In Central Texas, homes are being built with 3D printing technology

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ROUND TOP — Layer by layer, a robotic arm lays streaks of concrete that rise to become the walls of five small vacation rentals tucked in the corner of The Halles event center in this Central Texas town.

Round Top is not new to the short-term rental market. Round Top, a town with less than 100 inhabitants, attracts tourists to its antique events and music scene. It has more than 200 Airbnb rentals listed.

But these new additions, named the Casitas at the Halles, represent what Hive3D founder and CEO Timothy Lankau hopes is a revolution in construction — 3D printed homes built mostly by machines. His Houston-based business was founded in 2022. It has since built six houses.

“There’s something of a housing crisis in America, which I think is the stupidest crisis I can possibly imagine, ” Lankau said. “With all of the ingenuity and resources we have, as a people, the fact that we can’t figure out a better way to build walls and roofs so that everyone has a nice house seems just baffling to me.”

Lankau, as well as other companies that are embarking on the 3D home project, believe the technology will help to reduce the housing shortage and in a way that is climate-friendly.

It is still a novel concept to 3D print residential structures. The first 3D-printed home, a 3,000 square-foot residence in Yaroslavl (Russia), was completed in 2017.

One year later, Icon, a startup based in Austin, displayed its first 3D-printed building at South by Southwest’s technology section.

“We ultimately needed to find ways to build a lot more homes a lot faster. And we landed on 3D printing, using concrete-like material,” said Tom vonReichbauer, the CFO of Icon, which is building an entire subdivision near Austin using 3D printing technology. “Advanced robotic construction is the most promising path forward.”

A small 3D-printed home’s walls can be built in under 24 hours, with printing on larger single-family homes’ walls ranging from 10 to 45 days.

According to eXp Real Estate, it takes an average of six to eight month to build a single-family house using traditional methods.

“When you take construction, and you bring automated technologies to it and do robotic construction, you’re able to help shrink the timeline it takes to build a home,” VonReichbauer said. “You’re able to print [a house] There is far less waste. If you’ve been to a traditional construction site, you’ve seen the amount of waste that’s produced there.”

The foundation is laid just as in traditional construction. Rebar is then placed to support the walls of the interior or exterior, which are then printed on top. The robotic arm of the 3D printing machine lays the cement like layers of frosting — leaving a hollow space for electrical wiring and plumbing that’s later filled in with more concrete. The robot moves to the next wall once a wall has been completed. The finished walls feature a horizontally ribbed texture.

Workers install windows, doors and roofs after the walls have been completed.

Both Hive3D and Icon use alternatives to portland cement — cement production is one of the biggest sources of greenhouse gases in the construction industry and is responsible for about 8% of the world’s CO2 emissions per year.

Hive3D partnered with Utah-based Eco Material Technologies, which creates a range of eco-friendly alternatives to concrete called “green cement,” which includes fly ash — a common byproduct from coal-fired power plants.

Eco Material Technologies CEO Grant Quasha explained that, unlike portland, the mixes created by Eco Materials Technologies do not mill and heat limestone. The process is responsible for most of its pollutants.

Quasha said the green cement doesn’t have an entirely carbon-neutral footprint because the mix requires transportation to the work site and electricity is used to run the mill to mix the materials together once it arrives, but the company claims it keeps over 6 million tons of CO2 out of the environment each year with its cement alternatives.

VonReichbauer claims that Icon uses portland cement in its concrete alternative, Lavacrete. He added that the company is working on ways to make it eco-friendly.

Built for climate

Walking through the first single-family home that Hive3D is building in Burton, which is about halfway between Austin and Houston, Lankau noted that the house was significantly cooler than the outside temperature on a blazing August day — even though the air conditioner had not yet been installed.

Lankau said the thick foamed concrete walls help give the homes an above-average R-value — which refers to a material’s resistance to heat transfer. Although Texas is experiencing more extreme heat, concrete construction’s insulating qualities should help keep the homes cooler, which could lower utility bills.

Lankau also added that the concrete walls will make the homes safer and more resistant to extreme weather like hurricanes, tornadoes and other severe storms.

“We prefer to build with more curved shapes and less flat surfaces for wind to push against. The roofs are tied all the way down to the foundation and into concrete rebar,” Lankau said. “It’s a serious structure when it comes to wind.”

Lankau also said that concrete buildings are more likely than other structures to survive a flood without major structural damage. When floodwaters inundate sheetrock, wooden framing and insulation in traditional frame homes, they often need to be restored.

“When you have these foot-thick concrete walls, they are bulletproof, everything-proof. From the foundation up to the roof line, everything is inorganic, so there’s nothing to rot and degrade over time,” Lankau said. “So it should, over time, not change much, this house should look the same today as it’s going to look in 100 years.”

The affordability of housing and the crisis

Icon, in collaboration with Florida’s largest developer Lennar, is printing 100 homes in Georgetown about 30 miles north-east of Austin.

VonReichbauer said the city “has been incredibly receptive to what we’re doing” and the first homes sold within a few days of being listed.

Lennar has listed the homes at a price range of $470,000-$579,000. The average cost for a home in Georgetown is $459.933.

VonReichbauer stated that the company also built 3D printed homes in Mexico, with New Story an organization focused on helping the housing crisis around the world.

Ten homes have been built in Tabasco, just outside Nacajuca for families who are financially in need. They will move in in November 2021.

Icon also partnered with Austin’s Mobile Loaves & Fishes to build six 400-square-foot homes in an east Austin community run by the nonprofit for chronically unhoused people.

Lankau wants to do the same as Hive3D grows. He believes his Round Top rentals — which range from 450-square-foot studios to 850-square-foot two-bedrooms — can serve as a model for building affordable homes in a state with a growing housing shortage.

Lankau says Hive3D is willing to act as its own developer to ensure that their homes are priced affordably and he wants to see the company sell to all types of consumers.

“There are different bands of affordability. There’s government-subsidized housing and there’s housing that is just built for people on median incomes to afford. We’re open to all of that,” Lankau said.

However, James Tate, an assistant architecture professor at Texas A&M University, expressed skepticism about the long-term ability of these companies to keep their prices affordable and compete in the Texas housing market.

“In this state, there is no requirement for developers to have affordable housing units, there’s no incentive other than individual developers who say, ‘I believe that there should be fair housing,’” Tate said. “This state is very willing to allow housing discrimination to happen all the time.”

Tate is also sceptical that 3D-printing can transform the construction industry and solve the housing crises.

“As a researcher and design faculty at a university. I can’t help but feel a need to be optimistic,” he said. “But I know enough about the history of architecture and construction. In every attempt that has been made to address our housing challenges, when we take a step forward another challenge arises … all property and real property is subject to forces of capitalism.”

Todd Wiseman has contributed to this article.