(a) The height limitations contained in the District Regulations do not apply to spires, belfries, cupolas, antennas, water tanks, ventilators, chimneys, or other appurtenances usually required to be placed above the roof level and not intended for human occupancy except where the height of such structures will constitute a hazard to the safe landing and take-off of aircraft at an established airport.
(b) Necessary mechanical appurtenances and elevator bulkhead may exceed the permitted height standards by up to fifteen (15) feet, but must be shielded from view by design features of the building.
(c) School sports stadiums shall be allowed at a height up to twice the permitted height for the district in which they are located, but in no case may exceed sixty (60) feet in total height.