Lever House is the first office building in which modern materials, modern construction, modern functions have been combined with a modern plan. Lewis Mumford
Lever House is often mentioned as an example of the aesthetic program of High Modernism - The building, designed for a leading American manufacturer, was intended to project a new corporate identity: a prism-like, polished, slab-like,24 story tower floats above a horizontal podium which in turn is detached from the ground, supported mainly by piloti, creating a courtyard at ground level and a roof terrace. The structure of both tower and podium is concealed behind a polished glass gridded facade - a symbol of corporate rationalism.
The architect - Gordon Bunshaft responded to clients needs and wishes, providing narrow office floors to achieve city views and well lit floor area, larger stories for business machines and a public open space on ground level. Yet, possibly more signific ant is that with this image of The-tower-in-the-plaza, slick, abstract, removed, dematerialized , Lever House became a model for new commercial buildings. According to Tom Caroll then Lever president, it produced for the company 4 million dollars wor th of advertisement (the building cost 7 million). The architects on the other hand assumed a leading position in the area of corporate architecture......
At the time, the new building was a symbol of Forward looking Architecture, not only because of its image but also due to the various technological innovations that it offered: It was one of the first office buildings to offer a complete air conditionin g system, to completely seal the building and to create a very thin building envelope. To accommodate the need to keep the building sparkling a new apparatus for cleaning a sheer glass wall with no access from the inside was invented. To cut down on the use of elevators and office boys - a vertical and a horizontal correspondence conveyer which links all floors was installed.
Nevertheless, the architect's attitude regarding utilitarian building systems can be seen as that of denial or accommodation:
Lever House can be used as a model for analyzing the consequences of the high modernist parti. Our report will discuss the ways with which the building's structure, envelope, environmental controls and maintenance had to compensate for it's image-oriented demands.
Lever House employs a typical office tower structural system: Steel frame, metal deck floors, drywall. Yet the building deviates from the typical skyscraper in the way that it distributes gravity and wind loads. In the typical skyscraper there is a separa tion between the two structural functions - a hinged frame which carries the vertical loads to the ground and a stiff core resisting the wind forces, whereas in Lever House the architectural intention of tucking the core at the back of the tower required two systems to resist north-south winds. In the west side of the tower wind trusses around the core stiffen the building, while in the east side of the tower expensive moment connections between columns and beams provide the required rigidity. Thus, the steel frame's role is double: it carries vertical loads to the ground as well as participating in resisting wind forces.
Thus, as seen in the FBD for gravity, gravity loads move from slabs to beams to columns to foundation. As seen in the FBD for wind, the wind load moves from facade through outriggers to beams. At the western end it continues through the wind trusses to the ground; In the eastern portion it continues through the moment connections to the columns and ground.
The bare steel grid of the structural system has very little space to hide mechanical equipment. The electrical wiring and small pipes are integrated in the cellular steel cells of the floor slabs while the larger HVAC ducts are hung under the floor and a re hidden by a hung ceiling. Structure and mechanical equipment are all hidden behind the building envelope, which in turn, hangs from the structure
The delicate blue-green glass enveloping the building as a thin skin is held in place by a grid of stainless steel tubular mullions which in turn are hung from the building's main structure. The pattern of this steel framework is based on the different sizes of the panes of glass.
To support the desired image of the thin skin the mullions had to be flush with the glass and the envelope sealed - there are no operable windows in this curtain wall. The practical aspects of a sealed building are reduction in noise level and dust penetration, but the main interest in sealing the building was an aesthetic one.
The glass conceals the interior structure. Two types of glass panes were chosen. For the transparent areas a light blue green colored glass was picked - not only for it's aesthetic, ethereal quality but also for it's heat absorption qualities. To achieve a consistent exterior surface, spandrels beneath the windows were glazed with smaller panes of wire glass to meet city codes.
About 3" behind the wired glass black cinder- block fire walls were set at the back of an air space. The air pocket was designed to avoid heat build-up in the glass; the walls were built to meet fire codes, as well as to mask floor slabs, radiators and the suspended ceiling with it's mechanical and electrical ducts.
The framework of the enclosure - a vertical grid of double 16 and 18 gauge stainless steel channels is secured between steel sections riveted to the top flange of the steel spandrel beam. The steel framework is flush with the glass except for projecting m ullions marking the columns behind.
The framework has to maintain a delicate balance: it should be sufficiently rigid to prevent continuous flexing. Yet, it should allow for expansion and movement due to wind load, change of temperatures, corrosion and movement in the structure of the build ing. Thus,
The wind force travels from glass panes to mullions to outriggers to the building's structural steel frame.The gravity load in the envelope travels from glass and cinder- block to facade framework to outriggers to the building's structural frame.
The curtain wall was built as a "face sealed" system, based on the principal of keeping water out altogether. To control moisture, infiltration and condensation weepholes and flashing were provided at spandrel level. To make the spandrel as water tight as possible small "flaps" were placed over the weepholes in the metal frame. joining materials was a subject of experimentation - the sealant used was polysulphide.The cinder-block wall at the back of the glass serves as a "cavity wall" to resist wind driven rain.
The success of the curtain wall as a sparkling skin depended on a regular use of a cleaning apparatus developed especially for the project. According to a "Fact Sheet" provided by Lever brothers (as of May 1994) it was established that it was more economical to wash the entire building than to wash the windows only in the traditional manner. The cleaning apparatus is stored on the roof. The windows are washed from a motor driven gondola suspended by a 10 1/2 T crane which runs around the parameter of the roof on standard railroad tracks. Vertically, the gondola is guided on nearly invisible flanged stainless steel T shaped tracks mounted on every sixth vertical mullion.
Here are some statistics on the machine:
In a sealed building such as Lever House ventilation is a function of the complete air conditioning system which consists of individual induction units for the glazed periphery of the structure (up to 15" from windows) - fed with high pressure water and air; and in the center of the office space - a high velocity duct system which distributes air though ceiling diffusers.
This split system makes it possible to keep duct size to a minimum while addressing strong heat gain and loss at the periphery and at the same time satisfying the relatively steady cooling needs of the center of the building.
The mechanical rooms are placed at the bottom and at the top of the building.The compressor and a fan room to ventilate the garage are on the subcellar level. On the second level is the main fan room which supplies air to the rest of the building. through a shaft in the core. Evaporation units and cooling towers take house in the equivalent of three floors above the twenty first story of the tower. Externally, this mechanical space is hidden behind the glass skin of the building with only a change of pattern in the glass hinti ng at the change of program. The location of the a/c plant at the top of the building satisfies the needs for fresh air and headroom .
Construction sequence
The above was done for sections of floors from the bottom up. While the upper floors were built, the lower floors were completed with the following:
In 1982 a battle was fought over the designation of Lever House as a landmark and it's rescue from demolition. Two reports on the building condition were prepared (by Welton Becket Associates and by Swanke Hayden Connell). Problems in the curtain wall - mainly in the wire glass spandrel - were attributed to both corrosion of the steel parts by moisture and lack of resistance of the glass to temperature fluctuations.
About 30% of the panels have been replaced causing the surface of the building to have a checkered look.
Some vision panes have cracked as well, possibly due to failure of early polysulphide sealants, thermal movement or degradation of the steel subframe that has corroded due to leakage and condensation in the spandrels.
The original HVAC system was also evaluated. The consultants criticized the cost and energy inefficiency of the system both in terms of equipment and ductwork and the extended areas of glass which is not double glazed. Nevertheless, they pointed out that the original system performs very well.
The building today is a landmark.
Telephone interviews
Carol Herselle Krisky, Gordon Bunshaft of Skidmore, Owings & Merrill , The Architectural History Foundation, New York, New York Christopher Woodward, Skidmore, Owings & Merrill, Simon and schuster, New York Ernst Danz, Architecture of Skidmore Owings and Merrill, 1950-1962, Frederick A. Praeger, New York
Saving face: Preservation, Curtain wall restoration / Architecture: the AIA journal,Nov. 1990,p.105-114
Lever's Landmark Status Upheld/ AIA journal, Apr. 1983, p.17-18
Icons of modernism or machine-age dinosaurs?/ Architectural record, June 1989, p.142-147
Will Lever house be saved?/ Progressive architecture, Mar 1983,p.25-26
Architecture historians quoted as witnesses against Lever House/ Oculus, Mar 1983, p.3-4,14
25-Year Award goes to Lever House/AIA journal, Mar 1980, p.76-79