King County is the most populous county in Washington — but if you're in unincorporated King County (outside Seattle, Bellevue, and other cities), the county's own building code applies. Sheds under 200 square feet are exempt from a building permit per KCC 16.02.240, but there are conditions: 24-inch max eave overhang, 3-foot clearance from adjacent buildings, and 5-foot minimum separation from all other structures. Height and setbacks depend on your zoning district, and critical areas (wetlands, steep slopes, floodplains) can override the exemption entirely. Here's what the code actually says.
For unincorporated King County areas. Incorporated cities may have their own requirements.
| Shed Permit Rules | Unincorporated King County |
|---|---|
| Max Shed Size (No Permit) | 200 sq ft |
| Max Shed Height (Overall) | Per zoning district* |
| Setbacks (Side/Rear) | Per zoning district — check your parcel |
| Setbacks (Front) | Per zoning district — check your parcel |
| Min. Separation from Other Buildings | 5 ft |
*King County does not publish a specific overall height limit for accessory structures — the zoning district height applies. For permit-exempt structures (≤200 sq ft, one-story), IRC defaults apply: 10 ft eave height for one-story detached accessory structures. Check your zone's height limit at the Parcel Viewer.
“One-story detached one- and two-family residential accessory buildings used as tool and storage sheds, playhouses, tree-supported structures used for play and similar uses, not including garages or other buildings used for vehicular storage, provided the floor area does not exceed 200 square feet, the roof eave does not project closer than three feet to any portion of an adjacent building and does not exceed twenty-four inches measured horizontally from the exterior wall, and the building is separated a minimum of five feet from all other buildings.”
KCC 16.02.240 — Permit Exemption for Accessory Structures →
“Exempted structures do not require a building permit from the County but must comply with all King County code requirements.”
KCC 16.02.240 — Exemption Does Not Override Code Compliance →
Have questions about permits or zoning? We don't have all the answers, but we deal with this stuff regularly and can usually help you figure it out. Reach out with your address and we'll point you in the right direction.
Building codes and permit requirements are subject to change. Contact your local building department to verify current regulations before beginning your project.
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