MADISON, Wis. — Neutral, a real estate development company focused on creating sustainable and healthy mixed-use communities, has presented the results of a 3-hour fire test for a hybrid mass timber building assembly with standard connectors.

Neutral conducted a series of fire resistance tests to determine a 3-hour fire-resistance rating (FRR), proving equivalent performance of the mass timber structure with IBC construction type I-A. Test results exceeded expectations: the assemblies performed exceptionally under loaded fire conditions.

"One major challenge for the success of, not just the Edison, but future tall timber buildings across the industry, was that many standard connection configurations had never been tested under a 3-hour fire-resistance rating (FRR)-a requirement essential to advancing tall mass timber construction, following the fire rating standards for IBC construction types I-A," explains Josh Dortzbach of Forefront Structural Engineers.

The test was conducted in the Spring of 2025 at SwRI lab in San Antonio, Texas. It was prepared in collaboration with Forefront Structural Engineers, Arup as fire protection engineers, CDSmith as the general contractor, HPA as the architect, and other industry professionals.

"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," says Daniel Glaessl, partner and chief product officer at Neutral

Neutral is publishing the test results (report 1, report 2) for open use by industry researchers and practitioners around the world. This is the first successful implementation of the three-hour fire test of a mass timber assembly that illustrates the safety and potential of mass timber application in high-rise construction.

Tests of such complexity are often cost-prohibitive for private developments. By publishing the results in the open domain, Neutral hopes these results can be used as a reference for the proliferation of more sustainable development across the United States and the world.

"As we look to build more sustainably, there is value in making fire resistance tests available so that they can be utilized by other developers and designers as part of their justification for a high-rise mass timber building," says David Barber of Arup, a leading fire safety engineer.

The final round of column tests took place in late August 2025 and passed. The project team will soon publish its report as well.

For the full report and list of contributors, visit neutral.us.