Bothell, WA Fence Regulations: Retaining Walls (2026)

BMC 12.14.152 treats retaining walls, rockeries, modular block walls, rock walls, and any structure that retains soil, retains earth surcharge, protects an exposed soil face, or acts as a gravity retaining wall as a retaining structure in the City of Bothell.

Height is measured from the point where the city-approved finish grade meets the structure to its highest point. For outward-facing walls, visible to adjacent properties, the structure and its footings must sit at least one foot, or a horizontal distance equal to its height, whichever is greater, from any property or right-of-way line, unless the applicant records an easement from the neighbor. Inside rear and front yard setbacks the limit is four feet, and two or more four-foot walls are allowed if separated by two times the wall height. The slope between walls cannot be steeper than 4H:1V. Inside side yard setbacks the limit is six feet. Outside the setbacks, walls can reach 12 feet, separated by a distance equal to the height of the downslope wall.

The community development director, in consultation with the public works director, can waive or reduce separation, allow a 3H:1V slope, and allow more height when needed to reduce impacts to a critical area or buffer, retain significant trees, permit transportation improvements, or serve the public interest.

Facing rules apply to visible walls: four feet or more must be built of or faced with brick, stone, split-face or fluted block, textured poured concrete, or similar texture, and walls over six feet need hanging or climbing vegetation or bas-relief art approved by the director. Inward-facing walls are capped at 12 feet of exposed height unless mitigated and sit at least 10 feet from the face of a building.

Under BMC 20.02.095(B)(1)(d), a retaining wall not over four feet, measured from the bottom of the footing to the top of the wall, needs no building permit unless it supports a surcharge or impounds Class I, II or III-A liquids.