STRUCTURAL GLASS FACADES - USC School of Architecture

1.2.5 The Advent of the Curtain Wall
This use of glass as a predominant element of the building facade exploded in the 20 th
century fueled by Modernism, especially post-war Modernism, and the development of steel
frame structures and curtain wall cladding systems. After some initial stunning architectural
innovations like the Bauhaus Building in Dessau by Gropius in 1926, the Seagram Building
in New York by Mies van der Rohe in 1954, and the Lever House by SOM in 1952, this
ultimately led to a plethora of cheap, sterile, and poor performing glass clad towers
populating, some would say polluting, the skylines of the world’s major cities; what Wigginton
(1996, p.96) refers to as, “a sort of ‘International Style’ without the style.” Regardless, it
significantly boosted the glass industry.
Flat glass for architectural applications is produced today through the float process. Invented
by Alastair Pilkington (no relation to Pilkington the glass producing company) in the 1950’s,
the process was commercially viable by the early 1960’s. The float process provides the
convenience of making glass horizontally, similarly to the older casting processes. The
bottom side of the cast glass sheet suffered from poor surface quality that could only be
remedied by expensive grinding and polishing. The float process solved this problem by
floating the liquid glass on a bed of molten tin. The resulting high quality product is flat,
smooth and transparent. The float process provided the fabrication technology required for
the next boom in the use of glass in architecture, replacing the drawn glass process of the
time.
Glass, as discussed above, was becoming increasingly available and economical. The new
steel-framing technology opened the door to the dramatic and extensive use of glass in
building skins. But designers were struggling with solutions to replace the masonry practices
dominant at the time. In the early 20 th century, aluminum was becoming available in larger
quantities and lower prices. By the 1920’s it was beginning to see significant use in
20