You wouldn't 3D print a house, would you?

Most homes built in the United States today are platform construction: skinny two-by-fours are stacked and stacked to create studded walls. Each floor is framed above the other. It's fast, relatively cheap, and easy to learn. However, it is not without drawbacks. Some estimates place the amount of waste generated per square foot (0.09 m2) at approximately 3.9 lbs (1.8 kg).

Timber framing is an older style where giant beams are used to create the structure of the house. Each wood is carved and shaped by hand, which requires skill and precision. Some cabins are still built this way because it is easy to source wood locally and cutting large logs is less labor intensive than cutting lots of small logs. It is relatively environmentally friendly, but slow and requires skilled labor.

We live in a world where there is a huge need for cheaper, faster and more environmentally friendly housing, but finding a solution that ticks all the boxes is extremely difficult. Can 3D printed housing achieve these three goals? We're not there yet, but we're working on it.

Current state of the art in 3D houses

The idea of ​​a machine to build houses has been around since 1930. The idea behind 3D printed houses is that by eliminating some of the human labor required, it can scale better and reduce costs. But despite the new machines, the overall methods of building homes haven't changed much. Broadly, there seem to be three categories on the market today: prefabs, prints in place, and cuts in place.

Prefabricated

Prefab is exactly what you think. Parts are printed at a facility, ideally close to the jobsite, then shipped to be assembled by a team of workers. This allows prints to benefit from a controlled environment with calibrated and reliable tooling. Or even to print very large parts like this absolutely massive printer in China. Companies such as Mighty Buildings are working on pre-engineered modules and entire units constructed from fiberglass-reinforced thermosetting resin. The advantage of a thermosetting material is that it cures stronger and harder than the traditional resins you might see in a printer. However, layer-to-layer adhesion suffers.

Mighty Buildings came up with a clever solution by using multiple UV sources. The layers only partially harden when the top layer is deposited, then are fully hardened later as the layers stack on top. It is important to note that these buildings are not much cheaper or faster than a prefabricated house made with traditional methods, but there should be less waste and more flexibility in the design.

Print in place

On-site printing often involves a giant on-site 3D printer setup like this in 2015. Over the years, advancements have been made to make the printer faster, more accurate, easier to configure, easier to carry, etc. on. However, one area that seems to be much more difficult to understand is what to actually extrude.

The real benefit of these systems is that they can run around the clock, slowly printing structures as needed. But if it's printing unattended and the nozzle clogs or the layers aren't adhering, that's a big deal. Can those who own 3D printers imagine starting a four-day print on their printer? One that you can't just scrape off the bed and throw in recycling when it goes sideways? You have to get it right the first time.

Most companies use some kind of concrete mix that has been optimized to flow cleanly through a nozzle. However, concrete is not particularly known for its environmental friendliness as it is a major contributor to greenhouse gases emitted around the world.