Shoreline, WA Accessory Structures: Shed & Carport Rules (2026)

Shoreline's setback code, SMC § 20.50.040, generally bars any accessory structure from sitting inside a required front, rear, or side yard setback. Subsection (I)(11) carves out one exception sized specifically for backyard sheds and greenhouses: a single, uninhabited, freestanding structure under 200 square feet in footprint and less than 10 feet high may be placed inside the required rear or side yard setback, provided it keeps the fire separation distance the adopted building and fire codes demand between structures. If that small shed sits in a side yard rather than a rear yard, SMC § 20.50.040(I)(11)(b) adds a further condition: it must sit at least five feet further back from any street than the principal house on the lot, a rule illustrated in the code's own Figure SMC § 20.50.040(I)(11)(b).

The 200-square-foot threshold is not just a zoning number; it lines up with the building permit exemption in SMC § 15.05.030(A), which amended International Building Code Section 105.2(1) so that one-story detached accessory structures used as tool and storage sheds, playhouses, and similar uses need no building permit at all as long as the floor area stays at or under 200 square feet (18.33 square meters). Cross that 200-square-foot line, or build the shed taller than 10 feet, and both the setback exception and the permit exemption disappear: the structure must meet standard setbacks under SMC § 20.50.040 and go through the ordinary building permit process the Planning and Community Development Department administers.