Charles Koch Arena, Wichita, Kan., has been a prominent fixture at Wichita State University (WSU) since its construction in 1953. The arena, which often is called "the Roundhouse" because of its circular shape, can accommodate up to 10,572 fans who come to cheer on the WSU Shockers (the nickname given to early university students who earned money by shocking, or harvesting, wheat in nearby fields).
The arena was constructed as the University of Wichita Field House and has since changed names several times. In 2002-03, the arena underwent a $25 million renovation commonly referred to as the "Roundhouse Renaissance"; the renovations were sponsored in part by a $6 million endowment from Charles G. Koch, and the renovated arena came to be known as Charles Koch Arena.
The renovations did not include reroofing the arena's SBS polymer-modified bitumen dome roof system—which was installed in 1991 by Charles E. Mahaney Roofing Co. Inc., Wichita—because the existing roof system did not exhibit any leaks or problems. However, following the renovations' completion and because of extenuating factors, the roof system developed two leaks.
"We learned about the project through the architect who contacted us before writing the specification to discuss how prior work was done," says Mike Boyd, president of Charles E. Mahaney Roofing. "We were the successful bidder to remove and replace the dome roof and adjacent low-slope roof on the complex."
The process
A Charles E. Mahaney crew of 10 began removing the arena's 70,000-square-foot existing roof system in July 2008; there is less activity at the facility during summer.
"The existing roof was not thick, so we were able to manually cut the roof, slide pieces of debris down the dome and collect it on the low-slope roof area at the dome's base," Boyd says. "We then removed the debris using a crane."
Starting at the building's east end, the crew removed the existing roof system and fastened a vented base sheet to the existing gypsum deck using two-piece impact nails. On the low-slope roof areas, workers set tapered polyisocyanurate insulation in Firestone Building Products' ISO Spray Adhesive. Workers then torched on Firestone Building Products' APP 160, a smooth-surfaced APP polymer-modified bitumen sheet, on the dome and low-slope roof areas.
"We completed half of the roof, restaged our work area on the building's west side and did the other half," Boyd says. "Once we had the entire existing roof removed and the base sheet and APP 160 in place, we cleaned the roof's surface and applied Firestone Building Products' APP 180, a white granule-surfaced APP polymer-modified bitumen sheet.
"Part of the crew torched rolls in place, and the remaining crew members used a smaller torch to seal the laps," Boyd continues. "Doing the laps separately and using a smaller torch prevented torch blowback from marking the finished roof surface. When workers sealed the laps on the granule-surfaced sheet, they worked off a commercial-grade carpet to prevent displacing granules or damaging the finished roof."
There were numerous reasons Charles E. Mahaney Roofing selected a polymer-modified bitumen roof system for the project.
"The roof's dome has some areas where the slope exceeds 8-in-12 (34 degrees)," Boyd says. "In the center of the dome is a 'lantern' roof area that has louvers in its sides. Maintenance people sometimes have to access the area; a granule-surfaced roof can be climbed whereas a TPO roof system would be slick and could cause problems for maintenance people.
"Also, the state of Kansas is self-insured," Boyd continues. "In instances of hail, which we have fairly often in Kansas, the state must pay for repairs. Polymer-modified bitumen has an excellent record of resisting hail damage, so we figured this type of roof would continue to perform and not cost the state a lot of money to maintain."
Dome considerations
The arena's dome roof system presented some obstacles.
"A dome roof creates challenges, including making sure water runs over or parallel to laps, sheets run perpendicular to the dome's base, and the finished appearance is neat and clean," Boyd says. "All these factors had to be considered when determining how to set the rolls so they would be straight, how much overlap needed to be taken and how to limit foot traffic on finished roof areas."
The length of the dome's rise is 124 feet, which meant Charles E. Mahaney Roofing needed to install the finished roof membrane in four separate "rings" around the dome. The challenge, according to Boyd, was ensuring the rings were level, the material properly back-nailed and the subsequent overlap properly trimmed to make a continuous line around the dome.
"When we installed the existing roof system on the arena 18 years ago, I determined the amount of overlap for each ring using a ratio of the diameter between the upper and lower rings, which worked fine but was rather slow because it required each sheet to be measured at the top and bottom," Boyd says. "One day, I noticed we had increased production by 50 percent, so I went to the site to see what had caused the positive change. The crew had erected a pole at the dome's high point and ran every roll directly from the pole. The lap was perfect, and all the rolls' lines pointed directly to the center and top of the dome. Consequently, when we reroofed the dome this time, we used the same technique."
And to ensure safety, crew members wore body harnesses attached to nylon ropes when working on the dome.
"There was a more than 6-foot-tall wall around the low-slope roof areas, so we only had to secure crew members working on the dome," Boyd says.
The finished product
Charles E. Mahaney Roofing completed work on Charles Koch Arena in October 2008, only a few days behind schedule.
"Our production rate was good, but we had several delays because of bad weather," Boyd says.
However, overall, the project went off without a hitch.
"Firestone Building Products gave us strong support with materials, and the project site had a huge parking lot with good access," Boyd says.
And Boyd is pleased with the project's outcome.
"Having WSU, other roofing contractors and even university students tell us how good the roof looks has been the most rewarding part of the job," he says. "The roof is extremely visible in the community, and we wanted to make sure its finished appearance would be striking."
Ashley St. John is Professional Roofing's associate editor.
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