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After more than 40 years of chronicling the nation’s storied exploration of the sky and heavens, the Smithsonian Institution’s National Air and Space Museum in Washington, D.C., was, in a word, tired.

Since opening in 1976, the museum has welcomed more than 350 million visitors attracted by exhibits ranging from the Wright Brothers’ original 1903 Flyer to the command module that just 66 years later brought the Apollo 11 astronauts home from the first manned landing on the moon. As the decades passed, however, the iconic building on the National Mall increasingly displayed the effects of age, use and the elements. There was a lengthy list of envelope deficiencies, most notably a deteriorating roof, leaking skylights and a failing curtain wall and facade that also bore the effects of a 2011 earthquake.

The museum’s building systems were nearing the end of their service life as well, making it difficult to reliably maintain consistent interior temperature and humidity. “Without those type of controls,” explains Jim Evans, the Smithsonian’s assistant director for logistics, “it’s difficult to provide the best environment for the artifacts within the building.”

Hundreds of space age artifacts had to be protected and carefully relocated during renovation.
Photo by Jim Preston, courtesy Smithsonian National Air & Space Museum

Later this year, the Air and Space Museum will reach substantial completion on a comprehensive, multi-year renovation seemingly as complex as sending humans and probes into space. Led by the construction manager at-risk team of CSC, composed of Clark Construction Group, Smoot Construction Co. of Washington, DC and Consigli Construction, the program has encompassed a full replacement of the exterior stone facade, glass curtain wall and skylights and the addition of a tensile roof entrance canopy whose abstract winged shape was inspired by images of the early flying machines developed by Leonardo da Vinci. The team also updated mechanical and electrical systems serving gallery and presentation spaces and performed other building improvements.

The Smithsonian has not disclosed the total cost of the renovation program, which was launched with a $650-million congressional appropriation and augmented by an effort to raise $250 million from private sources for new exhibitions.

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Photos by Jim Preston, courtesy Smithsonian National Air & Space Museum

“A lot of planning went into things like electrical connections and transition-ing from temporary to permanent arrangements so that we’re doing our work on one side of the wall [while]the museum on the other side can stay open.”
—Jared Oldroyd, Division President, Clark Construction

Preparing for Takeoff

Deep familiarity with the Smithsonian’s processes and preferences proved advantageous for the team, which began preconstruction work at the 35% stage of architect Quinn Evans’ renovation design. That design was based on extensive research into the building’s condition and sustainability-focused corrective alternatives, with an eye toward achieving LEED Gold.

To identify the best approach to implement the renovation while limiting the closure of one of the world’s most popular museums, the Smithsonian and project team collaborated to refine the original seven-year, zone-by-zone renovation plan into a two-phase approach, allowing sections of the building to remain open to visitors while others were closed off.

Jared Oldroyd, Clark Construction division president says that besides trimming overall construction time by a year, the simplified approach helped reduce costs and keep the public safe. “For many visitors, the museum is a once-in-a-lifetime experience,” Oldroyd says. “A lot of planning went into things like electrical connections and transitioning from temporary to permanent arrangements so that we’re doing our work on one side of the wall [while] the museum on the other side can stay open.”

The team was technically challenged to fit the thicker building envelope into existing space while replicating the original appearance.
Photo by Jim Preston, courtesy Smithsonian National Air & Space Museum

The renovation’s initial construction phase began in fall 2018 on the museum’s west side, and work was minimally affected by the pandemic, according to Oldroyd. A seven-month full closure of the building in 2022 allowed the team to complete and reinstall that side’s new galleries. It also gave the project team a chance to join the Smithsonian in a family-oriented “soft” grand reopening of the west side before starting the second-phase makeover, currently scheduled for substantial completion in November. “We usually go straight through to finish,” he says. “The event allowed everyone on the team to have a moment to reflect and celebrate what we’d done.”

That effort included rectifying many deficiencies that could be traced back to the fast-tracked construction effort in the early 1970s in a scramble to have the museum ready in time for the nation’s bicentennial celebration. “The building opened on time and on budget,” says Leora Mirvish, principal at Quinn Evans, “but it’s been paying the price ever since.”

For example, the original facade consisted only of 1.25-in.-thick Tennessee pink marble with spray foam insulation on back. That almost immediately led to cracking, cupping and potential separation due to the accelerated thermal hysteresis of the area’s freeze-thaw cycles. In addition, an experimental air-return plenum between the facade insulation and interior drywall meant that the stone sealant was the envelope’s sole water barrier.

“The only thing that kept the building from growing mold was the fact that we had air moving in this plenum,” Mirvish says.

Colin MacKillop, Quinn Evans project manager for the modernization’s exterior work, says that subsequent Band-Aid projects to rectify design issues such as acrylic dome skylights—substituted for the originally intended glass units—had done little to solve the problems. MacKillop says that the newest renovation “would be a generational project, one designed to last 100 years. The approach was, ‘Let’s get it right and make sure it’s comprehensive.’”

Creating a 21st-century exterior would require stripping all 13,000 stone panels and other elements down to the structural frame. Oldroyd says the new facade is a stone-clad curtain wall system that includes metal panels behind the stone to provide multiple weather barriers from the exterior elements and an air barrier system that meets the humidification requirements of the interior gallery spaces.

Topped with a tensile roof canopy inspired by Leonardo da Vinci’s designs of early flying machines, the museum’s new entrance vestibule improves security and accessibility while also providing added protection to the artifacts.
Photo by Jim Preston, courtesy Smithsonian National Air & Space Museum

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The facade replacement was completed in December 2023. “It was technically challenging to fit the thicker building envelope into the same space and replicate the original appearance,” he says. “A lot of custom design went into making it work.”

A steel-reinforced aluminum mullion system was incorporated into the double-glazed curtain wall system to improve impact resistance, while massive temporary roof enclosures created what Oldroyd calls a “cocoon” around the skylit atriums for glass replacement and structural modification work. Multi-pane glass, thermal breaks and a combination of tint and grit are designed to mitigate light intrusion, while fixed baffles and motorized shades will help manage the amount of sunlight entering the galleries.

The outmoded air plenum system was replaced with ducted HVAC services and advanced controls that will provide more precise temperature and humidity control, adjusting automatically as both interior occupancy and outside conditions change. Terrazzo flooring in the concourse and main gallery—which replaced carpeting that Evans says produced dust that was harmful to the museum artifacts—gives the interior “a fresh look and feel.”

The team had to relocate a 18,700-lb F1 rocket engine and a 2,000-lb quarter-section rocket engine. The engines were loaded onto custom steel rigging with skates and maneuvered the length of two football fields through exhibit galleries to their new location.
Photo by Jim Preston, courtesy Smithsonian National Air & Space Museum

Handling With Care

From the outset, protecting museum artifacts was a priority for the team. Hundreds of items were meticulously relocated around the museum or to a storage facility near Washington Dulles International Airport before construction began. Particularly large artifacts, such as the nose of a Boeing 707 jet, remained on site, protected in place by a combination of soft materials and hard surrounding structures equipped with internal environmental controls. “It really multiplies the complexity of the job when you’re talking about moving airplanes,” Oldroyd says with a laugh.

“We pulled a lot of experience from a lot of disciplines to do this,” Evans adds. “A complete modernization of a museum facility of this magnitude is one of those once-in-a-lifetime projects that you’re proud to have been involved with.”

The biggest challenge, Oldroyd says, was relocating an 18,700-lb F1 rocket engine and a 2,000-lb, quarter-section rocket engine. After developing “inch-perfect” computer-generated simulations charting the travel path through the museum, the engines were loaded onto custom steel rigging with skates and maneuvered the length of two football fields through exhibit galleries to their new display locations. Once placed in the exhibit gallery, the engines were carefully rotated 90 degrees, hoisted vertically and suspended overhead from new structural-steel supports.

As the renovation headed into its final months, CSC says all major building work is substantially complete. Remaining tasks include completing the turnover of second-phase gallery spaces and finishes. The Smithsonian says most of the remaining exhibits will be in place in time for the museum’s 50th anniversary in 2026.