Central Roofing Heads Off Problems at New Thrivent® Headquarters
When the doors open in early 2021 on their new glass-and-stone headquarters building in downtown Minneapolis, the 900 employees at Thrivent® will not have to worry about the roof overhead. The team at Central Roofing has installed a waterproof barrier on the eight-story structure to provide long-term protection from harsh Minnesota weather.
Thrivent, a Fortune 500 diversified financial services organization, has 264,000 square feet of open work spaces at its new location. Inside the structure, which connects on the second floor to the Minneapolis Skyway System, employees will find a credit union, coffee shop, chapel, fitness center and underground parking. On the summit of the building they’ll find a rooftop terrace with a fireplace and a natural green roof system.
There are three different roofing systems on the towering Thrivent structure. Once the building was half way through construction, the scope of the roofing project changed. The main roof deck was a poured-in-place concrete deck. Unfortunately the deck never fully cured and held water for an extended amount of time. As a result, the original vapor barrier could not adhere, causing a poor drainage situation.
Central Roofing Company was brought in to find a solution to the problem.
“The main roof was originally supposed to have a fully-adhered EPDM roof,” says Matt Barlau, estimator/project manager with Central Roofing Company. “After many discussions it was decided to change to a Styrene Butadiene Styrene Copolymer (SBS) hot applied roofing system from Johns Manville. This durable roof system is reinforced to accommodate high-traffic situations and does not have drainage issues.”
Right Products for the Roof
To help facilitate the solution, McGough, the general contractor on the project, started by grinding off the top layer of concrete on the original roof deck. The area was then covered with tarps. Blowers were brought in to dry the concrete. That’s when the Central Team got to work installing a 2-ply built-up roof (BUR) vapor barrier in order to hot apply the insulation and roofing membrane.
Additional materials used on the main roof include Johns Manville Dylalastic, Retrofit cover board, Tapered Energy 3 insulation and concrete primer.
“When it came time to roof the skyway system, penthouses and stair tower roofs, we again relied on Johns Manville products,” says Barlau. “This time we did use the fully-adhered EPDM roofing product.”
Moving on to the amenity terraces on levels 2 and 3, Central Roofing used the <Hydrotech® hot fluid applied waterproofing system. Two layers of 60 PSI extruded insulation were used and then Hydrodrain 400 drainage composite. Reinforcement was a prime concern on these roof systems, so Hydroflex 30 protection mat plus a Hydrotech® Monolithic Membrane (MM) 6125 waterproofing systems was installed. To bond all the materials to the deck, Hydrotech®Surface Conditioner was chosen.
Overall, the roofing project includes more than 27,600 square feet of EPDM and SBS roof.
“This alternative worked very well for Thrivent Center,” says Barlau. “The McGough team worked great with us. They even left their tower crane in place for an extra two months. That helped so we had the ability to safely transfer hot asphalt to the main roof for the SBS aspect of the project.”
To help the roof last longer and reduce membrane maintenance, a LiveRoof® Hybrid Green Roof System was installed on the roof. The interlocking trays of plant life were placed over the six-inches of extruded polystyrene insulation. The system provides the look and function of a conventional green roof “membrane” system, but with the turn-key benefits of a modular system.
Finally Hanover® Prest® Pavers were added to the rooftop. Also installed over the extruded polystyrene insulation, the charcoal-colored pavers with a Tudor finish are set in place on pedestals. This way they’re level with door thresholds to meet ADA requirements.
“The finished roof on Thrivent headquarters looks sensational,” says Barlau. “There will be 900 employees in this building. It’s great to know that the rooftop has been set up to serve as an oasis for them in the middle of downtown Minneapolis.”
Thrivent is a diversified financial services organization that helps people achieve financial clarity, enabling lives full of meaning and gratitude. It offers its more than 2 million clients a broad range of financial products, services and guidance. Thrivent and its subsidiary and affiliate companies offer advice, insurance, investments, banking and generosity products and programs over the phone, online as well as through financial professionals and independent agents nationwide. Thrivent is a Fortune 500 company with $152 billion in assets under management/advisement (as of 12/31/19). Thrivent carries an A++ (Superior) rating from AM Best, a credit rating agency; this is the highest of the agency’s 16 ratings categories and was affirmed in June of 2020. For more information, visit Thrivent.com.
About Central Roofing
Central Roofing Company is a nationally-certified woman-owned and operated private corporation based in Minneapolis, MN. Established in 1929 the company has more than 200 union employees. Central Roofing Company focuses on projects for commercial roofing, exteriors service, and metal wall panels. For more information, visit www.CentralRoofing.com.