Rooftop additions get scrutiny

Developers love adding new units atop old buildings, but doing so is complicated in a historic district. Five items on the Landmarks Preservation Commission’s next meeting agenda involve rooftop additions. The commission’s general rule is that rooftop additions should not be visible from the street in historic districts. The LPC recently sent back proposals for a Norman Foster-designed 22-story glass tower above 980 Madison Avenue and a substantial addition to a two-story building at 746 Madison Avenue.