As London’s very wealthy homeowners run out of space in their mansions, they’re no longer trying to add additional floors. Instead, they’re looking down. In the past decade, so-called “mega-basements” have gained popularity among London’s floor-space-hungry elite. Because authorities want to protect the capital’s historic skyline, building up is actively discouraged, if not outright banned. To make room for that swimming pool, gym, tennis court and private cinema, some Londoners are literally breaking new ground in their properties. These expensive, expansive subterranean extensions—sometimes dubbed “icebergs”—can run several stories deep. In Kensington & Chelsea, one of London’s most exclusive neighborhoods, home to Harrods department store and several embassies, the number of planning applications for basements jumped from just 46 in 2001 to 450 in 2013. Celebrities with mega-basements include Australian actress Nicole Kidman and British composer Andrew Lloyd-Webber.
Celebrity Spats
These billionaire basements are causing disagreements between neighbors over noisy construction work and, in some cases, cracks in walls. Last year, Led Zeppelin guitarist Jimmy Page criticized singer Robbie Williams’ plans to upgrade his $25 million mansion in Holland Park; Williams was forced to scale back plans for a two-story basement extension. Joan Collins, the actress, has also complained about them, telling a local magazine that she found it “shocking that people are digging down to put in swimming pools and bowling alleys when they only live here for two or three months of the year.”
Council Crackdowns
Some neighborhoods are doing more than just complaining to the press. In December 2014, officials in Kensington and Chelsea limited the scale of basement development, arguing that many of its residents “have experienced years of misery from noise, vibration, dust and construction traffic.” This included a reduction in the maximum extent basements can stretch under the garden, from 85% to 50%, with that 50% being in most cases a single story (although there are exceptions for large sites). At the end of last year, Westminster confirmed it would limit the size and depth of basement construction. The inner London borough will also implement rules, forcing residents to secure planning permission. Robert Davis, Westminster Council’s deputy leader, told The Daily Mail, “Our residents have been facing an underground epidemic on their quiet residential streets, and I want to help stop the horror stories of people living next to mega-basement construction.” Similar changes have come to other London neighborhoods, including Islington and Camden. The latter includes Bishops Avenue in Hampstead, dubbed “Billionaires Row.”
Scaling Back
Experts stress that these extravagant icebergs are just a small percentage of the basements being excavated each year. It’s the demand for single-story renovations that is still very much alive and growing at a quick pace. Driving this trend, in part, are higher stamp duty rates on London’s more expensive properties, making it prohibitively expensive for many homeowners to move. Even expensive renovations look like the best option for getting more space. “The single level basement is only gaining in popularity,” said Rosie Caley, design director at Oxford and London Building Company. “People are increasingly motivated to work on their own homes. This year, I would say we have noticed the greatest upsurge in interest in our 15 years of digging basements.” Alan Everett, director of Knowles, another company specializing in London basement construction, sees another factor at work. As more homeowners see what can be done with this unused underground space, they consider basement expansion more seriously. This, in turn, leads more companies to specialize in the field.