The Urethane Blog

Printing a 3D House with Spray Foam

Watch This Robot 3D Print a Building Out of Spray Foam

This MIT robot can autonomously build a giant dome

Construction seems like an industry that, were I still living in Silicon Valley, I would be tempted to call “ripe for disruption.” Researchers at the MIT Media Lab agree, pointing out in a paper just published in Science Robotics that construction “relies on traditional fabrication technologies that are dangerous, slow, and energy-intensive.” Hey, sounds like a job for some robots, right?

The Media Lab’s paper introduces the Digital Construction Platform (DCP), which is “an automated construction system capable of customized on-site fabrication of architectural-scale structures.” In other words, it’s a robot arm that uses additive construction techniques to build large structures safely, quickly, and even (in some cases) renewably.

MIT Media Lab’s Digital Construction Platform (DCP) is mobile (with a top speed of 0.5 m/s) and self contained. It’s battery powered (with a few solar panels on it and an option for more to be attached), so it can potentially run forever, or as long as you have sun. Otherwise, the DCP mimics much of the functionality of a 3D building printer: It has a long reach, giving it a maximum printable volume of 2,786 cubic meters. The robot itself is made out of two arms, modeled loosely on a human: There’s a big long arm with 4 degrees of freedom (DoF) that does all the gross motions, and one small, dexterous 6-DoF Kuka arm that takes care of fine motions like our hands and fingers would. Put it all together, and the total system cost comes to US $244,500, which is really not that bad.

The construction technique that the DCP uses is straightforward: There’s a sprayer at the end of the small arm that combines two chemicals into a liquid polyurethane foam that rapidly expands and hardens. You can program the DCP to print anything you like, but in the demo in the video above it’s whipping up a 14.6-meter-wide, 3.7-meter-tall hemispherical open dome at a rate of 1.728 cubic meters per hour, printing layer on top of layer. Rather than build the entire structure out of foam, the DCP is actually creating a concrete formwork: Two foam walls, one nested inside the other, with a space in the middle that you can pour concrete into to make a more permanent and resilient structure (or backfill it with dirt or anything else in a pinch), after dropping in plumbing and electrical and stuff. Leaving the foam in place after you do this just adds to the insulation of the resulting building.