Additive manufacturing (AM) has been getting a lot of attention over the years, with its use in construction a recurring theme. Generally this brings to mind massive 3D printers that are carted to construction sites and assemble entire homes on the spot. That’s the perspective with which a recent ZDNet article by [Rajiv Rao] opens, before asking whether AM in construction is actually solving any problems. As [Rajiv] notes, the main use of such on-site AM construction is for exclusive, expensive designs, such as ICON’s House Zero which leans into the extruded concrete printing method.

Their more reasonable Wolf Ranch residential homes in Texas also use ICON’s Vulcan II printer to print walls out of concrete, with a roof, electrical wiring, plumbing, etc. installed afterwards. Prices for these Wolf Ranch 3 to 4 bedroom houses range from about $450,000 to $600,000, and ICON has been contracted by NASA to work a way to 3D print structures on the Moon out of regolith.

Naturally, none of these prices are even remotely in the range of the first-home buyers, or the many economically disadvantaged who make up a sizable part of the population in the US and many other nations in the Americas, Africa, etc. To make AM in construction economically viable, it would seem that going more flatpack and on-site assembly is the way to go, using the age-old pre-fabrication (prefab) method of constructions.

This is the concept behind the University of Maine’s BioHome3D, which mainly uses PLA, wood fiber and similar materials to create modules that contain insulation in the form of wood fiber and cellulose. These modules are 3D printed in a factory, after which they’re carted off to the construction site for assembly, pretty much like any traditional prefab home, just with the AM step and use of PLA rather than traditional methods.

Prefab is a great way to speed up construction and already commonly used in the industry, as modules can have windows, doors, insulation, electrical wiring, plumbing, etc. all installed in the factory, with on-site work limited to just final assembly and connecting the loose bits. The main question thus seems to be whether AM in prefab provides a significant benefit, such as in less material wasted by working from (discarded) wood pulp and kin.

While in the article [Rajiv] keeps gravitating towards the need to use less concrete (because of the climate) and make homes more affordable through 3D printing, AM is not necessarily the panacea some make it out to be, due to the fact that houses are complex structures that have to do much more than provide a floor, walls and a roof. If adding a floor (or two) on top of the ground floor, additional requirements come into play, before even considering aspects like repairability which is rarely considered in the context of AM construction.