Concrete is durable, cost effective, and fire resistant, which is why builders are using it to rebuild after the Eaton Fire.
Residents walking through Altadena, CA, recently were struck by an odd sight this week: A large gantry crane appeared to be "printing" out 11-inch-thick concrete pillars and walls.
The robotic 3D-printed machine, designed by Dutch company COBOD, was being used to rebuild a home that had been destroyed by the Eaton Fire in January 2025, extruding layer after layer of concrete and shaping it into walls.
The home is a project of Emergent Home, a Los Angeles-based builder that's been contracted to produce seven concrete-printed homes in Altadena.
Emergent was actually founded in 2019 to help rebuild after the Carr Fire destroyed more than a thousand homes in Northern California.
With 3D concrete printing, an architect's CAD design is fed to proprietary software which then designs concrete pathing for the tool. (VCG via Getty Images) 3D-printed concrete has gained attention in recent years because of its sturdiness and cost effectiveness—especially in fire-prone areas. The precise nature of the process reduces construction waste and completion time. According to COBOD, homes can be completed twice as fast as conventional construction and at up to 30% less than conventionally built homes.
Most importantly, the homes are fire resistant.
A worker oversees the construction of a 3D-printed concrete home in Altadena. (VCG via Getty Images) The January 2025 Eaton wildfire ravaged more than 14,000 acres and destroyed more than 6,000 homes. Yet despite the numerous fires and climate risks, the vast majority of homes in the area continue to be constructed with wood.
"Ninety-five percent of this community is rebuilding with wood," Ken Calligar, the CEO of building technology company RSG-3D, previously told Realtor.com®. "It's insane."
"A 6-year-old could have said this wasn't a good idea," he continued. "These towns are so vulnerable, they have no idea. To me, it's so obvious what the solution is."
RSG-3D builds with framing panels made of steel wire and expanded polystyrene wrapped in concrete skins—and is somewhat different from the 3D printed concrete Emergent Construction is using.
The share of 3D-printed concrete homes in the U.S. remains relatively small. So far only a couple hundred homes have been built using the technology. But proponents believe that as climate disasters continue to plague homeowners, and as costs continue to hobble the building industry, the technology will grow in popularity.
The Eaton Fire destroyed more than 9,000 building structures in Altadena, CA, including 6,000 homes. (Mario Tama/Getty Images) 
A concrete 3D printer helps rebuild a home destroyed in the Eaton Fire. (VCG via Getty Images) Already, one homeowner is getting ready to move into her 3D-printed concrete home. In September, PCI Builders collaborated with RIC Robotics and Stone River Dynamics to produce the first permit-approved 3D-printed concrete house in the area.
The home was for Cindy Lopez, an Altadena resident whose home burned to the ground on Jan. 8, 2025.
“This home represents more than my own recovery, I hope it helps other families see what is possible while encouraging local governments to recognize and invest in 3D-concrete printing as a meaningful option for communities facing increasing wildfire risk," Lopez said in a statement.