Construction 3D printing has come a long way in the last decade from being just a pipe dream to an actual available service. Construction 3D printing has thus far flourished by and large in the prefabricated houses market.

Slowly and surely, mobile construction 3D printers are gaining both the stability as well as the quality needed to cope with printing on-site, and on-location in a variety of construction conditions.

Based on the method of construction, 3D printed houses right now fall into two categories:

1. Modular/Off-site 3D Printed Houses
2. On-site 3D Printed Houses

Modular/off-site 3D printed houses

With the accuracy and resolution of construction 3D printing comes the ability of 3D printing a complete house, in parts, off-site and then later transporting and assembling the same onto the final location.

Many 3D construction printer companies, most notable Winsun, have made this into a viable business model.

Advantages of off-site 3D printed houses

The advantages that come with 3D printing off-site include:

• Much greater control over the 3D printing process: Printing off-site allows the manufacturer to treat building the house the same as manufacturing any other good. That is, the factory can be tailored to the exact needs of the construction 3D printing process. Temperature and humidity control are just the tip of the iceberg.
• Less risk of damage to the expensive construction 3D printing equipment: While the 3D construction printer itself is not a multi-million-dollar investment, it still is a very capital-intensive move for any construction company to invest hundreds of thousands of dollars in a construction 3D printers. 3D printers are sensitive and precise computerized machines. Printing off-site ensures that the construction 3D printers never leave the safe confines of a suitably large hanger.
• Permanently installed construction 3D printers: Large-scale gantry style construction 3D printers can be used instead of expensive robotic or mechanized arm-based ones. Gantry-style construction 3D printers are both faster and much easier to maintain than more advanced robotic construction 3D printers. Thereby further reducing construction times for the customer.
• Increased worker safety: Worker safety has long been one of the biggest concerns of large-scale construction projects. Labor workers on-site are exposed to a variety of hazardous situations and oftentimes life-threatening levels of work-related risks. Construction 3D printing done off-site alleviates a lot of these risks and allows for the company to always have necessary medical facilities on-hand too.
• Greater design freedom: On-site construction 3D printing can quickly devolve into simply a battle with mother nature. Especially in trickier climate and/or terrain conditions. 3D printing inside factory premises allows for much greater flexibility in both design as well as the allowed versatility. The Future Foundation Office of Dubai serves as a prime example.
• Cost Savings: From economies of scale, to lower failure rates, to savings in transportation of raw material costs—off-site construction 3D printing considerably brings down the costs of construction. This in turn makes construction 3D printing that much more viable and brings down housing costs as a result.

Disadvantages of off-site 3D printed houses

While prefab construction 3D printed housing certainly has plenty of positives going for it, certain drawbacks have kept it from becoming the housing revolution that is so needed in today’s world.

These disadvantages include:

• Unpredictable durability: While it is easier to 3D print off-site, 3D printed house done without considering the exact ambient conditions that the 3D printed house will face may cause some serious question marks over how long the resulting 3D printed house would last after being moved to the site.
• Costs of Assembly: The biggest promise of construction 3D printing, like its smaller desktop sibling, is the cost savings that come with additive manufacturing. The cost of transporting and assembling the 3D printed house then, becomes both counter-intuitive to the tenet of this technology, and, from a practical point of view, it diminishes the materials and labor costs saved during the construction process. Transporting many tons of solid concrete, or other material, even when done in parts, adds up to quite a hefty transportation cost. This is exacerbated further still if the parts have to be shipped overseas or trans-nationally.
• Increased Lead Times: Construction 3D printing is fast. A 3D printed house can be ready in days, as opposed to the months-long wait. But if you are going to be transporting and assembling a whole house to a location, this adds a good deal of additional lead time to a project.
• Risk of Damage On the Road: While any self-respecting business would try its best to ensure that the shipping and transport of the 3D printed house or building are safely secured during the move, the reality is that accidents do happen and worse still is when a part gets damaged in an imperceptible way. This runs the risk of the house getting assembled only for the structure to fail later on. The last thing anyone wants is for an assembled house to be structurally unsound, be it the manufacturer, or the people that are going to occupy it.
• Limited reach:There will inevitably be limits to how multiple tons of concrete could feasibly be transported for the purpose of on-site assembly. While cost and time are two factors, the inability to 3D print on-site means that for persons who do not have the money and time to bear the carriage costs, or even those who live too far away for off-site prefabrication of a 3D printed house to be considered feasible would automatically be stuck with the costly and inefficient conventional methods of construction.
• The “Mobile Home” Stigma: Ever since manufactured homes became a viable housing solution, there has persisted a stigma that prefabricated housing is only purchased by those of a lower income class who cannot afford a constructed home. This stigma alone, is an extremely strong adversary to overcome for off-site construction 3D printing companies. It is unreasonably difficult to convince and overcome the psychological barriers of the masses, who would love the cost savings of construction 3D printing but would quickly flinch and leave at hearing the word “prefab”.

On-site 3D printed houses

On-site 3D printed houses promise far greater disruption in the housing and construction industry than off-site ones. The primary reason is that on-site construction 3D printing actively takes business away from conventional construction technology.

The savings in labor cost, and just the sheer amazement of seeing an entire habitable house get constructed in a matter of days instead of months means that on-site 3D printed houses have a bigger audience to cater to before even completely hitting the market.

Advantages of on-site 3D printed houses

On-site construction 3D printing is now being hailed as the future of construction as a whole by a lot of industry experts, its advantages include:

• Increased Apparent Durability: On-site constructed 3D printed houses have to be drawn from the foundation to the top roof. This means that the entire construction 3D printing apparatus needs to be set-up such that it can effectively, reliably and accurately deal with whatever conditions that the site may present, which sometimes could even include earthquakes and other violent acts of mother nature. Clearly while this is a more challenging construction landscape, the fact remains that if a 3D printed house is successfully 3D printed in such an environment, the questions regarding its durability and strength should be far fewer than with an off-site constructed 3D printed house.
• Adaptable Design: Unlike off-site construction of 3D printed houses, on-site construction 3D printing can be adapted to the specific needs of the customer as the construction process is on-going. Maybe they would prefer the boundary wall to be twice as thick, or they would like to add a curved corner to the front of the house. Such last-minute requests simply cannot be entertained when the house has been prefabricated and is only going to be assembled on-site.
• Cost Savings are transferred: While off-site construction 3D printing adds additional carriage and assembly overhead costs to be borne by the customer, the cost savings of on-site construction 3D printing are a lot more likely to be transferred to the new home owner since the construction company would still be able to keep a hefty profit margin despite the overall reduction in costs.
• Flexible Construction Materials: Off-site construction 3D printing is limited to the types of raw materials that are available to the construction 3D printing company. However, with on-site 3D construction printing, it is possible to choose the best material mix in terms of cost as well as environmental impact to ensure that the 3D printed house is sustainable both during its construction as well as when it is eventually going to be repaired.
• Time Savings: With on-site 3D construction printing, a 3D printed house may very well only take a matter of days including complete finishing and furnishing. These time savings are directly transferred to the customer since the absence of transportation lead times means less of a headache for the construction 3D printing company. That is more opportunity to 3D print more houses and not just have a backlog of orders that need to be shipped and assembled.
• Greater reach: On-site construction 3D printers are usually designed with mobility in mind. This means that the only transportation and carriage would be for the 3D construction printer itself, the raw and finishing materials, and the furnishings. It is far easier to transport a truckload of bags of 3D printing concrete, mortar or clay than it is to transport tons of prefabricated house parts. Inevitably this means that construction 3D printing companies can cater to a larger audience and even entertain projects in remote locations since the costs of transportation would in large part be reduced by sourcing the raw and finishing materials as well as the furnishings locally, closer to the actual site of construction.

Disadvantages of on-site 3D printed houses

While on-site construction 3D printing is poised as the future of home building, it still has some drawbacks that have yet to be overcome. These disadvantages of on-site construction 3D printing include:

• Loss of printing quality: While it is true that on-site construction 3D printing promises more durable 3D printed houses by tailoring the material mix as well as the design to the on-site requirements, another fact is that by focusing so much on battling the ambient conditions, the print quality both aesthetically and design-wise would have to face compromises in order to complete a successful on-site 3D construction print.
• More expensive failure: When a module of a modular off-site 3D construction print fails, only that specific module needs to be reprinted and replaced. However, when an on-site 3D construction print fails, the damage is usually far more expensive both in terms of material costs as well as the time it would take to repair the said failed area of 3D print. By design construction 3D printing on-site is broken into a number of major construction chunks. Usually building the walls of a single floor in one go. If a 3D construction print fails, then usually a very large part of the structure needs to be redone since the 3D printing materials are by their very nature designed to be quick setting.
• Higher risk to construction 3D printing equipment: Printing on-site would always pose a much greater risk to the 3D construction printer, needlessly causing damage to these high accuracy construction machines. This matter could further be exacerbated if the construction 3D printing company charges any abnormal damage to the customer. Construction costs are one thing but paying for damage to a 3D construction printer could easily take the project out of budget for any potential 3D printed house owner.
• Less Safety for Workers: On a normal on-site construction 3D printing project, only one or two operators are engaged to mind the 3D construction printer while it does its own thing and constructs up the gray structure. However, a lot of 3D printed houses are designed such that all the electrical as well as insulation work needs to be done alongside the 3D printing process. This may be done both to reduce construction time, but also to streamline the construction 3D printing process when using quick drying materials. This puts workers directly in a less safe working environment especially since with a computerized piece of equipment, there is little that can be done if something were to go wrong.
• Construction Regulations or lack therof: There is very little in the way of construction 3D printing regulations, leading to a case by case analysis for most construction 3D printing projects. You may simply not be allowed to employ construction 3D printers commercially on a piece of plot you own if it is in an area where specific construction permits are required. Consequently, the only work around would be to print off-site, if faced with such a hurdle.
• Site Preparation: A construction 3D printing site, much like its desktop counterpart, works best with a leveled “print bed”, what this means is even before the foundation can be laid, the site needs to be made perfectly flat and perfectly even. With off-site 3D construction printing, this is never an issue, and the foundations are used to straighten out the ground same as it is done in conventional construction. However, with on-site 3D construction printing, a leveled site is crucial for successfully 3D printing the structure. Any flaw here would potentially lead to a failed or undesired 3D print, which is a lot more costly if the failed print is the size of a house.