ADU Rules: Castaic vs Santa Clarita
How do adu rules rules compare between Castaic, CA and Santa Clarita, CA?
Castaic and Santa Clarita 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 →Santa Clarita, CA
Los Angeles County
Santa Clarita allows ADUs under state law (AB 68, SB 13, AB 881) and local regulations. One ADU plus one JADU per single-family lot. ADUs in flood zones must comply with FEMA requirements. CA HCD reviewed and provided guidance on the city's ADU ordinance in 2023.
View full Santa Clarita rules →Key Facts Comparison
| Fact | Castaic | Santa Clarita |
|---|---|---|
| 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) | - |
| Allowed | - | 1 ADU + 1 JADU per single-family lot |
| Max Size | - | Up to 1,200 sq ft (detached) |
| Owner Occupancy | - | Not required (state law through 2025) |
| Flood Zones | - | Must comply with FEMA requirements |
| HCD Review | - | March 2023 guidance letter |
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).
Santa Clarita FAQ
Can I build an ADU in Santa Clarita?
Yes. California law requires the city to allow ADUs. You can build one ADU plus one JADU per single-family lot, up to 1,200 sq ft for a detached ADU.
Do I have to live on the property to have an ADU?
No. California state law suspended owner occupancy requirements through at least 2025.
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