When One57, the highly anticipated Extell development at 157 West 57th Street, is completed sometime next year, it will stand 1,005 feet tall with 90 stories – making this the tallest residential building. Sales began in November 2011 and about 60% of the units are sold to-date. Certainly the buzz around the building is not concerning the developer Gary Barnett. What does have him more than concerned is a possible gripe fest in the tower’s top 15 floors, where the billionaires’ club is forming. Several of the new owners of the building’s top sections have commissioned their own designers to finish their full-floor apartments and the construction could become a potential disturbance to their well-heeled and fussy neighbors. They include the fashion moguls Silas K. F. Chou and Lawrence S. Stroll, the first billionaires to be identified as buyers. To prevent potential construction dust-ups, Barnett has made agreements with the full-floor buyers to allow Extell to do most of the heavy lifting. But in cases where agreements could not be reached, he has denied potential buyers access. Extell is also trying to accelerate construction so that the lower-floor residents can move in by the summer of 2013 and the owners on the upper floors can start moving in by the end of that year. Thankfully, the merely rich residents of the lower floors are expected to keep the building finishes done by Danish designer Thomas Juul-Hansen.