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Feb 21, 2023 Ricky McLain

What’s the Status of Building Code Allowances for Tall Mass Timber in the U.S.? 

The growth of tall mass timber construction in the U.S. is tied closely to the adoption and advancement of building codes that prescriptively permit its use. The 2021 International Building Code (IBC), initially published in late 2020, was the first version to allow mass timber structures taller than six stories. Changes included in the 2024 IBC, which have already been voted on and approved, will further the options for tall mass timber construction—most notably, increasing allowances for exposed timber ceilings in structures up to 12 stories. 

However, the IBC is far from uniformly adopted. While code language allowing such projects has been in place for several years at the national level, each state—and in some cases, each county or city—is responsible for adopting a given version of the IBC, with or without local amendments.  Some jurisdictions adopt the current version of the IBC soon after it is published. Some are on a cycle of adopting one version, skipping the next, and then adopting the following version on a six-year rotation. Others follow even longer code cycles. As of December 2022, some jurisdictions in the U.S. are enforcing the 2012, 2015, or 2018 IBC. However, a growing number are adopting the tall mass timber provisions of the 2021 or 2024 IBC, either by adopting the 2021 IBC in whole or just the tall mass timber provisions in the 2021 or 2024 IBC. At least 19 states, as well as several cities and counties, have adopted the tall mass timber code language so far. 

To help building developers and designers understand the current landscape of tall mass timber code adoptions and impacts on project design, WoodWorks maintains a list of jurisdictions that have adopted the provisions. For the current list, see the WoodWorks expert tip: Status of Building Code Allowances for Tall Mass Timber in the IBC