Will 3D Printing Revolutionize Housing?

The advent of 3D printing technology has sparked significant interest across various sectors, with the housing industry standing out as one of the fields ripe for transformation. This article explores how 3D printing could fundamentally change how homes are built and the potential benefits and challenges this technology may bring.

Understanding 3D Printing

3D printing uses materials like plastic, metal, or concrete to build objects layer by layer. This process starts with a digital blueprint, which a computer uses to direct a printer nozzle or other machinery. As the printer deposits material in thin layers, these layers solidify and bond together to form a three-dimensional structure. This method allows for intricate designs and complex details with less waste than traditional manufacturing processes. Originally used for creating prototypes, 3D printing has expanded into industries ranging from dentistry to aerospace.

In the context of home building, 3D printing translates digital designs into physical structures by extruding construction materials through a large, movable printer—essentially a concrete extruder attached to three robotic armatures that move it back and forth along each of the three dimensions. This printer, guided by precise digital models, lays down layers of material—commonly a special type of concrete—to form the walls and framework of a house directly on-site.

Extruding concrete layer by layer makes 3D printing similar to brick-based construction, where bricks are laid one layer at a time. Moreover, bricks cannot span a window or door gap without a lintel, a structure designed to redistribute the weight above. That said, bricks don’t have the complexities associated with the drying and hardening of the material, which we will discuss in more detail below.

The Pros of 3D Printing in Housing

1. Cost Reduction 

Cost reduction is one of the most compelling advantages of 3D printing in housing. Traditional construction methods involve numerous costs, including labor, materials, and time. 3D printing reduces costs by automating much of the building process. The printers can use a variety of materials, some of which can be sourced locally or are less expensive than traditional building materials. Labor makes up roughly 40% of construction costs. 3D printing offers the opportunity to save on labor by eliminating two of the most costly aspects of home construction: framing and the placement of drywall—the most expensive element of interior finish after cabinets (NAHB on Construction Costs). Framing and placing drywall are less necessary, and foam insulation can be applied with a hose, requiring less effort than installing insulation panels (Aerogel – Wikipedia). 3D printing will require a substantial initial investment, and the workers who know how to work this equipment may command a higher wage than other kinds of construction workers, but the technology offers substantial savings because the total number of man-hours will be much smaller.

2. Speed of Construction 

3D printing can dramatically speed up the construction process. A house that typically takes months to build could be completed in a matter of days. This efficiency not only reduces labor costs but also allows for quicker occupancy. When one considers that builders are often working with borrowed funds, projects that are completed faster cost less. Of course, time is money, and even if a builder is not borrowing the cash, the sooner he completes his project, the sooner he can see a profit and reinvest the proceeds. However, when the builder is borrowing the cash, the advantages of speed become all the more evident.  

3. Environmental Impact 

3D-printed buildings promise to be more environmentally friendly. The technology can minimize waste by using exact amounts of construction material; all else being equal, processes that shape by adding material, rather than removing it, are less wasteful.

4. More Consistent Build Quality

As the process is fully automated, there is potential for higher build quality in the long run. Of course, it is easier for human builders to make small adjustments to their build in order to account for previous mistakes/imperfections: So this increased consistency is both a blessing and a curse.

The Cons of 3D Printing in Housing

1. Technical Limitations 

While 3D printing technology is evolving rapidly, there are still limitations to the scale and types of structures that can be printed. Current technology is primarily limited to simpler, smaller buildings and may not yet be suitable for larger, more complex structures. Additionally, the quality and durability of materials used in 3D printing are still under scrutiny.

One of the main issues is the physical limitations of using concrete, which needs to be strong enough to support additional layers before it fully cures, posing a risk of structural collapse if layered too quickly. However, it also bonds less strongly the more slowly it is poured: A block of wet concrete poured all at once binds better than a layer of wet concrete poured onto hard concrete or semi-wet concrete. This has led to innovations like tapered walls, but such designs are not universally appealing and currently restrict building heights to mostly single-story structures. Additionally, using larger gravel improves the strength of the concrete mix but can cause uneven distribution when extruded through the printer’s nozzle, reducing the durability of the structure. Many companies opt to use just sand instead of rock to avoid these issues, but this results in a material that is more akin to mortar than concrete, which is prone to shrinkage cracking and high internal stress upon curing. 

Moreover, the broader application of 3D printing is further complicated by the inherent weaknesses of printed concrete, such as susceptibility to microcracks and damage from environmental factors like freeze-thaw cycles. This leads to potentially high maintenance costs and a need for specialized care, making 3D-printed homes less appealing compared to more traditional or prefabricated construction methods.  

As if these problems are not substantial enough, the ideal temperature for concrete extrusion is between 60–80°F, but it can’t be below 40°F or above 95°F. The concrete is mixed to account for the temperature and humidity levels at each site, but this can be difficult in areas with large temperature swings. The upshot of this is that builders must take measures to ensure the temperature conditions are right.

That said, innovations in materials may solve a number of these problems: While metal 3D printing is possible, and is already used in aerospace and other industries, it is not likely to see widespread use in residential construction. However, plastics, polymers, and composite materials other than concrete may provide a solution. 

Plastics and Polymers

These are among the first materials used in 3D printing. In construction, specially formulated plastics can be used to create components that are lightweight, resistant to water and decay, and easily molded into diverse shapes. These These were among the first materials used in 3D printing though builders have tended to prefer concrete. In construction, specially formulated plastics can be used to create components that are lightweight, resistant to water and decay, and easily molded into diverse shapes. These materials are particularly useful for creating components like fittings, fixtures, or even entire structures in environments where metal or concrete may not be suitable. Composites: Composites combine two or more distinct materials to capitalize on the beneficial properties of each. For example, a composite material used in 3D printing might blend a polymer with a fiber (like carbon or glass) to increase strength while maintaining a lower weight. Composites are beneficial for their enhanced mechanical properties and environmental resistance. That said, the first uses of this technology will be limited to one to two-story buildings—and the second stories might rely heavily on prefabricated parts.

2. Regulatory and Code Compliance 

Building codes and regulations are established based on traditional construction techniques. Integrating 3D printed structures into these regulatory frameworks poses significant challenges. Authorities must develop new codes to address the specific nuances and safety aspects of 3D-printed buildings, which can be a slow and complicated process. (NAHB on 3D Printing and Code Compliance).

3. Aesthetic and Cultural Limitations 

3D printed houses might not appeal to everyone, particularly in cultures with a strong attachment to traditional building styles. Moreover, the uniformity of printed structures could potentially lead to monotonous urban landscapes, lacking the architectural diversity seen in conventional cities. 3D printing also requires making homes in rounded shapes, as the extruder has a tendency to leave excess material, i.e. slop when performing a sharp turn. While some people may like these rounded structures, it means architects might have to give up the clean lines associated with traditional styles. Moreover, as anyone familiar with the architectural style of brutalism can attest, concrete does not weather well and can be hard to repair and maintain. 3D printing that relies on concrete may have some of the same problems. One final problem is that precisely because it is less labor intensive, it may become associated with more affordable/low-income housing and consequently develop a stigma. 

When and where will 3D printing become widespread?

Texas has the largest number of 3D printed homes for a reason. Areas that have a relatively free regulatory environment and high labor costs, as Austin Texas does, along with a tech-savvy workforce will adopt this technology first. I expect it to become common there, though still a minority of total construction, over the next ten years, with adoption in Colorado and Florida soon to follow. California, with its more intensive regulatory environment and concern with earthquakes, will come later. Expect to see considerable use by the middle to late 2030s though don’t expect wood-based construction to disappear.

3D printing has the potential to revolutionize housing. However, housing is a highly regulated industry, and this means that promising new technologies are not incorporated as quickly as they could be. Until 3D printing can demonstrate that it is at least as safe as traditional construction, it won’t see widespread adoption, but once it does, it could change housing forever.

Franklin Carroll

Franklin Carroll is Kukun's VP of Modelling and Analytics; After finishing his studies at the University of Chicago, he worked at Fannie Mae where he helped build Collateral Underwriter, roll out the Value Verify initiative, and specialized in collateral related and credit related policy.

Published June 18, 2024