Houses that rise on floats could provide safer homes in areas prone to floods and tsunamis, according to a Bangladesh-born US architect.
Two such 'amphibious' house designs are being tested in Bangladesh, where proximity to the Ganges delta means that flooding is a frequent problem. When flash floods last occurred, in 2010, more than 10,000 people were made homeless.
"Flooding there doesn't allow people to maintain a safe lifestyle," said Prithula Prosun,a Bangladeshi-born lead architect of the Low Income Flood-proof Technology (LIFT) house project and a graduate architecture student at the University of Waterloo, Canada. "I wanted to give something back," she said, adding that her inspiration came from similar amphibious projects in New Orleans, United States.
The LIFT designs work by preventing lateral movement but allowing the house to move up and down on stilts. When floods occur, the house simply rises above the water. Both the house and the foundations need to be light and buoyant, and two foundation materials are being tested.
One is ferrocement, a lightweight local material made with cement, sand, water and wire or mesh — the other is made of plastic water bottles thrown away by local hotels.
"It takes 8,000 bottles for the foundations of a two storey home for one family," said Prosun. "The plastic will last longer than the rest of the building, so it is an extremely durable material for the buoyant foundation."
She added that the structure of the house is made mainly out of bamboo, which is widely available in Bangladesh, but still underused. And the house is environmentally friendly: it cannot be connected to conventional power, water and sewage systems, owing to its rise and fall, instead it is solar powered, has composting toilets, and collects and reuses rain water.
The houses were constructed at the Housing and Building Research Institute in Dhaka, with assistance from the housing and public works ministry of Bangladesh and the research team of the Centre for Urban Studies in Dhaka. So far, the designs have lifted up to three feet off the ground, but can be constructed to float higher according to flood levels.
Prosun said that at about US$5,000 — and scope for lowering the price — LIFT house is "an affordable project for low income communities".
Prosun added that the next steps would be to adapt the designs for diverse environments and to scale up production.
Srabanti Datta, marketing director of a construction company that is supporting the project in Bangladesh, said: "The community hopes that our government takes steps to grant land and arrange for building LIFT house neighbourhoods."
But Gareth Pender, head of the school of the built environment at Heriot-Watt University, United Kingdom, cautioned that more research is needed. "You need to be careful that it works in areas of high flow velocity as well as high water height," he said.