When a group of specialists from Tata Group was developing low-income homes for Indian city dwellers, its designers did something unusual – they went to look at the very houses they sought to replace.

“In the slums, people live in one room,” says Rajeeb Dash, head of marketing and product development at Tata Housing, part of the Indian conglomerate that last year began selling the Nano, the world’s cheapest car. “But we saw that at night they use a wooden platform to create a mezzanine floor, so a 150-square-foot room suddenly becomes two rooms. It is very creative.”

Tata, whose studios and one-bedroom apartments cost Rs390,000-Rs670,000 ($8,400-$14,500), is not alone in turning to existing housing for ideas. Fred Dust, a partner at Ideo, the international design consultancy, agrees that much can be learned from the way poor people build their houses. “There are parts and pieces that get assembled. The organic growth of the home is a real moment of ingenuity,” he says.