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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 have an internal floor-to-ceiling height of no more than 3 metres, and no greater than the internal height of any existing storey within the principal part of the house.
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
Replacing the window within a bay window is treated the same as any other window. Meaning that the replacement of windows which have a similar appearance to those previously used would not require an application for planning permission.
Repairs, maintenance and minor improvements will also not require an application.
If you live in a listed building or a designated area then different rules may apply.
For more details on replacing windows, visit our common projects section.
Planning permission is not required for moving internal walls in a flat.If the building is a listed building, you may require listed building consent.
Removing a load bearing wall will require building control approval as it is altering the structure of the property. You will be required to provide a report from a structural engineer who will provide structural calculations.
Work on internal walls may also affect fire escape routes, ventilation, drainage or electrics. These should be considered during the design process and work should be carried out by a member of the competent person scheme where possible.
Climbing frames are classed as ‘outbuildings’ meaning they are classed as permitted development, not requiring an application provided they meet the limits set out in legislation. One of these limits is that they cannot be in front of the house.
The key restrictions for a climbing frame will be the height; how close it can be to the properties boundaries and where it can be located.
A full list of limits and conditions can be found on our outbuildings common projects.
If the climbing frame exceeds any of the limits set out in legislation an application for planning permission is required.
Adding a porch canopy is classed as permitted development provided it meets the limits and conditions set out in legislation. Where this is the case, no application for planning permission is required.
Porches must meet the following limits:
- the ground floor area (measured externally) would not exceed three square metres.
- no part would be more than three metres aboveground level (height needs to be measured in the same way as for a house extension).
- no part of the porch would be within two metres of any boundary of the dwellinghouse and the highway.
Read our mini guide for additional information on installing a porch.
Running a taxi business from home will require planning permission as it constitutes a change of use of the property. The business may cause increased traffic or visitors, staff being in the property and external advertising, all of which would have an impact on the surrounding area.
You should contact your local planning authority or the Planning Guidance Service for more advice.
