Technically I believe that "sliver" buildings are defined as those on lots with a width of 25' ...
Here's some background on sliver buildings in NYC:
Allowance for sliver buildings (narrow lot, built above allowable FAR) is governed by text in the Zoning Resolution 72-21 on variances, particularly:
"(c) that the variance, if granted, will not alter the essential character of the neighborhood or district in which the zoning lot is located; will not substantially impair the appropriate use or development of adjacent property; and will not be detrimental to the public welfare"**************************************
An article on the Austrian Cultural Forum building:
At only 25 feet (7.6 meters) wide, the Austrian Cultural Forum recalls the "sliver building" craze of the 1980s and 90s, when developers in New York raced to raise emaciated towers on sites formerly occupied by lower structures not much wider than a townhouse.
Designed by architecture professor, architect, and theorist Raimund Abraham, who has taught at Cooper Union for the past 30 years, the ACF exhibits both the "thrills and spills" of buildings on such narrow sites.
From the Historic Districts Council website ( http://www.hdc.org/testimonyfeb2205.htm ) regarding a proposed building on Broadway in the Flatiron District:
Hearing Date: 2/22/2005
LPC Docket Number: 053944
Manhattan, Block: 846, Lot: 55
868 Broadway - Ladies' Mile Historic District
A Greek Revival style rowhouse constructed in 1847-48, altered in 1850 and the 1920's. Application is to request that the Landmarks Preservation Commission issue a report to the City Planning Commisison relating to an application for an Authorization pursuant to Section 23-111 of the Zoning Resolution.
HDC did not testify, but later sent the following letter:
Dear Commissioner Tierney:
I am writing to you on behalf of the Historic Districts Council regarding Certificate of Appropriateness 054790, an application to construct a new 15-story building on a parking lot within the Ladies’ Mile Historic District. At the time of the hearing, the Historic Districts Council did not present testimony. However, after viewing the presentation of the project and reading through the careful research done by Christabel Gough of the Society for the Architecture of the City, we would like to voice our opposition to this project.
This building, at 25 feet wide and 150 feet tall, situated in mid block, quite obviously falls within the definition of a “sliver building.” As you are aware, “sliver buildings” were banned by City Planning in a number of neighborhoods in the 1980’s due to their disruptive force on streetscapes. This type of development, contrary to evidence presented at the hearing, is quite alien to this district. While there are many buildings of varying heights, and some buildings of similar height to the proposed building within the historic district, they are situated between buildings of comparable heights. We fear that allowing for a building with a height differential of approximately 90 feet on both sides would not only set a terrible precedent within the Ladies’ Mile Historic District, but open the door to similar developments in other historic districts.
While we do not object to the basic design of this building, its massing, height, and relationship to the surrounding buildings and the district is not appropriate. We respectfully urge the Commission to deny this application, and to request a redesign from the applicant. We do not object to a new building on this site, but this new building must be more contextual than what has been proposed by the applicant.
Thank you for your consideration.