The following structures or parts thereof are exempt from the height limitations set forth in the zones indicated, provided that an increase in height shall not conflict with the provisions of the Mason City Municipal Airport Zoning Ordinance.

1.   In All Zones:

   A.   Chimneys or flues.

   B.   Church spires.

   C.   Cupolas, domes, skylights and other similar roof protrusions not used for the purpose of obtaining habitable floor space.

   D.   Farm structures, including barns, silos, storage bins and similar structures when associated with a farm.

   E.   Flag poles.

   F.   Parapet or fire walls extending not more than three (3) feet above the limiting height of the building.

   G.   Poles, towers and other structures necessary for essential services.

   H.   Roof structures, including elevator bulkheads, stairways, ventilating fans, cooling towers and similar necessary mechanical and electrical appurtenances required to operate and maintain the building.

   I.   Television antennas and similar apparatus.

2.   In the C, I and OBP Zones:

   A.   Grain elevators.

   B.   Radio and television communication towers.

   C.   Stacks.

   D.   Storage tanks and water towers.

In all zones, except the OGC Zone, the maximum height in each zone may be increased on the condition that for each foot of height increase above the maximum height limitation there is provided an additional two (2) feet of front, side and rear yards and that an increase in height shall not conflict with the provisions of the Mason City Municipal Airport Zoning Ordinance.