Penthouses, stage towers, scenery lifts, elevators, bulkheads, clock towers, cupolas, water tanks, and similar structures and mechanical appurtenances may be erected on a building to a height greater than the limit for the district in which the building is located; provided, that no such exception shall cover at any level more than 25% of the area of the roof on which it is located; provided further, that no such exception shall be used for sleeping or housekeeping purposes or for any commercial purpose other than such as may be incidental to the permitted use of the main building.

A parapet wall or cornice solely for ornamental purposes may exceed the height limit established for the district but shall not exceed three feet.

The height limitations of this chapter shall not apply to chimneys, church spires, belfries, standpipes, water towers, flag poles, monuments, transmission towers or cables, or radio or television antennas or towers, ornamental towers, unless specifically identified herein.