Basement extensions

Basement extensions are an increasingly common form of development in Westminster.

The council's policy on basements (CM 28.1 Basement Development) was adopted in July 2016 as a revision to the Westminster City Plan. This policy also requires applicants to comply with our Code of Construction Practice when undertaking  a basement development to ensure the environmental impact of construction is monitored, controlled and managed.

Find out more about submitting an application for basement development, including forms and checklists.

Adopted Supplementary Planning Document (SPD)

We adopted guidance on this issue in the 'Basement Development in Westminster' Supplementary Planning Document' (SPD), which was adopted by a Cabinet Member decision on 20 October 2014. This SPD predates the adopted basement policy and code of construction practice but much of the guidance is still relevant in determining planning applications.

It also includes advice on the other regimes used to control basement development such as highways and building control, as well as links to useful sources of information and contacts (section 7 and appendices).

The guidance note and associated documents can be downloaded below:


Last updated: 5 April 2018
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