American architectural firm ZGF Architects has completed the expansion of Portland International Airport’s main terminal, installing a massive, prefabricated-on-site solid wood roof to maintain airport operations.
The airport’s massive roof was constructed from metal and glulam and, according to the studio, consists of beams and lattices with a total area of over 37,161 square meters and spans nine acres.
The main terminal has opened, marking a major phase in the airport’s renovation that has been underway for a decade. ZGF Architects was commissioned to essentially double the operational space, incorporating facilities and mechanical systems built in various phases since the 1950s.
The roof extends over the entire central terminal, which includes an admission program, ticket counters, food stands and gates, and features a wave-like pattern with 49 skylights.
FZS compared the structure to the “top layer” of a forest – the uppermost layer of branches that forms the protective layer at the canopy level of a forest ecosystem.
“A 37,000 square meter ‘upper floor’ of glulam beams and lattices, winding in a basketweave of arches and scalloped shapes, is supported by a grid of 34 Y-shaped columns that branch upwards 11 meters above the terminal floor,” the studio said.
“The lattice is made of nearly 35,000 three-by-six-inch Douglas fir pieces.”
The structure is technically hybrid, with the timber attached to a series of 1.8 metre deep steel beams spaced 6 metres apart and spanning 45 metres. The largest timber beams are 24 metres long and the lattice is attached to these larger solid timber components.
To keep the airport operational during the renovations, ZGF decided to prefabricate the massive, domed roof on site. It was suspended by machines for construction and the individual sections were rolled into place before being attached to 34 massive concrete Y-supports and bolted together.
Skylights and mechanical components were all completed in the prefabrication process.
ZGF Architects also said the wood used for the engineered wood roof came from within 300 miles (482 kilometers) of the airport, underscoring the importance of local supply chains in mass timber production.
According to the studio, the building’s carbon footprint was reduced by 70 percent by building on site and using local supply chains.
Locally sourced wood was also used for the flooring and accent walls that run through the open main body of the building and its wings.
A series of concessions, lounges and hallways were divided into sections based on the “people-friendly scale” of Portland’s short blocks and surrounded by glass enclosures.
These areas were built modularly with wooden food stands that can be moved according to the needs of the administrators.
To continue the forest themes of the “overstory” idea mentioned above, the airport experience was designed to resemble a walk through a forest, according to the studio.
ZGF Architects worked with landscape architecture firm Place to plant 72 large trees – some up to 7.6 metres tall – and 5,000 plants.
Many of the plantings were designed as “hanging gardens,” with the vines hanging over large areas of glass to dim the light.
“The abundance of green spaces provides biophilic stress relief while reflecting Oregon’s native flora,” the studio says.
“Lots of natural light, a consistent indoor climate, and simple irrigation systems and maintenance protocols ensure that the plants stay healthy.”
In addition to reducing CO2 emissions through on-site manufacturing, the building also features electric heating and high-quality glazing, which reduces operational CO2 emissions.
“The project’s sustainable design sets a new standard for airports worldwide,” said ZGF Architects.
“The main terminal will double its capacity while achieving a 50 percent reduction in energy consumption per square meter using a highly efficient, all-electric ground source heat pump,” it added.
“Resilient construction strategies will enable the terminal to withstand a magnitude 9.0 earthquake in the Cascadia subduction zone.”
The final phases of the project are scheduled to be completed in 2026.
ZGF Architects has several offices across North America. The firm was involved in some previous work at Portland International Airport and has completed a number of sustainable architecture projects in recent years.
These include the PAE Living Building in Portland and the conversion of a Ford assembly plant into a research facility in Pittsburgh.
Last year, Dezeen launched “Timber Revolution”, a series of articles that took an in-depth look at the recent proliferation of mass timber in architecture.
The photography is by Ema Peter.
Project credits:
Architect: ZGF Architects
Contractor: Joint Venture Hoffman Skanska
Structural engineer: KPFF Consulting
Engineers (primary): Arup
Mechanical/Electrical/Plumbing: PAE Engineers (Primary), Arup
Trading partners for solid wood: Swinerton
Solid wood processors: Timberlab, Calvert, Freres, Zip-O-Laminators
Wood consultant: Sustainable Northwest, Sustainable Northwest Wood
Aviation planning: Arup
Landscape: Location Landscape Architecture
Biophilic design consultant: Pond Turtle Light Green
