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Do I need planning permission to build underground?
Creating a new basement will usually require planning permission, particularly if it affects the external appearance of the property. For example, installing a lightwell to bring natural light into the basement may be subject to stricter design rules if it is visible from the street, especially at the front of the property, compared to those at the rear or side.
Because basement construction involves significant excavation and structural work, permission is often necessary. It’s recommended that you consult your local planning authority early on to understand what is likely to be considered acceptable before submitting a planning application. Building regulations will also apply to a new or conversion of a basement.
Common Questions
A single storey rear extension can fall under permitted development, meaning planning permission may not be required providing it meets certain criteria.
In terms of height, the extension must:
- Be no taller than four metres at its highest point
- Have eaves no higher than the eaves of the original house
- Not exceed the height of the original dwelling
Read about planning permission for extensions on Planning Portal
The conversion of a garage, or part of a garage, into habitable space, will normally require approval under the building regulations.
As part of the garage conversion, it is likely that the original garage door will be in-filled with a new wall and possibly a window or door, and a new foundation may be needed for the new wall.
As well as the foundation, you also need to consider:
- Floor
- Walls
- Ventilation
Read more about the building regulations for garage conversions.
Approved Documents are official guides that explain how to comply with the building regulations. Published by the government, each document provides practical guidance on meeting the requirements of a specific ‘Part’ of the regulations. They cover a wide range of building work, including plumbing, electrical installations, extensions and ventilation.
The latest versions of the Approved Documents, which support the technical ‘Parts’ of the building regulations, along with Regulation 7, are available on Planning Portal.
You will not need to apply for planning permission if you wish to erect a new; or alter, maintain, improve or take down* an existing fence, wall or gate if certain conditions are met. If any of the conditions are not met, then you will need to apply for planning permission.
Find out about the limits and conditions for fences, gates and walls.
Fences, walls and gates do not require building regulation approval. Even though building regulations do not apply, the structures must be structurally sound and maintained.
If you share a wall with a neighbour, it may be classed as a ‘party fence wall’.
When you, or an agent acting on your behalf, have submitted a planning application, the local authority will firstly check the application to check if it’s complete. This validation process allows the authority to ensure everything that is required to decide an application has been received and provided correctly. They will contact you if they require any further information from you.
After the application has been validated, the determination process begins and takes up to 8 weeks for smaller applications, or up to 13 weeks for larger applications. The authority should be able to give you an idea about the likely timetable. The local authority will contact you with their decision.
Read more about the decision-making process for planning applications.
