As seen on page 74 – 80 of the NSI’s Spring 2024 issue of “Building Stone Magazine.” https://mydigitalpublication.com/publication/?i=825250&p=74&view=issueViewer
The Epic II Tower includes 7 levels of podium, followed by a smaller tower that continues upward through the 23rd floor. The height of the 7th level is nearly 20 feet, which creates a feeling of openness, enhanced by floor-to-ceiling glass between the interior space and exterior terraces. Granite is the primary material for the terrace flatwork. DBI set over 9,000 sq. ft. of stone.
Uber's new office in Dallas's Deep Ellum neighborhood is part of a two-phase multi-use project known as the Epic that includes offices, retail, multifamily residences, and a boutique hotel. Uber is located in Epic II, a 450,000-square foot 23-story tower, where the ride share company holds its presence to just the seventh floor. The iconic startup wanted outdoor space for its employees and others in the building. Hocker Design Group, the landscape architecture firm that designed the space, and the architect Perkins&Will, answered the call with an amenity deck that stands up architecturally to the contemporary building.
Epic II includes a 7th - floor amenity deck featuring serpentine wall structures, curved planters and seating areas made of Rockville White granite, in a design that stands up architecturally to the contemporary building. Photo by Millicent Harvey Photography
FROM INSPIRATION TO REALITY
Sitting atop a five-story parking structure, the Epic Il amenity deck is on the east, more public side, of the building. (Hocker designed a smaller amenity deck on the west side for use by Uber staff only.) "It's not the typical rooftop amenity deck with a little gas grill and a trellis," says Dylan Stewart, landscape architect and senior associate at Hocker. Stewart and the client, Westdale Real Estate Investment and Management, wanted to go big and "interject curvilinear forms onto the roof deck, do something different and interesting."
Epic II features serpentine wall structures, curved planters and seating areas made
of Rockville White granite. Hocker was inspired by Tokyo's Cerulean Hotel, with its undulating curved stone walls, and designs by the monk and landscape architect Shunmyo Masuno, whose work blends modern design and traditional Japanese elements. "In these Japanese designs, each stone is hand carved, and each has thoughtful detail that goes into it," Hocker says.
Achieving that level of customization took a great deal of collaboration between Hocker, Westdale, developer KDC, general contractor Balfour Beatty, Coldspring quarriers and fabricators, and the installers from Dee Brown, Inc. The challenge, Stewart says, was to "take this wild Japanese inspiration and figure it in a way that it could be built to a budget and to American fabrication methods. We couldn't have all these blocks cut into specific curved shapes to make these forms."
Quarry drill marks are usually a waste product, with fabricators sawing blocks into perfect cubes and turning this leftover skin into a variety of byproducts such as gravel. But Stewart wanted a mix of quarry drill marks and split face. "We wanted to embrace the marks as part of the story of the stone. You can see how it catches the light and adds a dynamic quality." he says. Photo courtesy of Coldspring
STONE COLD SAVINGS
Originally, the clients had Stewart look at Mesabi BlackR granite, but it was beyond the budget. Stewart decided on Rockville White granite. "In a world of black and white, this stone is aesthetically unique," says Bryce Kock, Coldspring's architectural director of sales. Stewart chose a "rub and sand" finish, softening the color to more of a gray to "complement the tones of the building," Stewart says. The stone also had the right Solar Reflectance Index of 0.38. "Since it's on an elevated roof deck in Texas, it needed a higher reflectivity. A darker stone would absorb heat and make the environmental conditions unpleasant." Stewart wasn't going to have each stone carved as in Japanese design, but he did want the stones to be unique. He chose a cutting method that achieved this and saved time and money.
Blocks are either sawn or drilled out of a quarry, leaving distinct drill markings on some of the faces. Quarry drill marks are usually a waste product, with fabricators sawing block into perfect cubes and turning this leftover skin into a variety of byproducts such as gravel. But Stewart wanted a mix of quarry drill marks and split face. "We wanted to embrace the marks as part of the story of the stone. You can see how it catches the light and adds a dynamic quality," he says. "Once all the pieces were in the larger composition, the textures play nicely together."
Another way they adhered to budget, Stewart says, was to pick a width of "nine or 12 inches or some other whole dimension. There were hundreds of these blocks. If you thought of them individually, it would take too long during the cutting process to recalibrate the machine. I didn't want to make a backlog for Coldspring, and I wanted to make an easier install for Dee Brown."
The mockup showed where joints might open. The way the pieces would stack, installers would have to eliminate voids by overhanging the face and protruding out to cover the horizontal joint. Coldspring would have to put a split face finish on a portion of the stone then route that back and put a slope on it at times. Photo courtesy Dee Brown Inc
PLANNING AND LOGISTICS
Stewart stuck with four basic cutting sizes and played with the stones like a puzzle, knowing the design included a lot of curved and battered, or stair stepped, elements, and the variance in elevation added even more complication. "It was important to understand the proper block size to make the curves and keep the joints between the blocks as minimal as possible," he says.
Using 3-D models, Coldspring created fabrication tickets, with each piece individually numbered. Then they gave the installers piece-numbered shop drawings to follow. Because it was a complicated project, says Jason Frank, Coldspring sales coordinator, they did dry lay mockups at their facility for approval prior to shipping
to Dallas. Dee Brown also dry laid pieces numerous times in the field before permanent installation.
There was also a second, more detailed mock-up at Dee Brown's, where they built a wall section true to what it would be in the field including the structure in the image to the left. Because the amenity deck is above a parking garage, they needed to keep the weight down. To support the stone blocks, they used foam blocks cut with a hot wire to the correct elevation and curve. Concrete or masonry would have been too heavy and less forgiving. But, says Stewart, "We didn't want the walls to be unstable since people might sit or walk on them, so the mock-up process was critical to test the stability of the block configuration. Dee Brown anchored the bottom and topmost course into a concrete curb and CMU backer wall respectively. The rigidity of the assembly locked in the middle courses set on EPS foam blocks cut to size on-site."
They also were concerned that water would get in behind the open joints. "Foam filled 95 percent of the wall and where there was a void we'd have to place gravel behind it," says Tim Hughes, senior vice president at the installer Dee Brown. "That would let water held in the cavity flow out the open joints."
While these stones are not hand carved, Stewart's choice to show a mix of drill marks and split face makes the project unique. The "rub and sand" finished used on the paving gives the predominantly white/gray stone a softer look and adds texture. Photo by Millicent Harvey Photography.
Stone was shipped to the project between 4:00 a.m. and 6:00 a.m. then loaded onto an outside elevator that took it to the seventh floor. The crane that could access the deck had been removed before Dee Brown began installation. Stones were stored inside the building. "Since this project is like a jigsaw puzzle, it can only go together one way. You can only take out the stones needed for a particular day. The balance was left inside the building," says Hughes. "We did the walls first and then the pavers. Wheeling a 5,000-pound pallet of stone across the pavers, which were to be set on a pedestal, would have broken the pavers."
Between the bottom and second row is a Styrofoam backer, ultimately hidden by soil and plantings. The high-density Styrofoam was needed to keep down the weight of the project. Photo by Dee Brown, Inc.
COURSE WORK The stone courses are basically set as blocks, with the bottom and top course set using traditional masonry methods. To make things easier for the installers, Coldspring bore four holes in the bottom of the blocks for stainless steel dowels to help lock them in.
To add variation and for it to feel like the courses have some movement, Stewart says, "the second course has multiple blocks stacked on top of each other to create a swooping effect. There are no mortar joints in between."
While the installers were generally able to keep the joints tights, some did "open up a bit," Stewart says. "Dee Brown stuck shims a few inches down and put in some backer and infill with caulking for the larger joints. Stepping back, it looks like dry laid stone.
The other big challenge was the irrigation for the two large planters. Stewart specified drip irrigation and lightweight soil, "expanded shale," so water drains faster. The top-most stone course is doweled into CMU blocks, which go straight down to structural concrete. "The GC had to X-ray the structural slab because it's a post-tension area," Stewart says. "When they tied in the CMU block, they didn't want to hit the rebar." CMU was needed to keep the water from pooling on the grounds. "Planters are like bathtubs with drains set within them," Stewart says, noting that three years after completion, he so far hasn't seen water stagnate.
The amenity deck gets used all year round, with visitors enjoying the garden and the terraced seating. Says Kock, "You're right in the middle of a city and between these huge towers is a beautiful natural stone getaway. The stone and landscaping transport you. It's truly impressive to have that natural stone design in such an urban setting."
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