Accessory Structures in Sammamish, WA (2026)
5 verified accessory structures rules for Sammamish, Washington, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Sammamish permits up to two ADUs on lots with a detached single-family home. A detached ADU may be up to 1,000 sq ft; an attached ADU up to 50% of the house or 1,000 sq ft, whichever is larger. No extra parking is required if the lot already has four or more spaces.
Sammamish Accessory Dwelling Unit (ADU) Rules
Few RestrictionsShed Rules
Sammamish does not require a building permit for a storage shed that is no more than 200 sq ft and no more than 12 ft tall, on a site free of critical areas. Larger sheds need a permit, and all sheds must meet zone-based setbacks (front 10-20 ft, rear and side 5-10 ft).
Sammamish Shed Rules
Some RestrictionsGarage Conversions
Converting a garage into living space in Sammamish generally creates an attached ADU, which the city allows. An attached ADU may be up to 50% of the home's size or 1,000 sq ft, whichever is larger. Permits are required, and any new parking demand is evaluated under the ADU parking rules.
Sammamish Garage Conversion Rules
Some RestrictionsCarport Rules
Carports are treated as residential accessory structures in Sammamish. A simple storage structure of 200 sq ft or less and 12 ft or less may be permit-exempt, but most carports need a permit and must meet zone-based setbacks (front 10-20 ft, rear and side 5-10 ft) and height limits.
Sammamish Carport Rules
Some RestrictionsTiny Homes
Sammamish has no separate tiny-home ordinance. A permanent tiny house on a foundation is treated as a detached ADU, capped at 1,000 sq ft, and the city allows up to two ADUs per single-family lot. Movable tiny houses on wheels are not recognized as permanent dwellings.
Sammamish Tiny Home Rules
Some RestrictionsLooking for King County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Sammamish city rules.
Accessory Structures in King County →