Permitted obstructions refer to any structures or objects that may be located in a yard or open space. They may also be allowed to exceed height limits, setback areas, or sky exposure planes. NYC’s 2016 Zoning Resolution (Article II, Chapter 3, Section 23-61) outlines an exhaustive list of permitted obstructions for buildings in both residential and commercial districts. The list remains largely the same for both types of zoning districts. (zr.planning.nyc.gov, 2016)
Notable permitted obstructions include building columns, whose widths cannot exceed 20% of the aggregate width of street walls, elevator and stair bulkheads, roof water tanks, and added roof thickness up to eight inches to accommodate additional insulation. Moreover, skylights, clerestories or other means of providing daylight to the roof of a building must be less than 10% of the lot coverage of a roof, and cannot be installed on or above a roof with a slope greater than 20 degrees.
Under NYC’s Zone Green text amendment, permitted obstructions were expanded to include rooftop solar energy systems, vegetated (green) roofs, and wind energy systems on buildings higher than 100 feet. Rooftop solar systems must not exceed four feet in height, or may exceed four feet only if the system is set back at least six feet from the street wall and limited to a lot coverage no more than 25% of the total lot coverage of the roof. Vegetated roofs must be no more than 3 feet, 6 inches in height, excluding vegetation.