Federal Way, WA Fence Regulations: Retaining Walls (2026)

Federal Way follows International Building Code Section 1807 for retaining walls, as adopted through the Washington State Building Code and FWRC Title 13. A retaining wall over 4 feet in height (measured from the bottom of the footing to the top of the wall) requires a building permit with stamped engineering calculations from a Washington-licensed engineer. Walls supporting a surcharge (driveway, pool, building, slope loading) require a permit regardless of height because the additional lateral pressure requires structural analysis. Tiered walls that act structurally as a single wall (stepped walls within a horizontal distance less than twice the lower wall height) are treated as one wall for permitting purposes. Federal Way has significant sloped topography, especially near Steel Lake, West Hylebos, and the Puget Sound shoreline, making retaining walls common. Walls in geologically hazardous critical areas require a geotechnical report under FWRC 19.145. Shoreline walls require Shoreline Substantial Development Permits. Permit fees are based on wall area and engineering review time.