PVC System Is the Answer for U.S. Bank Stadium Roof

U.S. Bank Stadium is topped with a PVC roof system that display’s the company’s logo. Photo: Johns Manville

When discussions began about the new U.S. Bank Stadium in Minneapolis, Minnesota, there was a request for an outdoor stadium. However, state and local government provided funding specifically for an indoor stadium that would be able to host major events like the professional football championship game and the college basketball championship game. As a result, a translucent roof and mobile front windows were designed to allow natural light to enter the stadium and to give fans a view of downtown Minneapolis. The mobile windows also allow fans to experience outdoor elements while providing protection from snow, rain and cold winter weather. The roof design was developed taking into consideration the budget and the region’s weather; it would be costly to make it retractable, and a sloped roof lends to a more secure option for snowy weather.

Challenging Task

Berwald Roofing Company Inc., headquartered in North St. Paul, Minnesota, installed an adhered PVC roof system manufactured by Johns Manville over the structure’s metal deck. In all, 280,000 square feet of grey 60-mil PVC were installed. The system also included a vapor barrier and two layers of 1.6-inch ENRGY 3, a rigid roof insulation board composed of a closed-cell polyisocyanurate foam core with fiberglass reinforced facers. Half-inch DensDeck Prime cover board from Georgia-Pacific was also installed.

The roofing portion of the project began in April 2015, with an aggressive completion deadline of November 1, 2015. The schedule and logistics on the project posed major hurdles. “Getting material 300 feet up to the roof was our biggest challenge,” says Berwald Roofing Senior Project Manager Steven Hegge. “A big part of that was scheduling time to share the cranes with the iron workers and general contractor.”

Another challenge was storing material during the installation due to the limited amount of space on the roof. “All the decking had to be installed as we went along, just before roof installation,” Hegge states. “We were on a very tight time schedule in this multiple-phase construction project.”

“The general contractor and Berwald Roofing have worked with Johns Manville on numerous stadium projects in the past and preferred to use JM PVC on this complicated stadium project,” notes Johns Manville sales rep Bob Deans. “This application is on a 3.75-inch to 12-inch slope on the north side of the building, which adds to the difficulty of installing a fully adhered PVC roof assembly.”

The Solution

Due to restricted loading space at the jobsite, materials arrived to Berwald’s yard directly from the manufacturer. They were then loaded on Berwald Roofing semi-trucks each day for delivery. Once they arrived at the site, they were immediately lifted to the roof via tower cranes and installed in the most efficient time frame, to meet the owners expected installation timeline.

The stadium seats approximately 65,000 people for most games. However, this space is built to be expandable to hold up to 73,000 attendees for special events such as the professional football championship game, which the stadium is scheduled to host on February 4, 2018, and for events like the college basketball championship game, which will be held there in 2019. U.S. Bank’s logo is prominently displayed on the rooftop. Charcoal grey 60-mil PVC membrane was cut to specification using a computerized cutter to create an exact replica of the U.S. Bank logo. Berwald Roofing then adhered the charcoal grey PVC on top of the grey 60 mil PVC membrane using JM PVC low-VOC membrane adhesive and then heat-welded the edges of material to finish the application of the logo.

TEAM

Architects: HKS Inc., www.hksinc.com; Studio Hive, www.studiohive.com; Studio Five; and Lawal Scott Erickson Architects Inc., http://lse-architects.com
General Contractor: Mortenson Construction, Minneapolis, Minnesota, www.mortenson.com
Roofing Contractor: Berwald Roofing Company Inc., North St. Paul, Minnesota, https://berwaldroofing.com

MATERIALS

Roof System: 60-mil PVC, Johns Manville, www.jm.com/roofing
Vapor Barrier: Johns Manville
Insulation: ENRGY 3® Insulation, Johns Manville
Cover Board: DensDeck Prime, Georgia-Pacific, www.gp.com

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