PROTOTYPING AND TESTINGThe $137 million facility is the first major hospital project in the U.S. to use components prefabricated

off site within a field-built hospital structure.

Prefabrication yielded higher quality construction, a safer work environment and a faster construction schedule. In the right hands, prefabrication is an innovative method offering potential for an

accelerated project schedule, increased quality, increase safety and reduced construction waste at a reduced cost.

At Miami Valley, prefabrication yielded higher quality construction, a safer work environment, and a faster construction schedule. This project raises the prospect that if prefabrication can be used successfully in a

complex hospital project, it may also be a sound methodology for constructing affordable multifamily housing, college and classroom buildings, university residence halls, medical offices buildings, laboratories,

hotels, senior living facilities, and other building types with numerous repetitive components.

At Miami valley, five key component types were

constructed and assembled off site:

• Patient room toilets, casework, and headwalls

• Integrated MEP racks above corridors

• Modular workstations for staff

• Unitized curtain wall sections

• A temporary pedestrian footbridge

PREFABRICATION TO CONSTRUCTION

Components built off site in a warehouse afforded a higher quality construction environment, which allowed for

tighter tolerances,

less waste,

no injuries

and lower labor costs.

One hundred and eighty patient rooms and 210 overhead MEP racks (mechanical, electrical and plumbing assemblies) were

constructed virtually in BIM and then assembled in a warehouse before being transported to the worksite.

This approach had several advantages: the prefabrication process was up to three times faster as the small crew of

workers could cut, weld, and inspect at ground level without exposure to weather.

THINKING ‘PREFAB’ LEADS TO HIGH-FLYING BRIDGE

SOLUTIONThree buildings had to be demolished to make room for the new addition, which created the need for a

temporary bridge to maintain pedestrian circulation between buildings during construction.

Building Team came up with a unique solution: have an airport jet way vendor build it. JBT AeroTech built

the bridge in five sections using an off-the-shelf design.

Workers on site poured the foundations, set the sections in place, and connected them in just three days, with no disruption to pedestrian traffic. The

cost: $980,000.

A TOILET UNIT

FACTORY-BUILT MEP RACKS

MANUFACTURING THE COMPONENTSOnce the decision to use prefabricated components was made, NBBJ went searching for suitable off-the-shelf

bathroom modules—to no avail.

“We couldn’t find anything that met our standard for quality,” says NBBJ’s Hullinger. They had no better luck finding modular MEP racks. The Building Team quickly realized that there was only one way these elements could be made:

Skanska and its subcontractors would have to manufacture them themselves. Skanska rented an old furniture warehouse less than three miles from the hospital as the fabrication plant. Before ramping up the assembly line, workers constructed a bathroom mockup at the warehouse. Nurses and other hospital professionals critiqued the design; as a result of their input, certain fixtures were repositioned to make patient care and maintenance easier.

All components were custom-assembled and constructed using conventional building materials. Tradespersons assembled the patient room “blades”—the room-dividing walls and bathrooms for 180 patient rooms—and the

overhead MEP racks. All metal studs, ductwork, conduits, and pipes were ordered to length, reducing waste material almost to nothing. The 8x22-foot MEP racks were built to fit within 16-foot-wide corridors that spanned five patient-room floors. Exactly how the blades and overhead racks would be lifted and placed in the building was something

that the contractor determined after the modular components were built.

“We took them to a truck stop to have them weighed so we would know how much weight we were hanging off of the steel.” With little room at the construction site to store components, workers employed just-in-time delivery of the

modules from the warehouse to the hospital. Crews built a custom dolly to position the blades after they were lifted into the building. Notches were sunk into patient floors exactly where the bathroom modules were placed—an

instance where precision was critical.

In any building project that makes extensive use of prefabrication, modular elements have to be largely complete when put in place and must fit precisely into the structure—on-site alterations are a no-no. That’s why competence with BIM has to be pretty much a given for any Building Team using a lot of

prefab components. Skanska and subcontractors TP Mechanical, Dalmatian Fire Protection, and Chapel Electric used Autodesk Navisworks to coordinate design and construction of the MEP systems.

According to NBBJ principal-in-charge Tim Fishking, AIA, using BIM not only improved accuracy and precision, it also “greatly enhanced” the team’s ability to solve the design problems associated with the

components.

Bim Aids Accuracy, Precision, Problem-solving

RESULTS VINDICATE THE PREFAB APPROACH

HEADWALL SYSTEM DETAIL

 A modular medical headwall system for mounting on a wall of a structure having a floor and a ceiling, the system comprising:a plurality of headwall sections including a first section and a second section, wherein each of the headwall sections is configured to

be arranged side by side with another headwall section to form a headwall, and wherein each such headwall section comprises:

a frame comprising first and second studs and having a width and a bottom; and•at least one medical service outlet supported on the frame; and•a base assembly comprising:•a horizontal support track configured to receive the bottom of the plurality of headwall sections when the head wall sections are arranged side by side; and•a floor rail attachable to the floor of the structure;•wherein the support track is adjustably supportable on the floor rail so that when the head wall sections are arranged side by side in the support track the plurality of headwall sections can be collectively leveled regardless of irregularities in the floor.

BIBLOIOGRAPHY

http://www.sabmagazine.com

Miami_Valley_Hospital_nbbj_case_study.pdf

http://www.modular.org

http://www.bdcuniversity.com