Target keywords: King County building permit | permit unincorporated King County | deck permit King County WA | King County DPER
If your home is in an unincorporated area of King County — meaning you’re not inside city limits — you work with King County’s Department of Permitting and Environmental Review (DPER), not a city building department. This covers large swaths of the county including parts of Covington, Maple Valley, Black Diamond, Carnation, Duvall, and other communities.
Does My Project Need a Permit in King County?
King County follows the Washington State Building Code with some local amendments.
Decks Attached decks require a permit. Detached platforms under 200 SF and less than 30 inches above grade are typically exempt.
Fences Standard residential fences up to 8 feet are typically exempt. Fences in flood zones or critical areas may have additional requirements.
ADUs and Additions All ADUs, additions, and new structures require a full building permit. King County has specific setback and lot coverage rules that vary by zone — confirm your parcel’s zoning at the King County parcel viewer before starting.
Siding and Roofing Re-roofing over 25% of the roof area typically requires a permit. Re-siding usually does not unless structural work is involved.
Interior Remodels Structural, electrical, and plumbing work requires permits. Cosmetic work does not.
King County Permitting Department
King County Department of Permitting and Environmental Review (DPER) – Website: kingcounty.gov/dper – Online portal: permits.kingcounty.gov – Phone: (206) 296-6600 – Address: 35030 SE Douglas St, Suite 210, Snoqualmie, WA 98065 (and other service centers)
King County has service centers in Snoqualmie and Auburn. Online submittal is available for most project types.
Permit Fees in King County
| Project | Estimated Fee |
|---|---|
| Deck (200–400 SF) | $450–$850 |
| ADU / DADU | $2,000–$5,500+ |
| Room addition | $1,200–$3,000 |
| Kitchen/bath remodel (with mechanical) | $600–$1,500 |
How Long Does Permitting Take in King County?
- Simple projects: 2–4 weeks
- Standard residential: 6–14 weeks
- Complex/large projects: 4–8 months
King County DPER tends to run slightly slower than Seattle DCI, especially for larger projects that require environmental review. Submit complete applications — missing items add weeks.
What King County Inspectors Check
King County inspectors focus heavily on setbacks and site coverage (how much of your lot is covered by structures), storm drainage impacts on neighboring properties, and standard structural requirements. For exterior projects in flood zones or near critical areas (wetlands, steep slopes), additional review applies.
Let Prolific Handle the Permits
We work in unincorporated King County regularly and know which projects trigger environmental review. Get an estimate →
Schema: King County Permitting Guide
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