The restoration of the Air Force Academy Chapel is the U.S.’s most complex modernist preservation project ever

Designed in the 1950s and completed over a decade, the United States Air Force Academy near Colorado Springs, Colorado, marked a watershed moment in American architecture. Built at the peak of the high-stakes Cold War era, the campus was arguably the most expensive federal project in American history.

Listed as a National Historic Landmark District, the Air Force Academy campus is still one of the most advanced fusions of technology, education, art, and architecture that the country has ever seen. At its heart, Skidmore, Owings & Merrill’s Walter Netsch Jr. designed an aluminum skinned chapel pointing straight up to the sky and the heavens beyond it.

Upon opening in 1963, the Cadet Chapel’s bold expression of lightness and form soon became a global symbol of America’s vision and technological promise. Unusual for most religious buildings, the chapel was designed as a non-denominational facility with worship spaces for multiple religious beliefs. Its soaring presence served as a daily reminder for cadets of the American ethos, and their mission to protect its freedoms of religion, speech, and assembly.

Like many modern icons, the chapel’s envelope has leaked for years. Over the decades, accelerating water and microclimatic effects threatened permanent damage to structural systems, stained glass, wood pews, and even the chapel’s two iconic historic organs.

President jfk descending stairs amid a crown
President John F. Kennedy visiting the Air Force Academy campus in 1963 (Courtesy the Air Force Academy Archives)

Modernist Renewal

The $158-million, four-year project remedies several original design and construction shortcomings that led to the building’s deterioration. One of the biggest, of course, is water infiltration. Walter Netsch originally designed a complex network of rain gutters and a flashing system beneath the exterior aluminum cladding. But congressional debates and subsequent cost value engineering led to the substitution of the gutter system with extensive caulking between the exterior panels.

In 2015, the Air Force Civil Engineering Center selected an AECOM team led by Steve Robinson, AIA from AECOM’s Indianapolis office, and Sean Reish, PE, from their office in Colorado Springs, to restore the iconic building to its former glory. Included in the broader team are Bruce Kaskel and Bryan Rouse of Wiss, Janney, Elstner Associates Inc. for envelope repair, and, for technical preservation, Mary Katherine Lanzillotta, FAIA of Hartman-Cox Architects.

JE Dunn is the lead contractor. To meet federal historic preservation requirements they enlisted Michael Bjornberg, FASLA, from LEO A DALY’S Minneapolis office as their Historic Treatment Specialist.

Now in its second year, the chapel repair and restoration is probably the most complex modernist preservation project ever attempted in the United States.

Tracking American change

Since the Wright Brothers, aviation had moved so fast that, by 1955 when SOM won the commission to design it, the Air Force knew that its future leaders would no longer merely take part in battle—they would manage it.

Nuclear war would be fought with satellites, missiles, computer simulations, and guidance systems. What mattered was the power of abstract thinking. The Air Force Academy Motto is Integrity First, Service before self, Excellence in all we do. For cadets, learning how to fly was optional, learning how to think and manage with superb precision was required.

Thus, it makes sense that SOM planned the Academy’s campus as an abstract ideal, a city of ideas built on an open plane based entirely on a 7-foot-by-7-foot grid, a campus for the future engineered with the precision of an advanced aircraft.

Black and white historic photo of the air force chapel being framed
The chapel being framed (Courtesy the Air Force Academy Archives)

A who’s who of American culture

To win this extraordinary commission, SOM invested years in concept development and a staggering $100,000 ($1,000,000 in today’s dollars) on a roll-out exhibition that became a multi-media artwork itself. Gordon Bunshaft and other firm leaders enlisted Ansel Adams to photograph the 3,000-acre site’s expansive sky, shifting light, and vistas. The great architectural photographer Ezra Stoller also contributed. As typical of other big projects of the era, after winning the commission, SOM created a museum show with models, photography, plans, and renderings that opened at the Colorado Springs Fine Arts Center in May 1955.

The architectural selection committee, led by Eero Saarinen with members including Welton Becket and Pietro Belluschi, later had a strong influence on the campus plan. Anchored by SOM, the eventual planning and design team became a virtual who’s who of 20th-century American culture.

Eero Saarinen proved to be a major influence on the overall campus plan and the chapel siting, orientation, and design. He called for lowering the height of the chapel’s podium so that it could feel more integrated with the core campus and the daily life of cadets. Saarinen led enriched the quality of the campus inside and out by reaching out to American design leaders such as the industrial/interior designer Walter Dorwin Teague.

Saarinen, who had already worked with Kiley on several projects, chose him to design the outdoor campus spaces. The design team even included the movie mogul Cecil B. De Mille, who designed the cadet and officer uniforms, pulling designers off the set of The Ten Commandments movie to do it. The Air Force intended the Academy campus to become a National Historic Monument—an all-compassing experience of space, architecture, landscape, and color—and a symbol of the American future.

Black and white landscape photo of the mountains of colorado
A site survey taken by Ansel Adams (Ansel Adams)

The mid-1950s marked a cultural turning point when modernist office towers, college buildings, and even new glass bank locations challenged everything that came before. As a religious landmark, Netsch’s chapel soon became a target for critique.

Like the Trump Administration’s failed effort to mandate neoclassical architecture in federal buildings, members of Congress at the time, architects, self-styled critics, and masonry industry leaders lambasted SOM’s modernist vision.

Bjornberg shared some of the most stinging attacks in his presentations on the chapel’s current restoration: Naysayers branded Netsch’s design as: “alien to American monumental design,” “a social and spiritual fiasco,” and “a deliberate insult to God the almighty.” They also argued that the chapel resembled “an accordion” and that “worshipping in it would be like worshipping in a skating rink.”

A year earlier, Walter Netsch, then 34 and SOM’s lead designer for the chapel, was worried that traditionalist calls for another West Point or Annapolis could win the day. In preparing for the finalist presentation, Gordon Bunshaft sent the young designer abroad to visit religious landmarks. Netsch later recounted that:

I was really worried because Gordon had sent me to Europe to look at Gothic architecture and Renaissance architecture. ‘Because you’re going to do another controversial building, Walter, and you’ve got to be able to say that you’ve seen Chartres and Notre Dame.’

The trip took three weeks. I came back saying, ‘Gee, we don’t have stone masons today. We don’t have the love of labor through which something is added within the same vocabulary every decade. How can you achieve that effect, but do it all at once?’ We made a little model of a folded plate, which was au courant. Take a piece of paper and bend it, and so forth. Origami. I started scribbling, drawing, trying to get a repetitive feature.

Like the 7-foot campus grid based on the tatami mat layouts that Netsch had seen while living in Japan, he sought out an organizing system to unify the chapel and its structure. Without even knowing it, he came up with the defining tetrahedron concept for the roof. Fortunately, Netsch’s colleague, the engineer Ken Nasland, was there to tell him what it meant:

Ken said, ‘What are you doing? Trying to draw a tetrahedron?’ That’s the way he talked. Very straight forward.

I said, ‘No. What’s a tetrahedron?’ He drew me an equal tetrahedron. But I said that wouldn’t work. ‘Well, make one of your own,’ he said. So, I went home and got the tetrahedron to work…. I got it to flip-flop. That was the great thing. I could flip-flop it, turn it upside down, inside out.

The city on the plain

The campus plan and the chapel’s seventeen steel and glass spires (21 prior to value engineering), each composed of 100 tetrahedrons, grew out of a rationalist epistemology based in calculation, clarity, and distinct purity. Details could be precisely measured and replicated, even reversed. Walking distances, co-adjacency of departments, and even the Dining Hall were collectively designed for quantifiable efficiencies as if set down on earth by a remote yet purely rational mind.

In the Discourse on Method (1637), the French mathematician and philosopher René Descartes claimed that the city planned by a single mind is more pleasing and ordered than those designed by many minds and forces over time. As a metaphor for his rationalist belief in the clarity of measurement and valid knowledge, he argued that:

…there is less perfection in works composed of several portions, and carried out by the hands of various masters, than in those on which one individual alone has worked. Thus, we see that buildings planned and carried out by one architect alone are usually more beautiful and better proportioned than those which many have tried to put in order and improve, making use of old walls which were built with other ends in view.

In the same way, also, those ancient cities which, originally mere villages, have become in the process of time great towns, are usually badly constructed in comparison with those which are regularly laid out on a plain by a surveyor who is free to follow his own ideas.

Such Enlightenment rationalism has shaped the American political landscape ever since, beginning with the Jeffersonian national grid based on 6-mile-square townships and 640-acre sections, the Radiant City with its federal legacy in public housing projects, and the Interstate system. SOM’s campus plan organizes time and space with machine-like perfection. The original designers developed cadet flow diagrams to study building relationships to ensure that there were no wasted steps in a cadet’s strict daily schedule.

black and white photo of a construction site
The Mitchell Dining Hall under construction (Courtesy the Air Force Academy Archives)

For example, Air Force planners reasoned that pilots and base staff did not need more than thirty minutes for lunch. Thus, the Mitchell Dining Hall, used three times daily, was located at the center of cadet activity. SOM fine-tuned the exterior doors, circulation, exiting, and serving procedures to accommodate a simultaneous meal for all 3,000 cadets and staff in under 30 minutes. Every meal served at the tables in under 5 minutes would be equally warm, allowing 20 minutes for consumption and 5 minutes for exiting. Today, the Academy can serve over 4,300 meals in that 30 minutes.

The Dining Hall is considered one of the largest mass dining halls in the world at 1.4-acre of open plan. The column-free truss frame span of the 266-foot Dining Hall was designed by architect Gertrude Peterhaus (Kerbis). She used a newly developed University of Illinois computer system in a pioneering application for structural analysis. The prefabricated truss structure was assembled on the ground and the 1,150-ton roof was hydraulically raised in place in just over six hours, a technique that had been usually used in concrete-lift slab construction. Photographs of the truss design were published throughout the country showcasing the use of new technology.

Peterhaus studied at Harvard, M.I.T. and I.I.T. She received an undergraduate degree in architectural engineering at the University of Illinois and a master’s degree from the Illinois Institute of Technology. She worked for and studied under some of the 20th century’s most significant modernist architects—including Carl Koch, Walter Gropius, Mies Van Der Rohe, and Frank Lloyd Wright. Being an all-male campus at the time, Peterhaus was unable to witness her truss system being raised in place.

Like a proven equation or Platonic form, this campus scheme and the chapel itself were never intended to change. Thus, remarkably for a new 20th-century campus, the plan never anticipated significant future growth.

A black and white photo of men around a model campus and the air force chapel
Walter Netsch over a model of the academy campus (Courtesy SOM)

Preserving a changing campus

Sixty years after its founding, the Air Force Academy has grown significantly but retains its core character-defining features in spatial patterns, circulation, and scale. To repair and restore the campus’s most visible building, the design team had to work at all scales.

After reviewing original construction documents and placing monitors throughout the building, the AECOM team created repair documents for removing the existing aluminum skin and constructing a second line of defense system within the tetrahedron volume. The old aluminum skin is now being recreated to aesthetically match the original— effectively introducing a new “rain-screen” wall design that looks like the original.

This extensive construction process will remove the exterior and interior skins to reinforce the existing structural frame, thereby stiffening the building to reduce the existing 8” movement swing and to allow the reconstruction of a gutter system and appropriate flashing system that alleviates the water infiltration.

AECOM is also removing some of the over-cladding of the intervening years to reveal obscured original Netsch details in the design. As with all federal properties, especially those with such high-level historic significance, the entire chapel project complies with the Secretary of Interior’s Standards for Treatment of Historic Properties. Planning has been closely coordinated with the Academy and the Air Force and continues to be reviewed in construction by the National Park Service and the Colorado Historic Preservation Office.

Attention to craft and handmade materials

LEO A DALY’s Michael Bjornberg, FAIA, and Kimberly Sandbulte, AIA, are advising on the treatment of historic materials and finishes, including exterior and interior aluminum panel replication, Dalle de Vere glazing, interior plaster replication, curtain wall replacement, wood pew restoration, and the two iconic M.P. Moller organs, designed by internationally recognized organ builder Walter Holtkamp.

For the last year, construction crews have been planning and preparing for the dismantling of the 52,000-square-foot chapel roof piece-by-piece to address the failed building envelope and resulting water infiltration dating from its completion. Bjornberg and Sandbulte are now overseeing specialty contractors as they begin the delicate process of repairing and replicating the shell materials and protecting the historic interiors.

The Dalle de Verre glazing will be inventoried, cataloged, removed, and repaired. The north and south curtain walls will be replicated with insulated glass. The combined 8,000 pipes of the two pipe organs have been carefully removed, crated, and transported off site to be repaired and restored.

For review and monitoring, Bjornberg and Sandbulte travel monthly to the Air Force Academy campus and to the specialty shop facilities of preservation sub-contractors including: pipe organs in Lithonia, Georgia, the Dalle de Verre glazing in Los Angeles, the metal panel fabricator in Kansas City, the interior plaster wall/ceiling panels and, for the restoration of the American walnut and mahogany pews, specialists in Garden of the Gods, Colorado.

the pointed air force academy chapel wrapped in a scaffolding
The chapel as it stands today, swaddled in a scaffolding cocoon (Michael Bjornberg)

This attention to detail is essential for any structure with the chapel’s historic architectural and engineering significance. Bjornberg noted that Walter Netsch originally hand-selected the location of each of the 2,000 panels of Dalle de Verre glazing. This requires precision in the removal, repair, and reinstallation of each of those 24,000 unique slabs.

Such a high-level of preservation architecture requires extraordinary technical and organizational skills in documentation, data management, and quality assurance. No stranger to large-scale preservation architecture, Bjornberg led the restoration and updating of the neo-gothic style Notre Dame campus as part of its $500,000,000 Colloquy for the Year 2000 campaign for campus renewal and expansion. Starting in 2005, he also oversaw HGA’s multi-year $317 million restoration of Cass Gilbert’s Minnesota State Capitol Building, lavishly built with Georgia marble and St. Cloud Granite. Sandbulte joined that project in 2012.

From these and other projects, the two have become self-trained architectural historians with expertise in using archives, oral histories, materials research, and the interpretation of plan documents and specifications.

Bjornberg continues to give presentations to client groups and others about the Academy’s design history and the details of the chapel renovation, including the surprising fact that the Academy was not designed to be a flight training school.

Sacred space and the march of time

Of course, the Air Force Academy campus has changed over the decades. Over the last thirty years, enrollment has grown from 3,000 to 4,300 cadets with an expansion of the Dining Hall and student housing to support it. From a historic preservation perspective, such campus changes are inevitable, yet they need not detract from the original design intent. New construction can and should reflect such “character-defining features” of materials, fenestration, massing, and scale.

As a gleaming sacred setting for many faiths, the chapel, lies at the campus heart yet transcends the Academy’s everyday flow of space and movement just as Saarinen intended.

Some argue that buildings like the French cathedrals that Bunshaft sent Netsch to visit should ideally not change at all. But we do not live in a changeless world or in perfect Cartesian buildings that never age. For preservation engineers and architects, the challenge is to steward their unique character through the ravages of human wars, gradual deterioration, and now, the effects of climate change.

A woman in construction gear
Kimberly Sandbulte at the top of the interior scaffolding (Michael Bjornberg)

How should modern landmarks age over time? Is the patina of aging part of their character today? For the Cadet Chapel, one of the biggest challenges is to match the exterior panels made from an aluminum that is no longer manufactured. The exterior panel selection process reviewed original specifications and has gone through years of samples and development to reach accurate replicas. In a 2020 interview with Bjornberg and other team members, Andy Sturdevant noted:

One of the biggest challenges for the architects and contractors is replacing the exterior metal panels with modern-day aluminum that closely approximates the ethereal qualities of the original after decades of weathering in the High Plains sun, rain, and wind. There’s no way to recreate aluminum from the 1950s and 1960s because metallurgy has made enormous advances over the past 50 years. The project team is going to great lengths to create the best match, and the process for that is part chemistry, part forensic science, and part historical reenactment.

Hence the preservation conundrums: How can architects match the nuances of aging found in no longer available materials? If the patina of time is part of their value, at what point in time should we seek to document and replicate it?

Even though modern landmarks like the Cadet Chapel, the Seagram Building, and Louis Kahn’s Salk Institute were rendered and built as pure and finished statements, they never really are. Nor are their preservation treatments. Modernist building preservation is grounded in traditional preservation but adapts to the unique challenges of modernism’s materials, 20th-century construction techniques, and design intent. In the generations to come, the Cadet Chapel will be repaired and “preserved” many times with new methods and technologies. Much of what is being done today will be subject to improvement.

Sacred sites and buildings live on in a different pace of time from most of what we build. In the great landmarks of modernism, time proved that their original systems, water barriers, and climate controls were not good enough. On opening day, their materials seemed so timeless and pristine, yet they were already transient.

Rather than framing sophisticated restoration projects like the Cadet Chapel as a return to perfection, preservation specialists are handing on today’s best practices for future preservationists who will ask the same questions of character and authenticity that we face today.

For preservation architects like Michael Bjornberg and Kimberly Sandbulte, the genius of design is to develop new preservation methods and technologies that work for the foreseeable future while taking the time to revisit the character of every pane of glass.

The author would also like to give a special acknowledgment to Michael Bjornberg for his help in collecting the historic images and connecting the parties involved with the restoration.

Architecture and Engineering Restoration:
Architect and engineer of record: AECOM
Preservation architect: Hartman-Cox Architects
Structural and envelope consultant: Wiss, Janney, Elstner Associates
Organ consultant: Bynum Petty

Contractor: JE Dunn
Historic treatment specialist: LEO A DALY
Organ restoration: AE Schlueter Pipe Organ Company
Curtain wall replication: Alliance Glazing Technologies
Interior ceiling panel replication: EverGreene Architectural Arts
Dalle de Verre glass restoration and repair: Judson Studios
Pew restoration: Woodwork Restoration
Aluminum exterior panels: A Zahner Company

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