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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.
Common Questions
Planning permission is not required if the home will be used as a short-term let for 90 days or less throughout the year.
If you plan on using the home as a short-term let for more than this time period, then you will need to apply for planning permission for a change of use.
If you rent a room in your property while you still live there, you will not require planning permission.
Changing from a commercial use (use class E) to residential(use class C3) falls under permitted development rights, meaning an application for planning permission is not required.
To use the permitted development right you must meet the rules and regulations set out in legislation, this includes submitting an application for prior approval to the local planning authority. The full list of conditions is available on the government website, or our online application form will tell you whether you are eligible.
If you are not eligible for the permitted development right, you will have to submit an application for full planning permission.
If you want formal confirmation that the existing use of a building is lawful for planning purposes, or that your proposed development does not require planning permission, you can apply for a Lawful Development Certificate(LDC). An LDC can be useful in situations where you need assurance that a particular use, operation, or development is lawful under planning legislation.
Read more about Lawful Development Certificates.
Applications for a Lawful Development Certificate can be submitted online to your local council using Planning Portal. You must include enough detail and evidence to support your case; if the information is insufficient, your application may be refused.
Increasing the size of a window will often fall under permitted development rights, meaning an application for planning permission is not required to make the change, provided limits and conditions are met.
Any new window must be of similar appearance to the original which you are replacing.
Permitted development rights do not apply to flats. To increase the size of a window in a flat or maisonette you will require planning permission.
If you live in a listed building, you will require listed building consent for any major changes.
Where the work has as significant impact on the external appearance of the house, especially on the principal elevation, planning permission may be required.
Building control approval will likely be required where the change impacts the structure of a building, this primarily occurs when an opening Is widened. When altering walls you may want to consult a structural engineer.
Building control will also consider energy efficiency, glazing, ventilation and fire safety.
Demolishing and building a new lean-to will still have comply with planning requirements.
If you live in a conservation area or listed building you may require approval for the demolition.
Whether a lean-to requires planning permission will depend on what the lean-to is used for, it may be an extension, pergola, carport, conservatory or gazebo.
In some cases a building a lean-to will be classified as permitted development, meaning an application for planning permission is not required provided specified limits and conditions are met. If these are exceeded, then you must apply for planning permission.
Permitted development rules vary based on the type of work you are completing, visit our interactive house mini guides for details on the specific rules.
If you live in a listed building, you will need listed building consent for any significant changes.
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