With advances in computer-aided design, big contractors have
embraced the use of prefabricated building components.
Prefabrication — a decades-old concept for saving money and
time in construction once dismissed as synonymous with low quality — is making
a huge comeback in an era when advances in computer-aided design have
reinvented the idea into an indispensable tool for some of the biggest
commercial building projects.
The “prefab” concept blossomed in the 1950s, when it became
shorthand for slapped-together housing erected as quickly as possible to meet
the needs of the baby boom generation. For the first time, builders used
components that were assembled in off-site workshops and shipped in on trucks
in order to mass-produce millions of starter homes across the country.
The results were often less-than-stellar, derided in popular
culture as cookie-cutter and soulless — think Pete Seeger’s song “Little
Boxes.”
Skip ahead to 2014, when multimillion-dollar apartment
buildings, hospitals, massive data centers and commercial buildings of all
types from major builders such as Opus Design Build and Mortenson Construction
are incorporating 21st-century versions of prefabrication on a big scale — and
turning those negative perceptions on their head.
The builders say that with the adoption of computer
technology such as building information modeling (BIM), which allows for 3-D
visualization and management of construction projects, and the resulting closer
communication between contractors and other team members, tapping prefab parts
to save time and money can be accomplished without any drop in quality — in
fact, just the opposite.
Opus has extensively used prefabricated wood-frame exterior
wall panel sections in the construction of three University of Minnesota-area
student housing buildings — Stadium Village Flats, the Station on Washington
and the Venue at Dinkytown — as well as on its boutique Velo Apartments effort
in Minneapolis’ North Loop.
“The use of prefabrication is everywhere now,’’ said Tom
Becker, Opus Design Build’s director of project management. “The reason is that
with the projects essentially existing in the computer before they do in the
real world, people are able to lay out all the walls, all the openings,
basically every detail ahead of time and share it with manufacturers who can
produce the components. It injects a layer of quality control that you don’t
get any other way.’’
Becker said the process of having the wall sections built in
South Dakota and trucked to the Twin Cities resulted in a 20 percent labor cost
savings over assembling them by hand on site.
Mortenson, as well, has been extremely active in
incorporating off-site prefabrication in many of its building projects, marking
it as a key element in a companywide push for “lean innovation.”
The Golden Valley-based company this month published a
cost-benefit analysis of the prefabrication techniques it used in the building
of the 826,000-square-foot, $400 million Exempla St. Joseph Hospital in Denver,
which is scheduled to open in December. It concluded that for every dollar
spent on prefab, approximately 13 percent of the investment was returned as a
quantifiable benefit to the project.
The use of prefab exterior wall panels, for example,
resulted in 3.7 percent of direct savings, while scores of preassembled
bathroom pods — made off site and inserted fully made into the building — saved
the equivalent of 52 days of construction.
Troy Blizzard, Mortenson’s director of operations, said
clients are routinely seeking the use of prefab elements in today’s market.
“Locally, we’re installing preassembled ductwork-and-piping
‘racks’ in the hallways of a major data-center client we’re working with, and
we also used that technique on the top floor of the Radisson Blu hotel at the
Mall of America,” he said.
Source: Star Tribune
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