With the exception of single- and two-family dwellings as permitted in this chapter, roof equipment structures for the housing of elevators, stairways, ventilating fans, air-conditioning equipment or similar equipment required to operate and maintain the building and fire or parapet walls, skylights, amateur radio towers, spires, cupolas, flagpoles, chimneys or similar structures may be erected above the height limits prescribed by this chapter, but in no event shall these structures exceed 15 feet above the roofline of the building on which it is located. The height limitations required in each zone shall not apply to house of worship steeples, public school buildings and structures, municipally owned buildings, masts, flagpoles, barns, silos, water towers and commercial radio and television towers. The maximum height for these uses shall not exceed 50 feet.