Milestone Unveiled for Planned Tallest Mass Timber Office Building in US

A proposed office tower in the United States could soon become the tallest mass timber building in North America, marking a significant shift in modern architecture and sustainable construction practices. The project, named Bevel, is set to rise in downtown Bellevue, Washington, and stands at 12 stories with a height of 55 meters (180 feet). Designed by Mithun and Waugh Thistleton Architects (WTA), the building is being developed by Skanska, a firm known for large-scale projects such as MetLife Stadium in New Jersey and the iconic "Gherkin" in London. According to Skanska, Bevel is currently awaiting necessary approvals, though the developers believe its success hinges on treating timber not just as a supplementary material, but as the central element of the design process. If approved, the project would demonstrate that mass timber can be used effectively and economically on a large scale in commercial settings. One of the main challenges the team has faced involves interpreting existing building codes for a type of structure that has not yet been constructed in the U.S. While timber housing projects have been permitted under Type IVB construction provisions, which allow the use of mass timber or non-combustible materials with fire-resistance ratings, no commercial office building has yet been built under these regulations. According to WTA, Bevel's exposed timber structure is intended to push the boundaries of what is allowed under current codes, maximizing the height and story limits permitted by them. The announcement of Bevel follows another significant achievement in timber construction. Earlier this year, the Atlassian Central tower in Sydney, Australia, became the world's tallest hybrid timber tower, reaching over 180 meters (approximately 590 feet). Bevel is notable not only for its potential height but also for its innovative approach to design. Jennifer Cover, president and CEO of WoodWorks, highlighted that the project expands the possibilities of mass timber construction. She noted that while there are 22 tall timber buildings either under construction or already completed globally, only three are commercial. Bevel's design includes 100 percent exposed timber ceilings, offering a new model for architects and developers considering similar projects. Initially, the team considered designing Bevel as a conventional concrete office building alongside a mass timber version. However, after comparing costs, they found that designing specifically for timber resulted in nearly equal expenses compared to a traditional office building. This approach allows for the full exposure of mass timber columns, beams, and ceilings throughout the office floors and public spaces on the ground level. These structures will be supported by a steel core and lateral system, given the high seismic activity in the region. Additionally, the building will feature a concrete parking garage extending five levels underground. Beyond its structural innovation, Bevel is targeting LEED v4 Platinum certification, the highest standard within the U.S. Green Building Council's green building rating system. The sustainability efforts encompass integrated stormwater reuse systems, energy-efficient building technologies, including full electrification, and a site design focused on promoting biodiversity. The design incorporates biophilic elements, such as a nature-infused lobby with floor-to-ceiling windows, providing abundant natural light through full-height perimeter windows. These features collectively aim to create a more natural and welcoming work environment. The project underscores a growing trend toward using renewable resources in large-scale construction. As cities seek to reduce carbon footprints and embrace sustainable practices, the use of mass timber offers a compelling alternative to traditional materials. With Bevel potentially setting a precedent, future developments might increasingly consider timber as a primary building component, especially in urban environments where environmental impact is a critical concern.