King County, WA Fence Regulations: Fence Requirements (2026)

KCC Title 21A (Zoning) establishes standard residential fence heights. In residential zones (RA, R, UR), fences in the required front yard setback may not exceed 4 feet in height, while fences in interior side and rear yards may be up to 6 feet. Fences over 6 feet require a building permit and may need engineering. On corner lots, a vision clearance triangle at the intersection of streets or driveways limits fence and hedge height to roughly 30 inches within the sight-distance triangle per KCC 21A.12 and county road standards. Agricultural zones allow taller perimeter livestock fencing consistent with RCW 16.60 (fences and grazing stock). In Critical Areas including wetland buffers, stream buffers, and fish and wildlife habitat conservation areas, solid fencing can obstruct wildlife corridors and may be restricted or require wildlife-passage design (raised lower rails to allow small mammals). Shoreline fences within 200 feet of a salmon-bearing water or marine shoreline are governed by the Shoreline Master Program and typically must be open-design. HOA rules in developments like Klahanie, Issaquah Highlands (portions), and Sammamish Plateau often impose additional architectural restrictions.