In January 2019, the International Code Council (ICC) approved a set of proposals to allow tall wood buildings as part of the 2021 International Building Code (IBC). Based on these proposals, the 2021 IBC will include three new construction types—Type IV-A, IV-B and IV-C—allowing the use of mass timber or noncombustible materials. These new types are based on the previous Heavy Timber construction type (renamed Type IV-HT) but with additional fire-resistance ratings and levels of required noncombustible protection. The code will include provisions for up to 18 stories of Type IVA construction for Business and Residential Occupancies. Based on information first published in the Structural Engineers Association of California (SEAOC) 2018 Conference Proceedings , this paper summarizes the background to these proposals, technical research that supported their adoption, and resulting changes to the IBC and product-specific standards.

Learning Objectives:

1. Recall the efforts of the ICC Tall Wood Building Ad Hoc Committee and Group A proposals
2. Compare existing IBC construction types with requirements for new construction types, to include fire protection features
3. Visualize representative allowable building sizes as prescribed by the TWB Ad Hoc Committee
4. Summarize and discuss standards updates and next steps for tall mass timber construction