King County, WA Building Setbacks & Zoning: Setback Rules (2026)

King County Code Title 21A Chapter 21A.12 establishes setback requirements for all zoning districts in unincorporated areas including White Center, Skyway, Fairwood, East Federal Way, Vashon Island, and rural communities east of the Cascade foothills. Standard urban residential zones (R-4, R-6, R-8 — names reflect density per acre) typically require a 10-foot front-yard setback, 5-foot side-yard setback, and 10-foot rear-yard setback. Rural Area (RA-2.5, RA-5, RA-10) zones require 30-foot front setbacks and 10-foot side setbacks to accommodate larger lots and rural character. Agricultural (A-10, A-35) zones have 30-foot front and 50-foot setbacks from livestock structures to adjoining residences. Corner lots must observe the front-yard setback on both street-facing sides. Critical area buffers (KCC 21A.24) can significantly expand effective setbacks — wetland buffers range from 25 to 300 feet depending on category, salmon-bearing stream buffers are up to 165 feet, and steep slope buffers require setbacks from the top of slope. Shoreline jurisdiction under the Shoreline Master Program adds 100-foot to 200-foot setbacks from the ordinary high water mark of Puget Sound, Lake Washington, Lake Sammamish, and other shorelines of statewide significance. Allowed encroachments include eaves (up to 18 inches), bay windows, and mechanical equipment. Variances require hearing before the King County Hearing Examiner.