Sammamish, WA Outdoor Lighting: Dark Sky Rules (2026)

The Sammamish Development Code addresses exterior lighting in its design standards at SMC 21.06.020. Outdoor lighting may not exceed 5.0 lumens per square foot of hardscape outside the building structure. Outdoor light fixtures must be fully shielded and pointed downward, and maintained so they cause minimal or no light trespass onto adjacent properties - the core elements of a 'dark-sky'-style standard aimed at limiting glare and sky-glow. The code allows narrow exceptions: one partially shielded light fixture or sconce is permitted beneath a building overhang if it generates less than 630 lumens, and landscape or accent lighting is allowed provided the combined output does not exceed 2,100 lumens. These standards reduce upward light and spillover while still permitting reasonable security, entry, and accent lighting. The development code is administered by the city's Community Development Department, and the design standards apply broadly to development across residential and other zones. Because lighting standards can vary with zone, use, and project type, and the development code is periodically amended, property owners and builders should confirm the current shielding, lumen, and fixture requirements with the Sammamish Permit Center before installing or replacing outdoor lighting. The 5.0-lumen-per-square-foot cap and full-shielding, downward-direction requirements are the central performance standards to design around.