Sammamish, WA Fence Regulations: Retaining Walls (2026)

Sammamish treats retaining walls, rockeries, and berms together with fences placed on top of them. Under the City's landscaping and fence design standards (SMC 21.06.020), the height of a fence measured from the top of the rockery, retaining wall, or berm to the top of the fence generally shall not exceed 6 feet. The combined height of the fence and the wall or berm it sits on is also limited; in lower-density residential zones the combined total is capped at 10 feet. If the fence is set back at least 2 feet from the back of the rockery, retaining wall, or berm, the wall and fence may be measured independently rather than as one combined structure. Fences on a wall or berm located outside the required yard setbacks shall not exceed the building height limit for the zone. The retaining wall itself is a separate structure: walls over a code-defined height (commonly 4 feet of retained material, or walls supporting a surcharge) require engineered design and a building permit under Washington's adopted building code, and walls in critical areas or shoreline jurisdiction face added review. Always confirm setback and grading rules before building near a property line.