Structures
The United States has seen a slow , but growing adoption of mass timber as a building material over the last decade. From a sustainability standpoint, the switch to mass timber represents significant opportunities to reduce carbon emissions and promote sustainability goals. From a building and operational standpoint, mass timber is typically prefabricated, which reduces inefficiencies in the construction process–leading to less money spent on things like labor and fuel. According to Dennis Mordan, Vice President and Principal at O’Donnell & Naccarato, with such clear benefits for sustainability and efficiency, one of the biggest factors keeping mass timber from being adopted more widely is a lack of knowledge about its benefits and usage. Since 2019, Mordan has been using mass timber in O’Donnell & Naccarato’s projects. Still further, Mordan and his team are dedicated to spreading the word about the benefits of mass timber–forming an AIA-accredited program known as “Mass Timber 101.” Mordan understands that architects and contractors are reluctant to use unfamiliar materials, and that they will rely on and trust their experiences. Along with this unfamiliarity and hesitancy comes higher estimates. Understanding this, Mordan and his team designed “Mass Timber 101” to introduce architects, contractors, and developers to not just the basics of mass timber but the specifics. This includes both introducing the larger concept of mass timber–through materials such as CLT–and diving into relevant technical information such as code requirements, acoustics, connections, long term creep, vibration, and fire ratings. Another major component of the “Mass Timber 101” course are discussions about sourcing, which has historically been a limiting factor for wider mass timber adoption. For Mordan, this introduction to mass timber serves an important function in that it also provides important contextual information for its specific usage. More than just stopping at an introduction to the concept, “Mass Timber 101” allows architects, contractors, and developers to consider how these materials and processes can be adopted on their own projects. While better education is a major factor limiting the wider adoption of mass timber projects in the United States, potential issues with material sourcing can also greatly limit its wider use. Mordan also points out that, as mass timber becomes more popular in the United States, issues with sourcing will continue to exist. Mordan cites their recent project at 675 E. Swedesford Rd as an example of how sourcing materials can be a challenge for mass timber projects in the United States. With the project located in Pennsylvania, Mordan says they considered sourcing mass timber projects from two places: Germany and Canada. The decision to source materials from Germany over Canada, according to Mordan, was made because it carried a lower overall carbon footprint through the logistical chain. Issues with sourcing mass timber products in the United States are further compounded by standards for things Mass Timber in the United States: Part II By Luke Carothers
like glue for lamination. For projects in the United States using mass timber products, sourcing decisions often influence their overall design and aesthetic. Each species of tree has a different strength, and, of course, aesthetic appearance. However, Mordan believes that, as more manufacturers come online in the future, lead times for sourcing mass timber projects will continue to decrease. In the meantime, he suggests that these projects be open to considering alternative sourcing, which can again alleviate long lead times for mass timber projects. When speaking about the present and future of mass timber projects in the United States, Mordan outlines the immediate importance of hybrid mass timber projects like their Swarthmore College project, which features a second floor and roof made from mass timber as well as a traditional ground floor with steel beams, a metal deck, and concrete. These hybrid mass timber projects are a way to introduce contractors and architects to the nuances of using mass timber in their work. Furthermore, Mordan points out that these hybrid mass timber projects are more likely to pass with local code officials who might not be familiar with mass timber and, as such, are wary to approve entire projects constructed from mass timber. As more of these hybrid mass timber projects are introduced and completed, the popularity and industry knowledge surrounding these projects will continue to increase. Mordan believes that, over time, AEC professionals will become “more embolden '' to trying mass timber for new hybrid uses, which will only further generate excitement. For Mordan, the need for education, adoption, and innovation around mass timber is a way of moving mass timber from a “small category” within the AEC profession to unlocking its larger potential as a sustainable, safe building material. Through educational efforts like Mass Timber 101–which he has given to AEC professionals across the United states–and projects that are innovating its use in the United States, Mordan and the rest of the team at O’Donnell & Naccarato are demonstrating a well-founded belief that mass timber has the potential to drastically improve the way we approach designing and building structures in the present and future.
LUKE CAROTHERS is the Editor of Civil + Structural Engineer Magazine. If you want us to cover your project or feature an article, he can be reached at lcarothers@zweiggroup.com .
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csengineermag.com
September 2023
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