Islington council has become the latest planning authority in the capital to float the prospect of restrictions on the booming business of basement construction
Less than two weeks after the Royal Borough of Kensington & Chelsea won the backing of the Planning Inspectorate for its proposals to curb the growth of multi-storey ‘mega-basements’, the London borough has taken a fledgling step in the same direction.
Kensington & Chelsea’s new guidance will ban basements of more than one storey from being created under most structures, curtail the footprint of any project extending to more than 50 per cent of a garden area, and require detailed construction-management plans for submission along with planning applications.
Islington is asking for views on acceptable guidance it could consider, within parameters that include maximum depth, garden impact, environmental impact and neighbour disturbance. Nothing in the paramaters (see box below) rules out guidance similar to that created by Kensington & Chelsea.
Councillor James Murray, Islington’s housing and development lead, said the number of basement applications determined by the borough had increased by 50 per cent between 2013 and 2014, rising from 41 to 62.
‘We’re seeing a growing trend towards big basement extensions as the value of homes in Islington - particularly large ones – continues to soar,’ he said.
‘Not only are there more of these applications but their size and depth has also increased. We need firmer rules to protect the borough’s gardens and trees for the future, and to prevent long-term impacts on the character and structure of homes further down the line.
‘While basement construction has been around since the Georgians, the recent trend for excavation under residential gardens and under existing basements is unprecedented.’
Charles Humphries, director at Heat Architecture, said the rush to produce guidance to curtail basement builds failed to distinguish between construction-time issues and finished projects.
‘In my view there is a case for carefully controlling the construction of basements, but not the design,’ he said.
‘Most contractors will use specialist groundwork sub-contractors for the excavation and structural phase and the groundworkers at this level are highly specialised - used to working to tight tolerances in congested areas. It is common for the groundwork contractors to be better organised and more professional than the general contractors who follow on after to do the fitting out.
He added: ‘Generally, existing buildings in Islington are built on minimal foundations. The construction of a basement is equivalent to a kind of super-underpinning which stabilises and stops further movement in its tracks. The new construction provides better thermal performance than the existing fabric and they are usually considerably less damp.
‘If the basement is under the building or at the rear it is hard to see how it could possibly affect the character and appearance of an area: They are by their nature invisible; particularly compared with roof conversions or extensions and the amenity of nearby residents is completely unaffected.’
Humphries also questioned how well-placed planning officers would be to interpret ‘ecological connectivity’, ‘cooling effect’ and ‘flood alleviation impact’ studies that could be required for future developments.
Islington’s consultation is open until January 27. Its discussion paper can be viewed here.
‘Parameters’ for Islington’s basements consultation:
• Guidance about the garden area/unbuilt on area to remain unbuilt on, and the general depth that is likely to be acceptable for basements;
•Guidance about the design of basements under garden/unbuilt on area, referring specifically to replacement soil volumes, depth of soil, drainage requirements and access to deep soil;
•Specific guidance and information requirements for basements which involve impacts to existing trees/shrubs due to the added complexity of design considerations required;
•Guidance to ensure basement proposals are designed efficiently in terms of design and specification, including consideration of and minimisation of their contribution to CO2 emissions; and designed to adapt to climate variations without the need for energy intensive heating or cooling, or increase potable water demand; and
•Other guidance required to ensure basement development isproperly assessed and is designed to minimise site-specific impacts, whilst consideration is given to wider cumulative impacts.
Previous story(AJ 11.12.14)
Anger at plans to ban ‘mega basements’ in South Kensington
Guidelines setting limits on size of subterranean rooms a ‘dangerous precedent’
Architects have reacted angrily after a planning inspector approved plans to ban multi-storey ‘mega-basements’ in an exclusive part of west London.
In October, it emerged the Royal Borough of Kensington & Chelsea had placed about 220 planning applications in limbo while a planning inspector reviewed its proposed policy.
The decision last week means the ‘frozen’ applications for new subterranean rooms, swimming pools, and parking spaces will now starting moving through the system again – however, most are expected to be rejected.
According to Kensington & Chelsea the ‘vast majority of these cases would not comply with the new policy’.
Architect Ian Hogarth said the new guidelines setting limits on the size of basements, which were driven by residents’ anger over the inconvenience caused by basement builds coupled with a spike in applications, set a dangerous precedent.
‘Historically, neighbour disturbance has been covered by the environmental health department and has never been admissible as a valid planning issue,’ he said. ‘The decision now leaves this issue wide open, and could affect any development anywhere in the country.’
Hogarth added limiting the footprint of new basements was an ‘arbitrary’ measure that could dramatically reduce the opportunity to provide lightwells for builds at properties with small gardens.
Architect Chris Darling of Darling Associates said the planning inspector’s decision was ‘disappointing’.
He said: ‘Kensington & Chelsea is unique in combining exceptionally high density with exceptionally high land values. Kitchens, utility rooms, and gyms don’t need natural light and placing them in basements helped to retain precious above-ground space for living and bedrooms.’
Nick de Lotbiniere, a director at consultants Savills, said he believed the policy was ‘too restrictive’ and may be open to legal challenge.
‘The issue is whether construction noise and disturbance should be given so much weight,’ he said.
‘Policies designed to deal with basements could start to interfere with other forms of development.’
Ian Fergusson, associate director at consultants Turley, agreed that a challenge to the policy was possible, but said it may be hard to win.
‘The council and the inspector have been robust about their proposals, but there will be legal issues about the past two months, where there has been this uncertainty and we’ve heard of legal actions being prepared,’ he said.
The London boroughs of Camden, Islington, Richmond, and Wandsworth are understood to have been watching Kensington and Chelsea’s progress closely.
Both Hammersmith & Fulham and Merton already have basement-build policies in place.