"Bathroom finish colors and tile patterns are not typically set during the foundation-document phase," says Maja Rosenquist, project director with Mortenson Construction for the $623-million Exempla Saint Joseph Hospital, which has off-site-built elements and is nearing completion in Denver.
The early decisions for the Bronx project "put enormous pressure on us," says James McCullar. His eponymous firm is the architect for the 64-module project.
It's best to test the waters of modular in stages. Gilbane started with preassembled multitrade utility racks on a U.S. project. Then, it added vertical risers to the next job: the 270,000-sq-ft Global Technical & Innovation Center in Kerry, Ireland. The various prefabricated components sliced three months off the laboratory's schedule, says Gilbane. "The modular nature, developed in the [building information model], allowed us to run a number of layout and cost scenarios early," says Ian Howard, project manager for the client, the Kerry Group. "That gives us a high degree of confidence."
Discounting glitches with the buildings department that caused a three-month delay, the Stack would have taken two-thirds the time of site construction, says Peter Gluck, of Gluck+, the Stack's architect design-builder.
Mortenson commissioned the University of Colorado, Boulder, to do a study on its 831,000-sq-ft Denver project to compare it to site construction. The study concluded that the prefab approach for utility racks, bathroom pods, exterior panels and head walls reduced the schedule by 72 work days. The job used 29,500 fewer hours of labor, resulting in $2.6 million in productivity savings, and diverted 150,000 hours of labor off-site. There was $4.3 million in indirect cost savings, but direct costs were 6% more than site construction, according to the study.
"Certain elements were more expensive until the indirect costs were accounted for," thanks to the fear factor in the pricing, says Bill Gregor, Mortenson's construction executive for the hospital.
Mortenson holds a prefab charrette to determine the off-site path for a project. Another important step is a full-scale prototype to avoid repeating a mistake hundreds of times.
Some say design-build is the best delivery system for modular, but any collaborative approach will work. Architect James B. Guthrie, president of Miletus Group Inc., a modular design-build firm, has doubts about modular becoming mainstream any time soon. Until there is a better knowledge base and a better supply chain, "modular won't become widespread," he says.
The NIBS council was formed to fill the knowledge gap and gather metrics to prove the case, especially to reluctant owners. "We've recognized it's a challenge to capture some of the potential efficiencies," says Colker.
To help foster off-site, the council recently posted two online surveys. The deadline for responses is Oct. 15.