The building height limitations of these regulations shall be modified as follows:

   1.   Tall Structures. Chimneys, cooling towers, fire towers, grain elevators, monuments, penthouses, stacks, stage towers or scenery lofts, tanks, silos, water towers, ornamental towers and spires, radio or television towers or dishes or essential mechanical appurtenances may be erected to a height in excess of applicable district regulations by special permit issued by the Board.

   2.   Public or Semi-public Buildings. Public, semi-public, or public service buildings, hospitals, sanatoriums or schools when permitted in a district, may be erected to a greater height than otherwise permitted in the district if the building is set back from each property line at least one foot in addition to the minimum yard requirements, for each two feet of additional building height above the height limit otherwise provided in the district in which the building is constructed.