ADU Rules: Castaic vs South San Gabriel
How do adu rules rules compare between Castaic, CA and South San Gabriel, CA?
Castaic and South San Gabriel have similar restriction levels.
Castaic, CA
Los Angeles County
Castaic is an unincorporated CDP in Los Angeles County governed by LA County Code Title 22 §22.140.640 (Accessory Dwelling Units and Junior Accessory Dwelling Units), most recently amended April 2024. Single-family lots may add one ADU plus one JADU; multifamily lots may add up to two detached new-construction ADUs plus conversion ADUs created in non-livable existing space.
View full Castaic rules →South San Gabriel, CA
Los Angeles County
LA County's ADU Ordinance (amended October 2024) allows accessory dwelling units in all residential zones of unincorporated areas. Applications go through EPIC-LA and are reviewed by the Department of Regional Planning. Pre-approved plans are available.
View full South San Gabriel rules →Key Facts Comparison
| Fact | Castaic | South San Gabriel |
|---|---|---|
| Governing Code | LA County Code §22.140.640 | - |
| Single-Family | 1 ADU + 1 JADU per lot | - |
| Multifamily Detached | Up to 2 new (20 ft max) | - |
| WUI Fire Zone | Chapter 7A applies | - |
| Side/Rear Setback | 4 ft (new construction) | 4 feet |
| Max ADU Size | - | 1,200 sq ft |
| JADU Max | - | 500 sq ft |
| Max Height | - | 16 feet |
| Application | - | EPIC-LA portal |
Highlighted rows indicate differences between cities.
Castaic FAQ
Who regulates ADUs in Castaic?
Castaic is unincorporated, so LA County Regional Planning regulates ADUs under LA County Code Title 22 §22.140.640, not a separate city ordinance.
Are there fire-zone restrictions on Castaic ADUs?
Yes. Portions of Castaic are in LA County's Very High Fire Hazard Severity Zone, so ADUs must meet Chapter 7A wildland-urban interface ignition-resistant construction standards and LA County Fire Code §325 brush clearance.
Can a Castaic multifamily lot add detached ADUs?
Yes. Under LA County Code §22.140.640, multifamily lots may add up to two detached new-construction ADUs plus conversion ADUs within non-livable space (up to 25% of existing units).
South San Gabriel FAQ
Can I build an ADU in unincorporated LA County?
Yes. One ADU and one JADU are allowed per lot in all residential zones. Detached ADUs can be up to 1,200 square feet. Apply through the EPIC-LA portal.
Do I need to live on-site to have an ADU in LA County?
No. California state law eliminates owner-occupancy requirements for ADUs. You can rent both the main home and the ADU.
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