By: Sebin Joseph
Automated construction methods such as prefabs and 3D printing are gaining popularity, mainly because of high home prices. Concrete 3D printing has proved its feasibility through various projects around the globe. However, 3D printing is still in a pioneering stage, many iterations and experiments are needed for perfecting this technique. The results of the 3D printing construction projects are promising a solution for the labor shortage in the construction industry. Today, industrial 3D printing is a common practice in prototyping, but construction 3D printing is still evolving as a viable technique for construction. Around the world startup companies are working to bring the technology to the mainstream. Because of the popularity for 3D printing in recent years, the companies overwhelmed with orders and inquiries. Many people are in line for a 3D printed construction project; at present the lead time on a project can even be over a year.
3D printing companies keep their numbers secret and sometimes make claims that are not even close to the actual numbers. In 2019 Business Insider published an article with a misleading headline “These 3D-printed homes can be built for less than $4,000 in just 24 hours” and many other media outlets echoed this unverified claim. The misleading news reports has helped to create public interest in the technology, but the true numbers can be demoralizing to many prospective adopters. At present, a 3D printed house will cost more to construct, and the process will take months to complete. This article discuss about different aspects of the construction 3D printing, to provide an insight into the capabilities and prospects of this technology.
The 4000 Dollar home?
Home prices in the US have reached the highest point in history, partially due to the increased cost of the material and labor. While labor is the biggest cost in construction, the industry is also facing a shortage of skilled labor. 3D printing can offset a portion of this labor shortage thus reducing the cost. But at present 3D printing construction can be significantly costlier than conventional construction techniques. A few 3D printed houses have been built around the country, and the actual cost of these projects is rumored to be anywhere from 140 percent to 300 percent of conventional construction. The cost can vary depending on the type of system and material being used. There are many factors contributing to this high price, the main components of a 3D printing cost are discussed below.
- Material: 3D printing machines use engineered concrete mixes (ink) to create the desired structures. For a concrete mix to be a 3D printing ink the formability, consistency and curing properties should be within a defined range. Different companies like ICON, Apis-Cor, Mighty Buildings, etc. have developed their own proprietary inks for their own 3D printing machines. At present there is no fixed standard for these concrete mixes and companies are producing the material in batches for each project. There are no published numbers on the price or properties of these proprietary mixes, yet by analyzing the reported expense of 3D printing projects it is evident that the material can cost four times or more compared to regular concrete. This price of the material is the main reason behind the high price point of the 3D printing construction projects. Since the 3D printing concrete is a highly engineered concrete mix the price will never be lower than regular concrete, but in the future mass production can bring the cost down from the current point. If the price of ink falls to a comparable level to regular concrete, 3D printing construction can become cheaper than conventional construction.
- Machines: Construction 3D printers are a system of computer-controlled machines used for placing the ink layer by layer. Currently there are only a few companies manufacturing 3D printers large enough to build houses; the price of these machines can run anywhere from hundreds of thousands to millions of dollars. Apart from the gantry, or robotic actuator, there are other supporting systems such as material mixers, pumps, hoppers, nozzle assemblies, etc. needed for the printing operation. Some of these machines are more complex and sensitive than the gantry or the robot. The construction jobs may require additional machines like cranes, tractors etc. The total cost of all the machines needed for 3D printing a home can run into the millions. Because of the high demand and lack of competition, the price for these 3D printers remains high. Just like any machine, these early models are yet to prove their reliability and durability. A portion of the total price of machine and maintenance will be added to the total price of each project, but in the future more reliable and efficient models will bring this cost down.
- Transportation: Transportation cost is the cost associated with moving the machines, materials and people involved in the construction process. Due to the shortage of printers, the machines need to be transported long distances. The transportation of the entire 3D printing system and materials can take many truck loads and larger printers will need cranes to move its massive parts around the work site. Sometimes the printing will require a tent, and in that case the tent will also need to be transported. This will increase the cost of construction, but as more printers and subsystems become available in the market the cost of transportation will be lowered.
- Wastage: This factor is often overlooked. Getting a consistent 3D printing mix is still an art rather than science. A lot of factors can affect the consistency of the mix, and this consistency is important in making a high-quality wall. Before each project the team must do a lot of test prints to create the perfect mix for that specific job. The projects are not printed in one stretch either; all projects are printed in sections. Each time the machine starts, a lot of material is wasted in the process of setting the mix consistency for the actual printing. This wastage adds up to the tons by the end of the project. Due to the quick setting nature of the mix sometimes the material line can clog, and in that case the entire line needs to be flushed. Due to the high cost of materials, the cost of wasted mix will be significant, but as companies perfect their mixes and printing practices, the wastage in the process can be minimized.
- Operational cost: Operational cost is the expense of running an operation. The operational cost for 3D printing construction comes from wages, energy bills, set up cost and other miscellaneous expenses. Human operators are required to ensure the accuracy and precision of the printing operation, as any unnoticed changes in any stage of the operation may have serious consequences. Today, most 3D printing jobs need more than one person to operate and monitor the entire system. Setting up is the process of getting the printer and other machines ready for the actual printing of the house. This process may require cranes, tractors, generators, waterlines, etc. Today, the operations in a 3D printing construction site are far from optimized and it will take many years of experience to achieve. As time progresses, more trained professionals and optimized operational procedures will bring higher efficiency.
Build a House in 24 hours?
Home construction is a long process; a lot of money and labor is involved in it for many months. Shortening the construction timeline will obviously reduce the total cost of construction. The ability to build a house in 24 hours would be momentous but that is not a practical goal. Some companies may have claimed to build a house in 24 or 48 hours, but they are talking about the actual print time of the wall’s construction. A project is more than just walls, and even the wall printing is parted into sections. The total printing process taking one or two weeks to finish, and many test prints need to be completed before that. Because each layer of material will require a curing time to achieve the strength to carry the weight of the layers on top of it. After the walls are cured, other works need to be carried out to finish the project. Therefore, no 3D printed construction project can be or was finished in 24 hours.
3D printing has the potential to reduce the time for constructing the walls of the home. After the walls are installed, conventional roofing, electrical, plumbing and finishing processes need to be done. By 3D printing the walls the total time of the project can be reduced, but the total time will still be over a month. Reducing the time to build a home will increase the availability of homes, thus reducing the price.
The 3D printing operation is sensitive to environmental conditions, therefore variations in temperature and humidity will impact the timeline of the project. The printing mixes are optimized for a specific temperature and humidity level. A change in the specified climate conditions will negatively impact the quality of the print. For this reason, in most cases the actual printing had to be limited to a certain time of the day. And printing is impossible during a raining if it is not done inside a tent. Printing inside a tent can produce better quality walls, but it is obviously much more expensive.
What will happen to construction workers?
Labor is the biggest expense in construction. The labor shortage is increasing the cost of labor year by year. In this situation automating the construction processes is important to make affordable housing a reality. Construction is the only main industry that hasn’t seen any significant automation, and 3D printing is one way to automate to construction. 3D printing is not capable of offsetting all the manual labor, people are required for different procedures before during and after the 3D printing process. During the printing operation, people are required for inserting reinforcement, insulation, rough wiring, and plumbing, etc. After finishing the walls, roofing, flooring, and other finishes are to be done conventional contractors.
For every replaced job, automation will create more sophisticated jobs in the technology sector. Development of automated construction will create jobs for printer operators and robotic manufacturers. It will also open more research and development jobs in material science, software development etc. 3D printing construction is in a state like the industrial robots of the 1980s; today all factories are automated to different degrees, and the conditions are prefect for construction industry to adopt automated construction techniques.
A Dream come true for Architects
High cost of construction was always a limiting factor in architectural innovations in building designs. Architects usually come up with innovative shapes in their designs, but the cost of making the curved structures make the designs financially impossible. The advent of 3D printing is promising a new future for architectural design. 3D printing can make curved walls as easy as straight walls. Due to structural issues and code restrictions, 3D printing companies are taking baby steps in bringing this change into new construction. However, curved rooms will soon be a norm in the 3D printed homes. This architectural freedom can easily bring more innovative designs to no-permit required structures such as planters, firepits etc.
At present, the print mixes have similar properties to concrete; they are good with compression and poor with tensile loads. Therefore, rebar is inserted into the concrete. Developing new materials can change this, if a company come up with a 3D printing ink that can perform under tensile load it can ultimately accelerate the construction 3D printing technology.
The permit and code rules have some restrictions in place to protect the aesthetics of a neighborhood. But these restrictions were formalized before the advent of 3D printing technology as the technique mature the governing authorities will eventually adopt the new rules and standards. This is a field that need some focus from the companies involved in this industry. Engineering and architectural standards needs to be developed for 3D printing construction.
Construction is an essential process, with significant ecological effects. Sustainable housing is a long-sought achievement and 3D printing may be capable of making it a reality. Material scientists around the globe are working to develop an eco-friendly 3D printing mix. Construction is one of the largest CO2 producers, making the construction more sustainable will solve a lot of environmental issues.
At present most of the 3D printing mixes are cement-based. Cement is not an eco-friendly substance. Nevertheless, 3D printing is better for the environment because of the decreased waste of the raw materials. Good amount of research is dedicated towards creating alternative materials for construction. Recently, Omlab a Netherland based startup was successful in developing a bio-degradable 3D printing ink for construction. Wasp, an Italian startup has 3D printed a structure using soil and straw. If the researchers can produce an eco-friendly ink with similar properties of cement-based mixes, it can create a huge impact in the industry’s sustainability goals. 3D printing can also eliminate many intermediate steps in the construction process that will also reduce emissions and pollution.
All structures around us are overbuild, most of the material being used is for ease of construction rather than for structural integrity. 3D printing can reduce material usage by creating complex shapes for perfect load transfer. Today most structures are made as filled blocks, and most of the material in the structure is not required for its designed structural properties. By using 3D printing the required amount of material can be placed where it is required. This way, some structures can save up to 70% of material; it will have a positive effect on the price and sustainability of the buildings.
Concrete is fire-resistant in nature and using concrete instead of wood can reduce the risk of fire. This can result in lowered insurance cost. Concrete is also not susceptible to termites and other insects, resulting in lowered maintenance cost. Concrete, compared to wood, also has superior strength. Because of the strength the damages caused by natural disasters or adverse climate phenomenon will be minimal, saving a lot of money in damage repairs.
3D printing construction is here, and the technology has proven its ability to revolutionize the construction industry for the better. Despite some claims about the price of 3D printed homes being clickbait, the claims were generated popularity for the technology. By nature, 3D printed homes are better in many ways to conventional houses, but a lot of research and development must be done to unveil its full potential. The technology is growing at a fast pace, trying new techniques and materials. Soon, 3D printers will be a regular sight on construction sites. Innovative startups are racing to capture the once in a century opportunity. There are dozens of companies coming up with different types of materials and techniques to improve the quality and sustainability of concrete 3D printing. Despite the present cost of materials and machines being very high, the tipping point is not far away. By the end of this decade, fully automated 3D printing could be a common practice.