SOME of the edifices looming above the approach road to the Blackwall tunnel in east London now resemble follies - the Olympic stadium, for example. But others are thriving. Inside Attic Self-Storage, padlocked metal doors line corridors of what look like shipping containers. The reception area has sofas and bowls of sweets. The atmosphere, says Frederic de Ryckman de Betz, its owner, is meant to be "like a hotel, but a bit colder and without the carpets." Unlike in America, where a mobile population has long needed extra space, self-storage has only recently taken off in Britain. Business is now booming. In 2002 Britain had just 5m square feet of capacity, according to the Self Storage Association, an industry body. By 2013 that had swelled to 30m square feet. Growth has continued throughout the downturn, defying a stagnant housing market, weak bank lending and a surprise tax imposed by the Treasury in 2012. The industry at first grew by offering space for household stuff. Graduation, marriage, divorce, death: all create demand, points out Jimmy Gibson, the boss of Big Yellow, a self-storage chain that also has a branch near the Olympic stadium. Firms target affluent areas densely populated with young, mobile types; as a result, they are most concentrated in London and the south east. Most people use storage to keep bric-a-brac between moving homes, though there are exceptions. Mr Ryckman de Betz reports that one of his customers, a drummer, uses his unit as a studio. Since 2008 fewer people have been moving abroad, divorcing or buying new houses. But new customers have arrived. In 2012 fully 42% of Britain's storage floor space was taken up by small businesses, up from 36% in 2010. Customers range from tradesmen, who use their units to secure their tools, to import-export businesses, who like the flexibility to add to their space. For most, self-storage is an alternative to hiring a lock-up or a warehouse, without the burden of long leases or business rates. Many self-storage firms now provide offices too. As the economy recovers - and years of pent-up demand to move house or divorce is released - growth should soar. The trouble, says Mr Gibson, is finding places on which to build. Storage companies favour sites near main roads in densely populated residential areas; their buildings function as giant advertisements. Yet such sites are also popular with house builders, who will pay steep prices for land. Big Yellow has been looking for a site in Cambridge for a decade. For incumbent firms, that is hardly a problem: a shortage of supply means higher profit margins. For the rest of the population, however, it means the relentless squeeze on space continues.