page_title: Curtain wall (architecture)
section_title: History
hierarchical_section_title: Curtain wall (architecture) / History
context_page_description: A curtain wall system is an outer covering of a building in which the outer walls are non-structural, utilized only to keep the weather out and the occupants in. Since the curtain wall is non-structural, it can be made of lightweight materials, thereby reducing construction costs. When glass is used as the curtain wall, an advantage is that natural light can penetrate deeper within the building. The curtain wall façade does not carry any structural load from the building other than its own dead load weight. The wall transfers lateral wind loads that are incident upon it to the main building structure through connections at floors or columns of the building. A curtain wall is designed to resist air and water infiltration, absorb sway induced by wind and seismic forces acting on the building, withstand wind loads, and support its own dead load weight forces.
  Curtain wall systems are typically designed with extruded aluminum framing members, although the first curtain walls were made with steel frames. The aluminum frame is typically infilled with glass, which provides an architecturally pleasing building, as well as benefits such as daylighting.
context_section_description: Buildings have long been constructed with the exterior walls of the building supporting the load of the entire structure. The development and widespread use of structural steel and later reinforced concrete allowed relatively small columns to support large loads; hence, exterior walls of buildings were no longer required for structural support. The exterior walls could be non-load bearing and thus much lighter and more open than the masonry load-bearing walls of the past. This gave way to increased use of glass as an exterior façade, and the modern-day curtain wall was born.
  Early prototype versions of curtain walls may have existed in buildings of timber construction before the 19th century, should columns have been used to support the building rather than the walls themselves, particularly when large panels of glass infill were involved. When iron began to be used extensively in buildings in late 18th-century Britain such as at Ditherington Flax Mill, and later when buildings of wrought iron and glass such as The Crystal Palace were built, the building blocks of structural understanding were laid for the development of curtain walls.
  Oriel Chambers (1864) and 16 Cook Street (1866), both built in Liverpool, England, by local architect and civil engineer Peter Ellis, are characterised by their extensive use of glass in their facades. Towards the courtyards they even boasted metal-framed glass curtain walls, which makes them two of the world's first buildings to include this architectural feature. The extensive glass walls allowed light to penetrate further into the building, utilizing more floor space and reducing lighting costs. Oriel Chambers comprises 43,000 sq ft (4,000 m²) set over five floors without an elevator, which had only recently been invented and was not yet widespread.
  An early example of an all-steel curtain wall used in the classical style is the Kaufhaus Tietz department store on Leipziger Straße, Berlin, built in 1901 (since demolished).
  Some of the first curtain walls were made with steel mullions, and the polished plate glass was attached to the mullions with asbestos- or fiberglass-modified glazing compound. Eventually silicone sealants or glazing tape were substituted for the glazing compound. Some designs included an outer cap to hold the glass in place and to protect the integrity of the seals. The first curtain wall installed in New York City, in the United Nations Secretariat Building (Skidmore, Owings, and Merrill, 1952), was this type of construction. Earlier modernist examples are the Bauhaus in Dessau (1926) and the Hallidie Building in San Francisco (1918).
  Ludwig Mies van der Rohe's curtain wall is one of the most important aspect of his architectural design. Mies first began prototyping the curtain wall in his high-rise residential building designs along Chicago's lakeshore, achieving the look of a curtain wall at famed 860-880 Lake Shore Drive Apartments. He finally perfected the curtain wall at 900 910 Lake Shore Drive, where the curtain is an autonomous alumninum and glass skin. After 900 910, Mies' curtain wall appeared on all of his subsequent high-rise building designs including the famed Seagram building in New York. 
  During the 1970s, the widespread use of aluminium extrusions for mullions began. Aluminum alloys offer the unique advantage of being able to be easily extruded into nearly any shape required for design and aesthetic purposes. Today, the design complexity and shapes available are nearly limitless. Custom shapes can be designed and manufactured with relative ease. The Omni San Diego Hotel curtain wall in California (developed by JMI Realty, designed by architectural firm Hornberger and Worstel, is an example of a unitized curtain-wall system with integrated sunshades.
caption: Glass curtain wall of the Bauhaus Dessau, 1926
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