By Jacob Dunn, Principal, ZGF and Paul Vanderford, Senior Director of Wood Markets, Sustainable Northwest

Portland International Airport is the first major airport in the U.S. with a mass timber roof. The use of mass timber for the new terminal was a natural choice. It made PDX not only a highly sustainable and welcoming civic building, but the way the team sourced the wood reflects our project team’s values around environmental stewardship, climate action, and regional equity.

Transforming the Business-as-Usual Supply Chain

At the project outset, ZGF and our client, the Port of Portland, posed a question: Can we build this in a way that is better for the land and better for our local communities?

Their first decision was to build with wood. Wood is a beautiful, durable, and renewable building resource that provides biophilic benefits with its inherent warmth that helps ease the passenger experience. But the Port of Portland wanted to ensure that the wood also reflected our region, supporting healthy forests and communities. So they decided to also prioritize local wood, and to harvest as much of it as possible from landowners harvesting wood in a way that leaves the land better than they found it.

There were a lot of obstacles in the way of this goal. The biggest obstacle was tracking where the wood came from. This required a new way of doing business. The current opaque wood supply chain makes it difficult to know how the wood is harvested, exactly where it is harvested, who owns the land, and the values that drive the forest’s management.

This challenge became an opportunity to innovate our wood sourcing strategy and show what is possible in sustainable wood sourcing and traceability. Together with our project partners—a collaboration led by the Port of Portland, with ZGF, Sustainable Northwest and Sustainable Northwest Wood, Hoffman Skanska Joint Venture, Swinerton, and Timberlab—we embarked on a multi-year engagement with the wood supply chain, including landowners and mills across the Pacific Northwest, to track a good portion our wood back to its forest of origin and actually influence where it came from.

Where Does the PDX Wood Come From?

The terminal used wood in the roof deck, roof beams, and ceiling – as well as concessions, flooring, seating, and more. Because of the robust tracking, relationship building, and research along the supply chain, the airport sourced 100% of the wood from forests in Oregon and Washington, and all within 300 miles of the airport.

But we didn’t stop there. We also sourced as much wood as possible, 73%, from ecologically managed forests, and we traced as much wood as we could back to the forest of origin and the landowners working to ensure better outcomes for the forest they manage and their surrounding communities.

It was the first attempt at anything like this, and while we didn’t achieve it all, we reached targets no other projects have. Our hope is that by sharing our approach and impact, we can inspire and make it easier for more project teams to follow suit and ask where their wood comes from.

Setting a Sourcing Framework

First, the team determined the criteria for sustainable wood, establishing two definitions for sustainably harvested wood:

Certified by the rigorous U.S. Forest Stewardship Council (FSC)
Traced back to ecological forest management that goes above and beyond local regulations.

Ecological forest management in this instance refers to forestry that uses harvest practices that more closely emulate natural disturbances that cultivate diversity and maintain the integrity of forest ecosystems while balancing economic, environmental, and social goals. Allowing for pathways for compliance other than FSC certification opened the door to a more inclusive criteria where any landowner could participate as long as they could document meeting forestry practices criteria around harvest opening sizes, retention amounts, harvest rotation lengths, riparian buffers, multi-objective management plans, and limitations around pesticide/herbicide usage.

Adding it all up

This project was complex. It took six years, considerable research, relationship building, numerous site visits and forest tours, and a team motivated by shared goals. The result: all 3.7 million board feet of wood in the new terminal – the roof diaphragm, beams, lattice, concessions, floor, stairs, the TSA screening booths, everything made of wood – is sourced from forests in Oregon and Washington within 300 miles of the airport. In addition, 73% was either FSC certified or sourced directly from verified, ecologically managed forests, and 30% is traceable directly back to its forest of origin.

Underrepresented parts of the supply chain

One of the key goals was to target and celebrate the underrepresented parts of the supply chain. This meant going the extra mile to make sure we sourced from small mills, small family forests, non-profits, and tribal nations, and from forests in both the western and eastern regions of Oregon and Washington. Out of the total 3.7 million board feet of wood in the main terminal, 32% was intentionally sourced from underrepresented landowners: 16% from tribal wood, 3% from small family forests, 7% is from nonprofit forests, and another 6% from public forest lands.

*Image Courtesy Dror Baldinger | ZGF Architects*

Locally Sourcing a Nine-Acre Roof

The entire nine-acre roof structure features three different wood products: mass plywood panels for the roof diaphragm, glulam beams, and 3x6” timbers for lattice. It totals 3.5 million board feet, 100% of which came from Douglas fir trees sourced from forests in Oregon and Washington state:

850,000 board feet of 2” thick Mass Plywood Panel makes up the roof diaphragm, providing necessary strength and undulating roof form visible from your plane window.
2,000,000 board feet of glulam beams create a basketweave of arches and scalloped shapes and enable long spans.
600,000 board feet of lattice creates the ceiling and features 35,000 individual 3x6” timbers.

We know all of it came from Oregon and Washington because each producer was able to provide general information on landowner type and location. In addition we know:

73% of the wood in the 3.5-million-board-feet roof and ceiling is sustainably harvested, including:

61% certified as FSC Mix Credit claim
16% from forestry that restored wildfire resilience in dry-side forests in Oregon and Washington
47% from a more ecological version of even-aged management (this includes smaller opening sizes, more retention, or longer rotations)
9% from uneven aged management (this includes variable retention harvests, single tree and group selection, ecological thinning, and restoration-style treatments
Note: these numbers do not add up to 73% as some wood was both FSC certified and directly sourced from ecological forestry

Additionally, we were able to achieve something new for a project of this scale and trace 30% (over 1 million board feet of the total 3.5 million board feet in the roof and ceiling) directly back to its forest of origin. In other words, we know exactly where and who our wood came from, and worked closely with the supply chain to intentionally source from harvests or landowner that met the Port of Portland’s custom criteria around stewardship and equity.

We achieved this transparent sourcing in part because of our project partners, including our mill partners – Elk Creek Forest Products, Manke Lumber, Zip-O-Log Mill, and Kasters Kustom Cutting – who all agreed to segregate, store and deliver the parts of the glulam and all of the lattice wood separate from other wood.

That level of tracing back to a specific forest of origin has never before been done for a project this big. It is one of the many ways this project changed what’s possible, and helped catalyze a new level of rigor and options for sourcing mass timber and other wood products sustainably.

Many people ask if it was expensive. The answer is, only marginally more expensive, but that money stayed in the region and we hope this investment in doing things differently inspires others to take the model even further.

A closer look at the 3x6” lattice ceiling

Part of the 3.5 million board feet of timber is a lattice overstory, featuring 35,000 3x6” timbers that create a basketweave of arches and scalloped shapes. All of the 600,000 board feet of ceiling lattice can be traced back to its forest of origin from 11 different Oregon and Washington landowners, all of which are small family forests, local tribes, non-profits, community forests, university experimental forests, and other landowners practicing best in class ecological forestry.

These 11 landowners contributed all of the wood for the 600,000 board feet of ceiling lattice:

Camp Adams Youth Camp: 8,000 board feet
Camp Bishop Grays Harbor YMCA: 101,000 board feet
Camp Namanu: 9,000 board feet
Chimacum County Park: 70,000 board feet
The Nature Conservancy Central Cascades Forest: 101,000 board feet
Hanschu Family Forest: 12,500 board feet
Hyla Woods: 12,500 board feet
Joint Base Lewis McChord: 70,000 board feet
Roslyn City Forest: 101,000 board feet
Skokomish Tribe: 101,000 board feet
Willamette University Educational Forests: 12,500 board feet

A closer look at the glulam beams

Of the 2 million board feet of glulam beams, 95% was sustainably sourced as FSC-certified wood or is traceable back to harvests practicing ecological forest management above and beyond local regulations. The glulam is sourced from the following landowners:

Yakama Nation provided 370,000 board feet of lamstock to Zip-O-Laminators.
Coquille Indian Tribe provided 30,000 board feet of lamstock via logs purchased by Herbert Lumber and then sold to Zip-O-Laminators.
A mixture of Oregon landowners contributed the remaining 1.6 million board feet of lamstock, including:

Frank Lumber provided 1,308,000 board feet, of which 90% went to Zip-O-Laminators and 10% went to Calvert (now Western Wood Products Inc.)
Zip-O-Logs provided the remaining 323,000 board feet of lamstock.

All of the glulam beams were manufactured from lamstock into beams by Zip-O Laminators.

A closer look at the mass plywood panels

The 850,000 board feet of mass plywood panel is sourced from Freres Lumber, who provided high-level transparency data. They disclosed the volume of wood by landowner type, where 27% came from federal or state timberlands, and the rest came from a mixture of private landowners.

Beyond the Roof

Our procurement approach didn’t stop at the roof. In addition to the 3.5 million board feet in the roof, an additional 200,000 board feet of wood was used in the concessions, floor, stairs, and other finish products.

The wood floor features 51,000 board feet of Oregon white oak from Zena Forest Products, a local wood flooring manufacturer. Approximately 50% of the wood was sourced right on Zena’s 1,300-acre property, while the rest was sourced from 10 landowners located within 60 miles of Rickreall, Oregon, including Garnetts Red Prairie Farm.
The concessions structures feature wood from the Yakama Nation (64,000 board feet), JOSO Ranch and JayZee Lumber (19,000 board feet), and the Cow Creek Band of Umpqua Tribe of Indians (5,500 board feet).
The lattice wall in the Garden Area (behind the pre-security concessions) was built with 13,500 board feet of 3x3” wood members from the Cow Creek Band of Umpqua Tribe of Indians.
The TSA screening rooms also included 16,000 board feet of wood from the Cow Creek Band of Umpqua Tribe of Indians
Read more on our sourcing approach and landowners who contributed to the new PDX terminal, visit: