Fire Design of Mass Timber Members: Code Applications, Construction Types and Fire Ratings

For many years, exposed heavy timber framing elements have been permitted in U.S. buildings due to their inherent fire-resistance properties. The predictability of wood’s char rate has been well-established for decades and has long been recognized in building codes and standards. Like heavy timber, mass timber products such as cross-laminated timber (CLT) and nail-laminated timber (NLT) have inherent fire resistance that allows them to be left exposed and still achieve a fire-resistance rating. 

This paper has been written to support architects and engineers exploring the use of mass timber for commercial and multi-family construction. It focuses on how to meet fire-resistance requirements in the 2021 International Building Code (IBC), including calculation and testing-based methods. 

Companion to WoodWorks’ Inventory of Fire Resistance-Tested Mass Timber Assemblies