Unless a maximum height regulation is stated in § 27-305, Use Regulations, for a specific use, the maximum height of any principal building or structure shall be 35 feet or 2 1/2 stories, whichever is greater. For any building or structure accessory to a dwelling, which building or structure is located at the setback line applicable in the underlying zoning district, the building or structure shall be limited to a height of 14 feet; however, the height of the building or structure may be increased by one foot for every two additional feet the said building or structure is located away from the setback line to a maximum height of 25 feet. For exceptions, refer to Uses A1(3) [§ 27-305, Subsection 1, Use A1(3)], A3(5) [§ 27-305, Subsection 1, Use A1(3)], I6(2)(C) [§ 27-305, Subsection 9, Use I6(2)(C)], I8(3) [§ 27-305, Subsection 9, Use I8(3)] and § 27-1910.