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 'listed building' is a building, object or structure in the UK that has been considered as of national importance in terms of architectural or historic interest and included on a register called the List of Buildings of Special Architectural or Historic Interest.

Buildings are listed to help protect the physical evidence of our past, including buildings, which are valued and protected as a central part of our cultural heritage and our sense of identity. Historic buildings also add to the quality of our lives, being an important aspect of the character and appearance of our towns, villages, and countryside.

There are three listing grades:

- Grade I - Buildings of exceptional interest

- Grade II* - Particularly important and more than special interest

- Grade II - Buildings of special interest, warranting every effort being made to preserve them (this is the most common)

If you live in a listed building it means you cannot demolish or alter the building in a way that changes its character without Listed Building Consent.

Read detailed guidance on Listed Building Consent

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.

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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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If you plan to put up a small, detached building like a garden shed, garden room, garden office, annexe or summerhouse (all classed as outbuildings), building regulations generally won’t apply if the building has a floor area under 15 square metres and does not include any sleeping accommodation.

For buildings with a floor area between 15 and 30 square metres, building regulations approval is usually not needed - as long as the building does not include sleeping accommodation and either:

• it is at least one metre away from any boundary, or
• it is built mainly from non-combustible materials.

Read more about the building regulations that apply to outbuildings.

Don't forget to check the permitted development rights for outbuildings.

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