This Assembly notes that inappropriate basement development is an increasing problem within London. In the Royal Borough of Kensington and Chelsea, for example, planning applications for basements rose from just 13 in 2001, to 182 in 2010, and to 307 in 2012.  Some of these renovations are turning already-large homes into massive iceberg houses, and can cause flooding, sink holes and structural damage to neighbouring buildings.

Despite the rising concern, the draft Further Alterations to the London Plan (FALP) does not include a specific policy on subterranean development. Although draft Supplementary Planning Guidance and the current policy on sustainable design and construction require consideration of some issues, London must adopt stronger policies to help boroughs prevent unnecessary basement development, such as prohibiting extensions under listed buildings and limiting the size and depth of new and redeveloped basements.

This Assembly therefore calls on the Mayor of London to revise the FALP to include a specific policy against inappropriate basement development.