Duluth UDC § 203.05

a. Accessory uses or structures shall be permitted only in rear yards with the exception of detached garages in a residentially zoned area (RA-200, R-100, R-75, R-50, or any residential portion of a PUD), provided they are no closer to any street than the principal structure, except as otherwise provided in this Code. b. No accessory building shall be erected on a lot prior to the time of construction of the principal building to which it is accessory. c. Accessory structure requirements apply only to residential zoning districts. In a residentially zoned area, there shall be a minimum setback requirement from side and rear property line of 5 feet and a minimum separation requirement between accessory structures of 20 feet. Multiple accessory structures are permitted on a single platted lot, provided the combined square footage of the accessory structures complies with the size limitations set forth Section 344 Detached Structures. d. Any structure built on commercial or industrial zoned property shall be considered a principal use. 40 | P a g e Article Two. Use of Land and Structures e. The setback requirements of this Code shall not prohibit the placement of any necessary retaining wall nor prohibit any wall or fence except that in a residential district. See also Section 304.02 Fences and Freestanding Walls.