TechnicalSolutions
Fire Testing Completed on Full-Scale Mass Timber Building with Promising Results Kenneth Bland During the decay phase of test three, the charred surface of exposed CLT is visible. (Two-story cross-laminated building fire tests; Beltsville, Maryland; June 2017) Photo credit: Sam Zelinka (FPL)
While heavy timber construction (Type IV in U.S. building codes) is one of the oldest wood construction methods recognized in the codes, there are promising new framing technologies that have expanded what’s possible within this category using mass timber. This category differs markedly from traditional lightweight wood construction more commonly seen in the U.S. and building with these new mass timber structural systems represents the first significant challenge to concrete and steel in more than a century. However, as they gain broader acceptance among building designers for a variety of low- to mid-rise building types, the next hurdle to overcome is height and number-ofstory limitations set by the International 38
Building Code (IBC), which are currently 85 feet and six stories tall, respectively. Other countries have already begun to realize the benefits of tall wood building construction, including its low carbon footprint, ease of construction and reduced construction time, to name a few. From the Brock Commons Tallwood House demonstration project in Canada to Treet in Norway, several tall wood buildings have emerged across Canada, Europe and other parts of the world as interest mounts to find safe, carbonneutral and sustainable alternatives to incumbent structural materials of the urban world. To address current barriers and help create a pathway for high-rise mass timber
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buildings in the United States, the International Code Council (ICC) formed an Ad-hoc Committee on Tall Wood Buildings in 2015 to research the building science of tall wood buildings. This is a multi-year effort supported by numerous working groups made up of stakeholders, design professionals, code officials and other interested parties who are investigating the feasibility of and taking action to develop code changes for the use of mass timber in taller or “beyond current code” buildings. The goal is to introduce code provisions for the 2021 code cycle, with non-structural provisions expected to be submitted for consideration during 2018, and structural provisions to be submitted for review and approval during 2019.