Sheds and similar structures (detached garages, garden sheds, gazebos, greenhouses, pergolas, storage shelters, etc.) are subject to the Accessory Uses and Structures regulations found in RMC Chapter 15.04.601.010.
Height: In residential districts, the maximum allowable height for accessory structures shall be 14 feet. In mixed-use, commercial, and industrial districts, the maximum allowable height for an accessory structure shall not exceed the building height allowed in the base district unless a lower height is set in the base district regulations for such structures.
Location/Setbacks: Accessory structures may be located anywhere on a lot except within a required front or street-side setback. However, Accessory Structures not occupied by an accessory dwelling unit may be built to the side or rear lot line provided that no portion of such structure exceeds 9.5 feet in height within the required yard setback for the property. An accessory structure shall not be closer than five feet to a main building or less than five feet from any public right-of-way and property line. The width of accessory structures shall not exceed 80 percent of the average width of the rear yard. Accessory structures, such as covered patios, gazebos, or pergolas, that are open on three sides, may encroach into a required rear yard as long as such encroachment does not exceed 50 percent of the area of the required rear yard setback.
Operational Limits: In residential districts, where the rear yard abuts the side yard on an adjacent parcel, the accessory structure shall observe a rear yard setback equal to the side yard setback required on the adjacent lot. When located on a corner lot, the accessory structure shall not project into the required street side yard or its extension to the rear lot line. When the slope of a residential lot is 25% or more, an accessory structure may be located in the required front yard, provided every portion is located at least five feet from the front line, and the distance between it and the main building may be reduced to zero. If the residential lot slopes upward from the street, the accessory structure may encroach upon one side yard if the rear of its roof is at or below the natural ground level. Lastly, accessory structures in residential districts shall not exceed 75% of the floor area of the main building, including an accessory dwelling unit.