Julia Manglitz, AIA, LEED AP, APT RP, has worked on several building types throughout her career: county courthouses, state capitols and office buildings, university campus halls and community centers. What makes each of these public buildings unique is they’re all landmarks in their communities. Another thing each of them has in common? Almost all feature locally or regionally-sourced natural stone.

Manglitz began her work in Kansas, where limestone is plentiful. As a result, most of the older heritage and iconic buildings showcase local limestone. The featured projects were completed during her tenure as an associate principal of historic preservation at TreanorHL. She recently transitioned to senior architect with Quinn Evans.

Manglitz assessed sixty stone buildings on the Kansas State University campus in the summer of 2019. The buildings ranged in age from 20 to 143 years old; the study identified life-safety and water infiltration issues to help the University prioritize and plan façade repairs. Holton Hall (pictured here) was constructed in 1900 using Kansas Cottonwood and Junction City limestones. Photo credit TreanorHL.

Stone is one of the original regional materials

As an architect focused on historic preservation, Manglitz works with natural stone often. Stone has been used often throughout history for its durability and because it is fireproof. Manglitz notes that natural stone structures were also lower maintenance than wooden structures that required frequent repainting.  

As westward expansion began and immigrants from Germany, Sweden, Italy, England, and Ireland settled in or passed through states like Kansas, many brought with them a history of stonework and masonry. An abundance of usable stone in relatively modest sizes available in quarries throughout the Midwest made it easy to source and use.  

“There were various times of groups moving through. Some settled, some kept moving, but there were generally people around who understood what good material looks like, how to get it out of the ground, and how to get it shaped and put into buildings,” Manglitz says.

The case for regional natural stone

Kansas is known for its limestone. Manglitz notes that one of the most well-known stones is Cottonwood limestone, a light gray-to-cream-colored fine-grained limestone. Cottonwood is the main facing material for many buildings on the University of Kansas and Kansas State University campuses as well as much of the Kansas State Capitol.

Another local stone is Silverdale, a creamy limestone with gold color tones often used in split face veneer stone applications and cut limestone applications due to its tight grain and lack of holes or pits. 

“One of the more interesting stones that we run into a lot at Kansas State University is something called Neva, which is a slightly higher density limestone,” Manglitz adds. “It’s good for rough ashlar work and rock faced finishes.”

Neva is often mixed with Cottonwood, which is softer and can take a tooled finish.

The Kansas Statehouse exterior masonry restoration, completed in 2011, required over 7,000 dutchman repairs varying in size from a few pounds to several thousand. The façade features four types of limestone and seven granite, dating from the original construction to subsequent repairs. The project received a 2018 Tucker Design Award. Photo credit Aaron Doughtery/TreanorHL.

Historic preservation and natural stone

While limestone is readily available throughout the Midwest, Manglitz notes sourcing can still be challenging for historic preservation projects, since blocks are not always actively quarried in the same size that were originally used on a building. 

“Trying to get material in the size that you would like to get it can be a pretty important part of sourcing the stone,” she explains. “When we’re working in preservation, that’s really dictated by the existing building. When we have to go out looking for substitute materials, or substitute stones, it does get really challenging.”

In some cases, Manglitz is trying to match the original color on a building. Other times, she’s looking for a stone that can work with a particular finish. “A lot of the buildings that I work on have some sort of tooled finish to them or they have carvings incorporated, and trying to make sure that you can accurately replicate and get the same feel for it is important,” she says. 

OK State: From 2016 to 2020, Manglitz was the project manager for exterior masonry repairs to the 1917 Oklahoma State Capitol. The restoration included replacing veneer panels, dutchman repairs, crack pinning and injection, cleaning, and repointing. Tishomingo pink granite from Oklahoma clads the first floor, and Hoosier silver-gray from Indiana Quarries the upper floors. Photo credit F. Stop Photography/TreanorHL.

Victory Eagle connects with University of Kansas campus

Manglitz works to recommend stone based on everything from price to aesthetics. She and her team were called upon to work on a 1929 “Victory Eagle” statue in honor of Douglas County residents who lost their lives fighting in World War I. The bronze Victory Eagle monument features a mother eagle with her wings spread wide, defending her eaglets in a nest. 

The statue had seen better days after being stolen and thrown in a ditch before being rescued in the early 1980s. A new base needed to be designed before it could be relocated to Memorial Drive with other war memorials. The client initially wanted a base that wasn’t a native Kansas stone, but Manglitz recommended other stones that would be a more appropriate fit. 

Victory Eagle: The 1929 bronze sculpture, Victory Eagle, moved to a new home along Memorial Drive at the University of Kansas in 2019. The stone pedestal follows the pattern historically recommended by the Victory Highway Association, which organized the memorials in 1921 to commemorate the loss of life in World War 1. Silverdale limestone, quarried in southern Kansas, and Mountain Green granite from Coldspring form the pedestal. Photo credit Julia Mathias Manglitz.

She began by recommending granite for the first two courses. “Granite is going to hold up a lot better; it’s not going soak up de-icing salts that are likely to be used on the sidewalks and it will handle that installation much better than limestone,” she shared, adding that the dark green granite from Coldspring goes well with the overall landscape, since it sits on a site looking down into a forested valley.

The main shaft is Silverdale limestone from Kansas. “Silverdale has a little bit of a warmer color and it tends to go better with the existing architecture,” she says, again emphasizing the importance of regional stone used on other buildings throughout the area. “The more locally sourced stones historically used on the campus have a slightly warmer tone to them.”

Manglitz sees many benefits to choosing locally sourced stone over manmade materials like precast concrete in her work. She points to the lower embodied energy inherent in natural stone when compared to precast concrete as a major factor. “Precast you can do anywhere,” she says. “When you’re using a local stone product, you’re linking yourself to the history of construction within your particular region. It’s partly about place-making. It’s partly about the environment. And it’s partly thinking about durability for the next generation.” 

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Photos appear courtesy of Pavel Bendov/ArchExplorer.  

There aren’t many nearly freestanding buildings in the middle of New York City, but 2 Bryant Park is located on a unique site.

“The building, which is not the tallest building in the area, happens to be open on three sides,” Dan Shannon, architect and managing partner of MdeAS, an architectural company that specializes in commercial office building development, institutional, and multifamily residential developments primarily in the New York City and metropolitan area.

To give some perspective of 2 Bryant Park’s location, it is surrounded by Bryant Park to the south and the Avenue of the Americas on the west.  A public plaza is located on the north side.

The existing building cut the two parks off from one another and had a small, poorly positioned lobby. To better connect these spaces, the central column bay and structural slab were removed from the first and second floor, creating a double-height lobby concourse linking the two parks and pulling pedestrians from one space to the other. 

Shannon and his team wanted to take advantage of the unique footprint of the building and connect the park to the plaza visually. Choosing the right natural stone would prove to be a pivotal decision. They decided to create a two-story high entry lobby passage through the building and elevate that open space using Thassos White marble from Greece along the primary and surrounding walls.

Why Use Natural Stone? 

Shannon is drawn to using natural stone in his projects because natural stone represents quality, durability, tradition, and elegance. He finds we’re also fundamentally moved by natural materials like wood or stone.

“It’s part of our psyche. It’s part of where we came from. It’s part of where we’re going,” Shannon explains. “When people respond in a positive way to an architectural space, it generally has a lot to do with the use of natural materials.”

When he was working on 2 Bryant Park, Shannon was clear in his vision for the spacious lobby and entryway. Those who live, work, and visit New York City are often in a hurry. They need to get from one place to the other and don’t have time to notice the beauty in plain sight. He wanted people who walked into that space to stop—to notice and appreciate the natural stone. He wanted them to respond to it.   

The Different Facets of Thassos White Marble 

Thassos White marble offers different appearances depending on how it’s treated, and that’s one of the reasons he really wanted to use it in 2 Bryant Park.

The predominant walls were made of honed slabs and nylon brushed. “What the nylon brushing did was give it a very nice matte finish,” Shannon explains, “but it also unified the material.”

Shannon reminds us that all natural stone carries some blemishes because it’s a product from nature and not manmade. Through experimentation with their partner in Italy, Roberto Canali from Euromarble, they were able to cover or eliminate some of the blemishes through nylon brushing.

Nylon brushing is also commonly referred to as a leathered finish. “It feels like leather, it’s got a little bit of rippling, but it’s not as rough as thermal,” Shannon adds. “It came into prominence about five to ten years ago and they’re doing it mostly on marbles because it gives the marble a kind of old world look to it. It looks like it’s worn. It gives it a richness.”

Whereas part of the wall features a nearly pure-white sleek matte finish, he and the team wanted contrast for the sides, so they considered black Italian slate.

“Slate has that beautiful cleft finish,” Shannon says. “When it gets pressure along that grain, it cleaves and creates that nice texture cleft surface, which looks like you you’re looking at the topography of the world.”

While the design team and ownership really liked that look, it was decided that the black Italian slate was too much contrast for this room. “We all wanted a more subtle reading.”

This is where the versatility of Thassos White marble came back into play. Shannon went back to Canali to experiment with a different technique on the stone.

“We took large, thick pieces of the Thassos and put them into this hydraulic machine which had a blade on it, which puts pressure along the grain, on top of it, and it shears the marble,” Shannon explains. “What we found was within reason, with a certain size, with a certain amount of pressure, that we could get a positive result in terms of what we were looking for in the appearance.”

The appearance they were going for was that rougher quarry face when you’ve knocked out the blocks.

To achieve the look was the result of a process that involved finding the right size panels that would give them the kind of contours they wanted. “The bigger the panel, the more profile it was, and we couldn’t control it,” he notes. Finding the right size meant they could control the process better by placing the stone panels on wheeled carts so they could move them around. This allowed them to see how they each looked next to each other and get them closer to looking like they naturally belong to each other.

This process also allowed them to work on the panels by hand since some needed handwork to knock down some of the profile. “You may find a perfect piece but it had one bad part,” Shannon says. In that case, someone on Canali’s team would hit it with the chisel and be able to smooth out some of the imperfections or profiles that didn’t work with the adjacent material.

Natural Light Reflections on the Marble 

One of the things Shannon is most proud is how well the natural stone looks on the walls and how the impressive entryway connects to one of New York City’s popular green public spaces.

“It’s kind of like this kaleidoscope connecting these two worlds,” he says. “It really does happen during the day. Sometimes you get the green reflection of the trees that tint the stone because it’s white, and I think that’s just magical. It really is that contrast and the simplicity of it. That is fantastic, you know, just really unique.”

Shannon’s initial vision for the lobby of 2 Bryant Park was for people who walked into that space to stop, to notice and respond to the natural stone. There is no doubt that 2 Bryant Park has carved a name for itself thanks to Shannon and his team who were willing to experiment with what natural stone could do.

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Note: This article is part of a series about American quarries. If you work for a quarry that’s a member of the Natural Stone Institute and you’d like your quarry to be featured here, contact Karin Kirk. Thank you! 

Continents don’t come of age all at once. Rather, they are assembled, piece by piece, through the long process of plate tectonics. Every continent has a core—or a ‘craton,’ as geologists call it – that serves as its original landmass.

Onto this nucleus of a continent, new land carried along by plate tectonics eventually bumps into the craton, and becomes part of the new continent, growing it larger through successive collisions. Thus, most continents are oldest in the middle, with progressively younger parts added around the edges.

North America was “born” about 3 billion years ago with the assembling of the Superior Province, which makes up the bedrock in south-central Canada and north-central United States. A sequence of five events each added a new piece of land, as the young continent gained the real estate that became Manitoba, Ontario, the Great Lakes Region, and northern Minnesota. The youngest part of the original North American craton is called the Minnesota River Valley terrane, which is a chunk of land that slid into the young North American continent around 2.6 billion years ago. At the time of this tectonic collision, Minnesota and the Dakotas were home to soaring mountain ranges as landmasses collided and pushed rocks upward.

Pressure and heat from the tectonic activity caused the bedrock to buckle and melt, creating liquid magma. Pockets of molten rock flowed upward within Earth’s crust, but didn’t reach the surface, so the magma didn’t erupt like a volcano. Instead, these magma pools cooled slowly while still underground, forming crystals of feldspar, quartz, and dark mica. Western Minnesota contains several of these granite intrusions, and because geology has no concern for state lines, one lone spot of granite welled up in South Dakota, not far from the Minnesota border. This was the birth of the Dakota Mahogany Granite, in what is now Milbank, South Dakota.

The formation of Dakota Mahogany marks the last time the Midwest endured a tectonic collision. Since then, seas have advanced and retreated across the landscape, the continents have rearranged themselves in different parts of the globe, and vast ice sheets grew, then melted, then grew again, over the course of several ice ages. After 2.6 billion years of erosion, the Midwest’s former mountain ranges have been worn down, leaving the landscape mostly flat. Through all of this, Dakota Mahogany sat patiently, waiting for its day in the sun.

In 1925, the Dakota Granite company was incorporated, and the stone began its second life. 

“The Benchmark for Brown Granites” 

The trademark color of Dakota Mahogany has become recognizable around the world. It’s made of three minerals: brick red feldspar, grey smoky quartz, and black biotite mica. Taken together, the rich colors lend a deeper, weightier color than the light grey, tan, or pink hues that are more common for granite. The feldspar and quartz crystals are large enough to sparkle in the sun, and the stone holds a high gloss polish that will shine for decades.

Rick Dilts is the Marketing and Sales Manager at Dakota Granite. “Dakota Mahogany is kind of the benchmark of brown granites,” he says. “I think it’s been around longer than just about any other brown granite. You go anywhere in the world and you’ll find Dakota Mahogany from Milbank, South Dakota.”

Dakota Mahogany is primarily used for memorials—which can encompass everything from a simple headstone to intricately carved monuments, mausoleums, and customized designs that celebrate and honor the memories of our loved ones.  

For a stone as old and persevering as Dakota, a memorial seems like the perfect application. “Just the longevity of it,” says Dilts. “You look at concrete and how long that lasts compared to stone. Stone may cost a little bit more but in the long run it’s going to cost much less if you use a natural product like stone.” He muses, “Just look at the pyramids and consider how long they’ve been there.” 

Expanding the Palette 

Dakota Granite has been evolving and expanding, both in terms of the stone they quarry as well as how their stone is used. Beginning in the 1960s, the company started selling Dakota Mahogany blocks overseas, largely to Japan. Dilts recalls, “I was flying to China one year and walked into the restroom at the Narita airport, and from floor to the top of the walls were Dakota Mahogany. It was really cool to see that.”

Dilts continues, “In about 1990 we purchased a couple more quarries,” including another quarry that was already tapped into Dakota Mahogany, and a granite quarry just over the state line in Bellingham, Minnesota.    

In 2021, Dakota Granite was bought by the same company that owns Kasota Stone, and the two became sister companies. This allowed Kasota’s stones to become part of the palette of Dakota’s offerings and vice-versa. 

But the relationship runs deeper than simply selling the same stones; both companies share a business philosophy called the Entrepreneurial Operating System. Two managers from Kasota have moved over to Dakota to help grow the business: Jake Barkley and Colin Kimball. To say that Barkley and Kimball have passion for their work is an understatement. The pair appear to radiate energy and drive, especially as they play off each other and Dilts as they describe their roles in the company and plans for the future.

Kimball describes his job as “The Integrator,” as he ties together the people and departments throughout the company. “I’ve learned a lot from a lot of really great people,” he says. “And I’m proud to be a part of a big team out in Milbank.”

Barkley is the visionary – planning the broad strategy and direction. “My role is basically to set the course or the vision for the company,” he says. 

The management team is sharply focused on growth, but not simply for growth’s sake. Every business decision centers around the company’s core values. A key component of this strategy is to invest in and empower their employees. “As you start to center your culture around core values, it helps attract talented people to come work with us,” says Barkley. “It helps us coach our people as well.”

The “Wow” Factor 

A focus on people is an especially wise practice in a rural location, where hiring and retaining employees can be an ongoing challenge. “It’s a very rural community so Dakota Granite is one of the larger employers,” says Dilts.

Milbank has a population of around 3,500 people and is two hours from the nearest commercial airport. In this region, one can’t simply hire workers with specialized skills—the workforce needs to be cultivated over time.

Dilts explains, “We don’t live in one of the granite centers of the country. So we pretty much have to train everybody. We’ve been lucky enough to find a few hand polishers that came from the countertop industry. But as far as stonecutters go, I don’t know if we’ve ever found somebody with that experience.”

This is where the company’s people-centered approach gives them a leg up on hiring. Dilts observes, “We’ve got a really good reputation for how we treat our employees and I think that’s helped us draw in a lot of excellent people and retain them.” He continues, “We have one family, their fifth generation is working here now. Isn’t that amazing?”

Dakota Granite has a staff of around 93 workers, working year-round in the quarries, as well as in the cutting, carving, and polishing of finished pieces. Production work is done part by machine, and part by hand, and the company pairs high-tech CNC machines with timeless handwork.

Kimball appreciates the contrast between humans and machines. “We have a robot that can make these beautiful parts. And then we have true artisans that are making really beautiful parts by hand. To see the progression from what people can do by hand and what we can do with a piece of equipment is amazing. It’s fun to be a part of.”   

Barkley confirms that skilled handwork is irreplaceable: “Yeah, a lot of the hand cutting with hammer and chisel has to happen by hand to get a beautiful finish. It’s a special thing. You can’t replicate it.”

“There’s something extremely rewarding for people when they finish a beautiful part,” says Kimball. “I see guys and gals taking pictures with their phones of the work that they did.” Working with stone invokes a sense of permanence that can be hard to find in an era where too much seems disposable. Kimball derives deep satisfaction not just for himself, but for his employees: “To be proud of what you do at work every day and to know that you’re a part of something that’s gonna last for hundreds of years.”

“There’s so much ‘wow factor’ in our plant and our quarry,” says Dilts, echoing Kimball’s pride. “But watching the stonecutters is a big highlight for me. It’s just so fascinating to watch those guys hit that chisel with their hammer every time and not their hand.” Dilts laughs, continuing, “I’ve tried it. That doesn’t work very good for me.” Barkley and Kimball join in the laughter as Dilts continues, “But you know, the team is so good at what they do. It’s just so fun to watch them.” 

Bright-eyed Planning for the Future 

As Dilts, Kimball, and Barkley look ahead, they’re helping the company expand its focus into architectural work, including municipal projects and outdoor spaces.   

Barkley describes a current focus on landscape stone. Dakota’s current projects include “substantial outdoor infrastructure” where people can “walk in and around park-like spaces and get up close and personal to the stone,” say Barkley. He notes that the use of natural stone in outdoor spaces is a trend that’s been gaining momentum.

Even the most inspired designs can still get bogged down in today’s business environment, and Kimball explains how planning ahead is more important than ever. “On the back end of the pandemic it’s changed a lot of our behavior and our strategy. You used to be able to pick up the phone and get a few spare parts quickly from Amazon.” Supply chain bottlenecks, shipping delays, and staffing shortages have changed the nature of project management. “We’re doing a lot more in-depth planning. We’re preparing more for the future. We’re having more conversation around what potential pitfalls are around the next corner. I think it’s changed our behavior in a positive way. We now take a more realistic look at some of the obstacles that may occur and how to overcome them when we run into them.” 

The company’s local quarries offer a simple, domestic supply chain that keeps lead times short. In a competitive marketplace, “perhaps our shorter lead times and the availability of our products are what’s helping fuel our growth,” says Barkley. “Some of our customers are getting quotes for lead times that are three or four times what ours is. I think that is leading to some pretty substantial order increases.” 

Dakota Mahogany has been waiting 2.6 billion years for the right opportunity. The quarry is in good hands, with stewards who are eager to shepherd the stone to its best use. “We’re in a pattern of what I would consider extreme growth,” says Barkley. “We’re going to continue to grow this business until the next hurdle arrives. Then we’ll solve that problem, whatever it is.” 

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An earlier version of this article appeared in the Spring 2022 edition of Building Stone Magazine. Photos appear courtesy of PICCO Group.  

A stair project is typically all in a day’s work for an engineer, but what PICCO Group put together for a Toronto homeowner counters logic and the perceived limitations of natural stone.  

The home in question, nestled a few meters down a ravine and surrounded by dense forest in an exclusive neighborhood, was being renovated by Toronto contractor Clemmensen Builders. Sophisticated and modern, the multi-level home with a flat green roof needed a staircase worthy of its simple, elegant geometry.

Clemmensen Builders sought to incorporate stone into the feature stair that would run from the lower level to the main kitchen level. The original solution, developed by architect Peter Clewes of architectsAlliance in Toronto, would be stone “plank” treads cantilevered from an adjacent foundation wall. But that would “create more complexity, challenges, and issues by disturbing the existing old wall, which was thick and made of rubble stone,” says Karl Doucas, principal of the structural engineers PICCO Group, called in to work on the project.

With the intent to fit the home’s contemporary style, Clewes designed the first iteration of the stair with a zig-zag profile. “We wanted to 100 percent respect that design intent but alleviate the structural approach they’d been considering. We envisioned a post-tension stair where the tensioning would be done after the installation. It would be a self-supported stair that wouldn’t rely on the existing structure to support it,” Doucas says. “Although what we proposed was a complicated structure, it would simplify construction and be less disruptive.”

It took a leap of faith on everyone’s part to agree to what eventually would be a five-ton floating stone staircase.

Sourcing and Fabricating  

The kitchen, at the top of the soon-to-be showpiece staircase, had basalt flooring. PICCO Group looked locally for stone that would match the kitchen floor but were unsuccessful. “Generally,” Doucas says, “with flooring tile it’s slab or tile material. The stair is cubic material. Although the source may be the same, the procurement process is different.”

Doucas attended a building show while sourcing the basalt, where he met Chinese suppliers who might have what he was looking for. “Basalt is a common material in China but comes from only a few quarries that are under government control,” he says. Doucas decided to go directly to the source in China and began making phone calls to find a quarry/fabricator that could secure enough of the specific material, black basalt G684. He landed on Gonmar Trading Company in Xiamen, China.

“They walked us through the procurement process. We provided detailing of the stair and the quantities we needed as well as shop drawings, which they reviewed carefully,” Doucas says. While Gonmar committed to the project, Doucas admits he was still nervous. “Saying and doing are two different things.” After the initial mock-up and review of the first few treads, Doucas says PICCO Group was more comfortable with their choice. Then, the company air freighted material samples to PICCO Group’s Concord, ON office for inspection and material acceptance before work began. During the process there were a lot of virtual meetings and calls.

Aside from matching the kitchen flooring, PICCO Group also chose basalt because of its strength and quality, Doucas says. “In a staircase like this so much stress goes into the material. We needed to make sure the material would be appropriate for the function. But there are tradeoffs. Being a strong material makes it more difficult to fabricate. You need the right fabricator to do this.” Gonmar sent “small but specifically dimensioned stone to conduct ASTM tests domestically.”

Gonmar quarried the blocks from its own mountain quarries in Fujian and processed and cut them to the size needed. They flamed the basalt, heating the stone to a high temperature with a torch then quickly cooling it with water. Small bits of stone pop off the surface, giving it a jagged edge. Then they wire brush it to wear down the sharp edges. The stone has a subtle rough dimpled surface and is naturally non-slip.

The stones needed to be keyed, stepped, and notched to fit into each other. Each step also had to have three holes through which tension cables would run. The holes had to line up perfectly. “That was a key consideration,” Doucas says. “Would the fabricator have the capability of cutting the stone to our specific requirements and be able to do the coring?” Because the stones would be connected along a tension wire as if they were giant beads on a string, “even subtle misalignment of these holes would have presented risks of cable kinks and increased cable stresses.”   

PICCO Group worked closely with Gonmar via telephone, virtual meetings, and video exchanges in addition to quality control reviews by PICCO’s sourcing representative in the region to do dry laying and stone mock-ups. “The precision of drilled holes within tight tolerances through consecutive treads proved more difficult than we expected,” Doucas admits, but in the end, quality control at the Chinese factory showed fabrication and craftsmanship created near-perfect hole alignment.  

Once this almost nine-month process was complete, the stairs traveled for six weeks by boat to Vancouver and then by truck to Toronto.

Assembly Required  

Five pallets of stone were delivered to the site. Small booms craned the stones from the trucks to the pool deck on the home’s kitchen level. Master masons Precision Stone, from Westbury, New York, were tasked with erecting the staircase to exact specifications. Masons wrapped the heavy stones in chain falls (hoists) and dollied them into the house.  

At the top and bottom of the staircase, masons installed robust and heavy stainless-steel plates. On the bottom level, the plate serves as a stop to all the weight and load of the stair above it and was anchored with 12 bolts to an existing lower-level concrete slab that required the addition of a reinforced stair foundation pad.

They then set up a wood “crib” of scaffolding to mimic the final design and used a pulley system to lower each basalt step into place. Masons placed each block of basalt stair in its appropriate spot on the wood crib. They built the staircase from the bottom level up. 

The 19 steps, each weighing 550 pounds, are made up of ten-inch treads and 6 3/16-inch risers. Each step also has three one-inch holes bored through its middle (to house the tension cable) and one through its side (for the handrail connector).

As each block of basalt stair was set in place, masons fed the three 1/2”-steel tension cables through matching holes in the treads consecutively. Pulling wire became more difficult as each tread was placed upon the one below. It took about four days to erect the treads.

“Once you get to the top, you essentially tie off the bottom with a nut and cut off the excess cable. You pull from the cable at the very top to create the tension,” Doucas says.  

There were still a few critical finishing steps. They pumped Hi-flow, quick curing grout, into each cable chase and then sealed each outlet. The grout took a week to consolidate. Then they could remove the temporary wood crib and grout the joints between riser and tread.

The final critical moment for Doucas came when they piled the steps with CMU blocks to simulate the load. “It’s impressive to see all those blocks on there and the stair is really floating. You stand underneath it and say, ‘I hope this thing holds.’ But we had confidence this would work. Post tension stone has been done for hundreds of years in many applications.”  

Once the stair was complete, they incorporated the glass rail system. “We asked the test lab to further confirm the stone material capacity for the type of railing anchor installation specified,” Doucas says. The masons installed and epoxied a stainless-steel threaded rod into the side of each stone step. The design called for a two-pinned look on every tread. The pin goes from the step through the glass, and a decorative nut finishes it off. “It was important to be precise as the glass guard holes were pre-drilled. We had to make sure the final fit was as you see it.”

There is no hiding the “wow” factor of this staircase. “It just wouldn’t have been as impressive in wood,” Doucas says. Its sheer weight and size convey the difficulty in fabrication and engineering. And, he adds, “If you want to evoke a sense of authenticity and communicate durability and longevity there’s no alternative to natural stone. It’s historical, timeless.”

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