appeal of permitted development is the potential to extend and improve the exterior of your home, without the need to engage in the planning process. This appeal is increased by the broad array of works that are classified as permitted development. However, the rules can be complicated and many of the larger developments that are permitted nevertheless require an application for prior approval.

Permitted Development is undoubtedly useful for small projects. However, if you are planning a larger project, submitting a planning application may be a better route for you. With around 91% of householder applications receiving approval, this could allow you to avoid shoehorning your vision into the complex constraints set out. In any case, if you have any uncertainty around your project, you should seek professional advice from a planner or an architect.

*’original house’ refers to the house as it stood in 1948.