Fancy this: With the wave of a wand, your American dream comes true right before your eyes, move-in ready in just days and at a bargain-basement price.
That’s the wish of startups and labs expanding 3-D printing from architectural modeling and parts production to actual home building.
In brief, a robotic arm or scaffold-like machine dispenses a concrete or polymer compound in layers following preprogrammed digital renderings, fabricating walls for assembly or realizing whole-house shells onsite for finishing.
By diminishing construction time, labor, materials, and waste, this makes the development costs — and the sale prices — plummet.
Already happening in China and Russia, 3-D home printing could address critical Massachusetts housing issues — affordability, construction costs, environmental impact — if it becomes known and accepted here.
At least one Boston-area company is pursuing that. Prisna, of Everett, is promoting online its “patent-pending automated construction process,’’ transmuting 3-D computer models into “instructions for the robotic fabrication of structures.’’
They deem each model “mass-producible up to 1,000 units.’’
Prisna pitched this scheme as affordable housing for Boston to Mayor Martin J. Walsh’s Housing Innovation Lab in 2016. “They were creating new plastic out of recycled materials,’’ said the lab’s director, Marcy Ostberg.
“So we asked, ‘If the walls were plastic and not wood, how would you get to the plumbing? How would you hang pictures on the wall?’ . . . The lab provides a critique to help startups like this continue to improve their product to meet the needs of Boston residents.’’
Prisna has not responded to the lab since the pitch, Ostberg said, nor did the firm return calls from the Globe seeking comment.
State code-compliance testing mandates for new materials may be a hindrance to 3-D printing, Ostberg suggested.
This is one of several issues houses made with 3-D printing raise: Would they pass the municipal permitting process and meet state and international building codes?
“The biggest issue is getting cities and towns comfortable with the building-permit process for them, given the materials they’re made of,’’ said Greg Vasil, chief executive of the Greater Boston Real Estate Board. “They’re very different.’’
House-printing companies have to navigate permitting processes not designed for them and wait for the Commonwealth to adopt new building codes that recognize this type of construction, Vasil said.
All municipalities follow what’s known as the International Building Code, which is updated every three years, said Chris Goetcheus, spokesman for the Massachusetts Office of Public Safety and Inspections, which oversees the Board of Building Regulations and Standards (BBRS).
“Variances would be issued by municipalities, [but] again, no matter the method of construction, including 3-D, the structure must meet all required code,’’ Goetcheus said, noting that a 3-D printing company has not come before the BBRS — yet. “If this becomes a trend, we’ll look at them on a case-by-case basis as they’re forwarded to us by the municipalities.’’
Meanwhile, the Chinese and the Russians are ahead of the Americans in the 3-D printing race.
In April 2014, WinSun Decoration Design Engineering Co., of Shanghai, printed 10 houses in less than a day for $4,800 per home, using a mixture of concrete and recycled industrial waste, Inhabitat.com reported. The website said the basic components were printed separately and then assembled onsite.
Last December in Stupino, Russia, Apis Cor of San Francisco and Moscow printed a 400-square-foot home’s entire concrete-compound shell onsite. The circular studio home cost $10,134 to print, finish, fenestrate, roof, and retrofit — and it was built in 24 hours at the coldest time of the year. Did we mention it’s in Russia?
What if such low-cost housing were constructed in Massachusetts? “More product at varying price points would help the market,’’ Vasil said.
That is why many in the affordable-housing field are eager to learn more about 3-D printing for building homes.
“While new technologies have the potential for bringing down costs, zoning remains our greatest challenge,’’ said Rachel Heller, CEO of the Citizens’ Housing and Planning Association in Boston. “We don’t have the zoning in our communities to allow for the number of homes we need in Massachusetts. This is a major factor in our high rents and home prices. We need 17,000 new homes every year between now and 2040 to sustain our current job base and those retiring from the workforce.’’
Then there’s the issue of longevity. Apis Cor says its homes will last up to 175 years, the “average concrete life span.’’
But it could be less. According to a 2014 Northeastern University study, global warming is speeding up long-term chemical processes that can damage unprotected concrete structures.
Its authors, environmental engineer and assistant professor Matthew Eckelman and then-research assistant Mithun Saha, contended that higher temperatures and elevated carbon dioxide levels will speed up the diffusion of chloride and carbonate through the protective concrete cover, reducing the amount of time it would take to reach the building’s steel reinforcements — possibly corroding them and causing the concrete cover to swell and crack. Rising carbon dioxide levels could imperil new concrete buildings in 55 to 75 years, based on current codes, Eckelman said.
Possible solutions include increasing the thickness of the concrete cover, using protective coatings to mitigate corrosion, and/or building with a concrete mixture that doesn’t include lime, which would reduce the risk of carbonation-based corrosion, Eckelman said. Chloride-based corrosion would still be an issue.
Doug Smith, regional manager of Sika Corp. of Lyndhurst, N.J., a manufacturer of products for the construction industry, advocated for concrete-densifying agents such as Viscocrete, a polymer. These mixes can be designed to last 100-plus years, Smith said.
Another agent is silica fume, a silicon dioxide composite that “creates an impermeable surface’’ for concrete when mixed in, said Craig Dauphinais, executive director of the Massachusetts Concrete & Aggregate Producers Association.
Corrosion in concrete-printed houses could be eliminated by replacing steel bars with carbon- and glass-fiber reinforcing materials, said structural engineer Paul Kelley of Simpson Gumpertz & Heger in Waltham.
Furthermore, “use of these nonmetallic reinforcing materials also allows thinner concrete sections, which would have many benefits, including a reduction of shipping weights,’’ Kelley said.
In this case, Eckelman said, 3-D printing “makes more sense for a one-story home than for a large multistory building that would typically require structural reinforcement.’’
Branch Technology, of Chattanooga, Tenn., plans to print a “Curve Appeal’’ house in carbon-reinforced acrylonitrile butadiene styrene (ABS). This polymer, already approved for certain types of construction, would give the house a sculpturally sinuous form while solidifying its shell the way cellular geometries naturally strengthen trees and bones, said founder and CEO Platt Boyd.
Boyd added that a two-poundpiece of ABS — about the size of a concrete block — and spray foam could support up to 10,000 pounds at maximum cell-matrix density. “That’s three or four times the strength of wood-frame construction.’’
But does anyone want to live in a printed house?
Vasil is optimistic. “It would be a new product and may take time for some to become accustomed to it,’’ he said, noting that “there was skepticism with micro units, but now they are accepted.’’
Goetcheus reported that houses printed with 3-D methods were discussed at the BBRS’s Sept. 12 meeting and will come up again Oct. 10.
“I see this as a technology that’s here to stay in construction, but will the Boston-New England area be the best fit for the aesthetic that comes out of it? Probably not,’’ said A.J. Perez, chairman of NVBOTS, a Boston 3-D printer maker. “The fundamental issue is buyer’s taste, and until those millionaires want to buy concrete bunker houses rather than Tudor-style mansions . . .
“Construction 3-D printing will eliminate concrete-pouring jobs on construction sites. I believe the unions in New England will resist this disruption, but good luck.’’