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

SMC 16.20.200 lists work exempt from a building permit, and subsection (2)(a) covers IRC accessory structures used as tool and storage sheds, one-story tree-supported play structures, playhouses and similar uses, but specifically excludes vehicle storage. The floor area cap is 200 square feet, and except for tree-supported play structures the height cannot exceed 12 feet measured from the grade plane to the highest point of the roof. The exemption only removes the need for a City permit; it does not authorize work that would otherwise violate the Sammamish Municipal Code, and the opening paragraph of SMC 16.20.200 makes clear that permit exemptions for work outside the footprint of an existing legally established structure do not apply within critical areas or within standard shoreline setbacks, both common constraints on Plateau lots near wetlands or steep slopes.

A shed that exceeds 200 square feet or 12 feet in height falls back under the general permit requirement of SMC 16.20.195, which requires the owner or an authorized agent to apply to the permit center and obtain a building permit before construction. Once issued, a building permit is valid for two years from issuance under SMC 16.20.235, and the building official may approve one written extension request for one additional year if it is submitted within 30 days of the original expiration and half the original permit fee is paid, per SMC 16.20.237.