Onassis, protested in favor of ratifying Lever House's landmark designation. Mayor Ed Koch, a member of the Board of Estimate, published a letter to the other board members in which he asked them to support designation. The Board of Estimate ratified the landmark status that March. The landmark status was approved with a slim 6–5 majority, as all five of the city's borough presidents voted against the designation. Lever House's preservation was described by The Christian Science Monitor as "sparking heated debate only in New York City" because, nationally, there was a trend in favor of preservation at the time. Lever House was added to the National Register of Historic Places on October 2, 1983. Building decay and ownership changes As a result of Lever House's relatively small floor area, the land lot had of unused development rights, which under New York City zoning code could be transferred to nearby buildings. However, the LPC had not yet determined whether such a transfer would be applicable to Lever House. Accordingly, the landmark designation caused an impasse between the Fisher Brothers, Klein, and Lever Brothers. Both developers' plans were based on full control of the building and land, as well as lease negotiations with Lever Brothers, whose lease was still active for another twenty-seven years. Lever Brothers sued the Fisher Brothers in June 1983, alleging the latter was still attempting to gain ownership of Lever House so it could be demolished, thereby breaking Lever Brothers' lease. The Fisher Brothers relented that October, agreeing to sell its fee position to Klein. Sarah Korein acquired the land under Lever House from the Goelet estate in 1985, though Unilever continued to lease the building. Her daughter, Elysabeth Kleinhans, recalled that Korein referred to Lever House as her "Mona Lisa". Through the 1980s, the building's blue-green glass facade deteriorated due to weather and the limitations of the original fabrication and materials. Water seeped behind the vertical mullions, causing the carbon steel within and around the glazing pockets to rust and expand. This corrosion led to most of the spandrel glass panels breaking. At least some of these structural failures were attributed to the fact that the technologies used in Lever House's construction were relatively new. According to documents filed with the city government in 1995, forty to fifty percent of the original glass had been replaced. Consulting engineer Vincent Stramandinoli proposed erecting a new glass curtain