SDCI’s noise abatement group conducts inspections and noise advisory reviews for almost all residential side-yard mechanical installations. In a typical Neighborhood Residential zone, the Seattle Municipal Code (SMC) requires an overnight sound level limit of 45 dBA (decibels) at the property line during the overnight hours. Overnight hours are defined in SMC 25.08 as 10:00 p.m. to 7:00 a.m. weekdays and 10:00 p.m. to 9:00 a.m. weekends and legal holidays. Legal holidays are New Year’s Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day, Day after Thanksgiving, and Christmas Day. The 45 dBA standard is fairly restrictive because the City of Seattle makes resident’s ability to sleep and relax a major priority.
