Today’s world of National Collegiate Athletic Association (NCAA) Division I college football is effectively an arms race. If a program isn’t planning ahead, it’s falling behind! That’s why even with 47 conference titles and seven national titles to its name, the University of Oklahoma (OU) greenlighted a massive $350-million expansion and renovation project for its Gaylord Family - Oklahoma Memorial Stadium in 2015 after seeing several gridiron rivals capitalize on the ongoing stadium construction boom.
Along with numerous upgrades, their main objective was to enclose the formerly U-shaped stadium into a bowl — thus adding ~8,000 end-zone seats to squeeze in more crimson-clad Sooner fans into its capacity of over 80,000. To do so, regional contractor Chamberlin Roofing & Waterproofing was called on throughout 2016 and early 2017 to install over 200,000 square feet (18,580.6 m2) of waterproofing products and ~130,000 linear feet (39,624.0 m) of caulking to help seal the new, pre-cast concrete pours and prepare the stadium for the modern era.
“We had to install below-grade waterproofing, traffic coating, cold-applied waterproofing, joint sealants, expansion joints, and site caulking,” said Chamberlin’s Michael Brau, who served as project manager for the 15-man crew in Norman, Oklahoma. “Despite many logistical challenges, teamwork, innovation, and proactive planning made it possible.”
One of the main headwinds on a project of such scope was working around other trades. On this job, the contractor had to be proactive to ensure its crew worked in safe areas — since roof installation, concrete pours, masonry laying, and more were going on simultaneously.“Our site supervisor coordinated with the general contractor’s superintendent to plan their schedule day to day, so they would not end up working underneath any other trades installing about them,” Brau explained.
Even in contained areas, further precautions were required. Site-specific safety plans were developed by Chamberlin officials, and a job-hazard analysis covering each task was performed and communicated to crew members each day before work began.
Personal protective equipment (PPE) gear was regularly worn, including hard hats, vests, safety glasses, and work gloves. All safety equipment was inspected each day before use, and crew members also performed daily stretch and flex exercises.
Most of the work was completed over the first eight months of 2016, while a few smaller items were delayed until early 2017. Crew members routinely worked 60-hour weeks to get all major items done before OU’s season. “After our work was installed, we had to wait until football season was over to complete our punch-list items,” Brau said.
In those eight months, the crew effectively split the job in thirds, with three months spent applying below-grade damp proofing and cold fluid-applied waterproofing materials on the terrace decks; three months applying a traffic coating to the new bowl seating area; and two months on expansion joints and joint sealants on exterior masonry.
As always, surface preparation still proved essential. “We pressure washed the concrete that the waterproofing and traffic coatings were applied to,” Brau said. “Even though it was new, people walking on it and other dirt, dust, and debris made cleaning it necessary.” For expansion joints applied where the existing stadium met the extension, concrete on the existing side was grinded and patched by a subcontractor.
Using 9-inch (22.9 cm) rollers with a 0.75-inch (1.9 cm) nap, the crew first applied 8,000 square feet (743.2 m2) of BASF’s MasterSeal 615 — a water-borne polyurethane membrane with below-grade damp proofing properties — to elevated decks before topping it with a drainage board.
Then, 97,000 square feet (9,011.6 m2) of the cold-applied Tremco Tremproof 250GC polyurethane waterproofing membrane was installed at split-slab conditions. The liquid material was applied in one coat utilizing a specialized squeegee designed to apply at an average of 120 mils (3,048.0 microns) of wet film thickness (WFT), then topped with a drainage board and tapered insulation before the topping slab was poured.
Initially, a hot-applied waterproofing material was selected. However, in the planning phase, Chamberlin officials called a timeout to reassess. “Since concrete was being poured on a non-vented metal deck, a hot-applied product would require the concrete to cure for four weeks before being applied,” Brau said. “If not, water would become trapped between the deck and the membrane, eventually forming blisters, then holes, and ultimately failing. This [cold-applied] system needs water to cure, and it draws water from the concrete — therefore curing the concrete and adhering the membrane. This change not only assured a watertight system but also saved the project schedule from being pushed back at least two weeks.”
To apply the traffic coating, the crew moved section to section utilizing a three-coat Tremco Vulkem polyurethane system. The first coat of Vulkem 350 was squeegeed at an average of 25 mils (635.0 microns) WFT, followed by a second coat the next morning of Vulkem 950 via roller at approximately 12 mils (304.8 microns) WFT, with sand broadcast into the second coat. That afternoon, excess sand was blown off before rolling out Vulkem 951 as the third coat at an average of 12 mils (304.8 microns) WFT. While the system is typically applied in two coats, the unique requirements of a stadium prompted an audible.
“While the traffic coating works well for horizontal surfaces, the product is heavy for vertical application, causing dripping and difficulty in installation,” Brau said. “The vertical parts of the stair steps were the most complicated areas. To combat this, we amended the application process by reducing the millage of the coats and applying three layers instead of just two. This solution worked, leaving the bowl watertight with a continuous sleek look from top to bottom.”
Sealing a Win
The final months involved installing 127,000 linear feet (38,709.6 m) of gun-grade joint sealants on exterior masonry, along with 4,000 linear feet (1,219.2 m) of expansion joints in seating areas. An 80-foot (24 m) Genie boom lift was used to apply sealants to the stadium’s exterior.
While it seemed simple on paper, the crew quickly found out that it was anything but. The stair steps leading up the stands in the existing portion were not uniformly sized, contrasting with the uniform steps of the new, pre-cast concrete bowl and making it difficult to connect the two. Furthermore, the specified expansion joint was a wing joint, which required a block out in the concrete. The new concrete had this block out, but the existing concrete did not.
First, the concrete contractor filled in the block outs in the new concrete. Then, Chamberlin identified non-winged joint options that could join the two mismatching stair profiles and seal them. In collaboration with general contractor Flintco, they settled on Watson Bowman Acme’s Evazote joint (by BASF) — a foam block installed using an epoxy adhesive. This joint also proved more cost-effective compared to silicone-faced joints. In areas where adjoining steps differed in height, Chamberlin installed the joint to match the lower elevation before placing an aluminum plate over the joint, sloping from the higher elevation to the lower.
In the end, despite logistical challenges, Chamberlin’s innovative and detailed approach allowed the crew to complete its entire project scope on time and on budget. And OU, which secured Big 12 Conference titles in both 2016 and 2017 following the project, enters 2018 with an expanded and upgraded stadium to accommodate its appreciative fan base.
“Chamberlin left the OU Memorial Stadium watertight to serve its fans for years to come,” Brau said. As it turned out, the football program wasn’t the only team to score points there!
Editor’s Note: Chamberlin won 1st place in the Commercial Concrete category for CoatingsPro’s 2018 Contractor Awards Program for this project. Congrats to the crew!