Commercial modular building design, or factory-built design technology, is a way that architects and building owners are now saving money and completing construction in less time.
"In a normal construction project, you can't put the plumbing into the bathroom until the bathroom is installed," says Mike Zimmerman, principal and president of Sudbury-Mass.-based M/E/P engineer Allied Consulting Engineering Services Inc."But with factory-built interior spaces, while the construction frame is going up, the factory is making the interior simultaneously."
Zimmerman designs pre-engineered structures and buildings because he says the construction not only costs $10 to $15 a sq. ft. less, but provides "phenomenal efficiency." Factory technicians have perfected their specific function, as they build the same element on each unit, thus producing a higher-end product.
Zimmerman says that factory construction is oblivious to weather delays; and since the units are constructed at eye level, scaffolds and crane systems are not needed, providing for safer construction. Each module is inspected by a third party before being shipped to the site.
Currently, Zimmerman is working on his ninth pre-engineered building project, a senior living facility in South Hadley, Mass., in which 148 factory-built modules make up 90% of the building under construction. The modules, which measure 68x14x9 ft., are self-contained, with mechanical, electrical, and plumbing already installed.
According to Zimmerman, the architect designed the building specifically to be constructed off site. "As he designed the building, he had to understand the construction techniques and strengths and challenges that the factory has," he explains.
As for the role of the engineer, Zimmerman says his team not only designed the M/E/P systems to be built in the factory, but they also designed a way for each module, when placed in the building, to be connected to each other and to the larger structure, so as to avoid tearing out construction.
"We designed the building knowing that we would have to provide access for the seam connection, from module to module, vertically and horizontally," he says.
Each module in the project was constructed in a factory in Quebec. According to Zimmerman, this meant that each module had to be constructed with a higher level of sturdiness to survive the 400-mile trip from the factory to the site. Each module wall is made with four layers of sheetrock and is 9 in. thick, compared to two layers of sheetrock (51/2 in. thick) with traditional construction. Another strength of pre-engineered buildings is that the connecting walls are doubled, rather than single walls in conventional construction.
"When you have two walls holding up the building, instead of one, you've got to think it's a little stronger, and it is," Zimmerman says. "These buildings have a lot more structural integrity; everything is more precise."
For hotels, condominiums, and senior living facilities, Zimmerman says factory-built, modular construction is "a natural marriage." In these types of buildings, uniformity is what designers are looking for.
"You can't tell that the buildings have been built in the factory," says Zimmerman, who is also currently working on the design of the largest pre-engineered building project in the country, scheduled to break ground next spring in Vermont.