A new 3D printed ADU prototype made of concrete and other fire-resistant materials is under construction as part of a demonstration taking place this month in Walnut, California.

The first-of-its-kind project was born of a collaboration between the fire departments of both Walnut and Los Angeles. A local couple volunteered to give the host the design for general contractor Builtech Construction Group in the interests of applying lessons valuable for disaster prevention at a time when an influx of peri-urbanization has left the state more susceptible to fire-damaged structures than ever before.

The unit is both non-combustible and fire-resistant and is being constructed using contractor RIC Technology’s robotic 3D printer. 

Construction takes only 20 days from the start of the printing process to finish after the foundation has been laid. It yields a total of 1,200 square feet of space with 2 bedrooms and 2.5 bathrooms. The design works by eliminating any possible accelerants and fuel sources from the built environment, which, if scalable, would save money and time spent in the recovery process.

“This project can be the beginning of something meaningful — a wider application of 3D printed homes that are less susceptible to fires,” RIC founder Ziyou Xu said. 

A steel and sure-board demarcation from the typical wooden structural roofs customary in ADUs is another key component of the dwelling, which has bolstered eave vents and windows to provide additional fire safety protection. 

“The ADU will be built without a single piece of wood or nail — no ‘fuel’ on the main structure,” explains Builtech CEO Aaron Liu. “So we significantly minimize the likelihood of fire entering the home, reducing its susceptibility to fire.”

The ADU market in the United States is expected to grow to expand by a CAGR of 18.6% to $10.6 billion by 2030. In California, permits for ADUs have risen from just 1,300 in 2016 to over 25,000 in 2022. The same study conducted by the Joint Center for Housing Studies at Harvard University recently explained how proactive zoning impacted this rapid increase while calling for further production combined with more flexible and inclusive zoning regulations.