Going underground: in London, basement digging is a cheaper way to property expansion – but councils are getting tough on “iceberg homes”

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London’s Hanover Terrace, where Damien Hirst is planning an ambitious basement extension to his 19th century villa. Image by Spudgun67 via Creative Commons

 “It was the newly dug three-storey basement that had the guests buzzing. Below the cinema, gym and spa (complete with sauna, pool and massage table) sprawled an enormous six-car garage. But how did the vehicles get down there? Our host, an American who worked in finance, was only too happy to demonstrate: The cars were lowered down by a custom-built automobile elevator built into the parking pad in the side garden.”
Maclean’s 29 July 2015

Basement conversions and extensions are making a big noise in London. In 2001, the Royal Borough of Kensington and Chelsea received 46 planning applications for basement conversions. By 2013, that figure had soared to 450 applications. Rising house prices in the capital are making basement conversions more attractive, mostly to super-rich owners. The expansions can add millions to the value of their already expensive properties, and for those needing additional space a conversion can be cheaper than moving home.

But the trend to build down is not universally popular. Some conversions have hit the headlines because ambitious projects by rich and famous owners have triggered objections from their rich and famous neighbours:

  • in 2015, Jon Hunt, founder of Foxtons estate agency, won a legal battle with his neighbours (the French Embassy) to build an enormous basement to house his classic cars (the Embassy plans to challenge the ruling)
  • in 2013, Daimler-Benz heir Gert-Rudolf Flick got permission for a two-storey basement beneath his £30 million house in South Kensington. More than 50 local residents, including the cellist Julian Lloyd Webber, had objected to the construction plans, which they described as “entirely selfish”
  • last year, Queen guitarist Brian May launched a campaign to ban “iceberg homes” that can occupy more space below ground than the original property above

The bad feeling caused by these subterranean grand designs has spawned a new type of nimby – the “numbing” (Not Under My Bloody Idiot Neighbour’s Garden). Disgruntled neighbours’ concerns include:

  • the disruption caused by traffic, plant and equipment
  • the effects on the structural stability of nearby buildings and roads
  • the noise generated during construction (an experience described by Brian May as “an instrument of torture”)

The role of planning

Beyond the headlines, it’s planning authorities who have to deal with applications for basement extensions and to consider the implications.

Conversions of existing cellars don’t always require planning permission, unless the external appearance of the building is altered, for example by adding a light well. However, excavating the ground under a building to create a new basement may require planning permission, and these are the types of projects that can ignite disputes. As Westminster City Council’s 2014 planning guidance observes, with admirable understatement: “basement development is often contentious…”

Rewriting the rules on basement digging

In 2014, the rising tide of concerns prompted the Royal Borough of Kensington and Chelsea to revise its policy on basement development. The new policy restricts the extent of basement excavation to no more than under half the garden or open part of the site and limits the depth of excavation to a single storey in most cases.

Westminster City Council has moved to make similar changes to its basement extension policy, as has Richmond Council. As well as acknowledging residents’ concerns about noise and disruption, councils are anxious to address the wider environmental impact both during and after basement development. Westminster’s policy notes that:

“The uses associated with basement spaces may be more energy intensive due to additional requirements for lighting, ventilation and pumps, particularly where underground rooms house swimming pools and media rooms.”

Even if planning permission is not needed for basement development, the changes must comply with building control rules on fire safety, ventilation and structure. Neighbours affected by basement projects should also be aware of their legal position:

The only way is down?

The number of planning applications for domestic basements in London may have more than tripled since 2011, but a sharp deceleration in the rate of growth last year indicates that the trend may have peaked. As more boroughs tighten the conditions imposed on basement development, building costs are likely to rise and planning processes may be prolonged.

For some owners, however, thousands of pounds in additional costs is a drop in the ocean. Last month, artist Damien Hirst overcame council objections to extend the basement of his home in Westminster. Once the work is complete, it could more than double the value of his historic mansion, making it worth £100 million.

More people, more houses, more dissatisfaction… Are we ready for higher-density living in the UK?

abstract windows in flats (Unsplash)

By Morwen Johnson

We shape our dwellings, and afterwards our dwellings shape us (Winston Churchill)

It’s estimated that we need 240,000 to 245,000 additional homes each year in order to meet housing demand and need in England. Statistics show that we are consistently failing to meet this level of housebuilding but how we change this situation is a matter of debate. The UK Government’s recent Productivity Plan included proposals to make development on brownfield land easier as well as freeing up public sector land assets and supporting higher density housing around commuter transport hubs. Others are recommending more controversial solutions, such as increasing building within the green belt (for example see reports from London First and the Adam Smith Institute).

It seems inevitable that the future requires housing at greater density but, particularly in London, alarm is now being sounded about superdensity and potential hyperdensity developments, which have become the norm in many global cities.

What is high density development?

From a planning point of view, density is intrinsically linked with creating viable communities which have a population to make amenities and infrastructure sustainable and cost-effective. Higher density designs (in urban environments) also increase the amount of street activity and thus, the perceived safety and attractiveness of a place.

Appropriate density is of course relative to context, and guidance such as the London Plan density matrix reflects this. Although there is no hard and fast definition, within urban areas a general density of around 70 to 100 dwellings per hectare (dph) level is common. In terms of new developments in major city centres like London, superdensity has been used to describe densities over 150 dph (or 450-500 habitable rooms). Hyperdensity can mean 350 dph or more.

Higher-density living does not necessarily mean high rise buildings though – careful design can increase neighbourhood density via mixed-tenure mid-rise developments. A group of four London-based architectural practices recently published a report Superdensity which aimed to provide positive guidance on how to ‘combine ambitious densities with popular and familiar urban forms’.

Space as a luxury or a necessity

While this may at first sight appear to be a debate about the planning system, it actually raises more fundamental questions about the aspirations and expectations we have for how we live.

There is a legacy in Britain of thinking that high-density housing means tower blocks in undesirable areas. Much urban regeneration in recent years has focused on replacing high-rise buildings. Lower-rise developments can also be high-density, if well designed, so the issue is actually often about housing quality rather than increased density, and whether the housebuilding industry is delivering the types of housing that people want.

RIBA’s Future Homes Commission highlighted that a focus on number of bedrooms ignores the potential of rooms as functional spaces. Floor space in the UK for new build housing is the smallest in Europe. And research in 2012 suggested that people value natural light, space for storage and flexible spaces which allow for socialisation. There is also a general hierarchy of desirable housing which it is still often assumed that people will move through during their lifecourse, especially as they start families – i.e. starter flat, 2 bed flat, terraced house or maisonette, semi-detached house, detached house with garden – as well as a move from rented property to owner-occupier.

For many people however these aspirations are impossible. Drawing on 2001 Census data, research has shown that although social housing tenants make up only 21% of families with children, they make up 79% of those families living on the fifth floor of a building or above. In London, nearly one third (31%) of all families with children living in social housing were found to reside on the second floor or above.

Smaller dwelling sizes can also affect our health. Many people living in flats or tenements have to dry laundry inside, which has been shown in studies by the Mackintosh Environmental Architecture Research Unit and the University of Manchester to have health risks. Lack of outdoor space for children to play (whether communal or private garden space) also has negative impacts. It seems that many people have to downsize both their living space aspirations and their quality of life.

It’s hip to be dense

The fact that we pay a premium for space, just as people who can afford it can choose to pay more for housing near transport connections or in particular school catchment areas, is nothing new. But as the discussion on high-density housing and the quality of new housing shows, it can be argued that the trends of the housing market are disadvantaging a large proportion of the population, and also younger generations. Access to housing (and increasingly housing space) is becoming a highly political issue.

Public suspicion of high-density housing is being overcome through subtle rebranding – terms such as the ‘compact city’, ‘pocket housing’ and ‘micro-housing’ have a cool edge which try to appeal to young urban-living professionals. And many award-winning high-density schemes also now have a strong focus on communal gardens or space, providing elements that traditionally would be delivered in private space.

Regardless of the marketing (or policy impetus), the truth however is in the living. Do people feel they are compromising in their housing choices or is there a wider shift in aspirations? And more importantly, as space becomes a scarcer commodity, are we just introducing another marker of inequality into the mix?


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