In a sunny laboratory at the University of Southern California, a robotically controlled nozzle squeezes a ribbon of concrete onto a wooden plank. Every two minutes and 14 seconds, the nozzle completes a circuit, topping the previous ribbon with a fresh one. Thus a five-foot-long wall rises—a wall built without human intervention.
The wall is humble but portentous. “If you can build a wall, you can build a house,” says Behrokh Khoshnevis, an engineering professor, as he watches the gray mixture squirt out in neat courses from what he calls a contour crafter, a machine about eight feet tall and six feet wide. If all goes as planned, Khoshnevis will use a larger, more advanced version of the device later this year to erect the first robotically constructed house in just one day.
Khoshnevis believes his contour crafter will revolutionize building construction, dragging it into the digital age. Today, despite the advent of tech tools like power saws, mechanized cranes, and pneumatic nailers, construction is essentially the same tiring, gritty job it has been for 20,000 years. Workers still have to cut, grasp, hoist, place, and fasten materials, which is why labor accounts for about half of a building’s cost. The process is dangerous, slow, and wasteful: More than 400,000 American construction workers are injured each year, and a typical American house takes at least six months to complete, generating about four tons of waste.
