Imagine that you had a “command + P” option for building a house. This is the promise of 3D printing in construction: a cheaper, faster option for fulfilling one of the most basic human needs: shelter.
This year alone 3D printed construction projects have included a stainless-steel pedestrian bridge in Amsterdam, a 1,100 square foot single family dwelling in Milan, and a nonprofit startup that unveiled its plan to 3D print houses for as little as $3,500 in 24 hours for low-income populations in El Salvador. 3D printing in construction is hardly new — but 3D printing entire houses, and at such low costs, is. To figure out why this technology is suddenly being propelled to the forefront of the $10 trillion global construction market, NewtonX conducted a survey with three experts: two former senior-level employees with global infrastructure firm AECOM, and one former senior engineer with Arup, a built environment firm.
The survey findings indicated three discoveries:
- House 3D printers still require human labor for electricity, plumbing, and other accessories beyond the basic structure.
- While 3D printers can erect walls and build structures faster and cheaper than humans can, the machines themselves typically cost upwards of $450,000 — which, at current scale, makes them more expensive than human labor.
- 3D printed houses have captured public interest, which will fuel investment in the technology — making it faster, better, and cheaper over time.
House 3D printers are promising, but have limitations
House 3D printers operate like cake frosting dispensers: paste material (typically concrete, but university researchers in Nantes, France has also used foam) is pushed through a nozzle in layers. Acting like a robotic arm, it can erect the frame of a house much faster than a team of humans can. The result is usually not particularly impressive from an aesthetic standpoint, but the primary use cases for 3D printing are currently low-income housing and prisons (the steel bridge in Amsterdam notwithstanding).
The alternative to 3D printing is Portland cement technology, in which cement is mixed with sand and water, and then placed into wooden or metal forms where it sets. The primary problems with this method are that it’s slow and completely manual.
While 3D printing does ostensibly fix this problem, it comes with other limitations, including that it can only print using one material, meaning that the same printer that prints the frame cannot be used to print the building services. Additionally, reinforcing steel, glass for windows, and plumbing all needs to be added to the structure by hand — and that installation can be quite costly.
A former senior engineer at Arup explained that in many ways, 3D printing is not hugely different from modular construction, which has been in use for years. Modular construction refers to a construction model in which units are built off-site and then assembled in place. For instance, WinSun, a Chinese 3D construction firm and one of the earliest pioneers in 3D printing for house construction, prints its houses in the factory (which also drastically reduces dust and noise pollution on-site) and then ships them to the building site. Dubai has already commissioned 17 WinSun 3D-printer built office buildings that will be constructed in China and shipped. The company also plans to build the pillars and seats for Hyperloop, Elon Musk’s transportation project, and has invested heavily in developing interior furniture development.
The model is not significantly different from, for instance, New York City’s Carmel Place, a modular construction apartment building. In fact, Mayor Bill De Blasio’s Housing New York 2.0 plan, outlines how modular construction can create micro-apartments at reduced costs. The approach has also been used in Tokyo, where space is likewise at a premium. In 2015, BSB built Changsha’s 57-storey Mini Sky City in 19 days using modular construction. WinSun is essentially using this same approach, but is ostensibly building the modules even faster and cheaper by using 3D printing technology.
While on-site 3D printing is certainly in the works with other companies (including New Story, which plans to 3D print houses for low-income families), WinSun is are the forefront of the movement, and has set a precedent for a modular approach.
Costs are a major constraint of 3D printing
While cost is lauded as the primary benefit to 3D printing — because it is fast and automated — companies using 3D technology tend to be opaque when it comes to the real associated costs. WinSun has existed since 2002, but this was its first profitable year. 3D printers cost anywhere from $400,000 to several million, not including the cost of materials and assembly of parts that the 3D printer cannot do.
New Story in conjunction with Icon, an Austin, Texas, 3D-printer construction startup, claims that printing a home is projected to take 24 hours, cost $4,000 and use half as much iron rebar as traditional construction methods, which require about 15 days and $6,500 to build. Similarly, WinSun claims that its houses cost just $4,800 and estimates that 3D printing technology will save between 30-60% of building materials, shorten production times by 50%, and decrease labor costs by 50-80%.
This may be true – and judging by the international contracts WinSun has brokered (the Egyptian government ordered 20,000 units of houses that WinSun claims can each be printed in a single day), governments are betting on the technology’s promises. As WinSun and other 3D printing companies ramp up production, the cost of the actual 3D printer will become smaller and smaller relative to production scale. Perhaps this uptick in demand explains why the company became profitable last year.
Outlook for 3D Printing Beyond 2018
The Amsterdam bridge was printed side to side in one-millimeter-thick blobs at a time. The project took eleven months with a team of four 3D printers. Would it have taken less time with humans? “It’s really difficult to say,” explained a former AECOM employee. “Construction projects take a long time for numerous reasons, not just human labor, and these 3D printing projects that you hear about are often funded and organized differently from the majority of infrastructure investments.”
That said, the other AECOM former senior-level employee noted that 3D printing isn’t going anywhere anytime soon. “It’s a self-fulfilling prophecy at this point. Was the technology that impressive or revolutionary when it got its first big boom in 2014? No. But because we’ve continued to invest in it, it’s bound to become cost and time effective in the near future — if not already.”
3D printing can help promote material recycling and reduce on-site pollution, both of which are huge factors for infrastructure projects in urban areas. Whether or not the robotic arm stacking layers of concrete is truly revolutionary doesn’t really matter; with the amount of money and public interest it’s getting, it certainly will be.