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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
A roof window (or skylight) is fitted flush within the slope of a roof, while a dormer projects outward, creating additional headroom and floor space.
Both can be installed under permitted development but must meet specific size and position limits to qualify.
Also consider building regulations for a new dormer, find out more on Planning Portal
A ‘P certificate’ may refer to confirmation that electrical installations within a building are compliant with Approved Document P of the building regulations.
An electrician who is Part P certified is able to self-certify domestic work they complete, meaning you do not have to submit a building notice. To ensure your electrician is Part P certified, use a registered competent person.
In many cases, you can extend a house without applying for planning permission by using what's known as permitted development rights, provided certain limits and conditions are met. However, if your plans go beyond these restrictions, you will likely need to apply for householder planning permission.
Planning permission is unlikely to be required for the installation of external damp proofing unless the work will change the external appearance of the building or is part of a larger project.
If you live in a listed building you will need listed building consent for any significant changes, this can include external damp proofing. Additional rules may also apply if you live in a Conservation Area or other protected area.
Building regulations approval is not required for installing an external damp proof course (DPC).
Most garden ponds will fall under permitted development rights, meaning an application for planning permission is not required. In planning terms a pond will be classed as an outbuilding, to read the full rules around installing an outbuilding, visit our common projects section.
For ponds which are particularly deep or large, you may need to apply for planning permission. If you are unsure, you should contact your local planning authority for advice.
In a listed building you will require listed building consent for any major changes.
When installing a pond, you should take into account other regulatory considerations such as environmental permits or any protected species which may be impacted. Further thought will have to be placed when creating ponds near riverways or in areas of flood risk.
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