.svg){kind=small}
.svg){kind=small}
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
In many circumstances, rules known as ‘permitted development’ rights allow you to extend a house without needing to apply for planning permission, providing specific limitations and conditions are met. If you want to exceed these limits and conditions, then it is likely that an application for householder planning permission will be required.
You can find information about the limits and conditions, prior approval and the building regulations on the Planning Portal by using the links below.
Read about planning permission for extensions
Read about prior approval for larger single storey extensions
Find out about building regulations for an extension
There is no single legal definition of "habitable room", as its use and meaning are subject to context. Generally, a habitable room is a space in a building that is designed for people to live, sleep, or spend extended periods of time in, but does not include bath or toilet facilities, corridors or utility rooms.
Building above an attached garage is treated the same as adding a storey to the rest of your home. This is considered to be permitted development, not requiring an application for planning permission provided you meet the set rules and requirements.
You will still need to submit an application for prior approval to your local planning authority.
Read the list of rules and requirements for extending upwards.
It is likely that you will require planning permission to extend an existing front porch to add a toilet.
Adding a porch falls within permitted development rights meaning an application for planning permission is not required provided specified limits and conditions are met. However, to fall under permitted development rights for a porch, the total ground area must not exceed three square metres. This is unlikely to be enough room to fit toilet and the required additional components.
Read the full rules for porches under permitted development on our mini guides.
If your porch exceeds these limits, it will be classified as an extension. These can be permitted development but come with a different set of rules.
Extensions are not permitted development if they are built forward of the ‘principal elevation’ of the house. As such, you will be required to submit an application for planning permission to your local planning authority.
If you live in a listed building, you will need listed building consent for any significant changes.
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.
Ask another question
Can’t find what you’re looking for?
