Underlayment is more than a checkbox

By Emma Peterson. 

Bob Woykin shares why underlayment plays a critical role in the long-term performance of roofs.  

Recently, we had the opportunity to interview Bob Woykin, the director of sales for Sentry Building Innovations' Canadian market. In this role, Bob focuses on “connecting product performance with real-world jobsite needs.” His day-to-day job consists of working alongside the Sentry R&D teams, contractors and other distributors, ensuring that Sentry is building products that “solve problems on the roof — not just in a lab.” 

And one of the biggest factors Bob has seen that differentiates the performance of products in the lab and in the field is how they are used in a system. He explained:  

Everything we do ultimately ties back to system performance. The roof isn’t just shingles or metal — it’s a layered system. If one layer fails, the whole system is compromised. In my role, I focus on making sure the underlayment that Sentry produces don't just work well on its own but does its job reliably as a part of a system.  

What is the underlayment’s role in a roofing system? Too often Bob has seen people overlook underlayment as a small part of the system that they just need to have to be code compliant, but it’s more critical than that. He noted, “In some cases, underlayment is still treated like a commodity — something you check off the list. It can be chosen based on price or habit, not performance.” 

But this couldn’t be further from the truth. Underlayment is not just another layer; it’s a foundational safety net for the entire roofing system. Bob explained, “Shingles shed water — but underlayment is what protects the structure when things don’t go perfectly. Wind-driven rain, ice dams, delayed installs — those are real-world conditions and the underlayment is the final layer that controls the water and keeps structures dry, durable and performing long-term.”