Menu Home

SEA Previews Incredible Improvements Ahead with C Concourse Expansion

Renderings illustrate vision for airport experience and sustainability
March 17, 2022

SEATTLE – Seattle-Tacoma International Airport (SEA) revealed today 30 percent design renderings of its next marquee capital improvement project. The C Concourse Expansion will elevate SEA, literally, by adding four additional floors above the existing building and raising the bar on the airport experience and sustainability. 

The project spans the C and D Concourses with 145,530 more square feet of dining and retail, sought-after amenities such as an Interfaith Prayer and Meditation Room and Nursing Suite, and an all-new, more than 20,000-square-foot Alaska Airlines Lounge. The heart of the space – The Grand Stairs at C – will be an iconic destination that invites travelers to linger with seating, airfield views, music and art, or head upstairs for more elbowroom and dining and retail options. The expansion also encompasses office space for airport businesses, airlines, and the TSA. 

“We have a clear vision for how the airport will look and feel in the coming years,” said SEA Managing Director Lance Lyttle. “Making your experience less stressful and more predictable is at the center of our vision. You can feel the difference now at the newly modernized N Concourse and soon to open International Arrivals Facility. The C Concourse Expansion is what’s next in how SEA serves travelers, and we can’t wait.”  

A rendering of the exterior of the C Concourse Expansion with passengers deplaning from an Alaska Airlines aircraft
A rendering of the exterior of the C Concourse Expansion.

Bringing In, Seeing Out  

The C Concourse Expansion rethinks the airport experience where design creates an intuitive journey, a sense of calm, and climate consciousness. Miller Hull and Woods Bagot are leading the project’s design concept of bringing in and seeing out to create an interplay of environments between the natural landscapes of the Pacific Northwest and the energy and vibrancy of Seattle.  

The forests of this region inspire the building's design. From the light solariums and the canopy feeling of the Grand Stairs, created by undulating Douglas fir coffers in the ceiling transition down to a singular colossal pillar, travelers will sense the scale and grace of a Pacific Northwest forest. The Grand Stairs create a central gathering space designed to reflect regional public and farmers markets. Dining and retail will frame this tiered, open amphitheater with a stage for live music.  

Next, travelers are drawn to the upper level with restaurants above as well as views and the ability to look out over the entire facade. One of the most unique aspects of the C Concourse Expansion is its height and unobstructed views of the airfield and Olympic Mountains via a lookout deck encased in glass that will be available to all passengers.  

A rendering of The Grand Stairs at C.
A rendering of The Grand Stairs at C.

Sustainable Design Strategy  

The Port of Seattle, which owns and operates SEA, is working to be the greenest and most energy efficient port in North America where the health of the environment and the well-being of travelers is paramount. C Concourse Expansion is the first project of its kind to follow the Port’s Sustainable Project Framework, a process to transparently evaluate alternative, sustainable approaches to build capital projects where environmental and societal impacts inform project design, alongside cost and schedule.  

The sustainable features of this project will set the precedent for future capital projects at the Port, including:  

  • Rooftop photovoltaics and a solar panel array is projected to provide 15 percent of the C Concourse Expansion energy demand. 
  • Creating fossil fuel free systems for heating and tenant hot water and equipment with electricity that will save Scope 3 greenhouse gas emissions.  
  • Electrochromic glazing for windows will reduce peak cooling loads and annual cooling energy consumption. 
  • Installing dishwashing capability will reduce solid waste from disposal dishware and space for donated food storage will support the airport’s existing partnership with the Des Moines Area Food Bank.  
  • Embodied carbon reduction strategies such as lessened steel tonnage and associated manufacturing impacts and decreased cement quantity.   
  • Low-flow water fixtures that conserve potable water and a purple system to connect to future reclaimed water supplies.  
  • Biophilic design principles will create a connection to the outdoors with natural lighting, landscape features and other elements for a sense of well-being for travelers. 

Design Partner Quotes  

“The C Concourse Expansion is an inspiring gathering place that is a destination in and of itself. This ambitious project intertwines the very best aspects of placemaking, sustainability, and signature architecture. The expansion for SEA has many distinct attributes, but its Grand Stairs and focal pillar clad in locally sourced Douglas fir–from which sculptural geometries like curves and fractals emanate–are two emblematic features that succinctly convey the project's leading-edge take on contextual design.” – Matt Ducharme, Woods Bagot's Principal and West Coast Design Leader 

“Woods Bagot has an established track record of designing award-winning airport terminals that break from standard airport paradigms by prioritizing an elevated passenger experience with a deep connection to place that is underpinned by sustainable initiatives that protect our future. The C Concourse Expansion is no exception as our reimagined guest experience for SEA fosters a clarity of movement, a sense of calm, and connection to the Pacific Northwest, all through localized materiality, framed sightlines of the outdoors, public art, and climate-conscious integrations.” – Katy Mercer, Woods Bagot's Principal and Regional Interior Design Leader  

"SEA is Miller Hull's home airport making the new C Concourse Expansion a labor of love. Together with our design partner, Woods Bagot, we are excited to continue the sustainable legacy the Port of Seattle has begun by bringing our own expertise in northwest design and sustainability to create a place you’d recognize as singularly emblematic of Seattle and the northwest." – Rob Misel, Miller Hull Managing Partner and Project Partner-in-Charge 

"The folded façade addresses the challenging southwest-facing aperture through patterning inspired by northwest forests. Alternating south and west facing glass panels form vertical ribbons of light, each responding to the sun’s position and intensity with dynamic tinting electrochromic glass to prevent interior glare and optimize daylight. As the day progresses, the interior environment changes in direct response to the outdoor environment. Best of all, on our overcast, cloud-rich northwest days, visibility is maximized to celebrate the commanding views of the airfield and Olympic Range and bathe the interior with soft, even daylight." – Rich Whealan, Miller Hull Project Manager 

"The concourse C expansion will bring much needed light, air and passenger amenities to one of the busiest crossroads in the terminal. The new building was designed to bring back the excitement of flight with soaring interior volumes of space and multiple outdoor observation decks that reconnect us to the magic of travel and the iconic mountain and sound views that define the Pacific Northwest." – Brian Court, Miller Hull Partner 

Timeline and Budget 

Early work is slated to begin this summer with major construction beginning in mid-2023 and construction projected to complete in 2027. Turner Construction is the GCCM (General Contractor – Construction Manager). The Port is receiving Project Management and Construction Management support from Jacobs and Parametrix. Turner will open bid opportunities for this work on March 22, 2022. Explore procurement and contract information on VendorConnect

“Turner is excited to partner with the Port of Seattle on this first of its kind sustainable project," said Turner Vice President & Construction Executive Steve Rule. "The C Concourse Expansion is an important vertical extension for the airport, integrating dining, retail, and other amenities and services. Turner Construction shares the Port’s vision of advancing equity and addressing contracting disparities by increasing the utilization of WMBE and other disadvantaged firms; together, we will partner to build an amazing project while benefiting our local community.”   

The budget range for the C Concourse Expansion is $240M to $500M. $340M is currently approved by the Port of Seattle Commission, which can be amended as the project progresses. 


Perry Cooper | SEA Airport  
(206) 787-4923 |

Back to Top