Proving Performance - Reflections on a 3h Mass Timber Fire Test

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As structural engineers, we’re often asked to advocate for new systems, while also being responsible for public safety, durability, and long-term performance. That balance is exactly why participating in a full-scale, 3-hour mass timber fire test was so important to us at Forefront Structural Engineers. Working closely with Neutral Architects on projects like The Edison, we’ve seen firsthand how questions around fire performance can shape design decisions early. This test provided an opportunity to move beyond assumptions and codes alone, grounding those conversations in real, measured data. Read the test results here.

Mass timber continues to gain momentum across the U.S., but fire performance remains one of the most common, and understandable, questions from building officials, developers, and design teams. While prescriptive code pathways exist, there’s no substitute for real data gathered under real test conditions. This test was designed to push beyond minimum requirements and better understand how exposed mass timber assemblies behave during extended fire exposure.

The results were compelling. The tested assembly successfully achieved a three-hour fire resistance rating, demonstrating predictable charring behavior and structural stability well beyond typical design expectations. Rather than failing suddenly, the timber performed as intended: the outer char layer formed and protected the remaining section, preserving load-carrying capacity throughout the duration of the test. From an engineering standpoint, this kind of performance reinforces what many of us have understood analytically, but now can point to empirically.

For us, the value of this test goes beyond a single rating. It gives designers, authorities having jurisdiction, and owners confidence; confidence that mass timber can be deployed responsibly in larger, taller, and more complex buildings when supported by thoughtful detailing and rigorous analysis. It also provides clearer guidance on where encapsulation may or may not be necessary, helping teams balance life safety, cost, and architectural expression.

Perhaps most importantly, this effort reflects the collaborative spirit required to move the industry forward. Developers willing to invest in testing, fire protection engineers shaping the methodology, and design teams aligning around shared goals all played a role. As structural engineers, our responsibility is to synthesize that information into practical, code-compliant solutions that work in the real world.

At Forefront, we see this test as another meaningful step in the evolution of mass timber construction in the U.S. It reinforces our belief that innovation doesn’t come from shortcuts, it comes from doing the work, testing assumptions, and letting data lead the conversation. We’re proud to have been part of this effort and excited about how it will inform safer, more sustainable buildings in the years ahead.

True sustainability demands deep collaboration among developers, engineers, manufacturers, contractors, and future building users. Together, we’re not just building better buildings, we’re engineering a more sustainable future.” - Daniel Glaessl, Partner at Neutral