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

Spokane County Zoning Code Table 606-4 limits the combined square footage of accessory structures by lot size: 1,000 sq ft or 10% of lot (whichever is greater) on lots 30,000 sq ft to 1 acre, up to 3,000 sq ft on lots to 2 acres, 4,000 sq ft above that, and 10% of lot on very large parcels. One accessory structure may be built before the primary use exists, but it cannot be used for residential occupancy, business use, or outside vehicle repair. Setbacks (typically 5 ft side and rear in residential zones) apply even when no building permit is required. Under Washington's adopted building code, one-story detached accessory buildings under 200 sq ft are exempt from a building permit.