The London Borough of Islington is set to become the third London borough to adopt new planning rules effectively banning mega basements
Tomorrow night (14 January) the council is set to join Kensington & Chelsea and Westminster in resisting new basements of more than one storey in depth.
Councillors on Islington’s executive committee have been recommended to approve a new supplementary planning document (SPD) guiding policy towards applications for subterranean development.
A report going to the committee said: ’The increasing density of development in central London together with changing market expectations is creating a new context for subterranean development in the capital, and with it a new set of planning issues to be considered.’
The new rules would prevent excavation that would create basements deeper than one storey, which will also rule out downward extensions to properties which already have a basement.
They would also limit basement extensions from being more than double the ‘footprint’ of the original building or from taking up 50 per cent or more of the garden – whichever is less.
Applicants will also be required to provide detailed information on issues including the impact that any basement development would have on surrounding gardens and trees.
However, there is a small amount of flexibility on the depth of basements, with the SPD stating: ‘In limited circumstances, for example a major commercial redevelopment site or a detached residential house with generous distances to adjoining properties, it may be acceptable to have a basement greater than one storey in depth if robustly demonstrated via detailed evidence that there would be no significant impact upon the hydrogeology or the structural stability of buildings, trees and other structures, and the design complies with all other relevant guidance in this SPD.’
Islington says that the number of planning applications containing basement developments rose from 41 to 62 between 2013 and 2014.
The new rules, it said, are being introduced due to an increasing number of residents voicing concerns about nuisance caused by the excavation of large basements.
Westminster has already begun to give some weight to its basement policy revisions in planning decisions. Its proposed policies were submitted to the communities secretary in December, with an independent examination of the proposals expected to be carried out in March.