Architectural company ZGF Architects designed the expanded main terminal of Portland International Airport (PDX) in the US, made of mass timber.

ZGF Architects started its collaboration with the airport in 1965 when the Port of Portland first commissioned the form to double the size of the original 1959 terminal. The relationship spanned decades and resulted into multiple projects, from remodelling to expansions.

The latest project is also the most aggressive to date, doubling the capacity of the airport. The roof, measuring over 3.6 hectares (9 acres), is made of locally sourced wood, which comes from within a 300-mile radius of the airport. It consists of three different wood products: mass plywood panels for the roof diaphragm, glulam beams, and 0.9 x 1.8 m (3 x 6 ft) timbers for the lattice. In total, the roof weighs 817.000 kg (18 million lb). Currently, this is said to be the largest mass timber project of its kind in the world.

The glulam beam and lattice overstory is a basketweave of arches and scalloped shapes, inspired by traditional weaving techniques indigenous to the region. The beams were designed to eliminate the need for steel hardware, minimising the need for metals, reducing cost, and aesthetically highlighting the wood. The peaks and valleys of the roof design also conceal a myriad of systems within its hybrid structure and contribute to its seamless appearance. Adding to the grandness of the design, 34 massive Y-shaped columns hold the roof in place.

With the expansion, as much of the exiting terminal as possible was reused. With the wood, the use of steel and concrete were optimised as well, achieving a 70 per cent reduction in the overall structural embodied carbon footprint, compared to an entirely new terminal.

Photos: Ema Peter Photography / Dror Baldinger