Des Plaines, IL Outdoor Lighting: Light Trespass (2026)

Light trespass occurs when outdoor lighting from one property casts unwanted illumination onto an adjacent property. Des Plaines's zoning lighting standards address this primarily for commercial, industrial, and multi-family properties, requiring full cutoff or fully shielded fixtures and limiting illumination at any residential property line to a low foot-candle level (commonly 0.1 fc on residential property lines and 0.5 fc on non-residential lines). Sign and parking lot lighting must be aimed and shielded to prevent off-site spill. For residential properties, the City does not impose specific foot-candle limits but excessive porch lights, motion floodlights, or landscape lighting that casts significant illumination into a neighbor's bedroom window or living area may be addressed under the general nuisance provisions of the property maintenance code. Practical mitigation includes using fully shielded fixtures, lower-output bulbs, motion sensors with reasonable timers, and re-aiming lights downward. Resolving disputes neighbor-to-neighbor first is encouraged before involving code enforcement.