3D Printed Buildings: Boom or Bust?

Concrete infill being extruded in a 3D printed wall

Everyone, myself included, wants to believe the hype when it comes to 3D printing. But similar to most heavily-reported on new technologies, the reality of 3D printing can be much more tedious than we’d like to believe. A big part of my job is to stay on top of trends in the additive manufacturing industry and decipher which ones have the potential to make life easier, versus which might complicate the way we do things. 

An application I’ve been following for years is 3D printing concrete structures. The process has been touted as a way to solve the issue of homelessness and build liveable structures in space. More terrestrially, ICON, the forefather of 3D printing concrete, is already in the process of building neighborhoods with the technology. Based on the magnitude of positive news coverage it gets, you’d think we’ll all be living in 3D printed homes soon. However, it’s more complicated than that–there are certainly reasons to be excited, but also limitations that will take time and require innovation to overcome. 

Limitations 

Today, there are several factors that still make 3D printing buildings unrealistic for certain scenarios. 

3D printed homes in a Mexican community

It’s not well-suited for all climates 

You may notice that most current 3D printed homes and buildings are in warmer climates, such as the Southern US, Mexico, Central America, and India. This isn’t a coincidence -- it’s because the warmer weather prevents the concrete from experiencing frequent freezes and thaws, which increase the likelihood of structural damage. This disadvantage is exacerbated because 3D printed concrete isn’t reinforced with rebar or wire mesh like in traditional methods. The walls are also typically left exposed, and, given that concrete is a notoriously bad insulator, allow hot and cool air to easily transfer in and out of the structure.

Size and dimensions are limited

The stationary systems used to do most 3D printing can limit the size and shape a structure can be. Walls are only as thick as the extruder, and dimensions can’t exceed the printer’s axes. This means structures will typically be limited to a single story and relatively simplistic design, although the incorporation of more robotics may lead to more design freedom in the future.

It’s not easy to make changes after it’s printed

Unlike traditional construction methods, 3D printed parts and structures are not very changeable. Once your print is done, you can’t easily knock a wall down, add a door, or make changes to the electrical and plumbing. Concrete doesn’t tear down and patch up as simply as wood frames and drywall do.  Most structural and design elements need to be decided at the outset of the printing. 

It’s expensive

The concrete 3D printing systems used to build structures are not cheap by any stretch of the imagination. Research and development costs alone can range in the hundred of millions of dollars. Then you have to factor in the cost of manufacturing the systems and materials, the specialized software used to create the files, transporting the system to job sites, and paying a sophisticated crew to operate the system. The technology might make economic sense for an entire neighborhood, but not a typical one-off residential project.

 Most construction companies can’t do it

Your average consumer isn’t going to be able to call one of their local concrete construction companies about 3D printing a home. Only a handful of construction companies have the systems, equipment, or knowledge to be able to take on a 3D printed project at this time. The process requires a team of experts that has little professional overlap with traditional tradesmen. Smaller companies may need years to understand if the technology is worth investing in and adopting. 

There is limited long-term data

 The first livable structures have been 3D printed only over the last couple of years. We still don’t know how well they will hold up over time. We also don’t know who the target markets will be–individuals, businesses, or governments, as well as the subpopulations within these main categories. Most potential customers will remain in the “wait and see” phase before opting for a 3D printed structure. 

Advantages

There are still plenty of reasons to be optimistic about this technology and related advancements in the construction industry as a whole. 

Prefab 3D printed walls that will be assembled onsite

 You can build fast

 Once the design and file preparation is done and the system is onsite, printing can be completed within hours for a smaller project and days for a larger project. The process doesn’t require concrete forms or molds to be installed prior to printing like it does when pouring concrete, saving significant time. The specialized concrete formulas also harden faster than poured concrete so that layers can be extruded on top of each other without over-compressing. For a developer looking to quickly build out an entire subdivision, this technology could dramatically reduce the amount of time it takes to go from acquiring land to getting people into homes. 

New technologies are begetting new technologies

In a typically slow-moving industry, 3D printing is forcing construction innovation to happen much more quickly. A key advancement has been the types of concrete mixes that are being made available. Traditional concrete mixes cannot be used in 3D printing, so new formulas are being developed that require less cure time and are durable enough to not need rebar or wire mesh. These formulas can also be customized to account for environmental factors such as altitude and climate. 

 Less reliance on jobsite materials and labor hours

3D printing a structure in concrete reduces the need for building materials and equipment relative to traditional construction. Concrete walls mean you don’t necessarily need wood frames, sheetrock, or siding. AI software helps design the structure in a way that minimizes the amount of concrete used. The structures also require less people-hours for setup and finishing, and the labor jobs that do need to be done are less physically taxing. 

Circumvents (some) labor shortages

Even before the COVID-19 pandemic the US construction industry was experiencing a labor shortage. Using 3D printing systems reduces the need for jobsite labor, as there are no forms to be setup or taken down, no rebar or wire mesh to be installed, and far less finishing needed. However, highly skilled workers are still needed to operate the systems on site. Industry leaders will need to play an active role in educating a new generation of construction workers who are familiar with things like CAD, AI, robotics, and BIM.

Offers more design freedom

Although some systems limit print sizes and geometries, newer robotics systems are actually opening up opportunities for more unique structures. Robotic arms can easily achieve organic shapes that are difficult to create using traditional forms and molds. These structures can be further enhanced using parametric modeling software that optimizes designs to make them able to withstand greater loads using less material.

Verdict

3D printed military barracks in Texas

While there are some clear near-term drawbacks to 3D printing structures, much can and will be improved or eliminated through continued innovation. The speed at which buildings can be erected using far less manual labor clears two major drawbacks of conventional construction–slow processes, exacerbated by a shrinking workforce. I believe that we will continue to see an increase in the number and type of structures 3D printed in concrete, and industry leaders will more than recoup their R&D investments as this method of building grows significantly and takes share within the construction industry.

In the meantime…

Left: A 3D printed mold designed using 3D scanning. Right: a concrete pillar casted using the mold.

Beyond 3D printing concrete structures, there are still plenty of other existing applications for the technology within the architecture, engineering, and construction industries. 3D scanning is an effective way to create digital versions of existing structures that can then be modified to create 3D printable parts. This process makes it possible to create things such as concrete molds that can be used in renovation and restoration projects. CAD and BIM files commonly used in AEC projects can also be easily converted into 3D printable files to produce scaled architectural models. Physical models are excellent communication tools that have the ability to move projects forward faster.