§ 160.26 GENERAL USE RESTRICTIONS AND RULES OF INTERPRETATION.
   (A)   Principal permitted uses.
      (1)   No building, structure, land or water shall be used for any use that is not listed as a principal permitted use in the zoning district in which it is located, except for a use that is accessory to and customarily incidental and clearly subordinate to a principal permitted use on the same lot, and except for any conditional use that is listed in the district and that has been approved by the Board of Adjustment. All other uses shall be expressly prohibited unless judged by the Zoning Administrator to be substantially similar to a listed permitted use.
      (2)   For the purposes of determining whether a use is allowed, the permitted, accessory and conditional are listed in terminology intended to be consistent with the Standard Industrial Classification Manual, 1972 and the 1977 Supplement thereto, as issued by the U.S. Department of Commerce and on file in the office of the Department of Community Development (herein “SIC”), said SIC having subsequently been replaced by the North American Industry Classification System (herein “NAICS” which may hereby be utilized by the Zoning Administrator to supplement and interpret SIC codes according to conversions and revisions made in subsequent releases of the NAICS. The SIC and NAICS classify uses according to major groups designated by two-digit numbers, whose characteristics are described. Such group or industry code numbers are listed in parenthesis as appropriate for ease of reference to the SIC, and shall have no other purpose. Where a group or subgroup is listed as a permitted use it is intended that all individual uses listed by the SIC within such group or subgroup be permitted unless otherwise stated, subject to all requirements of this Code. It is further intended that where an individual use is listed as a permitted use only that use shall be permitted and all other uses within the SIC or NAICS group or subgroup are expressly prohibited.
   (B)   Accessory use or structure. An accessory use or structure shall not be allowed until the principal use or structure is present or under construction. Residential accessory uses shall not involve the conduct of any business, trade or industry except for the home occupations that are expressly permitted by this Code.
   (C)   Conditional use. A conditional use and any accessory use thereto shall not be allowed unless an application therefor is approved by the Board of Adjustment in accordance with § 160.63 and all other requirements of this Code, and subject to any and all conditions placed upon it by this Code or the Board of Adjustment. An approved conditional use shall be constrained according to its extent and conditions at set forth in the application that was approved, and shall not be expanded, amended, modified or altered in any way unless any such deviation from the approved application is first reviewed as approved by the Board.
   (D)   Reduction or joint use. No lot, yard, parking area, building area or other space shall at any time be reduced in area or dimension to less than the minimum required by this Code, whether temporarily or on a permanent basis. No part of any lot, yard, parking area or other space required for a structure or use shall be credited towards meeting the minimum requirements for any other structure or use.