ZGF Architects designs the new terminal at Portland Airport, the first major US terminal with a solid timber roof

Portland Airport’s main terminal expansion designed by ZGF Architects, which opened in August 2024 (Phase 1), is the most significant expansion of Portland Airport (PDX) to date. The journey to become America’s best airport has been decades in the making. ZGF Architects began its long association with Portland International Airport (PDX) in 1965, when it was commissioned to develop a master plan to double the size of its original 1958 terminal.

With an undulating solid timber canopy of more than 36,000 m2, the terminal core invites visitors to take a walk through the forest and celebrates Oregon’s history of forest product innovation with sustainably and locally sourced timber from landowners and sawmills located within a 500 km radius of the airport. Extensive glazing offers views of the airfield and surrounding wooded landscape, and interior finishes that reference the natural beauty of the region make it clear on arrival exactly where you have landed.

The forest as design inspiration

Designed to evoke the feeling of walking through the forest, the overall experience of the new main terminal transcends functionality and creates a sense of awe and beauty inherent in the natural beauty of the state of Oregon.

The interior environment is designed to increase passenger comfort and reduce the stress that many people experience when travelling. Over the years, PDX has always placed a strong emphasis on cultivating a strong sense of place by incorporating some elements of wood, plants and natural light into its design.

In collaboration with Terrapin Bright Green and landscape architect Place, ZGF Architects applied the concept of biophilia holistically throughout the airport. As a result, nearly every corner of the terminal features touches of Oregon’s distinctive vegetation and ample access to natural light. The walkways are lined with trees and plants, with 72 large trees, up to 25 feet tall, located along the seam and throughout the terminal; cascading gardens; and more than 5,000 strategically placed plants. The landscape conveys the feeling of walking through a forest and guides passengers from security checkpoints to their final destinations.

The distribution of spaces

ZGF examined urban planning strategies to determine the location of spaces within the expansive terminal. The large, flexible main terminal houses smaller-scale architecture that draws inspiration from the human scale of Portland’s city blocks, the rhythm of urban neighbourhoods, parks, and the city’s tree-lined, pedestrian-friendly streets, designed as a “cluster of spaces” that recreate Portland’s unique, walkable sense of scale.

On entry, the reconfigured and expanded ticket hall is designed to offer a clear and easy experience, and between descent and take-off, a central gate directly after ticketing transports passengers to TSA security checkpoints and then to their boarding gates.

This space offers a forest-like experience that surrounds visitors with trees and diffused light. The commercial space before the security checkpoint has stadium seating and accommodates one third of the total number of venues, which offer regional products and restaurants open to everyone. The rest of the shops are located on the other side of the security checkpoint.

Trees and planters contribute to a neighbourhood feel, with a central boulevard with cafés and street furniture inviting commuters to linger. The retail premises were designed as a “kit of parts” with “plug and play” utilities to facilitate installation and give operators flexibility and choice in configuration and branding.

The airport canopy

ZGF and Portland Airport (PDX) chose solid timber for the 36,000 m2 deck because of cost, ease of construction and as a nod to the Pacific Northwest’s thriving timber industry. PDX is the first major US airport with a solid timber roof. The use of wood celebrates Oregon’s history and the future of innovation, craftsmanship and ingenuity of forest products, and because wood captures carbon, it is also an important element of sustainability.

The daylighting strategy consists of 49 skylights of different shapes and sizes that filter daylight through the lattice of the solid wood roof and the large skylight openings, illuminating 60% of the terminal together with customised pendant luminaires.

The vast roof is built with more than 1 millionm2 of timber panels, composed of three different products: mass plywood panels for the roof structure, laminated beams and 0.90 x 1.80m2 timbers for the truss. The individual pieces of wood are visible, which makes the huge structure look handmade and connects it to the human experience on a large scale.

The laminated beam and lattice truss is a framework of arches and scalloped forms, inspired by traditional weaving techniques indigenous to the region. The beams were designed to eliminate the need for steel hardware, minimising the need for metal, reducing costs and aesthetically enhancing the timber. The peaks and valleys of the expressive roof design also conceal a myriad of systems within its hybrid structure and contribute to its seamless appearance.

In addition to the grandeur of the design, 34 huge Y-shaped columns support the 380,000 square metre roof weighing more than 8 million kg.

Expansion of the terminal while maintaining its operation

One of the biggest challenges was to modernise, renovate and expand the main terminal, keeping the airport fully operational during the works. Instead of building a completely new terminal, much of the existing infrastructure, including the baggage handling system, was reused. The masterplan consolidates nine buildings that had been joined together over time, creating a new floor plan and unifying everything under the large solid timber roof, and allowing the airport to grow on site and increase its capacity to accommodate 35 million passengers annually by 2045.

Another key solution was to prefabricate the modular roof structure nearby and place it on top of the existing terminal. Prefabrication of the roof allowed construction to be carried out without disrupting airport operations, which reduced construction times and logistics costs.

As passenger loads will continue to increase, it was necessary to design a flexible infrastructure that would allow for future innovations, sustainable design evolutions and the future need for extensions. The 100′ x 150′ spans between columns allow for continuous passenger flow, while providing long-term flexibility and adaptability as operational standards and traveller needs evolve. This innovative solution left more infrastructure in place and minimised operational disruptions during construction, saving time and money. These are also important measures to prepare the airport for the future, as they create more operational flexibility and allow the areas of ticketing, security, processing and retail to evolve.

Sustainable and earthquake-resistant architecture

The decision to reuse much of the existing terminal, together with the use of timber and the optimisation of steel and concrete, resulted in a 70% reduction in embodied carbon in the structure compared to the construction of a completely new terminal.

The highly efficient envelope increases energy efficiency, as does the conversion to a ground source system for heating and cooling, eliminating the need to increase the footprint of the existing power plant. Given the airport’s location the new terminal is designed to withstand a magnitude 9 earthquake. The roof is supported by 34 steel columns. The roof is supported by 34 Y-shaped columns designed with seismic isolation bearings at the top to allow the roof structure to move laterally – up to 24 inches – during an earthquake.

The wood sourcing strategy supported local economies and promoted forestry practices that protect Oregon’s natural resources. Nearly all glulam and lattice-laminated timber is sourced from ecologically managed forests. As in the farm-to-table kitchen, the glulam and lattice can be traced back to the forest of origin thanks to direct sourcing methods. This traceability allowed the project to tell the local story of the timber, its ecological impact and community benefits in a new way.

Project: Nueva terminal Aeropuerto de Portland.
Architecture: ZGF Architects.
Location: Portland. Oregón. EEUU.
Finished: 2024.
Structural engineering: KPFF.
Contractor: Hoffman Skanska.
Solid wood consultant: Swinerton.
Solid wood manufacturers: Zip-O-Laminators, Timberlab, Freres, Calvert.
Wood advisor: Sustainable Northwest, Sustainable Northwest Wood.
Sawmills: Elk Creek Forest Products, Frank Lumber, Freres Lumber, Herbert Lumber, Kasters Kustom Cuts, Manke Lumber, Zip-O-Log Mills.
Forests of origin: Camp Adams Youth Camp, Camp Bishop Gray’s Harbor YMCA, Camp Namanu, Jefferson County, The Nature Conservatory Central Cascades Forest, Coquille Indian Tribe, Hanschu Family Forest, Hyla Woods, Joint Base Lewis McCord, Roslyn City Forest, Skokomish Indian Tribe, Willamette University Educational Forests, Yakama Nation.
Photography: Ema Peter. Dror Baldinger Faia.
Text: ZGF Architects + DeepL

ZGF Architects

ZGF is an industry leader in sustainable and regenerative design. They embraced sustainable design as a core value long before green or leed became common expressions. As stewards of the built environment, their applied research and knowledge gained over the past 70 years enables them to invent new approaches that address urgent climate challenges in complex building types, such as laboratories, hospitals, learning spaces in schools and universities, and corporate headquarters.

Urban planning has influenced their work since the company’s inception: they design buildings and cities that take advantage of the opportunities of a carbon-neutral future. They also reinforce their clients’ ESG objectives with design solutions that represent their mission, vision and values.

They are dedicated to working with the entire industry to solve the pressing environmental and social issues of our time. As a firm, they are committed to the 2030 Challenge, the U.S. Architects’ Statement and are signatories to the AIA Materials Commitment.

With origins in Oregon, attention to craftsmanship and beauty is elemental to the ZGF culture. A deep respect for the built environment evolved from a reverence for the natural beauty of the Pacific Northwest landscape and a commitment to stewardship of the natural environment. Rather than reflecting a signature style, his work is derived from the particularities of climate, context and human experience. The instinct to build community, to create places where people come together for a common purpose, is central to his work.

ZGF has grown from a single office with strong regional roots to a firm with seven offices in North America and more than 750 employees. Its national reputation has been recognised with the American Institute of Architects’ Architectural Firm Award, which recognises “its high standards, humanistic concerns and unique ability to capture the spirit of a place and the aspirations of its inhabitants“.

Part of what attracts them to design is their deep desire to bring about positive change. Three core principles drive ZGF’s work: changing people’s lives, combating climate change and promoting social justice.

Sharron van der Meulen

Sharron is a driving force in blurring the boundaries between architecture and interior design, with the intention of influencing the holistic user experience. As Managing Partner of ZGF, she takes on the leadership of the firm, based on the belief that design can solve some of the world’s greatest challenges and make a difference in people’s lives. Sharron’s award-winning design portfolio has reflected the diversity of ZGF’s practice, spanning typologies ranging from workplace, healthcare and research buildings to cultural, higher education and aviation facilities, including, most recently, doubling the capacity of Portland International Airport, while maintaining its uniquely Portland character. Their humanistic approach to design is based first and foremost on understanding the client’s mission, aspirations and culture. Each solution is authentic and unique to that client’s story. Ultimately, he sees his leadership role throughout the company as advocating design excellence in all aspects of a project.

Source: ZGF Architects.

Project by Sharron van der Meulen. ZGF Architects