Logan Architecture is testing 3D-printed homes, using robots to build walls in additive layers as an alternative to traditional building methods. Two of Logan’s designs were realized this year in his hometown of Austin, Texas. One was a development of four two-storey houses in the east of the city, completed in September.
The lower decks were imprinted on site by a nozzle suspended from a flyover. Under the guidance of the program, the machine transfers narrow, parallel grains of cement, like toothpaste onto a brush, layer upon layer. Then the second floors, with the larger wooden frame, were erected over the printed walls.
Logan says 3D printing offers the freedom to design curved walls and corners — “more receptive to human circulation” — without worrying about over-paid merchants coveted using traditional methods. Logan says the technique has limitations: There is a maximum wall height of 8 feet 5 inches and drilling holes for hanging pictures can be messy and time-consuming—he’s installed picture rails on all the walls.
Features like vaulted master bedrooms and cedar cladding in East 17th Street homes allowed its developer, 3Strands, to market it for more than $400 a square foot, about 25 percent above the average Austin price listed by Realtor.com.
Across town, another 3D Logan design shows how the ability to build housing quickly and inexpensively holds the potential for social housing. Six 400-square-foot one-bedroom homes for the charity Mobile Loaves and Fishes, three homes printed at once in just a few days, are part of a project to rehouse the homeless in Austin.
The cost advantage of printing over construction methods that rely on human labor could drive the acceptance of the technology for mid-market home construction. Developer SQ4D has printed and sold a three-bedroom ranch-style home in the town of Riverhead, Long Island, this summer. It cost $20,000 but it would have cost $150,000 using traditional methods. “We listed it for $299,999,” says Kirk Andersen, COO of SQ4D. “There are homes in the area that are worth $550,000, so it’s about 50 percent less.”
SQ4D was founded five years ago by Andersen and three fellow building engineers to test additive manufacturing capabilities for residential properties. “We literally took a little plastic 3D printer and scaled it up . . . we pushed some concrete through it and said, ‘This is a real thing; we can actually do this!'”
Two experimental structures were used in 2017 and 2018 to improve the printer and the Portland cement-sand mixture used by the tubes. “We learned a lot about hoses,” Andersen says. We started with an inch and a quarter [nozzle] But like a clogged artery, it starts to shrink more and more.” Weather conditions are another consideration: On hot days the cement can dry out very quickly and create cracks. “You have to keep it moist,” he says. “We have misting systems.”
SQ4D uses a customized 32ft x 12ft giant printer, which can be assembled on site within six hours. The Riverhead home’s exterior and interior walls took 48 hours to print with only three clients on site to oversee the machine and cut holes in the wet cement for the windows. Andersen estimates that conventional construction of the same structure would have taken 10 weeks.
In addition to being faster and cheaper, Andersen says robots can improve construction health and safety — the industry is known for its accident rates. The environmental impact of printing presses is still under discussion. Carbon dioxide emissions from cement production are high, and although there are studies suggesting a smaller carbon footprint for 3D-printed structures, they used cast concrete walls as a comparison rather than bricks or wood. Andersen says SQ4D has investigated using recycled crushed concrete in its slurry and even pumping the carbon dioxide produced during mixing and printing back into the concrete for storage.
The only clue to the construction of a Long Island home is the pipe fissures in the exterior walls. “People call it the corduroy wall,” Andersen says. “These lines are the story of how your house was built.” But Andersen’s concern is primarily with the speed and economy of the new technology rather than its design potential: “We don’t want a crazy abstract house right now, we want it to be relevant.”
Elise Lutz and Harry Deckers live in a structure that brings more sculptural possibilities. In August, they became the first tenants in Europe of a full 3D-printed house. The 1,000-square-foot bungalow in the shape of a rock is one of five planned properties in the Meerhoven district of Eindhoven in the Netherlands, known collectively as Project Milestone. The scheme is a joint venture between the city authority, Eindhoven University of Technology, Vestida, a real estate investor focused on mid-market rental housing, and Saint-Gobain Weber Beamix, the specialist concrete maker that developed the 3D printing system. The single-story structure was printed in 24 sections by a robotic arm a mile away at the Weber Beamix plant, then assembled on the Milestone woodland plot.
Lutz and Dekkers, retired jewelry store owners, were living in Amsterdam when Lutz saw a call for applications to become test tenants. She attracted the couple’s sense of adventure, “I loved living in private spaces, and it was a neighborhood I didn’t know about,” she says.
Three months later, they became enthusiastic ambassadors for home planning and Open Curves. “It’s all a bit round, everything is organic shapes; it’s fun,” says Lutz. “You’ll never get bored,” Deckers adds. As with all 3D-printed buildings, the walls are a cavity construction. Lutz says its 7-inch thickness makes it “feel like an old castle – it gives you a very secure feeling.” Otherwise, they say, there are few differences from living on a traditional property.
Gian Stirkin, 3D Sales Project Manager for Weber Beamix, says the couple’s feedback informs the final design of the second home, which is due to be completed next year and will rise three stories in the shape of an obelisk. Others are also moving forward. Icon, which has printed designs for Logan Architecture, has announced a project to print 100 homes in Austin next year. SQ4D is building new printers and talking to municipalities across the United States.
Construction sites where he works only with what Andersen describes as the “babysitting man” may not become the norm yet. But these cotton walls could soon become a familiar sight.
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