Basements

A basement can offer new space for your home, becoming increasingly popular in dense city areas. Creating a basement can be expensive but is likely to have to adhere to a less strict set of planning regulations than one which is visible above ground.

Converting an existing basement

You are unlikely to require planning permission for converting an existing basement into a living space. If you are just redecorating an existing space, planning permission will not be required.

Planning permission will be required where you:

• create a new unit for residential accommodation
• change the use significantly e.g. to operate a business
• add a lightwell
• alter the external appearance of the property.

Creating a new basement

The creation of a new basement will commonly require planning permission, often due to the effect on the external appearance of the property. A lightwell may be installed to allow light to enter the basement; if this is on the front of the property and visible from the street there may be stricter rules on the appearance than if it is located on the rear or side of the home.

Excavating to create a new basement is likely to require planning permission due to the major works which are required. It is advisable to talk to your local planning authority to understand what they deem acceptable prior to submitting an application.

Local planning authorities may have their own rules around basements set out in their supplementary planning documents. These rules may affect the depth and size of the basement.

If you want to understand more around the process of planning a basement conversion, visit our project advice page on basement conversions.¹

Find your local planning authority ^{(https://www.planningportal.co.uk/find-your-local-planning-authority)}

1. https://www.planningportal.co.uk/permission/home-improvement/project-advice/project-advice-basement-conversion/planning-a-basement-build-or-conversion