The district height limitations stipulated elsewhere in this chapter may be exceeded, but such modification shall be in accord with the following:
A. 
Architectural projections, such as spires, belfries, parapet walls, cupolas, domes, flues and chimneys, are exempt from the height limitations of this chapter.
B. 
Special structures, such as elevator penthouses, gas tanks, grain elevators, scenery lofts, radio and television receiving antennas, manufacturing equipment and necessary mechanical appurtenances, cooling towers, fire towers, substations, and smokestacks, are exempt from the height limitations of this chapter.
C. 
Essential services, utilities, water towers, and electric power and communication transmission lines are exempt from the height limitations of this chapter.
D. 
Communication structures, such as radio and television transmission and relay towers, aerials, and observation towers, shall not exceed in height three times their distance from the nearest lot line.
E. 
Agricultural structures, such as barns, silos and windmills, shall not exceed in height twice their distance from the nearest lot line.
F. 
Public or semipublic facilities, such as schools, churches, hospitals, monuments, sanitariums, libraries, governmental offices and stations, may be erected to a height of 60 feet, provided that all required yards are increased not less than one foot for each foot the structure exceeds the district's maximum height requirement.
G. 
Small height additions. 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.
In residential districts, except for a corner lot, required setbacks may be modified in the following cases:
A. 
Where 50% or more of the frontage on a block is occupied by residences having setbacks less than that required by this chapter, setback on each remaining lot shall be determined in accordance with the following rule. The front building line of a proposed structure shall be no nearer the front lot line than a line joining adjacent front corners of the nearest principal structures which are in the same block frontage on either side of the proposed structure. If, on a block frontage, no principal structure exists to one side of a proposed structure, a structure may be assumed to exist on the corner lot which conforms to the minimum setback and side yard width requirements of this chapter.
A. 
The following extensions shall be permitted into required yards:
(1) 
Canopies and marquees in the Commercial District (not permitted in interior side yards): six feet.
(2) 
Cornices and similar extensions: one foot.
(3) 
Open fireproof fire escapes: three feet.
(4) 
Eaves: two feet.
B. 
The following restrictions shall apply to the permitted extensions:
(1) 
Cornices, canopies, marquees and similar extensions shall be at least 10 feet above ground level.
(2) 
Canopies shall, in no case, extend nearer than three feet back of the face of a curb.
Where an industrial district abuts a residential district, there shall be provided along any rear, side or front line, coincidental with any industrial-residential boundary, a buffer strip not less than 30 feet in width, as measured at right angles to said lot line. Plant materials at least six feet in height, of such variety and growth habits as to provide a year-round effective visual screen when viewed from the residential district, shall be planted within the exterior 25 feet abutting the residential district. If the required planting screen is set back from the industrial-residential boundary, the portion of the buffer strip facing the residential district shall be attractively maintained. The exterior 25 feet of the buffer strip shall not be devoted to the parking of vehicles or storage of any material or accessory uses. The interior 15 feet may be devoted to parking of vehicles.