The planning regime covering the creation of living space in basements is evolving and under review.
Converting an existing residential cellar or basement into a living space is in most cases unlikely to require planning permission as long as it is not a separate unit or unless the usage is significantly changed or a light well is added, which alters the external appearance of the property.
Excavating to create a new basement which involves major works, a new separate unit of accommodation and/or alters the external appearance of the house, such as adding a light well, is likely to require planning permission.
If you live in a listed building you are likely to need consent for internal or external work.
In all circumstances you are advised to contact your Local Planning Authority for guidance on local policy before starting any work.
Building Regulations apply. They cover areas such as fire escape routes, ventilation, ceiling height, damp proofing, electrical wiring and water supplies.
Underpinning and foundation work may also be needed.
You must also consider the Party Wall Act 1996 if other properties adjoin yours and you share walls.
The 'Basements for Dwellings' guidance was removed from the list of approved documents on 1st October 2010. DCLG and the Basement Information Centre are currently developing updated guidance on this topic.
This is an introductory guide and is not a definitive source of legal information. Read the full disclaimer here.
This guidance relates to the planning regime for England. Policy in Wales may differ. If in doubt contact your Local Planning Authority.