– b y M a r k Wa r d –
During 2012, the U.S. Census Bureau reports that construction activity totaled $225 billion in the lodging, office, commercial, healthcare, educational and religious building categories. According to the Modular Building Institute, an industry trade association based in Charlottesville, Va., modular buildings comprised 1.3 percent of this activity.
But despite the limited market share of modular building, some observers predict the construction method is poised for an upswing. A 2013 McGraw Hill SmartMarket Report cited prefabrication and modularization as an “important industry trend” but also acknowledged obstacles that currently prevent the method’s increased use.
When SmartMarket surveyed K-12 school districts, 37 percent of respondents reported they had used modular buildings. But 50 percent perceived prefabricated construction as low-quality, 32 percent cited a lack of building performance data, and 22 percent said their
architects and contractors were unfamiliar with prefabricated construction.
By contrast, a 2011 SmartMarket Report entitled “Prefabrication and Modularization” and cosponsored by MBI looked at the building method from the contractor’s viewpoint.
Among more than 500 survey respondents who have been involved in modular building, 92 percent say the method boosts productivity by improving project schedules, and 70 percent report higher returns on investment through reduced project budgets.
These results prompted 85 percent of the contractors to state that modular building gives them a competitive advantage.
The disparity between building owners’ perceptions and contractors’ positive experiences suggests that more education can spark more modular building activity.
“Owners’ perceptions of ‘prefab’ buildings as being low in quality and aesthetics are still the biggest barrier,” said MBI communications director Tracey Daniels. “But perceptions are getting better.”
For rural contractors, the biggest question surrounding modularization may be its applicability to the types of building they usually construct. Yet to make that judgment first requires an understanding of modular building basics.
The Basic Idea
The “modular advantage” comes down to two fundamental propositions. First,its modules are prefabricated on a factoryfloor under controlled environmentalconditions. Second, since modules are built off-site, construction activity and site preparation can occur simultaneously rather than in sequence.
In other words, modular building advocates claim, quality is improved since construction occurs indoors and through controlled factory processes. Materials are kept dry and humidity is regulated, so that mold-producing moisture is no longer trapped inside building components. Construction waste is minimized. The safety hazards, security concerns and traffic disruptions of on-site construction are eliminated. Weather delays are not a factor. And turnaround time is reduced since floors, walls and ceilings are built simultaneously – rather than, as with on-site construction, waiting for a floor to bear the walls and then the walls to bear the ceiling. “Since everything’s done in a controlled factory setting, you eliminate leaks, shorts and callbacks from building owners. It makes sense from a construction standpoint and makes sense in the field, where you save on labor,” said Scott Kriner, president of Green Metal Consulting, Macungie, Pa.
“And manufacturers can make modular buildings with the same materials, and to the same design specifications, as any site-built structure,” added MBI’s Daniels.
Then, too, even as the contractor is preparing the site, the building is being built. With conventional construction methods, the site is prepared and then the building constructed. But with modular building, once the site is prepared, then the building is delivered ready-made. Since interiors are already finished, all that remains is for the modules to be assembled and the electrical, mechanical, plumbing, HVAC and other systems hooked up and turned on. MBI estimates that, for most projects, prefabricated building modules are 60 to 90 percent complete when they arrive onsite. Thus, some 80 percent of construction activity has already occurred once the modules are delivered. Post-construction time to restore the site is also reduced since the site was far less disturbed by building activity. Projects are thus completed, reports MBI, some 30 to 50 percent faster as compared to traditional building methods.
In the 2011 McGraw Hill survey, 37 percent of contractor respondents who use modular buildings reported the method reduced their project schedules by four weeks or more. Twelve percent saved three weeks, and 15 percent saved two weeks. Largely due to these time savings, 30 percent of contractors responding to the survey said modularization shaved their project budgets by 1 to 5 percent. Another 21 percent of contractors reported a budget decrease of 6 to 10 percent. Eighteen percent of contractors cut their project budgets by 11 to 20 percent, and 5 percent of contractors realized budget savings of more than 20 percent.
Concept into Practice
While the concept of modularization is easy to understand, how it may work in practice for rural builders requires answers to two more questions: Can modular buildings be feasibly transported to rural locations? And are modular manufacturers set up to produce the kinds of structures that rural building owners need and want?
Some modular building manufacturers sell direct to users, while others sell through dealers. The MBI membership includes about 50 companies that sell direct, 30 that wholesale and 60 contractor/ dealers. Though manufacturers are spread across North America, MBI reports that many are clustered in Pennsylvania, Georgia, Texas, Indiana, California and Alberta, Canada. Most manufacturers are single-location operations, produce on average about 250,000 square feet per year and can deliver their products within a 500 mile radius.
“A good rule of thumb,” affirmed Daniels, “is that modular buildings can be transported up to 500 miles. Further than that, and the transportation costs can offset the other cost-saving advantages of modularization.”
Transportation restrictions can also be an inhibiting factor. Due to road restrictions, most building modules are between 12 and 14 feet in width. And of course, the building site requires adequate road access to complete delivery.
Nonresidential modular buildings can be divided, first of all, into two basic types: permanent and relocatable. Examples of the latter include temporary school classrooms, mobile offices, emergency facilities, workforce camps and field housing, construction trailers, medical clinics and security or ticket booths.
For permanent modular buildings, MBI lists six key nonresidential markets: education, healthcare, hospitality and retail, office and administration and multifamily. Municipal and religious buildings are also potential markets. “But I don’t know any modular building
manufacturers involved in agricultural buildings,” noted Daniels. “Most agricultural buildings would likely be made from prefabricated panels rather than true, three-dimensional modular construction.”
While modular construction has been successfully applied for complex multi-story projects, the industry’s bread-and-butter remains smaller low-rise structures. Transportation restrictions generally limit modules to no more than 16 feet in width, 70 feet in length, and 13 feet in height – though multiple modules can be connected on-site to form larger buildings. Thus, modularization may be an option in the light commercial projects typical for rural builders – from schools, libraries and churches, to strip malls, bank branches and convenience stores.
“You can either order the standard designs offered by a particular manufacturer, or have the modules custom-designed to fit the building owner’s needs,” said Daniels. “When they’re done, modular buildings are mostly indistinguishable from stick-built.”
Daniels further suggests that rural builders should be able to handle modular projects, “although it’s good to have somebody onsite who has experience with modular installation.” For example, most builders are accustomed to adjusting building tolerances
on-site and on the fly. But when a series of prefabricated modules arrive on-site, mismanaged tolerances can stack up and lead to larger problems.
The 2011 McGraw Hill survey, however, suggests that the biggest markets for modular construction may not fully align with rural building priorities. Building sectors in which 40 percent or more of projects use modularization include hospitals and healthcare (49 percent), colleges and universities (42 percent), manufacturing (42 percent), low-rise offices (40 percent) and public buildings (40 percent). Similarly, contractors involved in modular building reported that most of their projects were hospitals, college dorms
and public buildings.
By contrast, modularization was less prevalent in constructing automotive garages (14 percent of projects), restaurants and convenience stores (16 percent), banks (18 percent), apartments (23 percent), retail centers (24 percent) and hotels (29 percent).
The Drive Behind Modular
According to MBI and other advocates of modularization, three factors are likely to boost the industry’s prospects. First are the savings, described above, in project schedules and budgets. Second is today’s emphasis on sustainable “green” building. Factory controlled construction can result in “tight” buildings that are pre-engineered for energy efficiency. Moreover, the precision of factory processes reduces the amount of building materials that go into a project.
And modular building cuts waste. The Environmental Protection Agency estimates that, compared to conventional construction, a full ton of debris is saved for every 10,000 square feet built. Seventy-six percent of construction professionals who responded to the
2011 McGraw Hill survey reported that modularization cut waste, including 41 percent of builders who reported decreases of more than 5 percent.
Prefabricated units can even be “recycled.” “Modulars can be assembled, disassembled, and moved around as needs change,” said Scott Kriner. Thus, a school might re-purpose and reuse a classroom, or a warehouse re-configure its space, rather than tear
down and rebuild.
Finally, increasing use of Building Information Modeling (BIM) is seen by advocates as a driver for modular construction. Through computer simulations, a building’s performance may be predicted and its design optimized. Modular proponents argue that factory controlled construction is the building method best able to leverage today’s BIM tools.
“Modularization is on the increase – and even becoming part of traditional construction,” said MBI’s Daniels. “For example, I’ve seen builders put prefabricated bathroom pods into an otherwise conventionally built project.” Such incremental advances are a part, she believes, of breaching the main barrier to modular building. “It all goes back,” she said, “to perception.”