ADU Rules: Castaic vs Lancaster
How do adu rules rules compare between Castaic, CA and Lancaster, CA?
Castaic and Lancaster 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 →Lancaster, CA
Los Angeles County
California law (Gov. Code §65852.2) requires cities to allow ADUs on residential lots. Lancaster must comply with state standards for size, setbacks, and parking.
View full Lancaster rules →Key Facts Comparison
| Fact | Castaic | Lancaster |
|---|---|---|
| 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) | - |
| Max Size | - | 800 sq ft detached |
| Setbacks | - | 4 ft rear/side |
| Parking | - | None near transit |
| State Law | - | Gov. Code §65852.2 |
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).
Lancaster FAQ
Can I build an ADU?
Yes. California law requires all cities to allow ADUs on residential lots. Lancaster must process permits within 60 days.
Do I need to live on the property?
No owner-occupancy requirement for ADUs under current California law.
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