Building for Wildfire Resilience: How Fiberglass Windows Improve Protection Cascadia Windows & Doors

2025.08.05

Wildfires Are Changing the Building Landscape

Wildfires are becoming more frequent, more intense, and more destructive across North America. According to the Canadian Interagency Forest Fire Centre, the 2023 wildfire season burned nearly 18 million hectares of land, far exceeding the 10-year national average. In the U.S., states like California continue to experience record-breaking fire events that threaten entire communities.

As wildfires increase in severity, architects, engineers, and builders are under growing pressure to design structures with increased odds of surviving these new extremes. Jurisdictions like British Columbia and California have updated their building codes and guidelines to prioritize wildfire resilience, particularly in Wildland-Urban Interface (WUI) zones. These are the areas where development meets natural vegetation, and where building materials and design choices matter most.

Why Windows Are Often the Weakest Link

In any building envelope, windows are often the most vulnerable component during a wildfire. Even if the walls are fire-resistant, a window failure can allow radiant heat, flame, or embers to enter the building and destroy it from the inside out.

There are two main points of failure. First, thermal breakage of the glass can occur when the outer pane quickly heats up unevenly, causing it to crack or shatter. Second, thermoplastic window frames like vinyl can melt, deform, or ignite under high heat, compromising the entire opening.

Think of it like sunscreen. A high-SPF product does not make you immune to sunburn, but it gives you more time and protection. Wildfire-resistant windows work in a similar way. They cannot stop every fire, but they offer much greater resilience under extreme conditions.

Despite the growing wildfire risk, many designers remain unaware of how much window frame materials vary in their ability to resist fire. With limited standards and little widespread industry guidance, that’s understandable. But it also means many buildings may be more vulnerable than they need to be. That’s where fiberglass comes in.

Fiberglass Windows: Built to Withstand the Heat

Fiberglass window frames offer clear advantages over traditional materials when it comes to fire performance. Unlike vinyl, fiberglass does not melt or deform when exposed to heat, and it resists ignition at higher temperatures. It is one of the frame materials recommended by FireSmart and Natural Resources Canada’s wildfire construction guidelines.

California, which leads North America in wildfire building standards, lists fire-resistant windows as the top requirement for new home construction in high-risk areas. While Canada is still building awareness, California has already prioritized wildfire resilience in both policy and practice. Vinyl frames, by contrast, are typically not recommended due to their tendency to fail early under heat.

Cascadia is the first and only Canadian window manufacturer to have passed wildfire exposure testing. Our Universal Series™ fiberglass windows were evaluated by RDH Building Science using procedures based on California’s State Fire Marshall 12-7A-2 standard, which simulates direct flame exposure in a wildfire scenario. All tested windows met the performance criteria, showing strong resistance to heat, flame, and structural failure.

Full certification through an accredited lab is currently underway, but these early results offer compelling validation of fiberglass as a high-performance solution for wildfire-prone environments.

These test results highlight the important role that material selection plays in wildfire resilience. Choosing the right window system can significantly reduce vulnerability and help protect structures in high-risk areas. As building codes and best practices continue to evolve, staying informed about the latest wildfire-resistant technologies and standards is critical for architects and builders.

Join Us to Learn More About Wildfire-Resilient Windows

Want to dive deeper into the risks and design strategies for wildfire zones? Join our free webinar: Wildfire Resistance: Window Strategies for Wildland-Urban Interface (WUI) Design.

We’ll cover key fire exposure mechanisms, guidance from California and FireSmart BC, and how to specify high-performance window systems that meet the demands of wildfire-prone environments.