The wooden wave-patterned dome with 49 skylights covers the entire central terminal of Portland International Airport.
The main terminal roof made of wood at Portland International Airport. (Photo: Ema Peter Photography).
The American architecture firm ZGF Architects has completed the first phase of the renovation and expansion project for the main terminal at Portland International Airport, USA, by installing a mass timber roof, as reported by Design Boom on August 15. This is considered the largest mass timber project ever undertaken.
The roof of the main terminal is made from metal and mass timber, forming a structure that spans over 37,000 square meters, with beams and trusses. This structure features a wave pattern with 49 skylights, covering the entire central terminal, including the entrance area, ticket counters, concession stands, and gates. ZGF Architects likens the terminal roof to a “canopy” of a forest—the uppermost layer of branches that protects the forest ecosystem.
Technically, this is a hybrid structure with timber attached to a series of 1.8-meter thick steel beams, spaced 6 meters apart and extending 45 meters in length. The largest timber beams measure 24 meters long, and the truss framework is affixed to these large timber beams.
To keep the airport operational during the renovation, ZGF Architects chose to prefabricate the massive dome in a separate area of the airport grounds, away from the terminal. The project team used a roof hoisting machine to construct and position each component accurately, which was then attached to 34 concrete Y-columns approximately 11 meters tall within the terminal. Skylights and mechanical components were completed during the prefabrication process.
The airport terminal is designed to give passengers the feeling of walking through a forest. (Photo: Ema Peter Photography).
The wood used for the roof was harvested within a radius of approximately 480 kilometers from the airport, highlighting the importance of the local supply chain. According to ZGF Architects, on-site construction and the use of local supply chains have helped reduce the building’s carbon emissions by 70%. Timber from local sources was also used for flooring and walls.
ZGF Architects stated that the airport terminal is designed to make passengers feel as if they are walking through a forest. The firm collaborated with the landscaping company Place to plant 72 large trees—some reaching heights of 7.6 meters—and 5,000 other plants. Many of the planting areas are designed in a “hanging garden” style with vines draping over large glass panels to reduce brightness.
In addition to cutting carbon emissions through local manufacturing, the newly renovated terminal features an electric heating system and high-quality glass that reduces carbon emissions during operation. “The sustainable design of the project sets a new standard for airports worldwide”, ZGF Architects stated.
“The main terminal doubles its capacity while saving 50% of energy usage per square foot (1 foot equals 0.3 meters) thanks to high-efficiency all-electric heat pumps. Resilient design strategies enable the terminal to withstand a 9.0 magnitude earthquake in the Cascadia Subduction Zone“, ZGF Architects announced.
The second phase of the project is currently underway, with completion expected in 2026. During phase two, the terminal will continue to develop, providing additional retail and dining amenities to enhance the passenger experience.
