Flatiron District-based Rosin & Associates, headed by Max Rosin, has filed applications for a four-story, eight-unit residential building at 230 Boerum Street, in East Williamsburg, located three blocks south of the Montrose Avenue stop on the L train. The new structure will measure 5,553 square feet in total and its residential units will average 648 square feet apiece, indicative of rental apartments. There will be two units per floors, although one of the fourth-floor units will feature a fifth-floor penthouse. Alexander Stoltz’s Brooklyn-based SA-DA Architecture is the architect of record. The 25-foot-wide lot is currently vacant.