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.

Find contact details for your local planning authority.

If the conservatory is not separated from the house by external quality walls, doors or windows, then it will lose its building regulations exempt status. As such it will be required to adhere to thermal efficiency rules and ventilation rules.

The new opening created from removal of the door will also need building regulations approval.

Find out more from our conservatories common project

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Planning permission is not normally required to turn two properties into one by knocking through a party wall provided the changes are internal and do not impact the external appearance of the property.

You should check with your local planning authority that they agree, and there are not any previous planning changes or conditions which may have an impact.

Additional permissions may be required depending on the building’s history and their location. If the building is listed, an application for listed building consent will be required before any major changes are made to the dwellings.

The work will have to comply with building regulations, the focus will be on structural work and safety.

‍Read more about how building regulations apply to internal walls.

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.

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Planning permission will not be require to add an en-suite provided it is within the existing building and not part of a wider project such as an extension.

 Building regulations will have to be considered when adding an en-suite as it impacts drainage, ventilation and electrics. It is recommended that you have the work completed by a member of the competent person scheme.

Find a competent person