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Do I need planning permission to add a first-floor extension onto an existing ground floor extension?

Adding a storey on top of an extension will always require an application for planning permission.

If you want to add a storey on top of your house under permitted development rights, it must be on the principal part of the house.

If you want to add an additional storey on top of your house, it can be permitted development. It is only permitted development if it follows certain rules:

The current house

  • Is not a building containing one or more flats, or a flat contained within such a building
  • Was constructed between 1 July 1948 and 28 October 2018
  • Has not already had additional storeys added to it
  • Is not on Article 2(3) land or a site of special scientific interest
  • Was not changed to be used as a house (from a previous non-residential use) under permitted development rights.

How many storeys can you add?

  • If the house is one storey then one storey can be added
  • If the house is two or more storeys then two storeys can be added

Where can the storeys be added?

  • The additional storeys must be added to the principal part of the house. The principal part of the house is the main part of the house excluding any front, side or rear extension of a lower height (regardless of these being part of the original house or subsequent additions).
  • Engineering operations must only include works within the existing curtilage of the house to strengthen existing walls and foundations

How high can it be?

  • The house cannot exceed 18 metres in total height
  • Each storey cannot add more than 3.5 metres to the total height
  • If the house is not detached the total height cannot be more than 3.5 metres higher than the next highest building that the house is attached to, adjoins, or is in the same row as.
  • The additional storeys must not exceed 3 metres in height or the height of any existing storey in the principal part of the house (measured internally from floor to ceiling)

What materials can be used?

The materials used must be of a similar appearance to those used in the construction of the exterior of the current house

Where can windows be placed?

Windows must not be placed in any wall or roof slope forming a side elevation of the house.

Following completion of development:

  • The house must remain in use as a domestic residential property
  • No visible support structures must remain on or attached to the exterior of the house
  • The roof pitch of the principal part of the house must be the same as it was prior to the development.

 If any of the limits set out above are exceeded then an application for planning permission will be required. If you are unsure, you should contact your local planning authority.

Find contact details for your local planning authority.

Common Questions

Do I need planning permission to brick up an existing window?

Bricking up or infilling an existing window is classified as permitted development, meaning an application for planning permission is not required to complete the works. You will need to ensure that any materials used are of a similar appearance to the existing exterior of the house.

If you live in a listed building, then you will require planning permission and listed building consent for the change. In this instance it is best practice to talk to your local planning authority first.

What is the process for applying for planning permission?

When you, or an agent acting on your behalf, have submitted a planning application, the local authority will firstly check the application to check if it’s complete. This validation process allows the authority to ensure everything that is required to decide an application has been received and provided correctly. They will contact you if they require any further information from you.

After the application has been validated, the determination process begins and takes up to 8 weeks for smaller applications, or up to 13 weeks for larger applications. The authority should be able to give you an idea about the likely timetable. The local authority will contact you with their decision.

Read more about the decision-making process for planning applications.

Can I pave my front garden to use as a driveway?

You will not need planning permission if a new or replacement driveway of any size uses permeable (or porous) surfacing which allows water to drain through, or if the rainwater is directed to a lawn or border to drain naturally.

If the surface to be covered is more than five square metres planning permission will be needed for laying traditional, impermeable driveways that do not provide for the water to run to a permeable area.

This guidance applies to houses, there are different rules for flats and maisonettes, converted houses, new houses or areas where there permitted development rights may be restricted.

Read about paving your front garden

You may need to consider if a dropped kerb is required, largely dropped kerbs are not a planning matter but you will need to apply to your local council.  

Find out more about dropped kerbs

Do I need planning permission to render my house?

Rendering or cladding the exterior walls of your house may fall under permitted development rights, meaning an application for planning permission is not required provided you meet certain limits and requirements set out in legislation.

If you live in a listed building, you will need listed building consent for any significant works whether internal or external.

If you live in a Conservation Area, a National Park, an Area of Outstanding Natural Beauty or the Broads, you will need to apply for planning permission before cladding the outside of your house with stone, artificial stone, pebble dash, render, timber, plastic or tiles.

Outside these areas, cladding may be carried out without having to first apply for planning permission provided the materials are of a similar appearance to those used in the construction of the house.

If the new materials will not have a similar appearance to those previously used you will be required to submit an application for planning permission.

Read more about change to external walls on our common project.

Replacing existing render

Replacing existing render on the outside of your house with render of a similar appearance will not require planning permission as it is considered permitted development.

If you are changing the external appearance of the house or in a protected area such as a conservation area, then planning permission will be required. The external appearance of the house is likely to be changed when you are changing the type or colour of the render.

If the building is listed, then you will need listed building consent.

Do I need planning permission to build a basement underground?

Creating a new basement will usually require planning permission, particularly if it affects the external appearance of the property. For example, installing a lightwell to bring natural light into the basement may be subject to stricter design rules if it is visible from the street, especially at the front of the property, compared to those at the rear or side.

Because basement construction involves significant excavation and structural work, permission is often necessary. It’s recommended that you consult your local planning authority early on to understand what is likely to be considered acceptable before submitting a planning application. Building regulations will also apply to a new or conversion of a basement.

Read further guidance on basements.

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