Tuesday, October 20, 2009

Extreme Collaboration: Working With Subcontractors

by Dean Barnes
Associate Principal
Morris Architects, Houston

We're designing a lot of projects in BIM. That's proven valuable within the design team. Architects, mechanical engineers, and structural engineers are working together better, creating a coordinated design model. But then, for the most part, we're printing 2-D drawings because that's what most general contractors are looking for. It is frustrating to be unable to share all your efforts as the project is bid and moves into construction. You find yourself trying to find someone- anyone- to take the model.

On the recently completed Rice University South Plant project we found, for the first time, a subcontractor who wanted our model.

On a central plant project, the mechanical systems are even more critical than they are on a typical building. MEP doesn't support the program; it is the program. During the design process, we used the mechanical engineer's model to make sure the systems fit in the building. That was invaluable. But the designer's model will always be a design intent model. Without all of the equipment selected, without the detailing of pipes completed, it’s a useful approximation, but still an approximation.

When we found that the mechanical contractor WANTED the model, we were, of course, eager to share it. We thought it would help with the coordination drawings and the submittals, making our job easier. Little did we understand, they intended to model the entire mechanical system. Their goal was to create a highly detailed model of the mechanical components including specific equipment, valves, gauges, pumps and other accessories. We understood this level of detail would enable the mechanical contractor to fabricate as much of the system components off site as possible, reducing their field assembly, modification, and adjustments. The BIM model became a three dimensional shop drawing.

What we learned was this level of detailed modeling also provided the opportunity for the University’s operators to review and understand where different components of the mechanical system would be located, as well as how components could be accessed for repair and replacement if needed but also for operation. The University knew how to operate the system before any piece was fabricated or installed.

We brought not just the university’s planners and architects but also the central plant operators into the process. We walked them through the virtual model and discussed the details of operating the plant: ladders and catwalks, access to valves and gauges, and how components could be changed out. That feedback lead to several design changes, including a new catwalk in the boiler room.

But, thanks to the precision of prefabrication, that did not impact schedule or cost. The university got a better building, on time and on budget. It also had the early knowledge to eliminate the “Not what we expected” experience upon completion of the construction.

Because BIM is a fundamentally different way of designing a building and its components, we should continue to seek collaboration with contractors, subcontractors and fabricators. As the South Plant project shows, that will lead to better buildings. Architecture is ultimately about the building- the space people will experience and use- not about the plans, which are just a way to get there.

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