Anchored In Stone
An earlier version of this article originally appeared in the Spring 2024 edition of Building Stone Magazine.
95 State at City Creek is a marvel of efficient architecture, engineering, and construction, fitting snugly into limited downtown space and blending visually with its closest neighbors. Photo by Martin van Hemert Photography
In the heart of Salt Lake City, Utah, a new 25-story building serves multiple purposes for the city’s growing urban population.
Rising skyward with more than 515,000 square feet of mixed-use space—offices, a health club, and a meetinghouse for members of the Church of Jesus Christ of Latter-day Saints—95 State at City Creek is a marvel of efficient architecture, engineering, and construction, fitting snugly into limited downtown space and blending visually with its closest neighbors.
The top twenty stories present floor- to-ceiling glass windows on every level, but 95 State’s base anchors the tower with limestone, a complement to the masonry building next door, said Keith Boswell, architect with Skidmore, Owings & Merrill (SOM), the architecture firm of record for the project. “The building meeting the ground with masonry was a prime consideration,” he said. “Two large meeting rooms and other functions take place in this space, so that inspired the use of limestone to achieve the timeless character, solidity, and visual depth. These qualities were important during construction. Plus, it comes in thicker slab dimensions than we would get out of granite and other materials. It was just the right material fit for the design.”
Depth became a critical component of the choice of stone for the building’s complex façade. The design called for recessed three-story windows bordered with angled limestone walls in a sawtooth pattern, and deep soffits that create an extended overhang above a landscaped drip line. As striking and inventive as the design was, “We had to scratch our heads to develop this with the material in mind, and think of ways to make it happen,” Boswell said. “We went through a series of design development details, how we would anchor the stone at the vertical, how we would anchor it at the horizontals, what would go in first, what would come second. One of the things we were adamant about is that we never wanted a joint at the corner. We wanted solidity inherent in the proposed material to be evident from large scale to the smallest detail, so it would never be perceived as thin and veneered.”
With the project’s small footprint—squeezed into a corner lot with existing buildings on two sides—placement of scaffolding and delivery of materials required very careful planning. Photo by Scot Zimmerman Photography
These were tall orders, but the team at SOM worked to make certain that they had solutions for all the tricky features before they sat down with Okland Construction, the general contractor on the project. “It’s so much easier when you sit with a builder and a stone installer if you have an approach in mind of how you want to do it,” Boswell said. “Then that can be validated and enhanced by the builders, and we can get into fine-tuning and detail.”
Even with this preparation, the Okland project heads saw a number of challenges, said Mike Jueschke, Okland senior project manager. “I went into it thinking it was pretty straightforward,” he said. “But the geometry of wrapping around the art glass windows in a sawtooth pattern, understanding that geometry and programming the metal substructure (engineered by SM Haw Associates), getting the tolerances worked out, that was a challenge.”
SOM studied Indiana and Alabama limestone for the job, and selected Alabama Stone Company’s Sterling Vein Cut limestone, a porous stone that created its own set of challenges.“It’s a subterranean quarry, and there’s a high moisture content in the stone,” said Jueschke. “It’s going to arrive at the site very wet, and sections will dry at different rates. So you end up with a very splotchy look on the building. You have to have faith. When it was first installed, we were all a little bit nervous. But the architects and the fabricators said it would dry out, and it did.”
With the project’s small footprint— squeezed into a corner lot with existing buildings on two sides—placement of scaffolding and delivery of materials required very careful planning. Contractors sorted the limestone panels and stacked them in sequence, so setting crews pulled the panels from each labeled crate and installed them in order. Crews unloaded the stone at one end of the scaffolding and moved it to the exact spot where it was needed, keeping the process moving with as little road obstruction as they could manage.
The soffit required the stone contractors to use scissor lifts to install the stone panels. Photo by Scot Zimmerman Photography
“The coordination was very painful for the trade partner,” said Chad Robertson, Okland superintendent. “The scaffold process for the building exterior was very challenging. Raising the scaffolding platform as they went up was time- consuming. Then the sealing process had to wait for the limestone to dry out, to wick the water out of the stone. They had to come back and seal it after all the scaffolding was gone, to get that final layer of protection on the stone.”
While earthquakes in Utah are infrequent and tend to be smaller than in other western states, construction projects are required to take seismic activity into consideration. For each of the limestone “fins” between the windows, contractors used heavy gauge hollow structural sections (HSS) and additional hat channels with stainless steel anchors once waterproofing had been completed. At the bottom of the second story, the structure ends in a soffit, forming a sheltering roof over a ground-level row of ornamental grasses. Lined underneath with limestone, the soffit required the stone contractors to use scissor lifts to install the stone panels, the last task in a complex of delicate installations.
The finished façade accomplishes the marriage of the traditional with the contemporary, Boswell noted. “What I’m proudest of with the limestone is that it allows the material to express itself, especially the way corners are worked,” he said. “When I look back at stone masonry buildings from the 1920s and 1930s, it’s the solidity that comes through. The stone is shaped, and it creates the geometry and the relief in the wall.”
The team accomplished a marvel: a 220-foot-long marble wall with one consistent vein pattern. Photo by Martin van Hemert Photography
The Interior Lobby
A building as striking as 95 State required a dramatic lobby, especially as this one would face out onto a busy street corner with the limestone edifice covering most of the rest of the building’s first four stories.
The 95 State lobby is enclosed in glass at street level—“very Apple Store-like,” said Boswell, with maximum transparency for passersby to see inside. This main foyer features 30-foot-high walls with curves, and its interior extends into an interconnecting passageway, leading to the parking garage across the street. Skinning the walls of this entire space required 8,900 square feet of a singular material. “Our objective for the lobby stone walls was to have a visually active stone material,” Boswell continued. “The clients really embraced the idea.”
What the team accomplished is a marvel: a 220-foot-long marble wall with one consistent vein pattern, meticulously matched and protected until each piece went into place. The process began in August 2019, when team members traveled to China to look at their first choice of material: a marble with a wood grain-like appearance. In person, however, the marble did not quite meet SOM’s expectations. When COVID-19 arrived and exports from China halted indefinitely, the team decided to look for a different material.
“I made a phone call to Ivo Lensi at Campolonghi in Italy, who I’ve had a working relationship with on stone projects since 1983,” said Boswell. “We wanted one continuous vein line that is expressive of this marble, as if it all came from the same block. You have to go with someone you know can do it, and you need to be super deliberate with your graphics and drawings.”
The architects selected Lasa Bianca marble, a snowy white stone with deep gray veins and a calcium-crystal sparkle when sandblasted to a high finish. The plan also called for 13,000 square feet of black granite floor throughout the lobby, so Lasa became the perfect choice for the visually arresting vestibule of the architects’ dreams.
Choosing the stone was only the beginning of the process, noted Boswell. “When you get a stone block, it’s like eating an apple,” he said. “You never know if you’re going to have a worm inside. So the project team went to Italy and had a work session with all the participants in the process.”
The dramatic lobby features 30-foot-high walls with curves and an interconnecting passageway, leading to the parking garage across the street. Skinning the walls of this entire space required 8,900 square feet of one material. Photo by Martin van Hemert Photography
Quarry management had already determined that they needed nine blocks for the yield, accounting for the difficulty in finding exactly the right pieces to carry the vein pattern through the entire wall. “I looked at something like 40 blocks of stone that they had laid out, trying to see how consistently the veins ran through from one side of the block to the other, and picked the blocks,” said Boswell.
By this time, Salt Lake City based installer KEPCO+ had become involved in the process. “The book-matching had to be vein-matched, but also angle-matched,” said Jeremy Simmonds, project manager for KEPCO+. “You had to have large slabs to be able to reorient the material to match the veins. When they opened out the book matching, one of the solutions was to take a photograph of every slab, and before any of the material was cut, have a ribbon view of the whole elevation with the material lined up to match. So we did this with photographs before the cutting could begin.”
Accomplishing the nearly impossible involved some compromises that could move the project closer to reality. The team changed the original stone joint design from mortared to 1/4” open joints with very tight tolerances and decreased the specified stone thickness to 3 centimeters from two inches. “Around the windows, the stones were mitered together to maintain the look of the deep return stone depth,” said Simmonds. “The fabricator in Italy is the master of epoxy corners. You’d be hard- pressed to know that the corners were two pieces of three-centimeter stone, mitered together.”
Once the photographic pattern was approved, the quarry then cut the material to size and dry-laid it end to end in its airplane-hangar-sized facility. “Due to COVID and restricted travel, we were doing remote dry-laid reviews using a drone,” said Simmonds. “Even though the stone was laid flat on the ground, it gave us very good lighting conditions to see how it would look on the wall. It’s all quarter-inch joints, with discreet anchoring. We had to decide which material went at the bottom and which higher, so that was another complication. So the dry-laid process helped with that.”
It was time to ship the material to Utah. “That’s when we emphasized what we all knew—if you break one piece, the whole wall is shot,” said Boswell.
The marble arrived unscathed, but several steps still had to be completed before installation could begin. To apply sealant and lay out the pieces in the correct order, KEPCO+ created a 50- foot by 40-foot tented clean room in the basement at 95 State—an inconvenience for the other contractors, but a critically important step in keeping the now- irreplaceable marble absolutely pristine through the finishing process. The KEPCO+ team cleaned and sealed each individual stone and attached the back anchor system prior to installation. Using HEPA filtration and an evacuation system to remove fumes ensured that dust did not settle on the stone.
The quarry photographed the marble slabs before any of the material was cut, creating a ribbon view of the whole elevation. The result was a perfect match on installation. Photo by Martin van Hemert Photography
The following day, installers handset the individual pieces according to the grand schematic, the wall joints aligning perfectly with the granite flooring joints, the wooden ceiling, and the surrounding windows “They didn’t break a single piece,” said Boswell. “That’s a testament to the quality-minded people who were doing that work.”
The result, said Simmonds, is nothing short of astonishing. “When you look at it from the outside of the building, through the 25-foot-high windows, it looks like the two walls are continuous,” he said. “Everybody loves it. It gives that wow factor to the entranceway to the building. The huge panes of glass give that open feel to the atrium. With the wood block floor, the stone, the wood ceiling, and a large LED screen above the stone, it gives that experience of something spectacular.”
Okland’s Robertson agreed. “I was blown away by the detail in the fabrication, and the 1/32” tolerances. It’s lost on the average person who walks through that space, but that’s what we want—we want it to look like it’s simple. The experts in a subject make it look simple, and that’s what happened. You lose the complexity of the installation, which is what we want.” He added, “I pass this building all the time, and you can’t take your eyes off of the lobby. We bring our families down there and show them, and we tell them all the stories.”
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