No structure shall extend higher than the limit provided in each zone created hereunder for building height.

The height limitations created hereunder shall not apply to spires, belfries, cupolas or domes not used for human occupancy, or to parapets, walls or cornices extending not more than four feet above the building height limit.

The height limitations created hereunder shall apply to chimneys, ventilators, skylights, tanks, stair towers, elevator towers, appurtenances usually carried above the roof level and non-commercial radio and television antennas attached to a building, except that the same may exceed said height limitation by not more than 15 feet, except that skylights, heating and air conditioning equipment and ventilators may exceed the height limitation by no more than four feet. Such features shall not exceed, in total coverage, 20% of the total roof area.

Free standing non-commercial radio and television antennae and flag poles may exceed the height limits created hereunder by not more than 15 feet.