Decibel Limits: Altadena vs South Gate
How do decibel limits rules compare between Altadena, CA and South Gate, CA?
Altadena and South Gate have similar restriction levels.
Altadena, CA
Los Angeles County
Exterior noise in Altadena's residential zones is capped at 50 dBA daytime / 45 dBA nighttime (single-family); 55/50 dBA (multi-family); 60/55 dBA commercial; 70 dBA all hours industrial.
View full Altadena rules →South Gate, CA
Los Angeles County
South Gate Municipal Code Chapter 11.34 sets exterior noise standards in dBA Leq by land use category, inclusive of ambient noise. Residential zones cap at approximately 50 dBA daytime (7 a.m.–10 p.m.) and 40 dBA nighttime (10 p.m.–7 a.m.); noise-sensitive zones cap at ~45 dBA at all times; commercial at ~55 dBA. Measurements are taken at the closest adjoining property line between habitable parcels or at the nearest public right-of-way, four feet above ground, ten feet from the nearest wall. Chapter 11.34 Table 11.34-2 also caps temporary increases over ambient based on duration of the noise event.
View full South Gate rules →Key Facts Comparison
| Fact | Altadena | South Gate |
|---|---|---|
| Code Section | LA County 12.08.390 | - |
| R-1 Day Limit | 50 dBA | - |
| R-1 Night Limit | 45 dBA | - |
| Multi-family Day/Night | 55 / 50 dBA | - |
| Commercial Day/Night | 60 / 55 dBA | - |
| Code section | - | South Gate Mun. Code Ch. 11.34 |
| Unit | - | dBA Leq (A-weighted, equivalent continuous) |
| Residential day (7am-10pm) | - | ~50 dBA |
| Residential night (10pm-7am) | - | ~40 dBA |
| Noise-sensitive zones | - | ~45 dBA at all times |
| Commercial | - | ~55 dBA |
| Measurement | - | 4 ft above ground, 10 ft from wall, at receptor property line |
Highlighted rows indicate differences between cities.
Altadena FAQ
What's the legal decibel limit at my Altadena property line?
50 dBA day / 45 dBA night for single-family residential under LA County Code 12.08.390.
South Gate FAQ
How do I know if my neighbor is over the limit?
Measurement must be taken at your property line (or the nearest public right-of-way) with a Type-2 sound-level meter set to dBA fast-response, averaged as Leq. Code Enforcement officers carry calibrated meters; you can also document with logged readings from any reputable sound-meter app for an initial complaint.
Does ambient noise count toward the limit?
Yes — Chapter 11.34 standards are 'inclusive of ambient noise.' If background ambient from traffic on Atlantic or Firestone Blvd is already near the standard, even modest added sound from a source can constitute a violation.
What about temporary noise like a backyard party?
Table 11.34-2 sets maximum temporary increases above ambient by duration — the shorter the event, the greater the permitted excess. But sustained noise exceeding these caps, especially after 10 p.m., is a violation.
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