The Fenestration and Glazing Industry Alliance (FGIA) has released a long-awaited update to its technical guidance on preventing glass breakage in insulating glass units (IGUs), addressing one of the most persistent and costly challenges in fenestration and glazing.

The newly revised document, IGMA TR-3401-25: Preventing Glass Breakage During IGU Design, Manufacture, Transport, Installation and Use, replaces guidance that had remained unchanged since 1996. The update reflects decades of industry experience, evolving design practices, and a deeper understanding of how glass fails under real-world conditions.

At its core, the document reinforces a fundamental principle: glass breakage occurs when stresses from applied loads exceed the strength of the glass. While this may seem straightforward, FGIA emphasizes that glass strength is highly variable and is often compromised by microscopic damage to edges, corners, and surfaces. Even small, nearly invisible scratches can act as stress concentrators, dramatically reducing the load the glass can withstand.

The report also highlights the role of static fatigue, a critical but often underestimated factor in delayed glass failure. Under sustained loads, such as snow accumulation on skylights, continuous weight on glass shelving, or water pressure in aquariums, tiny flaws in the glass can slowly propagate. As a result, visible fractures may appear hours, days, or even months after the initial load is applied, long after installation is complete and responsibility becomes harder to trace.

IGMA TR-3401-25 takes a comprehensive, lifecycle-based approach to prevention. It addresses:

• IGU design considerations for applied loads and support conditions
• Fabrication practices that minimize edge and surface damage
• Proper storage and transport methods to reduce handling-related defects
• Installation practices that avoid unintended point loads and restraint
• Use-phase considerations that account for long-duration loading scenarios

By linking design, manufacturing, logistics, installation, and end use, the updated guidance recognizes that glass breakage is rarely caused by a single mistake. Instead, it is often the cumulative result of small decisions made at multiple stages of a project.

For manufacturers, processors, façade contractors, and specifiers, the revised document serves as both a technical reference and a risk-management tool. Applying its recommendations can help reduce unexpected failures, improve long-term performance of IGUs, and limit disputes related to delayed breakage.