They were prefabricating the hospital for builder Skanska USA in a former DHL Air Freight warehouse near the Delaware River. The construction would later be shipped and installed. "It's pretty dirty out. But our guys can come in here and work all day," boasted their boss, Skanska project executive and prefabrication manager Marty Corrado, who has been so busy starting construction assembly lines at projects around the country, his business card has three area codes.
Whartnaby's prefab crew is using technology that has become more common on low-cost American housing developments, but has been rarely used up until recently on high-end commercial buildings, let alone hospitals.
"It's very innovative. We're relearning the trade," said Whartnaby. "It's definitely good for the unions." The tradesman are glad to have work after the lean years of the recession.
"It's good for the customer . . . because you're getting the building done faster," he continued. "And there's a big safety factor. On a wet day like this, we have a very controlled environment. Nobody's going to fall over six feet on this job."
In the slow recovery from the construction slowdown, Skanska, owned by a Swedish company, has been adapting European prefab models to commercial projects, including both Nemours and an 800-unit, six-story dorm project at the nearby University of Delaware, among others.
"This is a radical departure," Corrado said. Instead of building every tray, curving every pipe, fitting every duct, and walking them up ladders to bang together into a suite of rooms, everything goes in what Corrado called "one big box." Then it is linked by headwalls studded with gas, water, electric, air and dentist-office-style folding booms, and approved, pre-installation, by inspectors from Underwriters Laboratories, as if each room was a giant appliance.
Then they "lift the box and hang it in the building," Corrado said.
"They built a mock-up across from the hospital," marvelled Colleen Davis, a Nemours nurse and one of 40 hospital professionals inspecting the prefab works on a recent Friday. Davis and her colleague urged such changes as moving shower nozzles in a way that would allow patients to roll in on wheelchairs.
"Normally we would have 25 or 30 tradesmen doing this kind of work, up on ladders," said Kenneth J. Schell, Skanska project director for the Nemours job. With prefab, "We have nine guys here today."
Not everyone is convinced of the advantage.
"Most large projects, including ours, have significant prefabrication of exterior wall systems. It's a little newer to have prefabrication of interior walls," said Douglas Carney, the architect who heads facilities, real estate and construction at Children's Hospital of Philadelphia.
CHOP has hired Skanska rivals such as construction outfits Turner and Intech to build projects from the ground up, as part of CHOP's $1 billion, multiyear expansion on both sides of the Schuylkill. FKP Architects, of Houston, Nemours' architect, is also working on CHOP's expansion, using more conventional techniques.
Prefab "is not a magic bullet," said Carney, who is also an assistant professor teaching construction management at Drexel. "A highly repetitive project, like those University of Delaware dorms, can really benefit from prefabrication off site."
Indeed, Nemours and its builders aren't saying prefab is saving money. "We think we are," said Corrado, stressing reduced injuries as one measure. "[But] this is still in its infancy."
"We're still using the same amount of material. We're fairly confident that we are using less labor," he added. But subcontractors are still reluctant to bid less on prefab commercial jobs, he said. The practice is that new.
Contact Joseph N. DiStefano at 215-854-5194, JoeD@phillynews.com, or @PhillyJoeD on Twitter.