Accessory Structures in Shoreline, WA (2026)
3 verified accessory structures rules for Shoreline, Washington, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
In the City of Shoreline, homeowners can build up to two accessory dwelling units per lot under Shoreline Municipal Code § 20.40.210, subject to the density formula in Table 20.50.020(1). Each ADU can share the primary structure or stand detached, but is capped at 1,200 square feet unless it qualifies for the interior-unit exception. All ADUs must meet the City's building and zoning codes.
Shoreline accessory dwelling unit zoning rules
Some RestrictionsShoreline Municipal Code § 20.40.210
A. Two accessory dwelling units per lot subject to the max density calculations in Table 20.50.020(1). B. Accessory dwelling units may be located in the same structure as a principal dwelling unit, or in a detached structure. C. Accessory dwelling units shall not be larger than 1,200 square feet. Exception to SMC § 20.40.210(C): An accessory dwelling unit interior to the residence may be larger...
ADU Impact Fees
Shoreline charges a park impact fee on every new accessory dwelling unit, but SMC § FEE.030 caps it at half of what the principal home on the lot would pay, or the ADU's own square-footage rate, whichever comes out lower. The fee funds park land and facilities tied to new residential growth.
Shoreline ADU Park Impact Fee Discount
Some RestrictionsShoreline Municipal Code § FEE.030
§ FEE.030. Park impact fees. ... A. Rate Table Type of Development Unit by Finished Square Footage Impact Fee Less than 500 $2,507 per dwelling unit 500 to 1,499 $4,460 per dwelling unit 1,500 to 2,499 $6,412 per dwelling unit 2,500 or more $6,940 per dwelling unit Accessory Dwelling Unit (ADU) 50% of the park impact fee that would be charged to the principal unit on the lot or the rate by squa...
Shed & Carport Rules
A backyard shed or greenhouse under 200 square feet and less than 10 feet high can sit inside Shoreline's required rear or side yard setback under SMC § 20.50.040(I)(11), and the same size threshold under SMC § 15.05.030(A) exempts it from needing a building permit, though it still must keep the fire separation distance the adopted building and fire codes require.
Shoreline Shed Rules: Size, Setback, Permit
Some RestrictionsShoreline Municipal Code § 20.50.040(I)(11)
11. No accessory structure shall be located within any required setback except as follows: a. One uninhabited freestanding structure less than 10 feet high and 200 square feet in footprint area, such as a storage shed or greenhouse, may be located within the required rear or side yard setback. This structure shall retain a fire separation distance as specified in adopted building and fire codes...
Looking for King County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Shoreline city rules.
Accessory Structures in King County →