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.

A pergola is classed as permitted development, meaning an application for planning permission is not required provided it meets specified conditions and limits.

Outbuildings cannot be installed on the principal elevation of the property, additionally any platform must not exceed 0.3 metres in height.

If the building is listed, then you will need to apply for listed building consent and planning permission for the change.

For more details read our outbuildings common project.

Maintenance of fascias and soffit boards such as replacement or painting generally does not require planning permission.

However, if you live in a listed building or designated area (conservation area, national park, area of outstanding natural beauty) you should check with your local planning authority before carrying out any work.

Building regulation approval is not normally required for this work, but you should ensure that the ventilation for the building is not impacted.

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Inefficient windows and doors can significantly contribute to heat loss. Replacing single glazed windows by installing double glazing can cut heat loss through windows considerably. Double glazing works by trapping air between two panes of glass creating an insulating barrier that reduces heat loss, noise and condensation.  

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If you can't replace all the windows, why not choose the rooms that cost you the most to heat? Other options to reduce heat loss through windows include sealing gaps or using thermal blinds.

You don’t usually need planning permission for repairs, maintenance and minor improvements or replacing windows and doors that are of a similar appearance.

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Building regulations apply to replacement glazing, in terms of thermal performance, air supply, ventilation, safety and means of escape.

Read about planning and building rules for doors and windows

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Whether you need planning permission to install an extractor fan depends on the size and placement of the fan.

For domestic installations, such as a bathroom or kitchen in your house, planning permission is not generally required. If the change significantly alters the external appearance of your home then permission may be required.

If you live in a listed building, you will need listed building consent for any significant changes.

Larger extractor fans for businesses are likely to require an application for planning permission to be made to the local planning authority. These extractors can impact the local area due to their noise, visibility and odour, as such the planning authority will need to assess the change.

Building regulations relating to ventilation and electrical works will have to be complied with, these are covered by Approved Document F and P respectively.

Read more about building regulations and the requirement for ventilation on our common projects.