Could home be a 3D printout?

New York

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 7-metre high, 500 square-foot, two-storey 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 this year.

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 equalised, the building envelope bulges. Because the cost of shipping construction materials more than 48 million km 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 officer.

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 labour 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 future.

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 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.

In September, Icon produced the first printed building, a 500-square-foot welcome centre, 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 this year. NYTIMES