Modular construction is having its own Renaissance right now—shedding the stigma of “prefab,” “manufactured homes,” or (horror of all horrors) the old “double-wide trailer.” High-end homes, apartment complexes, and even high-rise hospitals are going modular.
In this age of automation, the traditional model of constructing homes and buildings—where materials arrive at the project site and are cut and erected by skilled specialists—is being more closely examined due to the waste, complex timelines, and inefficiencies inherent on a jobsite. Instead, many successful projects are taking an automated assembly-line approach that’s different from the manufactured homes and buildings of the past. Manufacturing is in a factory setting, with on-site work akin to snapping building components into place, not unlike the ever-popular Lego building blocks. And the benefits of modular construction are telling.
Schedules and Errors
First and foremost, modular construction gets rid of jobsite issues such as access routes and traffic or security and storage of materials. Factories are typically located next to shipping hubs, aiding the flow of materials while reducing shipping costs. They are also located in neighborhoods where shift work is the norm, so construction work can take place around the clock as needed.
Additionally, the modular process allows some contractors to do foundation work at the same time others are building walls and components. This concurrent construction gets a jump on the structure, with walls going up as the foundation cures. With these schedule advantages, the Modular Building Institute estimates projects are completed 30 to 50 percent faster than traditional construction. And in the case of modular homes being constructed in California’s Napa Valley by Factory_OS, 1,300-square-feet structures are being assembled in a mere four hours—from foundation to turning the lights on.
Models and Materials
Reducing on-site measurement and construction work can yield a much more seamless building process that avoids the kind of errors that can grind a whole project to a halt. However, building with components requires a new level of design and control. For instance, instead of the typical mechanical, electrical, and plumbing process that takes place before interior and exterior finishes are complete, the modular building relies on chase ways (channels for electrical wire and communication cables) and plumbing components that click together upon assembly. It’s imperative that each component is engineered to exacting standards so each piece fits neatly with its neighbor.
Building information modeling (BIM) tools provide the key to much of the advancements in modular assembly as they allow for a detailed 3D visualization of components to ensure that the finished parts fit. BIM also provides the means to detail each component for precise manufacture that may include wall-assembly templates and jigs, subassemblies that fit within wall frames, and automotive approaches such as robotic welding.
According to a National Association of Home Builders (NAHB) study, an estimated 8,000 lb. of waste is created from the construction of a typical 2,000-square-foot home. With controlled factory settings, this waste stream is significantly reduced because the excess materials can be recycled onsite into other processes, and controlled storage reduces material damage from weather.
Labor and Safety
The factory setting helps maximize labor effort by automating repetitive tasks and assigning workers to smaller and more specialized tasks, helping to speed construction. On-site construction labor costs tend to be higher because the labor is more skilled, with workers responsible for a much wider range of tasks and a greater degree of customization in the end product.
The ability to put strict processes in place in the factory setting helps to improve quality standards, and these process improvements also have worker safety advantages. In fact, time-savings and increased safety are touted as the two distinct advantages over traditional on-site construction. It’s the controlled environment and the level of automated and repetitive tasks that lead to safety advancements and reduced costs.
Modular building approaches really shine in areas where there is a good deal of complexity that can benefit from repetition. Modular bathrooms and kitchens are a perfect example, as their complexity and repetition have resulted in the creation of “pods” that can be purchased to fit into traditional construction. There are many complex and repetitive buildings such as laboratories, hospitals, schools, and apartment buildings that also benefit greatly from an assembly-line approach.
The healthcare field is a leading adopter of large-scale modular construction, as the standardization of room environments greatly aids healthcare-worker efficiency and allows for flexibility of care. The level of standardization, such as with the Miami Valley Hospital Heart and Orthopedic Center’s 178 identical rooms on five identical floors, might be deemed boring in other settings, but the repetitive design allows staff to quickly locate equipment, and whole floors can be reconfigured to meet patient needs.
The modular and model-based approach of these structures provides benefits not only in the process, but also for ongoing maintenance. With the detailed model, the owners know exactly what lies within the walls and can confidently tackle upkeep. That can be particularly helpful for large buildings such as the Crowne Plaza Changi Airport hotel, a modular structure that was assembled in 26 days.
Without question, modular construction has turned a corner not only in construction techniques and materials, but also public perception as well. While traditional manufactured buildings for use in the military, schools, or even on traditional construction sites will continue, the needle is moving toward more experiments and incredible applications outside the norm.
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This article has been updated. It was originally published in October 2014.