A five-year collaboration restored the Georgia white-marble exterior of the historic Minnesota State Capitol Building.
By Jennifer Richinelli
Modeled after St. Peter’s Basilica in Rome, the Minnesota State Capitol Building revealed signs of aging after enduring the harsh winters of St. Paul for more than a century. The 111-yr.-old structure, which was designed by noted architect Cass Gilbert and earned a place on the National Register of Historic Places in 1972, is a solid display of Georgia white marble—quarried in Tate, GA, by the Georgia Marble Co., today owned by Canada-based Polycor.
The restoration of the stone façade began in 2012, and over a four-year period was broken down into five phases, which involved the reproduction of 3,949 custom stone pieces—each one assigned its own shop ticket and unique number. The marble pieces were fabricated by Tennessee Marble Co., Friendsville, TN; Cutting Edge Stone, Alpharetta, GA; and Traditional Cut Stone in Ontario, Canada. Additionally, detailed carvings were produced in Italy by Italmarble Pocai Srl and in Canada by Art Cubus International, as well as onsite by master carvers from Twin City Tile and Marble Co. (TCTM), St. Paul, who purchased the stone and facilitated the project. The stonemason for the project was Mark 1 Restoration of Dolton, IL.
With the scope of the restoration so immense—and the skilled team positioned throughout North America and abroad—organization, communication, and flexibility were all critical job components. It was imperative that a continuous flow was maintained between the architects, stone producer, fabricators, stone carvers, and masons to keep on schedule, and acute attention to detail and accuracy was a must. Above all, it was determined fairly early in the process that no assumptions should be made.
“It was a really complex team dynamic,” said architect Ginny Lackovic of HGA Architects and Engineers, Minneapolis. “Many of us had experience with historic restoration, just not at this scale. It’s always hard to get large projects started, and this one was no exception. It took a while to sort out everyone’s roles and responsibilities, but eventually each step in the process was dovetailed to create a continuous flow of work. After a few months, we realized that weekly meetings with the full team were the only way to make this happen. Another important aspect was general willingness to be flexible when possible.”
The architect also expressed appreciation for the general contractor for its role in the restoration. “A lot of credit goes to J.E. Dunn Construction, Minneapolis,” she said. “They did a masterful job with overall project and site management.”
Sylvie Beaudoin of Polycor proved instrumental in keeping the stone production and fabrication on track. “Everything went really well and on schedule,” said Beaudoin. “I became involved after the mock-up year phase. The general contractor started saying, ‘They want you there every third Tuesday.’ Communication and reassurance was important. Every month, I’d go to the jobsite in Minnesota to reassure everyone they would have stone. I’d let them know how many were coming, and then they would discuss the next phase. It kept communication going.
“In the beginning, it was intimidating,” Beaudoin continued. “No one knew each other well. All the teams were waiting for me. They wanted to know when the stone was coming. I’d go up there and tell them how it was. I didn’t just tell them what they wanted to hear. The truth pays. My role was to make sure all the fabricators were doing their part. I would push my fabricators. There was constant follow-up.”
Before the actual restoration began, the stonework needed to be assessed—a process that continued throughout all five phases, according to Lackovic. “Initially, exterior work was not included in the scope of the capitol restoration project,” explained the architect. “Several focused asset preservation projects were subsequently initiated to address water infiltration. One of these projects, focused on mitigating water infiltration at the dome, required extensive scaffolding. This gave investigators the opportunity to inspect architectural features at close range. Preliminary observations confirmed that some of the more sculptural elements, such as column capital features and window hood bracket scrolls, were consistently unstable.
“HGA was immediately commissioned to perform hands-on surface evaluation of stone using swing stages and mechanical lifts,” Lackovic continued. “Unstable fragments were also either removed or stabilized. This was the first opportunity to examine upper-story features of the main building wings. A large number of fragments, including several elements of significant size—10 to 15 lb.—were found to be easily removed with light tapping. The results of this survey led to the recommendation that a comprehensive exterior facade survey be performed as soon as possible.”
Wiss, Janney, Elstner Associates Inc., based in Northbrook, IL, performed this survey, sounding nearly every piece of stone on the building. “Information generated from this provided the foundation for early work-scope projections,” said Lackovic. “As part of the planning process, extensive full-scale mock-up trials were designed to test the various repair strategies under consideration. In order to insure that repair strategies were critically reviewed across a wide spectrum of influences, trials were performed in three locations. This allowed us to review results at various times of the day, in different ambient conditions. It also allowed investigators to evaluate whether exposure to differential climate factors influenced the natural weathering process. The trials provided an invaluable opportunity to explore options, demonstrate installation procedures, test process, inform schedule, generate unit accurate prices based on actual time and materials, and judge overall aesthetic impact ahead of time.”
While a significant number of stone pieces needed to be replaced on the exterior facade of the capitol building, the objective of the restoration was to preserve as much of the original stonework as possible. “Stone that was good enough to keep received minor repairs—cracks were filled, minor chips were occasionally patched, and rough, granulated surfaces were smoothed to facilitate water runoff,” explained Lackovic. The color-matched epoxy for the bonding and anchoring during the Dutchman installation, as well as any reattaching of broken marble, was supplied by Bonstone Materials Corp. in Mukwonago, WI. The products included Bonstone Clear Gel Epoxy and Last Patch Dymond. “We also provided a color-matched UV-stable—non-yellowing—patching system for the Dutchman joints and for chipped corners when needed,” stated Paul Klees of Bonstone.
Quarrying and Fabrication
Once the first phase launched in 2013, Lackovic and her team worked closely with Polycor to select blocks for the project that matched the desired physical properties. “Blocks were hand selected, ranked, and set aside for specific features,” said the architect. “Existing stone is highly variegated in color, and veining patterns have random orientation, for the most part. We did not have the luxury to match color and veining for every piece of stone due to cost and schedule implications. The compromise was to select blocks with midrange color and tone as a standard and then fleury-cut the blocks to help blend new work with existing. Where veining pattern was more intentional, we photographed the piece and requested that Dutchman be cut to match where possible.”
Although Polycor chose to control the fabrication, the responsibility of vetting the companies ultimately rested on Twin City Tile and Marble Co., according to Joe Becker, vice president of the company’s stone division. “Relationships were strengthened and expectations realized during the many visits to the fabricator facilities,” he stated.
According to Becker, individual stones selected by the architect were measured and hand drawn while on the scaffold or swing stage, and TCTM’s field engineer coordinated the offsite creation of digital shop tickets and full-size templates. “After roughly 200 tickets were created, they were sent for approval,” explained Becker. “Approval of the shop tickets resulted in the start of fabrication. This sequence of processing shop tickets was repeated until the phase was complete. Measuring took place through each season of Minnesota. There was not a stoppage during the winter months. A constant challenge our team faced was to make no assumptions in measuring, as there was no consistency of sizes in the same elements.”
Becker stressed the importance of this process. “I think the vital and crucial success of this project was the shop tickets,” he said. “It doesn’t sound that interesting, but they resulted in less than a 1% error rate. It was the heartbeat of the whole job. We were all working off the same thing. After the fabricators were through with the shop tickets, they went to Mark 1 Restoration. Because of the pace of the deadline, Mark 1 had to do demo before the stone arrived, so they relied on the shop tickets. To me, they are one of my biggest accomplishments.”
Monica Gawet, president of Tennessee Marble Co., was proud to be part of the restoration project. “Tennessee Marble has been a fabricating partner with Georgia Marble since 2000,” she said. “As a domestic and historic company that does restoration/renovation and historic material, we enjoy collaborating with other domestic partners. We were also excited because J.E. Dunn is a wonderful contracting company, and they chose TCTM. We have known Joe Becker for the past 10 to 12 years. I even knew Sylvie at Polycor. We had done a Georgia White job together. She’s a shining star—very committed and organized.
“This was certainly unique,” she said. “It was not just fabrication. It was carving and shaping. It was extremely high profile. We were very uniquely qualified to do this. We used a Gmm Litox CNC machine, which can accommodate large pieces. This was certainly critical for anyone doing this type of work. Hand carving would be great, but it’s way too slow.”
In total, Tennessee Marble Co. cut more than 500 of the nearly 4,000 custom stone pieces. “Georgia Marble would send us raw material in different thicknesses—nothing was cut to size,” explained Gawet. “There was a tremendous flow. Sylvie would get a batch of tickets of what was needed and Ryan Cole, our production manager, would review the tickets and tell Sylvie, for example, ‘We need X amount of raw material or this size slab.’ Sometimes, we would have to recut thicknesses. They were all over. Part of the challenge was to be good stewards of the raw material. We would utilize material based on the batch she gave us.”
According to Gawet, the turnaround time was fairly quick. “Maybe six weeks,” she said. “The challenge would be that you would get two pieces very similar in shape, but in some cases, there was a difference of 1/4 inch in size or shape. We would program the CNC for minor variations and then finish it by hand. Sometimes, we were programming for just a couple of pieces. Each piece was incredibly custom.”
Cutting Edge Stone was also working diligently to complete their assigned tickets. Over the course of the four-year fabrication span, Polycor supplied the fabricator with more than 130 full-sized slabs ranging in size from 4 in. thickness to 16 in.
By August 2016, Cutting Edge Stone had supplied 1,125 pieces of stone to the project, with each piece different from the next. Sometimes two or more profiles were necessary on an individual piece of stone. “Our state-of-the-art lineup of 14 multi-axis CNC cutting and milling machines, including six profiling saws from Gmm, three from Omag, and one from Prussiani, allowed for efficient and detailed machining of each piece,” stated the company.
Replicating the Stone Carvings
Decorative stones, such as capitals, scrolls, swags, and floral patterns, were carved to match the original stonework on the building. During the restoration project, TCTM had master carvers onsite to produce full-sized models when two or more matching elements were required. “Replicating a single model, a pilaster capital for example, hand carved by various craftsmen 110 years ago and each pilaster capital slightly differing, proved to be challenging for the entire team,” said Becker. “Communication between the architects and master carvers was critical, as elements from various building profiles were copied in the models. After models were approved, they were air-freighted to either Italy or Canada to be used by their fabricators.”
According to Becker, 3D scanning and digitizing was used to expedite a new element that could not afford the lea d time of a carved model. “While the idea of bringing the 21st century technology of digital template was worth a try, the end result was a mixed lot,” he explained. “The scanned model only reflected one element, whereas our carved models reflected the ‘spirit’ of many elements. Also, the scanned model reproduced deteriorated elements and our master carvers had to rework the scanned models to look like a new element.”
Lackovic explained that the carved pieces arrived at the jobsite for the most part finished to the project standard. “We would send models to Italy and Canada and say, ‘Make it look like this,’” she said. “The pieces would get onsite and they mostly worked, but sometimes they were different. When bringing [a carved piece] up to be installed, there still was the process to make it work. Many times they could get it in the demolition opening, but it didn’t fit. They had to be carved in the field to blend and match. TCTM had four carvers onsite, and then Mark 1 had a few that qualified, that were doing a lot more than just blending. Some were actually creating pieces from scratch—without a CNC machine. The carvers onsite were absolutely heroic. It was very impressive.”
If there was a unique “one-off” piece, time was taken to model it. “It didn’t make sense to send it offsite,” said Lackovic. “We would carve it onsite. Because of schedule though, we had to make sure not to have too many ‘one-off’ pieces. There were only so many people who had skills to do this, and they could only work for so long. They could only do so many pieces a month. It had to be well choreographed.”
After years of dedication and hard work, the expansive team involved in the stone restoration of the Minnesota State Capitol Building completed its enormous task in October 2016—a month ahead of schedule. “No one really knew if the best would be good enough,” said Lackovic. “We were so fortunate to have so many people that are still able to perfect this craft and produce this high-quality work. We ended up with the dream team.”
This article originally appeared in the Spring 2017 issue of Building Stone magazine. Reprinted with permission.
Jennifer Richinelli has covered the stone industry since 1996 and focuses largely on design. Her work has appeared in a range of consumer and shelter publications.