The incident happened on West 151st Street in Hamilton Heights around 5:30 p.m. Tuesday.
The 58-year-old victim lived in a second-floor apartment.
He had just filled his bathtub with water when the floor gave way, sending him plummeting to the apartment below.
Other tenants at first had no idea what had happened.
The building has been declared structurally sound, and the Department of Buildings is investigating whether the owner had the proper permits for the renovations being done.
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