JobSight: Target Field, Minneapolis
To incorporate stone into the façade, project leaders decided to set the material in precast concrete panels, which were then attached to the building.
“The panels were very much faster,” says Populous’ Miller. “It also took the weather out of the equation. We could set the stone panels all winter; if the stone had been traditionally set by masons, they would have had to tent and scaffold. This way, they were all prefabricated.”
To precast the panels, Mortenson hired Gage Brothers Precast Concrete, a Sioux Falls, S.D.-based firm that worked with the contractor on a number of large projects.
Tom Kelley, Gage Brothers president, says his firm entered the project as a consultant to Mortenson during the preplanning phases of the project, although it received the contract for Target Field only after a successful bid.
The process of getting the stone precast and delivered then became a matter of close coordination between everyone involved.
Ron Vetter – who says his company also worked with Gage Brothers on a number of projects before this one – explains that it took probably 18 months to simply amass what would become 100 semi-loads of stone for the project.
The Quarry Creek stone itself is somewhat special.
“It’s the very top piece of our block,” he says, adding that its location created the rough surface prized by the client. “We started getting ready for the project months before the stone was needed in order to amass the tops of hundreds of blocks.
“Some of these pieces were amassed in the course of normal operations, but many we had to cut specifically to keep up with the job.”
Also complicating the matter was the architect’s and client’s decision to go with a randomized pattern among the five different shades of stone that, in practice, wasn’t necessarily randomized.
“The dark colors they wanted to stay near the bottom of the building, where it would be more bold and solid-looking,” says Kelley. “Then, the idea was to get lighter as we got near the top.
“Consequently, ever stone had its own unique mark, which made the process of shaking out and inventorying pretty challenging. The color selection and its position on the building were determined at Vetter’s plant and were executed very well.”
Nor were those the only issues facing Vetter. Not all the piece sizes were the same –most were either 4’ X 4’ or 4’ X 5’ – and the surface finished varied.