3D printing paves the way for more affordable housing in the Valley and beyond.

From custom-fit shoes and car parts to personal protective equipment and more, 3D printing is now ubiquitous. But the idea of using the technology to build a home was an entirely new concept for Jason Barlow, president and CEO of Habitat for Humanity Central Arizona. When engineers and ASU alumni Clarence McAllister and Paul Mooney approached Barlow with a pitch to build Arizona’s first computer-generated domicile, the idea was immediately enticing. “They asked me if I’d be interested in some new, innovative, affordable housing solutions,” Barlow says. “Well, that took me about a nanosecond to say ‘of course we would be.’”

Thus began the monthslong process of designing, engineering, permitting and printing the Tempe dwelling. Phoenix Home & Garden Masters of the Southwest award winner and Habitat for Humanity Central Arizona board member Mark Candelaria and fellow architect and project manager Damon Wake worked closely with the charitable organization along with the City of Tempe and a team of engineers from Germany, where the printer is manufactured, to complete the project. “When Habitat decided to tackle their first 3D-printed house, we were thrilled to make that happen in Tempe,” says Tempe Mayor Corey Woods. “Innovating to find new models is the key to easing the affordable housing crisis, and we were determined to work side by side to see this unique project come to fruition.”

The main objective was to learn about the automated construction system, find its advantages and disadvantages and share findings with the national Habitat for Humanity community, as well as anyone interested in the practice. “This home was much more about the future, about what’s possible,” says Dusty Parson, chief marketing officer for the nonprofit’s local branch.

As the first of its kind in the state, the project presented challenges. Intense Arizona heat caused the concrete to crack and required a redo after pouring the first layers. 3D construction also requires extensive preplanning. Unlike building a traditional wood-framed, dry-walled edifice—where plumbing and electrical are added after building the structure—the plans necessitate programming into the BOD 2 (an acronym for Building on Demand)printer prior to execution. “You have to have a lot more planning up front,” Wake says. “So it really involves an entire team making a lot of key decisions and then locking those in at the time the printer is starting.”

But the benefits—including a more durable build and the leverage to incorporate otherwise expensive design elements easily and affordably—far outweigh the shortcomings, Wake says. “It’s the cheapest way to do complex, curved concrete walls. If you build a home with a unique shape and form using conventional methods, it can be rather expensive.”

The lessons may also change the future of the construction industry. “Once we work out the bugs and bring the cost down even more, I’m convinced that we can build entire neighborhoods with this technology,” Barlow says.

Candelaria and Wake agree. “This was a classic example of people from around the world working together to build something meaningful for a family in need,” Candelaria says. “It shows we can make this a better place—and to me, that’s the best part of the whole story.”

Printing Homes: How It Works

• First, six metal columns, each weighing about 1 ton, were installed around the concrete slab. These, along with crossbeams mounted to them, acted as the tracks on which the printer could move in any direction.
• Once the printer head was set to a zero position (the point at which the programmed blueprints start), it would begin creating layers of concrete to produce the outer and inner walls and interior features, such as the kitchen island. Each day, over the course of only a few hours, the printer would lay 18 to 24 inches of wall, which would then cure overnight.
• On the following day, the team applied an epoxy to the existing wall, which the subsequent layer would adhere to. After about four weeks of printing, the walls stood 8 feet tall, and the rest of the construction began, including the roof; insulation between the inner and outer walls; and remaining plumbing and electrical components.
• Architect Mark Candelaria used an existing floor plan from Habitat for Humanity and converted it to a digital version that the printer could replicate, and added his own distinct style. “We experimented with some ideas and came up with this fun, more modern version of the typical Habitat home,” Candelaria says. “We did a mono-pitch roof and brought a lot of natural light in and gave the floor plan its own character.”

Once the columns and crossbeams were placed over the home’s foundation, the printer created layers of concrete until the inner and outer walls stood 8 feet tall. The wood-truss roof, windows and other finishes were then added to complete the home.

SOURCES

• Habitat for Humanity, habitat.org
• Architect: Mark Candelaria, AIA, Candelaria Design Associates, Scottsdale, candelariadesign.com
• Project manager: Damon Wake, candelariadesign.com