Window Fire Performance Detailed at FGIA Conference
New FSRI research offers data on how glazing and frame materials withstand fire spread, aiding structural hardening and safety specs.
- By Jesse Jacobs
- Mar 17, 2026
Engineers from the UL Research Institutes’ Fire Safety Research Institute (FSRI) presented new data on the performance of window components under extreme fire conditions during the Fenestration and Glazing Industry Alliance (FGIA) Annual Conference.
The session, "How Window Materials Perform Under Fire Exposure," detailed how various glazing and frame materials respond to thermal stresses in structure-to-structure and wildland-urban interface (WUI) scenarios. For OHS professionals and facility managers, the findings provide a technical roadmap for mitigating fire-spread risks and improving the survivability of the building envelope.
“Most of these fires start from an ember,” said Gavin Horn, FSRI Research Director. “If those embers find a receptive fuel bed, they can directly ignite structures. We can take this information and help better prepare future homes by looking at individual components in a controlled manner.”
FSRI engineers Daniel Gorham and Joseph Willi identified building susceptibility as a function of fuel load, distance, and environmental factors. They emphasized that "hardening" a structure requires an integrated approach where the interface between the roof, siding, and fenestration products is treated as a singular safety system.
The study utilized structure-to-structure fire spread experiments to evaluate vinyl, aluminum, fiberglass, and wood frames. Key technical takeaways for safety engineers include:
- Glazing Specification: Assemblies with tempered glass on both the interior and exterior panes showed the highest resistance to thermal failure.
- Thermal Ignition Risks: Researchers warned that radiant heat transfer through glazing can ignite interior combustibles even if the window remains physically intact—a critical consideration for indoor material storage and workstation placement of the exterior wall.
- Frame Integrity: The research categorized "window events" such as back-side smoke and sash failure, noting that frame material is just as vital as the glass in preventing a breach. Vinyl and wood frames showed the highest susceptibility to early failure.
- Mitigation Materials: Preliminary data suggests that secondary protections like fiber cement board and intumescent wraps can significantly delay assembly failure.
The FSRI has conducted more than 50 building-to-building fire spread experiments to date. These findings are currently informing the evolution of safety codes and standards, providing OHS professionals with the data needed to make evidence-based decisions on structural fire protection.
About the Author
Jesse Jacobs is assistant editor of OHSOnline.com.