In unincorporated King County, sheds under 200 sq ft with no utilities are exempt from a building permit. The City of Seattle has its own rules. Setback compliance is required for all sheds regardless of size.
Jurisdiction: Unincorporated County vs. Seattle
King County contains Seattle plus dozens of other cities (Bellevue, Redmond, Kirkland, Kent, Auburn, Federal Way, and more). Each has its own building department. King County's Department of Permitting and Environmental Review (DPER) only handles unincorporated areas — land outside any city boundary. Most suburban residential properties in the county are inside incorporated cities.
Verify your jurisdiction at the King County Parcel Viewer. Enter your address and the parcel detail shows your jurisdiction.
Unincorporated King County — Permit Rules
| Shed Size | Permit Required? | Notes |
|---|---|---|
| Under 200 sq ft, no utilities, one story | NO BUILDING PERMIT | Exempt per WAC 51-50-0105. Setback and zoning compliance required. |
| 200 sq ft or over | YES | Apply through King County DPER at kingcounty.gov/dper |
| Any shed with electricity | YES | Electrical permit required through King County DPER. |
| Critical area (wetland, steep slope, flood zone) | YES | Critical Area review required even for small sheds. King County has extensive critical area regulations. |
King County Setbacks — Unincorporated Areas
Setbacks in unincorporated King County vary significantly by zoning district (Rural Area, Urban Residential, etc.). Typical residential accessory structure setbacks:
- Rear and side: 5 feet in most residential zones (Urban Residential zones)
- Rural zones: Often larger setbacks — 20 feet or more in some rural zones. Verify with DPER for your specific zone.
- Critical area buffers: Structures must maintain required buffers from wetlands, streams, steep slopes, and other critical areas.
City of Seattle — Shed Permit Rules
| Shed Size | Permit Required? | Notes |
|---|---|---|
| Under 200 sq ft, one story, no utilities | NO | Exempt per Seattle SMC 23.76.004. Must meet setbacks and lot coverage limits. |
| 200 sq ft or over | YES | Apply through Seattle DCI at seattle.gov/sdci |
| Any shed with electricity | YES | Seattle City Light electrical permit required. |
Seattle setbacks for detached accessory structures in SF5000 (typical single-family zone): rear yard 5 feet, side yard 5 feet. Seattle also has specific rules about accessory dwelling units (ADUs) that interact with shed permitting if you later plan to convert the shed to habitable space.
Critical Areas: A Key King County Consideration
King County has some of the most extensive Critical Area regulations in Washington state. If your property contains or is adjacent to a wetland, stream, steep slope (15%+ grade), landslide hazard area, or is in a flood hazard area, Critical Area regulations apply to any new structure — even small, permit-exempt sheds. Violations of Critical Area buffers can result in costly remediation requirements. Use the King County iMAP to check your property for critical area overlays before placing a shed.
How to Apply — King County DPER
- Apply online at kingcounty.gov/dper using the ePermitting portal
- Upload site plan, shed dimensions, and setback measurements
- Residential accessory structure permit fee: typically $150–$400
- Over-the-counter review available for simple permits; standard plan review 2–4 weeks