When will you need planning permission for a basement construction

The requirements for a basement planning application will depend on the policies of your local council. Consequently, your local council should be consulted in the early stages. Similarly, your Architect or appointed basement contractor will be able to advise of these requirements.

Existing Basement or Cellar

Converting an existing residential cellar or basement beneath a house into a living space is in most cases unlikely to require planning permission. This being said, planning permission will need to be obtained if a separate unit is created, the usage is significantly changed or a light well is added. Furthermore, any works which alters the external appearance of the property require planning permission. Finally, lowering the floor level of an existing cellar to increase the ceiling height can be considered as an extension, therefore may need planning permission. You can find more information by visiting the Planning Portal at www.planningportal.gov.uk.


Introductory Guide – document you would need for a planning application. However, for specific details, please contact your local planning authority for guidance on local policy

Architects existing and proposed drawings (Building Control/Construction Drawings not required for planning stage)

Flood Risk Assessment

Construction Method Statement

Arboricultural Impact Assessment (if the case)

Geo-Environmental Desk Study

Construction Traffic Management Plan

Your local council may request further documents. Also, special conditions may imposed on your application. As a result, the need of such documents will be advised by your Architect or contractor