Cupples Products: a Tall Tale of American curtain walling

History is unfair with master builders. Do you know the relationship between these four behemoths of the 20th century architecture: the John Hancock Center in Chicago, the Twin Towers in NYC, the Sears Tower in Chicago and the Hong Kong & Shanghai Bank headquarters in Honk Kong? The relationship is their skin. The curtain walls and external cladding elements of these four buidings were designed and fabricated in the same place: a factory in the plains near Saint Louis, Missouri.

Webb and Knapp Tower in 34th Street, NYC. I.M. Pei

That place had a name that was equivalent to glazed facades during the great decades of the sixties and seventies: Cupples Products Inc. To whom does that name recall anything? Well, ask Norman Foster or I.M. Pei (or Gordon Bunshaft from SOM or even Mies himself if they were alive). Of course, they would answer: Cupples was my curtain wall contractor of choice back then.

That was back then. Today, if you search Cupples in Google you get files from old legal actions and their last address, a suite in Saint Louis. The nearest website is a link to Enclos, the curtain wall company that lastly absorbed Cupples know-how in curtain walling at the turn of the millenium.

There is something to learn from this company, parallel to the growth of US cities in the second half of the 20th century. Cupples was one of the very early entrants into the new industry of curtain walling right after the war ended. Started in 1946 as a manufacturer of residential of window products, the company rapidly progressed into the design development, engineering, fabrication, assembly and field installation of custom curtain wall systems. Cupples became a provider of glazed solutions to architects and builders eager for new facade technology. One of their first client architects was I.M. Pei, for whom they delivered the curtain wall of Webb & Knapp Tower in 34th Street, NYC. This building was built in 1954 for the headquarters of Webb & Knapp , a local tycoon similar to Donald Trump, for whom young Pei worked as an architect during his early career. Pei would remain linked to Cupples as we will see.

U.S. Air Force Academy, Colorado. Cadets Chapel. Skidmore Owings and Merrill, 1959-1963

At the end of the fifties Cupples start working for Skidmore Owings & Merrill, another architect - contractor collaboration that would last long. The U.S. Air Force Academy in Colorado (with its characteristic Cadet Chapel pictured above, finished in 1963) is the most prominent of these early works. It is interesting to note that the chapel has just been refurbished, fifty years after completion. See the SOM webpage for details.

In the fifties and sixties curtain walling was an integrated business. In a way not rivalled by the biggest Chinese suppliers today, Cupples factory included under one roof these production lines: aluminium extrusion, anodizing and liquid coating, cutting, punching, drilling, curving, bending, mechanizing and assembly of curtain wall units. Their designers were able to study and solve the intricacies of a very complex facade; while at the same time they would deliver off-the-shelf simple systems as Horizon, a stick curtain wall very popular up to the nineties. 

Lake Point Towers, Chicago

In 1960 Alcoa, the aluminium giant, buys Cupples and the great story begins for the guys in Saint Louis. The sixties was the era of the sheer towers. New York adopted a zoning resolution encouraging architects to set off their buildings and to enrich land use. The new towers were pulled in from the building line to form landscaped plazas and obtain the maximum permissible sheer height. Soaring from open plazas, aluminium and glass enclosed buildings dominated the US cities. Curtain walling technology also experienced a jump forward: more sophisticated engineering and manufacturing techniques were developed, as pressure equalization and laser technology. Cupples introduced and became a leader in color anodizing.

The sixties were the golden years for Cupples. The list of buildings whose facades were clad by Cupples this decade is simply extraordinary.

The image above, the Lake Point Tower Apartments, is a project of Schipporeit & Heinrich in Chicago finished in 1968. The link to Mies Van der Rohe is obvious, although this is not a Mies's work. Please have a look at this video from 1969 - the third part of three explaining how the tower was built - here dedicated to curtain walling. A real piece of art for us conoisseurs. Cupples worked for Mies in at least two projects: the Pavillion - Colonnade apartments in Newark and the One Charles Center in Baltimore. Two minor projects for the German master but equally interesting.

Another project from the sixties, the John Hancock Tower in Boston, with I.M. Pei & H.N. Cobb (below left). It was actually completed in 1971, but was not opened until 1976. This is the famous (or better infamous) 'plywood building', so nicknamed because of the glass failures it suffered right before completion. This is still the perfect case study for climatic loads acting on insulated glass and how to avoid them - by reducing the stiffness of the bonding between the inner and outer panes of glass. But this is another story.

In San Francisco we find a good example of the decade: the Wells & Fargo Tower, finished in 1966 by John Graham (one of the corporate architects in those days). A very elegant and slender tower, better than most of the SOM buildings in the decade. I am not sure if the vertical shiny cladding is stainless steel or anodized aluminium, but in any case it reflects prosperity and optimism (see picture below right).

Left, John Hancock Building in Boston, I.M. Pei.     Right, Wells & Fargo Bank in San Francisco, John Graham.

Back to Chicago and we find one of the real giants: the 100-storey John Hancock Center, with Bruce Graham and Fazlur Khan (both from SOM) as main architect and main engineer respectively. Completed in 1969, its curtain wall took 2.5 million pounds (1,100 tons) of aluminium and brackets and 300,000 sqf (28,000 m2) of glass.

The John Hancock Center in Chicago by Bruce Graham and Fazlur Khan from SOM, finished in 1969.

During the installation of the John Hancock Center in Chicago, in November 1967, Cupples changed hands for the second time: Alcoa sold it to the metal company H.H. Robertson, and Cupples became Cupples Products Division within Robertson. The new boss was a giant of metal cladding and steel elements for slabs and ceilings, and would soon begin to be well known by their sandwich panels, branded as Formawall. Cupples had a unique position as the only aluminium and glass supplier in the conglomerate, thus allowing Robertson to provide one-stop-shop services for structure and cladding all around the world. Cupples employed 850 persons and was present in curtain walling, aluminium doors, window frames, store fronts, entrances and suspended ceilings at the time of Robertson's take over.

Between the sixties and the seventies, and both in Chicago, these are the two other big buildings clad by Cupples there: the Standard Oil Building and the Sears Tower. The Standard Oil Building, finished in 1972-73, has another interesting story of failure due to the Carrara marble cladding used (not by Cupples) which failed due to bending - a process known as thermal hysteresis. The solution was hard: to remove the whole marble cladding and to replace it with light coloured and thicker granite panels at an incredible cost. 

Left, the Standard Oil Building in Chicago by Perkins & Will with Edward Durrell Stone (Image credit: J. Crocker).  Right, the Sears Tower by SOM.

The Sears Tower, once again by SOM and finished in 1973, will deserve a future post only for itself, so no more comments by now.

We are now well into the seventies. The construction of the World Trade Center in lower Manhattan is going on and Cupples people are busy with fabrication and erection of the two towers, which by the time would be the tallest in the world. Minoru Yamasaki and Associates with Emery Roth & Sons were the architects. Skilling, Helle, Christiansen and Leslie Robertson were the engineers. Tishman was the general contractor. 

World Trade Center towers in lower Manhattan, 1973. Minoru Yamasaki and Leslie Robertson.

Many new design, engineering and construction techniques were required for the structures. The exterior skin was 2-million sqf (185,000 m2) of Cupples aluminium curtain wall. It used a then unique and progressive 'pressure equalizing' design which caused wind loads and pressures to be exterted directly upon the building structure rather than the aluminium skin. The steel frame work forming the exterior wall was installed by hoisting in place 3-module opaque prefabricated units, up to 36 ft high and 10 ft wide (11m high x 1m wide). Horizontal aluminium spandrel units - finished with Alcoa Duranodic bronze - were then spliced onto the adjacent unit. All aluminium profiles and sheets were supplied by Alcoa.

The two buildings included more than 44,000 glass vision units, recessed 10 inches in relation to the external column cladding, achieving some degree of protection from direct sunlight. Another very interesting feature was the anchoring system of the curtain wall to the bottom side of the floor slab. A viscoelastic interlayer between the bracket and the main structure allowed for wind gusts to be transferred but it absorbed part of the dynamic vibration of wind action. It remains to be studied what role - if any - did this viscoelastic shock-absorber have at the time of the planes crash in 2001...

WTC towers during construction. The yellow band between the curtain wall and the steel structure was the area of structure undergoing sprayed fireproofing.

Cupples completed some more interesting projects in the US during the seventies and the eighties. Among them it is worth mentioning two projects of Johnson & Burgee which exemplify the new style of architecture swifting to volumes out of the box or to pure postmodernism. The Garden Grove Community Church in California (aka the Crystal Cathedral) was finished by Cupples in the late seventies. 

Garden Grove community centre (also known as the Crystal Cathedral) by Johnson and Burgee

The Republic Bank Center in Houston, clad with units of pink granite and glass, is a perfect example of the eighties reaction to sheer transparency, which was not bound to last. Another interesting example of big space container made by Cupples is the State of Illinois Center in Chicago, by Murphy and Jahn.

Left: Republic Bank Center in Houston, Johnson & Burgee. Right: State of Illinois Center in Chicago, Murphy and Jahn. 

Republic Bank Center, stone curtain wall horizontal details. Above section @ vision glass, below section @ spandrel

The next - and probably the last - of the great buildings ever to be covered in glass and aluminium by Cupples was not in the US but abroad: the Hong Kong and Shanghai Banking Corporation headquarters in Hong Kong by Norman Foster, finished in 1985. This is a very successful and rare case of project management led by the architect. Foster proposed the Bank to arrange a team of specialists - architects, engineers and contractors - under a sort of design & build contract where architects were the leading partners both during design and construction.
 

HSBC headquarters in Hong Kong by Foster, 1985: the most expensive corporate building in the world...

The merit that this scheme could go well can be mainly attributed to Foster's bold vision, but the other players - Arup and Cupples among them - were also critical. It is worth mentioning here the role of Phil Bonzon, the engineer from Cupples that led the design and construction of the facade throughout the whole process. Bonzon's sketches were unanimously praised by Foster team members as the only way for them to understand the intricacies of what they were jointly designing. Again, the cladding of this building deserves a future dedicated post if not a whole PhD thesis...

Phil Bonzon's sketches for the HSBC facade design. These details prefigure many industry design features by at least ten years

Nothing can last forever. Cupples lagged behind during the nineties, due not to a specific reason but probably to a number of them. In my opinion the management team did not anticipate that the one-stop-shop model of vertically integrated production was untenable. Cupples people kept for too long a manufacturing structure that was becoming costly and outdated as years passed. The parent company, H.H. Robertson, was also under a similar stress.

Besides, Cupples was not alone in the market. A later entrant to the curtainwall industry had been operating over the decades under the names of Harmon Contract, Harmon Ltd, and finally Enclos Corp, completing many landmark projects. By the end of the 20th century the two companies, Harmon and Cupples, were operating as sister companies under the same umbrella with Harmon focusing on the domestic US market while Cupples tried to keep pace with international operations. Finally, the two companies became one under the same name, that of Enclos. It can be said that Enclos has inherited and continues Cupples history into the twenty first century.

Internal view of the assembly line during the eighties

Why am I interested in Cupples? Because of a personal reason. In 1991 I entered the facade business as project manager with Robertson in Spain, dealing with curtain wall projects and working closely with a number of some great American Cupples colleagues, then busy with projects in our country. I learned the first curtain walling lessons from them. People as Rick Hamlin, now in Trainor Glass; or site managers as James Jutson or Tom Watson, a couple of great chaps whith whom being on site was never boring. Those guys taught me the important lessons. That a facade design is not completed util it is installed - design, fabrication and installation being all part of one same process. That many things can go wrong along the process, and one has to be awake and alert to avoid mistakes and correcting them when things happen. That every step should be checked and re-checked before moving to the next one: it saves time, nobody is perfect. That, in summary, a building and its facade is a lineage of decisions made by a bunch of different people, and success is an outcome of everyone, not of the first one in the line. That being humble on site goes along with being better.

I will never forget those brown helmets with the Cupples name on top. Others will come and build great facades with promising new technologies. But we should never forget those who were so good at opening the trail before us. We owe it to them.