Home, Sweet Printed Home

On a hot day last May, Habitat for Humanity volunteers gathered around a cement slab in Tempe, Arizona. The organization, which operates in more than 70 countries around the world, builds affordable homes for families in need of a place to live. Since 1985, the Central Arizona chapter had already built more than 1,170 homes in the state. But this one would be different. As the volunteers watched, engineers from the German construction company PERI set up a 3-D printer. These devices print solid objects by building up layers of material. Desktop versions can create small items, like pencil holders, toys, or even prosthetic hands. But this 3-D printer was big enough to make a house!

The large construction printer had a nozzle that released a stream of cement specially formulated to be soft enough to pump through the printer but sturdy enough to hold its shape as it dries. “It comes out almost like soft serve ice cream,” says Dusty Parsons, one of Habitat for Humanity Central Arizona’s directors. As the nozzle slid back and forth, it deposited layer upon layer of cement, and the house’s walls rose before the volunteers’ eyes.

When 3-D printing experts first approached Habitat for Humanity with the idea of 3-D printing homes, the head of the chapter knew right away that they should try it. It was a natural next step, says Parsons, “because we are looking for new ways to provide affordable housing here in Arizona.” And the organization isn’t alone. Interest in 3-D printing for construction is growing as a potential way to solve a serious problem: a shortage of suitable homes for people around the world.

It was a hot day in May 2021. Habitat for Humanity volunteers gathered around a cement slab in Tempe, Arizona. The organization builds affordable homes for families who need a place to live. It operates in more than 70 countries around the world. Since 1985, the Central Arizona chapter had already built more than 1,170 homes in the state. But this one would be different. As the volunteers watched, engineers from the German construction company PERI set up a 3-D printer. These devices print solid objects by building up layers of material. Many 3-D printers fit on a desktop. They can create small items, like pencil holders, toys, or even prosthetic hands. But this 3-D printer was big enough to make a house! 

The large construction printer had a nozzle that released a stream of cement. The material is mixed to be soft enough to pump through the printer. But it’s also sturdy enough to hold its shape as it dries. “It comes out almost like soft serve ice cream,” says Dusty Parsons. He’s one of Habitat for Humanity Central Arizona’s directors. As the nozzle slid back and forth, it laid down layer upon layer of cement. The house’s walls rose before the volunteers’ eyes. 

3-D printing experts had approached Habitat for Humanity with the idea of 3-D printing homes. Right away, the head of the chapter knew that they should try it. Parsons says it was a natural next step, “because we are looking for new ways to provide affordable housing here in Arizona.” And the organization isn’t alone. Interest in 3-D printing for construction is growing. That’s because it could help solve a serious problem. There aren’t enough homes for people around the world.

The United Nations estimates that 1.6 billion people—more than one-fifth of the world’s population—lack adequate shelter. Traditional building methods aren’t meeting the demand. “Homebuilding hasn’t seen significant changes in over a thousand years,” says Jeremy Willis, senior testing manager at ICON, a company based in Texas that creates 3-D printing technology to build homes. “We believe the future is digital and automated, and that 3-D printing construction can deliver homes faster, more affordably, and more efficiently.”

Before printing a house, engineers create a computer model of the home based on plans drawn up by an architect. The digital model shows where the 3-D-printed walls will go and leaves space for plumbing, electrical wires, windows, and doors. Meanwhile, a crew prepares the construction site by laying a concrete slab for the home’s foundation.

The United Nations estimates that 1.6 billion people lack suitable shelter. That’s more than one-fifth of the world’s population. Traditional building methods aren’t meeting the demand. “Homebuilding hasn’t seen significant changes in over a thousand years,” says Jeremy Willis, senior testing manager at ICON. This company in Texas creates 3-D printing technology to build homes. “We believe the future is digital and automated, and that 3-D printing construction can deliver homes faster, more affordably, and more efficiently.”

Before a house is printed, an architect draws up plans. Then engineers create a computer model of the home based on those plans. The digital model shows where the 3-D-printed walls will go. It leaves space for plumbing, electrical wires, windows, and doors. Meanwhile, a crew prepares the construction site. They lay a concrete slab for the home’s foundation.

Next, the giant printer is transported to the site and assembled. Operators launch an application from a laptop, tablet, or smartphone. The app controls where the machine moves based on the computer model of the home’s layout. The operators supervise to make sure everything goes smoothly as the printer lays down concrete to build up the home’s walls (see How A 3-D Construction Printer Works). When the walls are finished, the construction team packs up the printer and moves it to their next job site. Workers then come in to put on the roof and install plumbing, electrical systems, and everything else needed to finish the house. At the Arizona project, Habitat for Humanity volunteers, along with the family who will live in the house, will complete this work together.

Next, the giant printer is moved to the site and set up. Operators launch an application from a laptop, tablet, or smartphone. The app instructs the machine to follow the computer model of the home’s layout. The printer lays down concrete to build up the home’s walls, and the operators make sure everything goes smoothly (see How A 3-D Construction Printer Works). When the walls are finished, the construction team packs up the printer. They move it to their next job site. Then workers come to put on the roof. They also install plumbing, electrical systems, and everything else needed to finish the house. At the Arizona project, Habitat for Humanity volunteers will complete this work. The family who will live in the house will help them. 

Experts cite several big advantages of 3-D printing construction over traditional home construction methods. For one thing, 3-D-printed walls go up much faster. “In traditional construction, there are many steps in completing a wall,” says Willis. Different teams of workers build the wooden frames, insulate the walls, and install exterior siding and interior drywall—a process that can take several weeks. “However, when using a 3-D printer, all these steps are done simultaneously while only two to three people are needed to operate the printer,” Willis adds. The walls can be finished in as little as two days.

Experts say 3-D printing construction has several big advantages over traditional home construction methods. For one thing, 3-D-printed walls go up much faster. “In traditional construction, there are many steps in completing a wall,” says Willis. A team of workers builds the wooden frames. Different teams insulate the walls, install siding outside, and hang drywall inside. This process can take several weeks. “However, when using a 3-D printer, all these steps are done simultaneously while only two to three people are needed to operate the printer,” Willis adds. The walls can be finished in only two days.

A 3-D-printed house is also more sustainable. That’s because building one generates less waste, which is better for the environment. For a traditionally constructed building, up to 30 percent of all materials delivered to the site may be wasted, with much ending up in a landfill. This includes cut pieces of wood and drywall and unused cement blocks. Not so with 3-D printing, says Willis. “You print what you need, and then you stop.”

Less time and less waste can translate into much lower building costs, which results in more affordable homes for buyers. There’s also an added perk: Cement is extremely durable and can weather disasters—such as earthquakes, fires, floods, hurricanes, and tornadoes— better than traditional building materials.

A 3-D-printed house is also more sustainable. Building one creates less waste. And that’s better for the environment. For a traditionally constructed building, loads of material are delivered to the site. Up to 30 percent of that material may be wasted. Much of it ends up in a landfill. This includes cut pieces of wood and drywall and unused cement blocks. That doesn’t happen with 3-D printing, says Willis. “You print what you need, and then you stop.”

Less time and less waste can mean much lower building costs. That results in more affordable homes for buyers. There’s an added benefit when earthquakes, fires, floods, hurricanes, and tornadoes strike. Cement is extremely sturdy. It can weather disasters better than traditional building materials.

For Willis, the most exciting part of 3-D printing construction is using technology in a way that changes peoples’ lives. “Usually, when the biggest, best thing comes out, only the wealthy can get ahold of it, because it’s a new technology,” he says. “But we’ve been able to bring this to people who need it the most.” His favorite project so far has been 3-D printing a group of homes for families in need in Nacajuca, Mexico.

For Willis, 3-D printing construction is exciting. That’s because it uses technology to change peoples’ lives. “Usually, when the biggest, best thing comes out, only the wealthy can get ahold of it, because it’s a new technology,” he says. “But we’ve been able to bring this to people who need it the most.” For example, he helped 3-D print homes for families in need in Nacajuca, Mexico. That’s been his favorite project so far.

Only a few companies around the world are currently involved with 3-D printing buildings, but the field is growing—and so is the variety of projects. During the past year, ICON listed four 3-D-printed houses for sale to the public in Texas, and PERI began printing a three-story apartment building in Germany. And the sky isn’t the limit: NASA even plans to bring the technology to space to build structures where future astronauts might live and work (see Mars Habitat).

Parsons says that the Arizona house was a proof of concept, or test project, to show that the method was feasible for Habitat for Humanity. The organization hopes to use the technology to print more homes with less cost, time, and waste. Parsons says the lesson to take away from the experience is “don’t be afraid to try something new.”

Right now, only a few companies around the world are 3-D printing buildings. But the field is growing. So are the kinds of projects. This past year, ICON listed four 3-D-printed houses for sale to the public in Texas. PERI began printing a three-story apartment building in Germany. And the sky isn’t the limit. NASA even plans to bring the technology to space. They want to 3-D print structures where future astronauts might live and work (see Mars Habitat).

Parsons says that the Arizona house was a proof of concept, or test project. Habitat for Humanity did it to show that the method would work for them. The organization hopes to use the technology to print more homes with less cost, time, and waste. Parsons says the lesson from the experience is “don’t be afraid to try something new.”