Working Backwards with Forward-Reaching Features

Lever House at 390 Park Avenue in Midtown Manhattan—an icon of International Style architecture—paved the way for exciting engineering innovation in using design features that, in part, were ahead of their time.

The now-landmarked, 24-story, delicate blue-green glass and stainless steel-clad office building completed in 1952 was designed by Gordon Bunshaft of Skidmore, Owings & Merrill (SOM) according to the design principles of Ludwig Mies van der Rohe for the leading manufacturer of household products the Lever Brothers Company (as the American subsidiary of Unilever). The building’s design is a prism-like, polished tower that floats above a horizontal podium, that in turn is detached from the ground, supported mainly by piers, and creating a planted courtyard at ground level. The second floor hovers over the entire site, and above the second floor the tower rises to accommodate 19 office floors (and three additional floors of mechanical equipment. This design enabled the building to be “slick, abstract, removed, dematerialized” in the new modern design era of the 1950s. 

The building’s shimmer could be maintained with the invention of a new apparatus in the form of a gondola that would clean a sheer glass wall with no access from the inside. It could be lowered from the roof and moved on a miniature railroad track behind the parapet. This new mechanism caught the eye of many New Yorkers, including Lewis Mumford, who wrote:

For a company whose main products are soap and detergents, that little handicap of the sealed windows is a heaven-sent opportunity, for what could better dramatize its business than a squad of cleaners operating in their chariot, like the deus ex machina of Greek tragedy, and capturing the eye of the passerby as they performed their daily duties? This perfect bit of symbolism alone almost justifies the all glass facade.

Lever House’s construction marked a transition point for Park Avenue in Midtown, changing it from a boulevard of masonry apartment buildings to one of glass towers as other corporations adopted the International Style for their new headquarters. “The mile-long stretch of Park Avenue from the Grand Central complex to East 59th Street changed in a single decade from an avenue of traditional masonry apartment houses to one of glass and steel office buildings.” By 1957, New York Times architectural design critic Ada Louise Huxtable commented:

As the old buildings disappear radical new ones rise immediately in their place, and the pattern of progress becomes clear: business palaces replace private palaces; soap aristocracy replaces social aristocracy; sleek towers of steel-framed blue, green, or gray-tinted glass give the avenue a glamourous and glittering new look. ... The staples of our civilization – soap, whiskey and chemicals – have identified themselves with advanced architectural design and their monuments march up the avenue in a proud parade.

As a result of the building’s unique design, only about 30% of the ground floor is indoor space. This is the result of the Lever House’s developers being was the first to take advantage of the city’s 1916 “Building Zone Resolution”, a/k/a the Zoning Resolution, the first municipal zoning legislation in the United States. This law authorizes construction to rise with no setbacks provided that the building covers only 25% of the lot. Lever House’s design broke the tradition since the 1910s of “shaped tower” skyscrapers. In a sense, it was arguably the early prototype for today’s physics-challenging, setback-free super-slenders such as One57 and 432 Park Avenue (albeit these newer buildings achieved this ratio by use of transferable development rights).

Lever House was also one of the first office buildings to offer a complete air conditioning system, to completely seal the building and to create a very thin building envelope. That decision required the special accommodation of an HVAC system fed with high-pressure water and air, and in the center of the office space a high velocity duct system that would distribute air through ceiling diffusers. It involved a split system to make 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. In sum, the building’s innovative design was the product of enormous thought and planning.

When completed in 1952, Lever House was the second curtain wall skyscraper in New York City after the United Nations Secretariat Building. (It is believed that the first glazed facade in the United States was the Boley Clothing Company Building, Kansas City, Missouri (1909), designed by the Canadian architect Louis Curtiss.) Using a curtain wall before its technology was fully tested over time to withstand the weather elements would come at a cost, however. The thin-skinned envelope was designed to be held in place by a grid of stainless-steel, tubular mullions anchored to the structural skeleton at every floor level. These mullions hold in place large and small panels of fixed glass. The large panels (the windows) are green-tinted, heat absorbing transparent glass, and the small panels are tinted wired-glass spandrels encasing the interior’s floor slabs. To support the desired image, the mullions had to be flush with the glass and the envelope sealed - there are no operable windows in this curtain wall.

The key to a successful full-envelope curtain wall appeared to be in the approach to sealing the glazed windows. Lever House’s curtain-wall detailing was “face-sealed”, meaning that the intent was to keep water out altogether. To control moisture, infiltration and condensation, vendors placed flashing and weepholes, i.e., holes to redirect and drain rainwater that would collect within the window frame, at the spandrel level. To make the spandrel as water-tight as possible, small “flaps” were placed over the weepholes in the metal frame.

Yet, the limitations of midcentury materials, such as early polysulphide sealants, coupled with the lack of resistance of the glass to temperature fluctuations, enabled water to seep in behind the structural, stainless-steel mullions, causing the carbon steel within the glazing pockets to rust and expand. This corrosion bowed the horizontal mullions and broke most of the wire-glass spandrel panels. In the early 1980s, during debates before the city Landmarks Preservation Commission about whether to designate the building as a historic landmark (decided in 1982), design consultants noticed that “[o]ver the years panels have cracked and broken and have been replaced by glass of two slightly different shades”. By the 1990s, only one percent of the original glass remained intact.

In 2001, SOM worked with the city’s Landmarks Preservation Commission to restore the building with a façade containing concealed aluminum glazing channels, stainless steel mullions and caps, and new panes of heat-strengthened PPG solex glass. In 2023, new operators Brookfield Properties and WatermanCLARK completed the revitalization with a completely-updated plaza and outdoor spaces, a fully restored lobby, and brand new mechanical systems throughout the building that improve its energy efficiency.

Notably, there is no public record of any dispute much less litigation involving the Lever House’s design or construction. Had the project participants been unable to resolve the window issues amicably, one would expect the type of finger-pointing typical of these multi-party business relationships.

Generally, an owner in this situation will invoke the warranties of its window manufacturer, which as a vendor will be bound by an implied warranty to supply a product that succeeds in its purpose. Where the problematic construction is due not to a faulty product delivered to the site, but seems to stem from a potential design miscalculation, the owner will tend to submit an E&O claim to its designer’s carrier.

There appear to be no published accounts of the type of project delivery or specific contract terms to which the Lever House project participants agreed. Given the era, this was likely a traditional design-bid-build set-up with prescriptive design specifications, versus performance specifications. With the former, the owner is responsible for the design (with the designer responsible to the owner), and the contractor is exempt from liability for defective construction so long as it complied with the specifications. Performance specifications, however, set forth the required results or standards that the contractor must achieve with the completed work, but leave to the contractor the discretion for how to accomplish those results.

In recent years, some project owners have become bolder in attempting to shift the design responsibility to the contractor either way. There are contracts that require the contractor to validate the design’s constructability, or require the contractor to assume responsibility for design adequacy in other ways, such as by allocating to the contractor the choice of a product that is the equivalent of a specific manufactured product -- which can be interpreted as a performance specification involving no implied warranty. Depending on the jurisdiction and context, and the explicitness of the owner's disclaimer, a contractor may be subject to liability for a design's failure.

A contractor that agreed to perform pursuant to performance specifications but encountered difficulties in successfully completing the project may have an uphill battle in overcoming a contract default, but it has some options. Specifications usually contain a mix of detailed design and performance requirements. A contractor may claim that the specification at issue was not, in fact, a performance specification. Or it may contend that its failure to successfully reach substantial completion was due to inconsistent design specifications, and/or that it was impossible to comply with the pure performance specification. With either affirmative defense, the contractor will possess the burden of proof, and resolution may be fact-dependent, requiring a trial.

Despite what may have severe headaches for the Lever House owner and operator for many years (decades), kudos to it — as well as its successors and current operators — for its continued open invitation to proceed beyond the planted courtyard (blessed with the opportunity for outdoor art) to the glassed-in reception area that serves as a small art gallery. Through May 31, 2026, visitors are welcome to view iconic works of Claes Oldenburg installed inside (and outside) the building – including with a mid-century modern living room set up with Claes Oldenburg coffee table books.

CREDITS

Skidmore, Owings & Merrill’s website’s project description of the Lever House.

Max Lakin, “Soft and Seditious, Claes Oldenburg & Coosje van Bruggen Take Manhattan”, NY Times, Jan. 9, 2025

Norval White, Elliot Willensky and Fran Leadon, AIA Guide to NYC, 5th ed., 2010.

Dolkart, Andrew S.; Postal, Matthew A. Guide to New York City Landmarks (4th ed.), New York: John Wiley & Sons, 2009

Columbia University Graduate School of Architecture, Planning and Preservation Technical Report

New York City Landmarks Preservation Commission Report on the Lever House, November 9, 1982

Leland M. Roth, A Concise History of American Architecture, Harper & Row, l980 

Ada Louise Huxtable, “Park Avenue School of Architecture,” New York Times Magazine, December 15, 1957

Lewis Mumford, “The Sky Line: House of Glass,” The New Yorker, August 9, 1952

William Shawn and Brendan Gill, “The Talk of the Town – Clean”, The New Yorker, April 18, 1952