Milwaukee Mass Timber Tower Advances With Breakthrough Fire Test

On Monday, Neutral released results from the first successful three-hour fire-resistance test of a hybrid mass timber building assembly with standard connectors, a milestone the company says will help advance high-rise timber construction.

Neutral is a real estate development company focused on creating sustainable and healthy mixed-use communities in Madison, Wisconsin, and San Jose, California. Its project in Milwaukee—The Edison—is slated to become the tallest composite mass timber building in the US. The structure will include CLT floor decks manufactured by Stora Enso and glulam beams and columns by WIEHAG.

One of the major challenges for the project team was that many standard connection configurations had never been tested under a three-hour fire-resistance rating (FRR)—a requirement for International Building Code (IBC) Type I-A construction.

As part of the building permit variance process for The Edison, Neutral conducted fire-resistance tests at the Southwest Research Institute laboratory in San Antonio, Texas. The tests evaluated glulam beams and columns in combination with off-the-shelf concealed connectors from Simpson Strong-Tie and WIEHAG.

Test results exceeded expectations, and the assemblies performed exceptionally under loaded fire conditions. Neutral said intumescent fire tape significantly contributed to limiting charring and protecting the connection region throughout the duration of the fire.

“This is the first successful implementation of a three-hour fire test on a mass timber assembly using standard, concealed connectors—demonstrating that tall timber systems can meet the highest fire-resistance requirements for high-rise construction,” the company said.

The tests were carried out in collaboration with Forefront Structural Engineers, Arup, CDSmith, HPA, and other industry professionals. Neutral has published the results for open use by researchers and industry practitioners worldwide.