A retrofit flashing reshapes rooftop problem solving

By Jesse Sanchez. 

A long-time roofer shares how firsthand experience led to a practical flashing solution built for modern roof obstacles and demanding climates. 

Garrdal Corporation emerged from decades of real-world roofing experience and a penchant for solving recurring problems many contractors know too well. During this episode of Roofing Road Trips®, Heidi J. Ellsworth spoke with Dennis Vowles, founder of Garrdal Corporation, about how frustration in the field can evolve into an innovation with lasting impact. 

Dennis traced the idea behind Garrdal to challenges he encountered often throughout his career. After starting out in Canada and relocating to the United States in the 1990s, he spent more than four decades working on roofs and repeatedly ran into the same limitation: standard pipe flashings worked well, but only when conditions were ideal. As soon as electrical wires, masts or other obstructions were involved, installations became inconsistent and unreliable. As Dennis explained, “Most roofers in Canada, we would cut up two, three in ones because nobody trusted what was out there or they’d reuse the old one, which is not a great solution.” 

That frustration ultimately shaped the product’s core design philosophy. Rather than forcing a flashing over obstacles, the two-part system was engineered to install around them. “This is designed to go around those obstacles rather than over them,” Dennis said. It became a solution that preserves watertight performance without disturbing surrounding roof components. The product’s name also reflects its personal roots. Dennis shared, “[Garrdal] is actually named after my sons, Garrett and Dalton.” 

Since its introduction in the late 2010s, the product has steadily expanded its footprint. Dennis noted that Garrdal is now available through roughly 1,300 dealers nationwide, with distribution continuing to grow in Canada. Even when a local branch does not stock it, the product is often still accessible. “A SKU can be found, even if a store doesn’t stock it yet, we’re in their system so they can order it for the roofers,” he added.  

Material performance was another major focus during development. Early skepticism about plastics gave way to research into modern polymers built for extreme exposure. “Plastics have changed in the last 40 years,” Dennis said. “We can make it bulletproof and see-through and that’s the same product.” That process led to the use of Copaline and Santoprene for UV resistance and performance in both heat and cold. 

Ease of installation and appearance were equally important. Dennis emphasized that the flashing installs quickly and blends in visually. “Garrdal looks like new construction from the ground,” he said, noting its value during repairs where shingles do not need to be replaced. 

Looking ahead, Dennis sees growing demand for adaptable rooftop accessories as systems continue to evolve. He also stressed the importance of education, advising contractors to keep learning as a way to make room for innovative ideas. 

Read the transcript or Listen to the podcast to learn more about Garrdal, its product design and how contractor-led innovation continues to influence rooftop accessory solutions!