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Now, with the unveiling of its newly renovated main terminal, PDX has reached new heights by embracing innovative design and sustainable building practices with a massive, undulating, 9-acre roof made from ultra-durable mass timber. This ambitious project, a decade in the making, involved a $2 billion transformation by a great team. The result is a stunning architectural achievement that pays homage to the Pacific Northwest's rich timber heritage while setting a new standard for sustainable airport design.
Instead of relying on traditional steel and concrete, the project team boldly decided to pursue the terminal's iconic roof using 3.5 million board feet of wood in total, sourced from forests within a 300-mile radius of the airport. This “forest to frame” approach, as described by Metropolis Magazine, is akin to the farm-to-table movement in the culinary world. It prioritizes local sourcing, reduces transportation costs and emissions, and supports the regional timber industry.
This commitment to sustainability extends beyond just the material selection. The project team, driven by a desire to "source all this wood in a way that is better for our forests and communities,” prioritized sourcing wood from landowners working to restore forest ecosystems, including small landowners, community forests, and sovereign tribal lands. That goal resulted in 100% of the 3x6" lattice timbers and 93% of the glulam being sourced from FSC-certified forests and landowners meeting the highest standards of sustainable forestry practices.
This allowed the team to implement a pioneering system to track as much of the wood as possible back to its origin. One million of the 2.6 million board feet comprising the glulam and lattice structures can be directly traced back to its forest of origin, including specific details about the landowners and their sustainable practices.
Wood for the project came from a variety of sources, including small landowners, community forests, and even tribal lands. Anne Niblett of the Coquille Indian Tribe, whose forest in southwestern Oregon, provided wood for the roof’s glulam beams, eloquently captured the essence of this collaboration, stating, "To me, it’s a beautiful love story, of what happens when people and the land come together" in Metropolis Magazine.
Chris Pitt, PE, SE, LEED AP , structural project manager and lead structural engineer for the new roof with KPFF Consulting Engineers, noted the complexity of "building a new terminal over an existing, operating terminal". The team relied heavily on prefabrication and modular construction techniques to overcome these obstacles.
Constructed offsite in 14 massive rectangular sections, known as modules, the roof was then meticulously assembled over the existing terminal in a carefully choreographed operation. This approach minimized disruption to airport operations while ensuring the highest precision and quality in the construction process. “In August 2022, when the terminal site was ready, the three prefab/modular roof sections were temporarily disassembled into varying-sized modules, the largest being 240-by-140 feet and weighing 1.4 million pounds. These modules were then rolled via a self-propelled modular transporter and slid into place over the terminal. The installation took place over a three-and-a-half-month period during an FAA-regulated window at night and when there were no people below the construction area.” - Christian Schoewe, Principal, ZGF Architects.
Jacob Dunn , a principal at ZGF Architects, highlighted the psychological benefits of incorporating natural elements into the built environment. “Just the exposure to natural wood material in a non-uniform pattern has a psychological effect on us,” Dunn explained - Forbes. The terminal's design incorporates an abundance of natural light, thanks to 49 strategically placed skylights that bathe the interior in soft, diffused daylight. Adding to the serene ambiance is a carefully curated collection of 72 mature trees, including black walnut, ficus, and olive trees, which thrive under the soaring timber beams and skylights.
Acoustic design played a crucial role in mitigating noise pollution and creating a calm and comfortable atmosphere. The latticed ceiling system, inspired by regional weaving traditions, serves a dual purpose – it not only adds visual interest but also acts as a sound dampener, trapping noise and creating a more peaceful environment for travelers.
The project stands as a testament to what can be achieved when stakeholders from across the timber industry, from foresters to architects, come together with a shared vision. As Tyler Freres, of Freres Engineered Wood, the supplier of the Mass Plywood Panels (MPP) used in the project, aptly stated, "Wood is the most sustainable building material we have available to us," and the new PDX terminal serves as a shining example of its potential on a grand scale.
One of the most significant was designing and implementing the roof's complex curved geometry. Tyler Freres explained that “transforming flat mass plywood panels (MPP) into the undulating forms dictated by the architectural design was a complex task. The process involved overcoming software limitations in translating the curved surfaces into precise cutting patterns for the #MPP. The team had to address unforeseen issues during the CNC cutting phase, including phantom lines and software glitches, requiring creative problem-solving and meticulous attention to detail.”
The engineers also had to ensure the structural integrity of the massive roof, particularly its ability to withstand seismic activity. It involved designing 34 steel Y-columns with seismic isolation bearings that allow the roof to move laterally during an earthquake. The project team relied on extensive physical testing, performance-based seismic engineering, and performance-based fire engineering to develop solutions beyond prescriptive code requirements, often requiring appeals and approvals.
This is a partial list of all the individuals and organizations that contributed to the PDX Airport project. In the comments section, please let us know if you contributed in any way.
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