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SLENDERNESS: NEW YORK | HONG KONG

SUPER SLENDER MIDTOWN TOWERS

Thursday February 19, 2009 | Steelcase Showroom

Click here for the online video archive of Slenderness: New York | Hong Kong!

"Hong Kong slender" describes a type of pencil-thin tower common in Asia's Manhattan and recently returned to New York real estate. In conjunction with its current exhibition, "Vertical Cities: Hong Kong | New York", The Skyscraper Museum examined the aesthetics, engineering, and economics of slenderness in a program highlighting three tall, super-slim residential towers recently reared in Midtown: Sky House, One Madison Park, and 785 Eighth Avenue. Team presentations by the architects, structural engineers, and developers explored the complex equation of twenty-first century slenderness.

Featured projects and building team presenters include:

SKY HOUSE
Frank Lupo, Associate Principal, FXFOWLE Architects
Silvian Marcus, CEO, WSP Cantor Seinuk
Veronica Hackett, Co-Founder and Managing Partner, The Clarett Group

ONE MADISON PARK
John Cetra, Principal Architect, CetraRuddy
Silvian Marcus, CEO, WSP Cantor Seinuk

785 EIGHTH AVENUE
Ismael Leyva, President, Ismael Leyva Architects
Ysrael A. Seinuk, CEO, Ysrael Seinuk, PC

New York was the birthplace of the improbably slender tower in the late nineteenth and early twentieth century when numerous buildings, such as the 1917 Bush Tower on W. 42nd Street or the 1897 Gillender Building at Wall and Nassau streets, rose as tall shafts over every inch of their very narrow and high-priced lots. "That was before the city imposed zoning laws that restricted, first, building heights and setbacks, then later, a maximum FAR (floor area ratio) formula," explains Skyscraper Museum director Carol Willis. "To erect a very tall building on a small site under today's zoning, a developer must purchase available air rights from adjacent low-rise properties."

The three buildings featured in the evening's program are the most slender towers recently completed, but also part of a renaissance of the type in New York.

Sky House is a 55-story through-block thin slice of a building with a 45-foot fa�ade on E. 28th Street, between Fifth and Madison avenues, and only 35 feet on 29th Street. The slenderness ratios for its 588-foot height are therefore 1:13 and 1:17. Similarly, the 42-story spike of 785 Eighth Avenue occupies a wedge-shaped site with narrow frontage of just 23 feet, 8 inches on its narrow side, so has a ratio of 1:18. At 621 feet, One Madison Park, a stack of glass cubes stretching 50 stories, is the tallest of the three buildings, but also relatively fat with a ratio of 1:12. Other tall, thin towers announced, or in the early stages of construction, include 610 Lexington Avenue, as well as 30 Park Place, 50 West Street, and 45 Broad Street, all in lower Manhattan.

The program also examines the engineering concept of slenderness. Structural engineers consider skyscrapers with a minimum 1:10 or 1:12 ratio-the width of the building's base to its height-to be "slender." (For the layman to visualize a 1:12 ratio, think of a ruler 1-inch wide and set on end.) Slender towers require special measures, and sometimes considerable expense, to counteract the exaggerated forces of wind on the vertical cantilever. These can include additional structure to stiffen the building or various types of dampers to counteract sway.

The most slender residential skyscraper in the world is Hong Kong's Highcliff, which rises 72 stories and 828 feet (252 meters) with an extraordinary slenderness ratio of 1:20. Extreme slenderness is characteristic of Hong Kong's tall buildings, and the city has more pencil-thin towers than any place in the world. In particular, in the 1980s, Hong Kong's high land values and liberal zoning laws spawned whole districts of extraordinarily slender and densely-packed apartment towers such as the Mid-levels where hundreds of apartment buildings exploited the permissible FAR of 1:18.

SKY HOUSE
11 East 29th Street, New York, NY
Slenderness Ratio: 1:12 and 1:17
55 Floors/ 588 ft
Frank Lupo, Associate Principal, FXFOWLE Architects
Silvian Marcus, CEO, WSP Cantor Seinuk
Veronica Hackett, Co-Founder and Managing Partner, The Clarett Group

ONE MADISON PARK
East 23rd Street, New York, NY
Slenderness ratio: 1:12
50 Floors plus cellar/ 621 ft
John Cetra, Principal Architect, CetraRuddy
Silvian Marcus, CEO, WSP Cantor Seinuk
Slazer Enterprises LLC

785 EIGHTH AVENUE
New York, NY
Slenderness ratio: 1:18 and 1:15
42 Floors/ 518 ft
Ismael Leyva, President, Ismael Leyva Architects, PC
Ysrael A. Seinuk, CEO, Ysrael Seinuk, PC
Jay Eisenstadt, Co-Chairman and President, Esplanade Capital LLC

HIGHCLIFF
41D Stubbs Road Hong Kong Island, Hong Kong
Slenderness Ratio: 1:20
72 Floors/ 831 ft
DLN Architects and Engineers
Magnusson Klemencic Associates
Highcliff Investment Limited


The Skyscraper Museum's current exhibition, "Vertical Cities: Hong Kong | New York" examines the parallels in the vertical identities of the world's two premier skyscraper cities. The Museum hosted an international conference, "Vertical Density | Sustainable Solutions," which expanded on many of the themes of the urban comparisons. Check out the video archive of the conference!








These programs were supported, in part, by public funds from the New York City Department of Cultural Affairs.
These programs were supported, in part, by public funds from the New York State Council for the Arts, a State Agency.