Brentwood, CA Noise Ordinances: Decibel Limits (2026)

030 assigns every property to one of three designated noise zones tied to the city's zoning map: Zone I (residential), Zone II (commercial) and Zone III (industrial). ; in Zone III (industrial) the limit is 65 dBA daytime and 60 dBA at night. A violation is not simply any noise above these numbers for an instant; the ordinance builds in graduated tolerances by duration, allowing the base limit for up to thirty minutes per hour, the limit plus 5 dB for up to fifteen minutes, plus 10 dB for up to five minutes, plus 15 dB for up to one minute, and plus 20 dB for any period at all.

If ambient noise already exceeds a tier, the limit rises in 5 dB increments to match the ambient level. On a boundary between two zones, the lower of the two limits governs. If the offending noise contains a pure tone, is impulsive, or carries music or speech, all of these limits are reduced by 5 dB, since such sounds are judged more intrusive. , again with graduated duration tolerances at 5 dB and 10 dB increments. 040.