How to build for a wetter world

By Kassia St Clair

Since 2004, there has been at least one catastrophic flood somewhere in the world every year, and flooding has become one of the most visible effects of global warming. The 2010 floods in Pakistan left 10m people homeless and the World Bank estimated the total cost of the disaster to be $9.7 billion. The price tag for the 2015 flood in Missouri, in the American Midwest, is estimated at $3 billion, while the flooding in Britain last winter came to £5 billion (just over $7 billion). As sea levels rise and the weather becomes more extreme, there is more to come.

Accordingly, architects are increasingly being asked to design buildings to resist deluges. Baca, an architectural practice in London, have become specialists in the field. The firm’s Amphibious House (below), completed earlier this year, was built on an island prone to frequent flooding near Marlow on the River Thames. Constructed in a purpose-built wet dock with a permeable base, it has buoyant foundations and can rise up to 2.5 metres above its normal position. The basement is fully waterproofed and habitable even when submerged. The terraced gardens, meanwhile, act as both a way of measuring a rise in the water level and as an early-warning system: when the first two terraces are submerged, the owners know that the Amphibious House should have begun to rise between its mooring posts. Since this project was completed, the firm has proposed a simpler, narrow pre-fab building that would float by the banks of canals, designed to help ease London’s shortage of affordable housing while leaving enough room for water traffic.