Building a roof that lasts

By Duro-Last.

How Duerson and Duro-Last delivered long-term protection to the Grinnell Mutual Reinsurance facility in Iowa.

Iowa might make headlines more often for their role as part of the infamous tornado alley in the United States, but that’s far from the only weather events the state sees. The Grinnell Mutual Reinsurance’s facility saw this firsthand in 2024 when a severe hailstorm left their roof in need for some care and repairs. They turned to a local contractor, Duerson Corporation. One of their sales managers, Jake Viggers, shared how it went down, saying, “We were contacted on a Sunday night and by Monday morning, we were already on-site, tarping the building and planning the next steps.” Duerson’s work on repairing the 135,000 square foot facility not only secured the facility, but it also netted them one of Duro-Last's 2024 Project of the Year Awards.

Going into the project, Grinnell Mutual’s primary concern was installing a system capable of withstanding future hailstorms, ensuring they wouldn’t face the same disruption again. Working closely with Duro-Last, Duerson Corporation devised a solution built around durability and weather resistance. The reroofing project covered 135,000 square feet and featured Duro-Last 60 mil tan membrane, chosen to match the facility’s previous color scheme. For added hail protection, Duerson incorporated DensDeck StormX Roof Board, a high-performance hail board designed to absorb impact, into the assembly. “Grinnell Mutual trusted us to recommend the best solution and they were fully on board when we explained the benefits of the proposed assembly for long-term protection,” Jake said.

The installation was complex, with different roof deck types requiring varied approaches. For areas with a metal deck, the Duerson team mechanically fastened the insulation and membrane. In sections with a gypsum deck, they fully adhered the system to avoid penetrations that could compromise the integrity of the deck. Across both deck types, two layers of Duro-Guard ISO insulation were installed, meeting an R-30 rating to ensure the building’s energy efficiency.

Sustainability played a major role in the project, aligning with the values of both Duerson and Grinnell Mutual. Duerson recycled the entire 135,000 square feet of the old Duro-Last membrane, along with the 95,000 square feet of Duro-Last tarp material used during the emergency storm response, through Duro-Last’s Recycle Your Roof program. “We’ve worked closely with Duro-Last’s plant in Sigourney, Iowa, for years and being able to recycle that much material was significant for both the project and the environment,” said Riley Duer, project manager at Duerson. The recycled materials were repurposed into new roofing products, including ROOF-TRAK III Walkway Pads, similar to those installed on the Grinnell Mutual roof. “It’s important to me personally to know we’re reducing waste and doing what we can for the next generation,” Riley added.

Another significant aspect of the project was the extensive exterior damage caused by the hailstorm. Duerson replaced more than 5,500 square feet of metal wall panels with EXCEPTIONAL Metals’ CF Mesa Insulated Wall Panels, as well as edge details and accessories. This included coping caps, gutters, downspouts and a variety of edge treatments, ensuring a seamless, durable and aesthetically consistent finish. “EXCEPTIONAL Metals gave us the flexibility to customize the edge treatments across different parts of the building, something many other manufacturers wouldn’t have been able to offer,” Jake said.

To ensure the project remained on schedule despite weather challenges, Duerson utilized both custom-fabricated deck sheets and roll goods to address the roof’s unique specifications, minimizing on-site labor. Upon completion, the Grinnell Mutual team was not only thrilled with the installation quality but also with the peace of mind that came from having a comprehensive 15-Year NDL Warranty from Duro-Last, offering Edge-to-Edge & Deck-to-Sky™ protection. “They were really pleased with the single-source solution we provided and the fact that it all came with one warranty,” Jake said. “If anything ever comes up, its one phone call.”

Make sure to check out this video from Duro-Last to see the whole project!