The new $1.2 billion Dallas Cowboys Stadium in Arlington, Texas required about 16 miles of roof caulk and structural silicone sealant on the exterior glass to waterproof the steepest retractable domed sports arena in the United States.
KPost Company of Dallas worked with subcontractor Haley Greer caulking and wet glazing all glass areas of the stadium through its Waterproofing Division.
"It was a challenge," said Ricky Harp, KPost Waterproofing Division Manager. "In the end, after three years, we are very proud of everyone who worked on it."
The roof consisted of acoustical insulation installed in the flutes of the metal decking; Sarnavap fully taped for a vapor barrier; 1.8-inch thick polyisocyanurate; ?-inch DensDeck Prime; and fully adhered 60-mil PVC G410 Sarnafil membrane.
The system was attached using 3?-inch Sarnafil screws and plates per FM Global requirements. The 60-mil PVC membrane was fully adhered using Sarnacol 2170 adhesive and the seams were heat welded.
"Sika is the Cadillac of single-ply roofing," said Thomas Williams, KPost Project Supervisor, noting the fastening pattern was a minimum 16 fasteners per 4-foot by 8-foot board per FM Global requirements.
Williams said the 1.5 inch iso and thicker DensDeck was also used in corners exposed to higher wind uplift. Pressure-treated lumber was installed at all perimeter edges and areas of transition using stainless steel screws.
Waterproofing a Dome
Adam Quilantan, a service supervisor in the KPost Waterproofing Division, said providing proper adhesive to the substrates was crucial for the new Cowboys Stadium.
"Each day we had three experienced journeyman caulkers and one helper to clean up for the structural glazing," Quilantan said. "The structural steel behind the glass (interior) had to be sealed to the glass before we could do the exterior weather stripping."
Quilantan said the enormity of the project was the biggest challenge to waterproofing the dome. "Another challenge was to have it aesthetically pleasing when (Cowboys owner) Jerry Jones inspected it," he noted.
KPost used Dow Corning 795 silicone, mainly in black, to seal about 90,000 linear feet of glass joints - that's close to 16 miles. "The silicone has elasticity that allows up to 50 percent of its width for movement," Quilantan said. "Preparation was important, and we had to break down the scope of the project on a daily basis. What's amazing is we actually keep that whole structure watertight."
Manhattan Construction Superintendent Richard Duchesne concurred saying the most difficult part of the project was getting the structure watertight. "But when we did, she came alive," Duchesne said of the new stadium. "It's the greatest feeling in the world to know this one-of-a-kind structure is open for business."
Roof work on the service building started in July 2007, although the "real roof work" began in March 2008, Williams said. The project was completed on June 1, 2009.
Williams said the project took longer than expected because of changes in the construction schedule. He said the degree of difficulty, particularly with stocking and installation, as well as the schedule delay by the weather resulted in additional labor above what was originally anticipated. Having said this, Williams was proud to report that "all work was completed on or ahead of schedule in support of the opening of the stadium." The Cowboys NFL regular season home opener was scheduled for Sept. 20.
KPost started with eight roofers on the service building. However, as the workload increased, crews increased to about 60 workers that consisted of a superintendent, safety monitor, four roofing foremen, 40 labor roofers, a sheet metal foreman, three sheet metal workers, two waterproofing foremen, and eight caulkers.
KPost Director of Operations Kelly Lea said all workers were tied off 100 percent of the time during the roofing project.
"Safety was the most important thing," Lea said. "I relied on Tom (Williams) to make sure our crews followed all safety guidelines. Cuts and bruises were amplified."
Williams said the wear and tear on the body was brutal on crews after dealing with constant loading of materials and extreme Texas weather conditions.
"We had to figure out logistics of where to be tied off, how to get up and down, and facing 30 mph winds and 100-degree days with 95 percent humidity," Williams said, noting the slope of the roof required that all material, tools and generators were anchored with straps and wood blocking.
"The logistics were a nightmare," he said. "The slope of the roof made it very difficult."
Williams said 200- to 240-foot safety lines were purchased from Superior Equipment in Fort Worth, Texas. The majority of harnesses were made by Fall-Tech and the roof anchors were made by Guardian Fall Protection. A full-time safety monitor was also on site during stocking and roof installation.
"You can't overestimate the amount of labor to stock the roof," Williams said. "We used 10 men to stock 80 squares a day."
The size of the project was monumental and the right manufacturer product needed to be used. Enter Rick Chappell, an account specialist for Sika Sarnafil who used terms like "sustainability" and "longevity" to define his product.
"Ricky Harp calls me and said they have a large project," Chappell said. "I saw where the architect was HKS Architects, which was the same architect I worked with on the American Airlines Arena in Dallas a decade ago."
Chappell said he was on the jobsite about 10 times during the single-ply installation. "I can sell it, but it's the roofing crews that make it as good as it looks," he said. "I'm amazed at what these guys went through during installation at 300 feet in the air."
KPost installed about 6,600 squares of fully adhered 60-mil PVC roofing membrane on the stadium roof, which included a small service building and restroom building (37 squares), two mid-level roofs (192 squares), eight clerestory roofs (29 squares), two low roofs (869 squares) and the fixed dome (5,462 squares).
One of the mid-level roofs and both low roofs were structural concrete decks, while all other roofs were metal deck with the dome being an acoustical deck. The low roofs, mid-level and clerestory roofs were fully tapered systems.
Moving and Securing Material
The general contractor, Manhattan Construction Company of Fort Worth, Texas, made sure KPost had an area for material to be secured to the roof.
"We were required to move the material on several occasions due to paving of parking lots," he said. "All of the Sarnafil G410 membrane was produced in a single run at the beginning of the project and stored in a local warehouse until needed at the jobsite."
Williams said KPost used a 300-ton crane from Crocker Crane in Irving to load material. The crane was outfitted with a 380-foot boom. However, a hydraulic winch was required to pull material to the top of the dome.
"All material and tools had to be strapped down due to the forces of gravity and high winds frequently present on the dome," said Williams, who noted both the Sarnavap and G410 membrane came in rolls, so unless the material was strapped down, it could easily roll off the roof - which it never did.
"With G410 membrane rolls weighing in at 391.5 pounds, we had to be especially careful when handling these items," Williams said. Rolling out a roll of this membrane on a standard flat roof requires one or two men, according to Williams, but handling a roll of membrane on the dome required up to eight workers.
Also, because much of the roofing was completed during the summer months in 2008, the Texas daytime heat resulted in crews starting work about 4 a.m.
Still, Manhattan Construction Superintendent Richard Duchesne said teamwork was the real reason behind a successful construction campaign. "To work with our peers, subcontractors, the big bosses, and safety teams is just a great feeling," he said. "The key is paying attention to fine details and KPost did a great job.
"Nobody's perfect. If you start to see things are not right, you fix it. If you run into obstacles, you get through it. It's a good feeling. Sure, there's going to be frustrations. You adapt and move on. It's been a great job."