One of the hot topics in the construction industry today is modular construction. This topic gets branded using several different descriptors: Modular, Off-site, Prefab, Industrialized, and probably a few more. Within the topic, there tends to be two different camps; the camp pushing modular prefabricated “panels”, and the camp pushing modular prefabricated rooms, which is often referred to as “volumetric”.
What both of these methods have in common is that they encompass a process by which facilities, or pieces of facilities, are constructed off-site, in an industrialized factory setting. What they also both have in common is that the resulting finished facility meets the same building code requirements as any other structure in the same area. For this conversation, I am not discussing what some people also call manufactured housing, or relocatable buildings, or any other facility that is manufactured to meet the requirements of some alternative code, such as the HUD Code in the U.S. This conversation centers around the concept of taking the same permanent facility design, and moving a portion of its construction off-site, into a factory setting. The plans and specifications are still reviewed by the local Jurisdiction Having Authority (JHA), the construction is still permitted by that authority, and the progress is still subject to inspection and approval by that authority.
So, what’s the point? Why move portions of the construction into a factory setting?
Some people will argue that the point is to standardize some of the designs in order to bring down costs by enabling repetitive activity. I am not one of those people. I don’t think that standardization of designs is realistic at this point, at least not on a grand scale. To be clear, I think that there is a place for standard, repetitive designs. Affordable housing is one segment that comes to mind. But in the grand scheme of things, this type of standardization is not realistic. Owners and architects do not want their facility to look like the project down the street. Uniqueness is not just desired, it’s often a requirement. Even when it isn’t an implicit owner requirement, things like site specific conditions, zoning requirements, and local style all inject an element of uniqueness into each project, and this is not likely to change any time soon.
Even without making every building look the same, there are many benefits to be had for modular construction. Increased speed and reduction of the overall schedule, improved quality, improved safety, reduced waste, and the potential to better control procurement and react to supply chain challenges are all possible.
Reduced Building Time
Regardless of the structure to be built, reducing the time from design to hand-off will always have benefits. Hotels can get paying guests in sooner, owners and tenants can move into houses and apartments sooner, and retail establishments can start stocking and selling. The owner may also be able to reduce the time, and therefor interest payment, associated with their construction loan. Reduced building time also means lower cost for general conditions and the general contractor can free up bonding capacity sooner.
In order to realize maximum benefits from reduced time to completion, these projects need to be planned as modular from the onset of design. In fact, the project delivery method and the selection of the design and delivery team should have modular design and construction as a core requirement. Integrated Project Delivery (IPD) or IPD Like, Design-Build, and CM at Risk can all support modular construction. The goal is early contractor engagement, and early adoption of modular processes into the design phase. Make no mistake here, there is no one-size-fits-all solution (at least not yet). Some projects will benefit from a panelized system, some will benefit from volumetric prefabrication, others could utilize both (think panelized structure with finished bathroom pods). Regardless of the solution, the project will always realize the maximum benefit when these options are properly explored near the beginning of the design phase, and when that conversation occurs between all three parties: the owner, architect, and contractor.
There will be considerations such as wall panel size and its effect on design, availability of systems, transportation; and timing can be critical. There may also be some time required to get the jurisdiction with inspection authority on board. Again, the modular components will be designed and built to meet standard building code requirements, but the construction will be done off site. This can pose a challenge for some building officials, particularly if the off-site facility is outside of their region. There are many solutions to this challenge, and there are enough successes out there now that this can be overcome, but it should be addressed early.
With design, construction, inspection, and logistics challenges solved, construction of the modular components can begin early and can commence simultaneously with the required on-site construction. Consider the time savings here; by the time the site work, utilities, and foundation are complete, the finished building elements can be delivered and set directly in place. The time savings potential is substantial.
The safety benefits cannot be overstated. Building components of the structure in a controlled environment offers many opportunities to eliminate hazards and reduce risk. Fall protection is much easier to plan when it only needs to be done once in a fixed assembly area. It’s even easier to plan when the hazard can be eliminated by building on the ground instead of up at heights. Struck-by hazards can be better controlled in a factory where separation can be maintained between people and equipment. It’s also much easier to control environmental factors and ergonomics in a factory than it is out on a job site. There is also the potential to make it easier to find, train, and retain people when they are going to be working in a fixed location and in a controlled environment.
There are additional risk factors that can be easier to control in a factory setting. Theft of tools and materials, risk of fires during construction, the impact of labor variability, and potential impacts to the public can all be easier to control in a factory environment. It can even be easier to facilitate the schedule because of the controlled environment, thereby reducing the risk of not meeting required milestones.
Reduce Waste, Improve Quality
The controlled environment of the factory setting offers opportunities for waste reduction and quality improvement that are very difficult to achieve on-site in the field. One of the best examples I have seen of waste reduction is the panelized construction method used by Digital Building Components (DBC) that was shown as an example in my LinkedIn Learning course, Construction Management: Modular Construction. Instead of cutting steel studs to length, the studs and plates are actually manufactured to length. Since these elements are individually manufactured to precise lengths from a roll of steel, the only potential for waste is when they reach the end of the bulk roll of steel.
The assembly line marks stud locations on the track as it is being manufactured. It cuts to extremely precise lengths. It also punches out openings for utility runs precisely where needed. This is all driven by the Building Information Model. This reduces waste and greatly reduces the potential for rework or improperly constructed elements. In many cases, the controlling factor in how these pieces are then assembled is the need for greater strength designs to withstand movement during shipping. Greater control over the assembly process and the ability to leverage manufacturing techniques such as robotic welding leads to improved quality and productivity.
There are many decisions to be made in the process. Are utilities pre-installed? Are both side of the wall finished at the factory, or is one side left open so inspection can be done on-site? Will the project utilize panels, or will it employ volumetric units that are almost completely finished? Regardless of the final solution, when these elements are manufactured in a controlled environment it can be much easier to conduct a thorough inspection, whether that’s for code requirements and acceptance, or for quality assurance. Any undesirable variations can be easily spotted and corrected before anything gets shipped to the project site.
Labeling of components, proper staging and delivery, and the ability to thoroughly preplan the on-site assembly process can also greatly enhance production on the project site.
Conclusion
Modular construction is not without its challenges, and not every project will present an opportunity to leverage this method. Not only does the time to complete get reduced, but the time frame in which changes will have minimal impact to the project gets shortened. Owner changes after the commencement of manufacturing can be problematic. Transportation and logistics planning needs more attention. There is also much thought and discussion that needs to occur around the issue of builder's risk and insurance, and when ownership of pre-manufactured elements is transferred between parties.
These challenges notwithstanding, there are many opportunities for the construction industry to benefit from modular construction. What is your take on this? Have you been involved in a project that has utilized modular methods? Comment on the issues and your experiences in the comments section below.
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