From our code definitions -
"Accessory structure" means a structure subordinate to the principal use of a building on the same lot, and serving a purpose customarily incidental and subordinate to the use of the principal building.
"Detached building" means a building having no party wall in common with another building.
17.12.070 Accessory uses and structures.
A. A structure or use which is clearly incidental to a principal structure or use, and is located on the same lot with the principal structure or use, is an accessory use. All accessory uses are subject to the restrictions in this section.
B. All accessory uses must meet the following requirements:
1. Be operated and maintained under the same ownership and use as the principal use or structure, and must be a permitted use in the zoning classification in which they are located;
2. Be subordinate in height, area, and purpose to the main structure or use. For the
purpose of this subdivision, area shall be defined as lot coverage;
3. All residential accessory structures and uses in a rear or side yard, not attached to or part of the main structure or use, shall be located at least two feet from any lot line, at least fifteen (15) feet from any street line, at least ten (10) feet from the main structure, and total lot coverage for all structures on the lot may not exceed the maximum allowed per Table A, at the end of this title. All residential accessory uses attached to or part of the main structure must meet all minimum requirements established by Table A, at the end of this title;
4. May not be erected prior to the principal use or structure;
5. May not be located in required front yard;