3D-printed homes have made headlines in recent years, but most have been more conceptual than practical. Now a boulder-shaped home in the Eindhoven suburb of Bosrijk has become the first legally habitable property with 3D-printed load-bearing walls—and on August 1, a retired Dutch couple, Elize Lutz and Harrie Dekkers, will officially move in. “My first feeling when I saw the picture [of the house] was like a child in wonder,” recalls Elize. “It’s a fairytale house—a gigantic boulder!”

The two-bedroom bungalow is part of Project Milestone, which aims to create the world’s first 3D-printed homes that meet statutory building requirements and are fit for habitation. During a six-month rental period, Elize and Harrie will keep track of their experience in the home to test whether this method of building is viable for the future.

“It will be a pleasure for me to share our living experience,” says Elize. “I am a diarist, and I enjoy describing the daily experience.”

An enormous robotic arm with a nozzle printed the home using an architect’s plan and a specially developed concrete that is printed in layers. According to the developers, printing with concrete has many advantages over traditional construction— including the ability to create interesting shapes without the need for formwork, a faster construction process, and the ability to create reinforcement and openings at the same time. And, due to the robotized nature of the technique, construction can take place 24 hours a day.

The construction also offers impressive sound insulation. “It is very quiet in the house, in every room,” says Elize. “As soon as you close the door, you don’t hear anything. You really are in your own bubble.” Extra-thick insulation and a connection to district heating mean the house is also highly energy efficient.

Project Milestone also aims to explore unusual building forms that are only made possible through the use of 3D-printing—the curvaceous, boulder-like form of the first home would be costly and difficult to build using traditional methods.

It took just 120 hours to factory print the home’s 24 sections—the largest of which weighs 12 tons and stands 2.5 meters tall—which were then transported by lorry to the site, and fixed to a foundation. The finishing touches, including the windows, doors, and roof, were then fitted on-site.

The learnings from executing this home will go on to inform the design of four additional houses that will make up the Project Milestone community. Each home will push the construction process further, and the fifth and final dwelling—a three-story, three-bedroom family home—is designed to be printed entirely on-site.

“Building directly from a digital design, without the construction worker, makes the mass production of individual designs via parametric models possible,” says Bas Huysmans, CEO at Weber Benelux. “Following topological design principals and combining 3D concrete printing with existing building methods like prefab and building materials like wood will change the construction industry.”

The entire process—from development to construction—is digitized, which optimizes the use of materials and construction time. It also means there is exciting potential for the new technology to create more affordable and sustainable housing that meets the demands of modern living.

As the first homes are completed in Eindhoven, the plan is to roll out Project Milestone to other countries. “The cost of house number one is high, but we have learned a lot,” says Huysmans. “We know that, in the future, 3D concrete printing will contribute to making construction faster, cheaper, and more sustainable.”

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