Dubuque quarry’s stone bests Stone City’s to be the face of the new federal courthouse

They've been at it 14 months now, and as spectacular a phase as there will be in the construction of the new $160-million federal courthouse here has now begun.

Stone masons this week began setting in place the first of an estimated 12,600 panels of limestone - limestone that has been taken from a quarry on the northwest edge of Dubuque and cut into panels of 10, 14 and 16 inches in height and 24, 28 and 32 inches in length.

And by Thanksgiving the buff-colored stone with areas of light gray will cover a large portion of the front of the eight-story building in an area 300 feet long and 100 feet high. The stone also will go behind the judge's bench in each of the building's five courtrooms.

No one knows for sure just how remarkable the stone is going to look once in place because the arduous process that went into picking the stone for the building was done with 4-ft.-by-4-ft. samples. “And this is going to be the size of a football field,” says Brad Thomason, team leader and architect for contractor Ryan Cos. US Inc. in Cedar Rapids, of the amount of stone that will adorn the face of the building.

There is no way to overstate it, “It's a very important part of the building,” says Jim Snedegar, project manager for the U.S. General Services Administration.

The actual exterior of the building in front of the stone will consist of 7-ft.-by-7-ft. panels of glass that Thomason says is made with a low-iron content so it is especially clear. “The whole idea is to see the stone,” he says.

After all, picking just which stone was right for the building was no simple matter.

The selection started with samples from some 30 to 40 quarries; with a selection team of architects, GSA officials, the federal judges who will occupy the building and others; and with the need, in the end, to settle for the low bid among the three most preferred stones.

Snedegar points out that the GSA cannot simply pick a particular product. It must have a least three options upon which to seek bids. Additionally, the agency can't limit purchases to local products. Even so, the process of stone selection began by establishing what Thomason calls an “aesthetic baseline,” which was Anamosa limestone from the Stone City quarry of Weber Stone Co. Inc. in Jones County, Iowa.

Thomason says stone was considered from quarries in Iowa, Minnesota, Wisconsin, Missouri, New Mexico and elsewhere as the number of favorites eventually was reduced to six. At that point, a sample of each of the remaining stones was displayed outside at the courthouse site in the same orientation to the sun as the face of the courthouse. Thomason then conducted a blind test, allowing the selection team to see only one stone at a time. There were multiple viewings and plenty of differing opinions.

In the end, the selection team settled on three stones to put out for bid after the team answered this question for each of the finalists: “Can you live with this one if it's the low price?” says Thomason.

The three finalists were Anamosa limestone quarried by Weber Stone Co. in Stone City; Mo-Keta limestone quarried by Becker & Becker Stone Co. in rural Dubuque; and Hebron Gold limestone from Israel. The bids consisted of both the cost of quarrying and cutting the stone and the cost of installing it.

Stone installer Seedorff Masonry Inc., Strawberry Point, Iowa, and the Mo-Keta stone won the bid. Becker & Becker took the stone from its quarry late last year, and now has cut it into 2-inch-thick veneer panels for the building.

During installation, steel clips are drilled into concrete block and each stone panel, with a groove on its top and bottom, is hung on clips. Caulking, not mortar, goes between the stones.

Snedegar says courthouses in the United States before World War II largely were made out of blocks of stone, not faced with stone veneers. But Thomason says stone veneers still drive home the point: “Yea, that's a courthouse.”

The fascinating thing about stone, says Thomason, is that you run the risk of it looking different (at different spots on the building) if you don't quarry all of it at the same time and place.

“That's what's nice about the stone,” he says. “There will never be another project that looks exactly like this.” He put the cost of the stone itself at about $600,000.

One portion of the building's front will feature stainless steel panels, and the building's sides and back will be covered with concrete panels. Construction of the courthouse is on time and on budget, Snedegar and Thomason report.

It's slated for occupancy in November 2012. The total cost is estimated at $160 million, $120 million of which is the cost of actual construction, the two say.