Not much has changed when building homes in the US. Dozens of workers show up at a dirt lot. Tons of materials are delivered. Crews hammer, pour, and nail them together over weeks and months, according to an architect’s drawings. One more family is housed, albeit often late and over budget, at an average cost of $428,000.

That equation isn’t working well in America’s cities. The affordable housing crisis has now spread from densely packed cities like New York to almost every major metropolis. Policy and zoning play a major role. Yet the cost of construction looms over everything.

The cost of building one unit of affordable housing—a unit, not a house—in a city like San Francisco can run as high as $750,000. At that price, the region will never serve the number of people it needs to shelter. We must make cheaper homes, at scale, and fast to ease the cost of living for working- and middle-class residents being squeezed out of cities.

Pre-fab is one solution

In the popular imagination, pre-fabricated housing brings to mind trailer homes or catalog-ordered log cabins. Both suffer from quality, code and aesthetic issues that make them unsuitable for cities.

Seattle-based startup Node sees an urban future for housing built in a factory. Node wants to be the Ikea of the home industry. The modular homes it is making can be flat-packed—the ultra-efficient technique popularized by the Swedish retailer—and then assembled in a matter of days on site. Shingles fasten into place. Walls snap together in metal brackets. No nails or screws are needed for assembly (a revolution for the construction industry). These aren’t sheds. Beautiful woods, expansive windows, and a modernist aesthetic recall modernist homes in Scandinavia.

Node’s technology, still under development, uses standard materials: wood, metal, and insulation. Its secret, says Bec Chapin, co-founder and chief operating officer, is how it’s all manufactured, assembled, and monitored. Software and sensors keep the home environment comfortable and carbon-neutral. Solar panels power the entire home. Specially designed brackets mean the entire home will be able to be put together in a matter of days. “It’s Legos,” says Chapin.