King County, WA Permit Requirements: Fence Permits (2026)

Under the Washington State Building Code as adopted by King County, fences that are under 7 feet in height do not require a building permit. This applies to all common fence types: wood, vinyl, chain-link, and metal. However, King County zoning regulations (KCC Title 21A) typically limit fence height to 6 feet in side and rear yards and 4 feet in front yards for residential zones. Fences exceeding the building code permit threshold (7 feet) require a permit with structural engineering. Retaining walls over 4 feet in height (measured from the bottom of the footing to the top of the wall) require a building permit and engineering calculations, regardless of whether a fence sits on top. Critical areas (wetlands, streams, steep slopes) governed by KCC 21A.24 may require wildlife-permeable fencing — solid fences in these areas could be restricted. Along shorelines managed under the Shoreline Management Act, fencing may require a Shoreline Substantial Development Permit if it could affect shoreline access or ecological functions. In rural residential zones, agricultural fencing (barbed wire, electric) is common and generally exempt from permits. Property owners are strongly advised to verify property lines with a licensed surveyor before fence installation, particularly in rural areas where boundaries may not be well-marked.