In a forested patch of Garrison, New York, on the Hudson River, a giant robotic arm looms over a platform. Later this month, the platform will start to rotate while the arm pumps out a gooey concoction of basalt and biopolymers. Round it will go, receiving layer upon layer, until the arm, like a demonic pastry chef, has extruded an entire egg-shaped house.

This 24-foot-high, 500-square-foot, two-story construction will have a sleeping pod, a bathroom with a shower, a study area and other amenities you might expect from a cool short-term rental. In fact, it will be a cool short-term rental, as well as a demonstration of the future of home building.

The project, called TERA, is one of the latest experiments in 3D-printed houses. Innovators in this arena are seeking to reduce the expense, environmental impact and hazards of construction methods that have remained fundamentally unchanged for more than 1,000 years. They are adapting a now-commonplace manufacturing technique in which a computer-controlled dispenser spews a malleable material that hardens into the shape of a pipe fitting, a chair or an internal organ — or, one day, a whole inhabitable building, with its myriad components and systems robotically extruded.

Architects and engineers are edging closer to this goal, by printing portions of houses and assembling or finishing them conventionally. (In TERA’s case the exterior shell will be printed on site and a separate birch plywood interior inserted.) They are testing different structural, surface and insulation materials and struggling to clear one of the highest bars in this technological obstacle course: the 3D-printed roof. (It’s a problem of weight. For TERA, the 3D-printed roof is an easily supported half-inch-thick dome.)

And many of these pioneers have their heads in the clouds.

TERA, which was designed by AI SpaceFactory, a Manhattan architectural studio, evolved from a prototype Martian habitat called MARSHA that won a NASA competition in May. (You can see details at the exhibition “Moving to Mars,” through Feb. 23 at the Design Museum in London.) MARSHA was destroyed as a final test of its stability — NASA wanted to see how much force it would take to crush it. AI SpaceFactory is recycling the crushed material in TERA to demonstrate its commitment to zero waste.


Mars’ atmosphere, about 100 times thinner than Earth’s, determined the habitat’s tubby shape: As pressure within the structure is equalized, the building envelope bulges. Because the cost of shipping construction materials more than 30 million miles is prohibitive, the design makes use of volcanic basalt rock, which exists on Mars, below a layer of dust. The vision is of an autonomous robot that collects, processes and prints what it finds.

Designing for extreme conditions in space helps solve terrestrial problems, noted David Malott, AI SpaceFactory’s co-founder and chief executive. The strategy of building homes on site with hyperlocal materials could have tremendous environmental benefits for our own planet. “It’s a high-tech way of going back to the Stone Age,” he said.

Printed houses have other advantages, proponents with and without cosmic ambitions believe. The speed with which the buildings are constructed makes them useful for emergency housing or to shelter the homeless. An efficient use of materials and the automated labor should drive down the cost of home construction. The potential for economy looks promising, but because the technology is under development, the savings still lie in the (possibly near) future.


And when designed with concrete — which offers strength and fire protection but is also implicated in climate change because of the amount of carbon dioxide that is released in its production — the material is used efficiently and sparingly compared with conventional slabs. The need to keep the concrete mixture supple but allow it to dry quickly has led to a number of mostly proprietary formulas.

While acknowledging that the automated technology would supplant some human jobs, supporters point out that 3D printing promises to reduce worker casualties. According to the Occupational Safety and Health Administration, one in five worker deaths in 2017 was on a construction site.

ICON, a construction technology startup in Austin, Texas, is among the socially motivated players in 3D-printed architecture and a leader in pushing it into the realm of practicality. Many of the intended beneficiaries are impoverished or homeless. “They are usually the last people on earth to have access to cutting-edge technology,” said Jason Ballard, the company’s co-founder and chief executive, who is also enrolled in a master’s degree program in space resources at the Colorado School of Mines.


Last year, in a widely publicized collaboration with the San Francisco-based housing nonprofit New Story, ICON introduced a 350-square-foot house in East Austin that has a conventional flat roof with standard framing lumber. The structure was printed with a machine called Vulcan I using a proprietary concrete-like material called Lavacrete. Construction took a total of 47 hours over several days and cost $10,000 for the printed elements.

In May, ICON and New Story again made news with their plans for a village of about 50 printed houses for a poor community in an undisclosed location in semirural Latin America. (An ICON representative recently declined to identify the site out of concern for the privacy of the families who will be chosen to occupy the houses, which are still awaiting construction.)

Now ICON is working with the nonprofit Mobile Loaves & Fishes on Phase 2 of Community First! Village, a 51-acre development that accommodates former members of Austin’s chronically homeless population in RVs, tiny houses and, soon, several 3D-printed cottages. In September, ICON produced the first printed building for the complex, a 500-square-foot welcome center, in a total of 27 hours over several days. The job was done with a Vulcan II, ICON’s next-generation technology, which can print three houses at the same time, each designed uniquely. ICON plans to print six houses for the village this year.

Because Community First! Village lies outside the Austin city limits, permits — a severe hurdle for companies building experimentally in the United States — are not required. Many building code requirements address strength and stability. Concrete used in home construction, for example, typically has some kind of steel reinforcement, but this is not easy to do with 3D printing.

But also in Texas, an entrepreneur named Larry Haines has designed houses that will meet building codes because they will be made with a machine that behaves like an inkjet printer rather than an extruder. The system allows for reinforcing bars to be designed into the floor, wall and roof systems. The printer then sprays geopolymer concrete over the insulation panels and rebar. (Geopolymer concrete is sturdier and much less environmentally damaging than concrete made with Portland cement.)

“As a contractor, I want to build houses, not walls,” Haines told the audience at a recent Texas Association of Builders show, referring to the wall sections that are the main products of architectural 3D printing. Motivated by the national crisis in affordable real estate and a plague of weather disasters, he estimates that a 1,000- to 1,500-square-foot house based on his Genesis design can be completed in 10 to 14 days for $100 to $160 a square foot (“You still need to put in flooring, sinks, cabinets, plumbing and electrical fixtures,” Haines noted, “and that depends upon local subcontractor availability.”) The wall systems were designed and tested to stand up to 200 mph winds. (A 2017 survey by the National Association of Home Builders gave $237,760 as the average total construction cost for a 2,776-square-foot single-family house, or $85 per square foot.)

Haines was in the midst of building a version of this house northwest of Austin this summer, when his California investor pulled the funding. “I’m not sure what the thinking was,” he said in a phone interview. “It’s tough if you don’t have stuff in nanotech or biomed or AI.”


In the Netherlands, where innovation is less of a loner’s pursuit, a cluster of 3D-printed concrete houses called Project Milestone is being developed by a variety of architecture, engineering and construction firms with input from researchers at the Eindhoven University of Technology. The five houses in the city of Eindhoven will demonstrate increasing degrees of material and structural complexity, beginning with a one-story printed concrete house with steel-reinforced walls and a wooden roof, to be completed early next year, and evolving into fully printed concrete models with multiple floors. All of the homes will be sold to a real estate company and leased out for occupancy.

Theo Salet, a structural engineer who is dean of the department of the built environment at the university, sketches a future of versatility for printed concrete. Walls will be thickened for insulation and etched for ventilation and material efficiency. They will be embedded with fibers that turn them translucent and strategically endowed with electrical conductivity that replaces wiring. “This makes it a smart material all of sudden and not just stupid concrete anymore,” he said.

Not least, Salet sees a world of customization, where homeowners will be able to modify a design in imaginative ways before the button on the printer is pushed.

Even in these early days, designers are entranced by the technology’s malleable-form language, which makes curves effortless and allows built-ins to be fluidly integrated. Yves Béhar, who designed the houses for New Story’s 3D-printed Latin American village, said he even likes the striated wall pattern made by the layers of printed concrete. “I personally think, especially for houses that are surrounded by nature, the horizontal texture is actually something beautiful.”

Also beautiful is the corrugated surface of an Italian house made of mud. Last year, WASP, a 7-year-old technology company inspired by the nests built by potter wasps, produced a 323-square-foot passive house, called Gaia, from soil combined with waste from rice cultivation (husks and straw) and lime. The walls were printed over a period of 100 hours, on-site, in the Emilia-Romagna region. Their several layers include pockets that were filled with rice husks for thermal insulation or left vacant as air passages. The foundation was concrete, and a timber roof was added on top.


Working with Mario Cucinella Architects, WASP is developing Gaia’s successor, a domed house called Tecla that will be constructed with two of its specially designed printers running simultaneously. “This smart and ethical procedure may be extended to wheat, barley, spelt and rye,” wrote Massimo Moretti, the company’s chief executive, in an email.

Is the future of housing on a troubled planet a boomerang toss to the past? Michael Morris, a New York City architect and co-founder of SEArch+, a studio that has designed NASA-competition-winning habitats that are also featured in the Design Museum’s Mars show, said he found it exciting to look in both directions. The new technology encourages a “movement back not to a primitivism but to an indigenism, building simply and efficiently with the materials you find, and supporting people.”

This is what the ancient Romans did, Morris noted, as they roamed the world with their armies, leaving monuments to their ingenuity. And today, there is something comforting about inhabiting the solid masonry created by 3D printing, which we rarely find anymore, Morris said. “It’s like an Irish cottage.”