Portable rooftop boxes, floating homes and converted schools are some of the housing solutions for large cities Our cities are bursting at the seams. With populations in London, Hong Kong and Shanghai continuing to expand, developers and architects are having to find imaginative solutions to the problem of housing everyone. In Berlin, an architect has created a portable home to place on the city's flat roofs; in London, schools are being converted into apartments, and a design company is developing luxury floating homes to maximise available space on the city's waterways - an idea that could also work well in Hong Kong. Waterspace operates from one of the two-storey fibreglass floating homes it has created, moored at the Chelsea embankment - proof that you do not need to buy one of the expensive apartments, houses or offices on land to have an impressive London postal address. These floating homes/offices are priced from GBP250,000 (HK$3.59 million). The two enclosed decks provide 1,050 square feet of living space, including an impressive double height, fully glazed atrium at the stern. There is also a small top-deck roof terrace which can accommodate a whirlpool bath. The company will design the interior according to customers' specifications. It can comfortably house two bedrooms with an en suite on the lower level. The top level works best as an open plan living area. The boats can be fully connected to mains utilities and will last 75 years. Two vessels have been sold in Britain as holiday homes, but Waterspace technical director Rory Boyle said they could contribute to easing the shortage of affordable homes in pricey cities such as London, Tokyo, Singapore and Hong Kong. 'Several people said it would go down well in Hong Kong, because accommodation is so expensive. You could make them fully air-conditioned and put them in the typhoon shelters. 'We reckon we have a market in the UK which is quite a hard one to crack. In Japan, we have interest from developers. There you could place it on inland waterways. Young people who want to do something different are interested; those of western influence, not traditional Japanese.' From living on water to living in the clouds: in Berlin, German architect Werner Aisslinger has created the Loft Cube, which turns rooftops into funky residential zones. 'The endless flat tops of the post-war high-rises in the city and suburbs are an undiscovered treasure of sunlit property,' he said. This single storey, wooden construction includes a bedroom-living area, kitchen and bathroom. It could be hoisted by crane or, for high buildings, set down by helicopter on to a flat roof. The 430 sqft cube would be accessed by the building's lift or stairs and would be connected to its utility lines. Gardens, boats and trucks are other potential sites. Mr Aisslinger said the Loft Cube, which costs Euro50,000 (HK$481,200), was ideally suited to the world's mobile, younger professionals, whose restless ways were not properly understood in the property market. Companies could accommodate overnight visitors on their rooftops too, he added. Closer to terra firma, in London, public and commercial buildings are being converted to residential use. In the early 1990s, ageing warehouses and offices were targeted; later, hospitals and army barracks; and now, schools and colleges. According to research, more than 700 apartments in converted educational buildings are in the construction pipeline. These include Urban 7, in Islington, north London, where developer Crest Nicholson is redeveloping a former Edwardian school into 35, one- and two-bedroom apartments, priced from GBP249,950. Sales and marketing director Michelle Harris said converted school buildings were popular because they had character.