Prefab or modular construction can be the solution to eliminate risk and changeability on construction projects. With the use of this construction method, contractors can avoid the possible impacts of fickle weather, transportation glitches and jobsite staging challenges — if the process, from start to finish, is well thought out. Prefabrication demands planning down to the smallest detail, and consideration of every possible project threat.
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"Embracing prefab technology can mitigate risk and diminish uncertainties within any given construction project," said Makenna Ryan, a civil engineer of Procore.
In a blog post on the construction software provider's website, Ryan and writer Cait Bladt talked about the pros and cons of modular construction.
"By adopting this approach, contractors can reduce the impact of inclement weather conditions and other factors that delay the project timeline," they said.
Prefabricated components have become mainstream in the transportation industry for bridge construction, drainage systems and modular pavement installs.
On bridge projects, the most common modular components include beams, girders, deck segments and pier caps, according to Ryan.
The various pieces are manufactured off site and transported to the job for onsite assembly.
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On water and wastewater projects, said Ryan, concrete pipes, boxes and drainage structures are installed to manage water flow around infrastructure.
Modular sections of pavement are quickly assembled on road and high projects to create durable driving surfaces, he said.
Why Prefab Construction Makes Sense
Prefabrication offers advantages in keeping a project on track, especially when schedule management is critical.
Prefabrication enhances site logistics by "streamlining the construction process," said Ryan, particularly on job sites with limited space.
"Since prefabricated components are manufactured in controlled factory environments, the need for onsite storage of raw materials is drastically reduced."
These components can be delivered just in time for installation, he said, minimizing the duration and extent of onsite material handling and storage.
The just-in-time delivery model benefits urban construction sites, where space is at a premium. Plus, the storage of excess materials on an urban site can impede traffic flow and increase safety hazards.
Ryan also pointed out that with immediate installation upon arrival of prefab parts, the construction timeline is accelerated. This rapid installation also reduces the environmental impact of material waste, he said.
"The reduction in onsite activity correlates with fewer disruptions to the surrounding community and a more organized and efficient job site," said Ryan.
Precision, in both the manufactured component and the installation phase is improved with modular construction.
Ryan said building elements in a factory with precision equipment allows for greater control over measurements and tolerances.
This control, in turn, ensures each component is produced to exact specifications and with uniform quality, he said.
"Design tools and manufacturing technologies further enhance this accuracy, reducing human error and material discrepancies," said Ryan."This meticulous attention to detail guarantees that the components fit together seamlessly during installation."
Quicker and more accurate installation results on the job site when modular components are assembled there as all parts are designed to connect perfectly
"The result is an overall increase in the quality of the finished structure, with reduced need for adjustments and rework," said Ryan.
Risk management involves controlling variables and prefabrication offers control of nearly every variable in the component's construction.
By shifting component construction from the job site to the "predictable confines" of a factory, prefabrication allows for a more methodical approach.
The timeline for construction "becomes more reliable, and quality checks can be conducted more thoroughly in a dedicated facility," said Ryan.
With prefabrication, the risks associated with weather, site conditions and labor are mitigated before the components reach the building site, he added.
"These proactive measures ensure that potential problems are identified and resolved in advance."
This, in turn, reduces the likelihood of costly and time-consuming issues arising during the crucial stages of on-site assembly, said Ryan.
The construction method can virtually eliminate delays caused by adverse weather conditions or the need for specific environmental settings for materials.
"Moreover, the ability to conduct comprehensive testing and refine aesthetic details within a factory setting ensures that components arrive on-site," said Ryan.
It also guarantees they arrive "in a state of near perfection, ready for immediate assembly."
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Frontloading the production and quality assurance phases in modular construction allows for parallel site prep, said Ryan, and expedites build time.
"The culmination of these factors is a streamlined construction process where speed is matched by an uncompromised commitment to quality," he said.
Labor issues plague the construction industry. But one of the biggest benefits of prefab construction, in Ryan's eyes, is maximized labor efficiency.
"By bringing together specialized labor in a controlled setting, construction teams can focus on precision and quality," he said.
And they can operate in tandem without the distractions and variables found at traditional construction sites.
"This not only improves the quality of work but also enhances safety and reduces overall project costs, allowing specialists to focus on their craft," he said.
Managing Risks Associated With Modular
For all its rewards, prefabrication is not without its risks. The process requires careful planning and consideration to fully realize the benefits.
Number one of Ryan's list is interface management — ensuring prefabricated components from different production sites fit together perfectly upon assembly.
Some materials are more forgiving when it comes to misaligned connection points, said Ryan. Wood and steel are two examples.
But, he said, regardless of the material prefabrication requires meticulous planning and precision engineering to avoid costly on-site adjustments.
"Successful interface management eliminates potential errors in manufacturing and is pivotal in maintaining project timelines and budgets."
The next modular construction con is liability, which Ryan said can be challenging in prefab construction.
This challenge happens particularly when issues arise from interface management discrepancies.
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"The responsibility for components that do not seamlessly integrate … should be clearly defined by the contractual agreements," he said. "It is important for all parties involved, from the general contractor to the modular fabricator, to understand where liability rests for each element."
Contractors should make sure project contracts clearly outline responsibility for defects or mismatches. This will ensure that parties are aware of their obligations and potential liabilities from the outset, said Ryan.
"In industries such as oil and gas, it is common for the general contractor to assume the bulk of the risk," he said. "This centralized liability model ensures accountability but also empowers the contractor to factor this risk into their pricing structure."
By proactively managing contracts and liabilities, said Ryan, prefab construction can maintain its efficiency advantage.
At the same time, the construction method can assure equitable risk distribution among stakeholders.
The transportation and storage of project components are often the greatest limitations to prefab construction.
"Virtually anything can be prefabricated with the right equipment, sufficient space and adequate infrastructure to transport it," Ryan said.
But the unique challenges of transporting oversized components, such as wind turbine blades or bridge sections, requires careful planning and coordination.
Ryan believes the success of a prefab project can be credited to logistics as much as the actual construction.
"For example, the average prefabricated blade for a wind turbine is about 120 feet long," he said.
That is more than double the length of a typical tractor tailor, already difficult to navigate through turns in many suburban areas, he said.
"Transporting an item of this size requires specialized route planning, considering the increased turning radius and weight of the item."
Ryan believes that most often the limitations of prefabrication are due to restraints in both manufacturing and transportation.
"If an item is being carried across a bridge, will it support the weight?" he said.
And, if the item has to be hoisted into place, is the crane powerful enough to get it there?
"These are the types of questions that need to be answered before committing to a specific prefab project," said Ryan.
Finally, there are design changes. "If there's one thing that is virtually guaranteed on any construction project, it's change," said the civil engineer.
Whether it's differing site conditions, material availability or design considerations, even small changes can render prefab components unusable, he said.
"Prefabricated components are manufactured based on design specifications and site assessments."
As a result, said Ryan, any discrepancies between the expected and actual site conditions can lead to complications.
"For instance, unusual soil characteristics or subterranean obstructions may require on-the-fly adjustments to prefabricated foundation elements," he said. "Similarly, design changes made after the commencement of prefab production can lead to costly rework."
Changes can even render existing components unusable if they no longer align with the revised design.
That's why stringent design freeze policies are often implemented on construction projects, in addition to thorough and regular site evaluations.
"Despite these challenges, the key to successful prefab construction lies in diligently managing the design phase," said Ryan.
It also lies in ensuring comprehensive site analysis to prevent expensive and time-consuming setbacks, he added. CEG
