A perfect solution for a business park
Northridge at Westfields, Chantilly, VA
• Details: 3 buildings totaling 62,490 s.f. of SlenderWall Panels and 8’ thick architectural precast panels
• Finish: Buff colored precast and architectural precast concrete brick finishes
• Architect: Architecture Inc.
• Owner: The Mark Winkler Company
• Contractor: Trinity Group Construction
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A Towering Project in Precast
When Builders and Architects started planning Virginia’s tallest structure, they didn’t want to take any chances when it came to strength and durability. SlenderWall offered the solution.
Virginia Beach has always been known for its high-priced real estate, and that real estate just got a little pricier with the completion of the Westin Hotel and Residences at Town Center, the city’s “new” downtown about 10 miles from the oceanfront. The 38-story structure now ranks as Virginia’s tallest, and its penthouse condos have sold for as much as $4 million each, ocean views included. The new condo owners will also be paying the highest tax rates in Virginia Beach. But those owners consider the price well worth it to live in what has instantly become the city’s most coveted real estate. And that real estate owes a lot of its value to the strength of precast concrete, which makes up the vast majority of the 900,000-square-foot building’s façade.
LIGHTWEIGHT ARCHITECTURAL PRECAST MAKES THE GRADE
The Westin project, which began in 2006, has a structure of cast-in-place concrete with a structural precast garage. The lower four stories of the building’s imposing tower are brick in keeping with the surrounding architecture, but the rest of the Westin’s exterior actually sports more than 77,000 square feet of an innovative, lightweight architectural precast panels known as SlenderWall. Most of the structures in Virginia Beach’s Town Center are clad in some type of precast concrete or brick. The panel system consists of a lightweight architectural precast concrete, hot-dipped galvanized welded wire for strength, insulated Nelson anchors for attachment, and galvanized or stainless steel studs on the interior side.
Architects originally intended for the Westin’s exterior to be made of an Exterior Insulating Finishing System (EIFS), but the building’s contractor and owner, Armada Hoffler, decided on a tougher system that would stand up to severe weather and the test of time. Ashley Smith, president and chief operating officer of Smith-Midland Corp., the precast provider on the Westin project, suggested the lightweight precast panels, as he knew they would allow for a direct swap of materials from EIFS without the need for additional structure.
One of the major attributes that made the panels attractive to Armada Hoffler was its light weight. The product weighs about 30 pounds per square foot. In addition, the panels are only 2 inches thick. Traditional materials would have been much heavier than the panels, says Bahram Kamali, project architect and partner with Brennan Beer Gorman Architects, Washington, D.C. The lightweight precast panels meant they could be larger, as much as 35 feet tall by 14 feet wide, reducing the number of lifts for the crane as well as allowing greater speed in enclosing the structure and making it weather-tight, as obviously there were fewer joints to seal. The panels were installed vertically with each one covering three stories of the building.
Smith-Midland Corp. developed a special connection system for the Westin project that allowed the weight of the panels to distribute evenly across the three floors to avoid adding extra steel to the building’s frame to support the panels’ weight. Had traditional materials been used, the builder would have had to add concrete beams around the structure’s perimeter to support the weight. This would have meant additional cost for Armada Hoffler. “Using heavy (materials) in a beach area would have added 45 pounds per square foot to the project,” Smith explains. “That means more than 3 million pounds of additional weight on the building.” It also would have meant driving more pilings into Virginia Beach’s poor, sandy soil to support the structure. As constructed, the building already rests on prestressed concrete piles driven 60 feet into the ground. More weight on the building would have meant more and deeper pilings. The lightweight panels also offered additional structure protection in the event of high winds associated with hurricanes. Because the panels are attached using anchors and are not welded to the building’s frame, the panels can move independently of the frame during times of severe wind loading and seismic shock. “This reduces wind load on the structure,” says Smith. “There is independent movement of precast from the frame and structure of the building.” Armada Hoffler and Smith-Midland tested the panels’ ability to bear the high winds Virginia Beach frequently experiences during hurricane events. The panels performed successfully in winds up to 169 miles per hour, the speed at which testing stopped. “Those panels passed with flying colors,” says Smith.
FEWER PANELS MEANS FASTER CONSTRUCTION
The lightweight panels also allowed for lower transportation costs to the building site. “The panels were shipped on flatbed trucks,” explains James McRoberts, Armada Hoffler’s senior project manager. “There was one panel per truck, and the largest panel was 400 square feet,” he says. Once on site, the panels went up pretty quickly. “We were on a fast-track schedule,” notes Smith. “The contractor wanted the panels to get installed about 10 to 12 floors behind the framing of the building.” This meant the builder was creating the frame for upper level floors while panels were being installed on lower floors. Because both processes required the use of a tower crane, builders worked on the frame during the day and then used the crane to attach panels at night. With round-the-clock construction, the 525 precast panels were installed on site in just over three months after only five months of production time in the factory. McRoberts feels the panels went up quickly, especially considering the fact that progress was often sidelined by weather. “You can’t install a three-story concrete panel in high winds,” he points out.
The inside surface of the panels consists of 16 gauge, 6-inch galvanized steel studs vertically spaced at 2-foot centers. This provided for easier and faster construction since the panels’ metal framing can be used for mounting interior gypsum board with no additional metal studs required. The precast panels are also virtually maintenance-free, no small consideration in a building that is 38 stories tall. Kamali says the Westin was his first experience with the panel system. “I think it’s a good product, and it’s cheaper than traditional (materials),” he says. “And you can have any shape and texture you want.”
One of Kamali’s biggest concerns with the lightweight panel system was the waterproofing of the project’s façade. “The watertightness relies heavily on how well the sealant is installed and how durable it is,” notes Kamali. “The standard method of double-caulking a joint (with two standard backer rods) cannot be used, because the panel is too thin.” Kamali says Smith-Midland Corp. addressed this concern by providing a unique double caulk system with a thin backer-rod material. Chipping, cracking and warping are other concerns that give rise to architect and contractor anxiety, but strict quality control during every step of the manufacturing and delivery processes helps to allay these concerns. Another challenge is the color matching of the panels. In the case of the Westin tower, the panels feature two tones: a light acid wash and dark brown accents for trim around the window punches. The controlled environment inherent with precast concrete provides consistent results with each cycle of the manufacturing process. “To have the right architectural effect, the colors have to be correct,” notes Kamali. The Westin, which opened for business last November, includes 236 luxury guest rooms, more than 100 condominium units, heated indoor pool, fitness center, restaurant, more than 35,000 square feet of retail space and a 947-space parking garage. “SlenderWall was the right solution for us,” says Lou Haddad, Armada Hoffler’s president and CEO. “This is the tallest building in Virginia, so we didn’t want to experiment.”
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MIxed use project shines on New Jersey's Gold Coast
N.J. Mixed-Use Development Gets Back on Track – With Style – Thanks to SlenderWall
Cliffside Park, N.J., town officials had big plans for revitalizing their downtown when they began assembling properties for a new, signature mixed-use development back in 2002. With 13 stories of rental apartments atop a two-story retail level, Cliffside Park Town Centre was seen as a way to bring new energy into a tired business district. While a major recession and unforeseen subsurface challenges forced some major delays in the project’s timeline, the use of SlenderWall precast panel assemblies helped the effort get back up to speed.
SlenderWall assemblies, which combine an exterior architectural precast concrete façade, vapor barrier, closed-cell foam insulation and interior framing studs, were shipped to the site, ready to install, providing significant labor savings. The panels’ unique M-shape also allowed for larger windows, giving future tenants even greater access to dramatic views of the Manhattan skyline. And the availability of acid-washed and sandblasted finish options ensured both designer and developer would get the natural stone appearance they wanted for this prominent project.
Challenges force a design re-think
The central location and magnificent opportunity for views across the Hudson River to Manhattan would seem to make the Town Centre’s site a no-brainer for a signature residential high-rise. But the area had, instead, languished, earning the designation of “redevelopment zone” when this project was first envisioned. Cliffside Park planners hoped the effort would kick-start interest in the surrounding downtown district.
“The intent was that it was going to replace underutilized properties to revitalize the center of town,” says James T. Virgona, architect with Edgewater, N.J.-based Virgona + Virgona Architects and the designer of the project. However, just as the 3.3-acre property was secured, the Great Recession put the project on hold. When it started up again several years later, a new hurdle emerged: under-surface conditions included both a base of extremely hard rock and a previously unknown underground spring. The latter forced the design team back to the drawing board, as it meant the entire project had to be raised by four to five feet.
Already leaning toward “classically inspired modernism,” Virgona doubled down on this approach as the raised site began to resemble a plinth – the base of many traditional Greek and Roman columns. That plinth has taken the finished form of a broad public plaza, with a decorative central fountain and surrounded on three sides by two stories of retail space. With three levels of parking below and a transit stop in front, the plaza was designed as a gathering space for both building residents and casual shoppers – and as a possible business booster for other stores and restaurants in the area.
A perfect structural match for SlenderWall
To give residents of the Town Centre’s 300-plus luxury apartments maximum flexibility – and to minimize obstacles to the stunning views – Virgona’s design incorporates a staggered-truss structural system that significantly frees up interior space. Using floor-to-ceiling steel trusses in a pattern that alternates from floor to floor, this approach transfers the entire building load to exterior columns.
“The structural system used about half the steel as a typical design, “ Virgona says – though he noted the 13-story project still required more structural steel than was used in New York City’s Madison Square Garden. “Yes, you have very large exterior columns, but you have no interior columns.”
As is typically the case, the staggered truss system was paired with precast concrete plank flooring. The floor planks were fabricated with attachment plates for connecting the SlenderWall exterior panels. This installation process was choreographed to such a degree that, according to Virgona, “the panel façade was being applied to the building even as the structure above was still being constructed.”
Virgona and his team worked closely with the technical staff at Smith-Midland, the SlenderWall manufacturer, to develop the highly coordinated delivery and installation schedule. And, the architect says, the staff’s in-house architectural and engineering experts also were helpful during the project’s design – especially with a two-story retail wing that appears to curve out along the left side of the central plaza.
“It’s not really curved, it’s segmented,” Virgona explains, noting that the detailing at the points where glazing, steel structural elements and SlenderWall panels come together at segment joints became quite a challenge – a snug fit was essential for both building tightness and aesthetics. “The challenge was, how were we going to fill all the gaps,” he says. “Smith-Midland was helpful in coordinating the product with all the other elements.”
Engineering expertise proves a valuable bonus
As a design pro who was new to the SlenderWall offering, Virgona found this level of customer service to be especially helpful. He says this assistance extended to suggestions for design detailing that maintained larger project goals while reducing the number of custom forms that needed to be produced. The result was a modular approach to the forms that allowed a single form to be used to create multiple panel shapes, which helped keep the project on budget.
Among Virgona’s biggest concerns with SlenderWall was just how well the panels’ thermal barrier would work in isolating the panel face from the assembly’s steel frame. A nearby structure, completed a decade earlier, was clad in a competing product and already is showing signs of premature aging, with stains already appearing at attachment points – and the architect feared the possibility of something similar happening on this project.
“It was a good example of what to avoid,” he says. “But they were able to create a thermal barrier between the face and the frame. The product has really been designed to address the pitfalls – they really thought the solution through.”
Virgona says he’s already explored using SlenderWall in at least two other projects – and he’s recommended it to others who’ve gone on to specify the product in their own work. The combination of product performance and design assistance have him sold on this highly efficient approach to building-envelope development.
“They don’t think about just their product, but how it fits into the rest of the system,” he says. “We would be more than happy to work with them again.”
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Hotel Project Team Finds Value is More Than Skin Deep with Precast-Alternative Cladding
Cleveland Clinic chooses SlenderWall by Smith-Midland to envelope it's own hotel.
Cleveland Clinic is a world-class research and clinical care institution, with more than 40 buildings (including a hospital with more than 1,400 beds) across its 165-acre grounds. Patients and their families come to the Clinic from across the United States and around the globe for treatment. The need for nearby lodging to serve these visitors became obvious when the Clinic chose to demolish a former guest house to make way for a new medical-education complex.
The hometown firm of Kaczmar Architects, Inc., (KAI) landed the design contract for the 276-room hotel, operated under the Holiday Inn brand, that was intended to take the place of the previous guest house. This firm’s first task was ensuring its plans meshed with Cleveland Clinic’s well-defined architectural guidelines. KAI wasn’t a newcomer to these requirements – as architects for several other recent projects on the campus, they were very familiar with their client’s fit-and-finish priorities.
KAI architects have frequently turned to traditional architectural precast panels as exterior cladding for other hospitality projects, as well as other KAI projects on the clinic’s grounds. Initially, Kaplan and his team were focused on this material for the nine-story Holiday Inn, as well. But when the building team, which also included contractors Walsh Construction and Forest City Erectors, started costing out installation – including the large cranes required to lift very heavy precast panels to eight-story heights – it became very clear an alternative solution was needed.
Representatives from Chicago-based Walsh Construction had worked successfully with SlenderWall on previous projects and suggested that Kaplan take a look at the product. He quickly saw opportunities for budget savings, without compromising the design, given SlenderWall’s significantly lighter weight and faster installation time. Because SlenderWall panels combine multiple building elements into a single system, they can shorten a project’s overall construction schedule significantly. “The initial reaction was, ‘What’s the catch?,’” he says, remembering some initial skepticism from the building team. “Then we soon realized there was no catch.”
“I can’t think of any hiccups, and I can’t think of anything I’d want to change,” says Kaplan, who says he’ll be coming back to SlenderWall for future projects, thanks to this experience. “Any time you can just watch things go up as you expect, that works for me.”
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Johns Hopkins chooses SlenderWall for critical medical facility reconstruction
Their choice of SlenderWall® from Smith-Midland Precast plays an important role in the successful reconstruction of a critical 1970’s medical facility. Announced on April 16th, 2015, The Nelson/Harvey Building has been recognized as an ACI Excellence award winner.
SlenderWall architectural precast concrete panel system has been chosen as the exterior cladding for the renovation of the 9-story Nelson/Harvey inpatient facility on the Johns Hopkins Medicine Baltimore Campus.
After decades of wear the hand-laid brick envelope of the facility began failing. The architectural firms Wilmot Sanz and Ayers Saint Gross needed a solution that met two criteria: one, that is was lightweight enough to prevent any need for additional superstructure or foundation costs; and two, that the facility would be able to stay operational during the exterior renovation. SLENDERWALL met both requirements. Its 28 lbs. per square foot specification and unique composite construction will allow for the re-cladding to take place without the removal of the old fascia. The 158 SLENDERWALL panels (27,164 sq. ft.) are designed with a factory-applied Endicott brick facing, keeping in continuity with the campus and the original 1970’s exterior. Johns Hopkins also chose to include factory-applied closed-cell foam insulation and the proprietary H2Out advanced sealant system with leak detection. The addition of these options will provide not only savings in time and onsite trades, but insurance against future air and water infiltrations, as well as continuous insulation adding significantly to the enclosure’s thermal performance.
The project will be certified under Baltimore City’s Green Stars program, at the level equivalent to LEED Silver. This is the first healthcare project to seek certification under this program.
In March 2013, SMC began delivery to the contractor, Whiting-Turner. Completion of the cladding portion of the project concluded in June. The short schedule showcased the benefits of SLENDERWALL in reduced times and costs for production, shipping and installation, as well as decreasing the need for some onsite trades.
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