All buildings and structures shall be required to conform to the maximum height regulations specified within the pertinent zoning district, except roof structures for the housing of elevators, stairways, tanks, ventilating fans or similar equipment required to operate and maintain the building, skylights, towers, flagpoles, chimneys, smokestacks, antennas, utility poles, farm silos, spires on places of worship, or similar structures. However, no penthouse, roof structure or any space above the height limit shall be allowed for the purpose of providing additional floor space for any use.