The origin of a better pipe flashing

By Jesse Sanchez.

A roofer’s frustration sparked a solution that’s reshaping pipe penetration practices on shingle roofs.

In this episode of Roofing Road Trips®, host Karen Edwards begins by highlighting a common theme in the industry: many innovations are born from the frustrations contractors face on the job. She invites Dennis Vowles, founder of Garrdal Corporation, to share how his own experiences led to the development of his original product.

That question opens the door to a candid story of persistence, practicality and innovation — one that led to the creation of Garrdal, a patented retrofit pipe flashing system designed to solve a problem that roofers had been hacking their way through for decades.

“I put hundreds of split boots on houses, and I knew there was going to be a problem at some point,” said Dennis, recounting how traditional split boots often failed in the harsh winters. “Snow would come down the roof, pop the clips off. So, roofers would cut up two, three-in-one and put them back together around a pipe with a bunch of sealant… it looked kind of janky, but they trusted it more.”

That hands-on experience, combined with a need for a clean, lasting solution, drove Dennis to develop Garrdal. But it wasn’t easy. Initially resistant to plastics, he sought a metal-based design — until a conversation with an engineer changed his perspective.

“He said, ‘well, what if we could find a plastic with all the properties of metal, but it ships lighter and doesn't dent or rust’ And I thought, okay,” Dennis said. The result was a rigid-base design that physically presses the gasket against the pipe, maintaining a tight seal — even if the pipe moves.

Dennis noted that Garrdal’s strength lies not only in its functionality but in its durability. “We put a Garrdal in front of a hail gun… seven times it got hit and there was no impact,” he said. “It didn’t have any effect.”

The real power of Garrdal, however, might be in its relatability. It wasn’t cooked up in a lab — it was born from years on rooftops, encountering the same challenges thousands of roofers face. That kind of straightforward thinking, rooted in real-world experience, is exactly what makes the product resonate with contractors.

With Garrdal now available in over 1,600 dealer locations and used on shingle roofs across North America, it’s become a solution that’s both innovative and, crucially, familiar to the contractor's eye. And as Dennis continues to expand the product line with models for steeper pitches and lower profiles, one thing is clear: this isn’t just about solving leaks — it’s about raising the standard.

Read the transcript or Listen to the podcast to learn how this humble invention grew into a game-changer in the roofing world — and why some contractors regret not following through on the same idea decades ago!