ADU Rules: Castaic vs Los Angeles
How do adu rules rules compare between Castaic, CA and Los Angeles, CA?
Los Angeles has fewer restrictions than Castaic.
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 →Los Angeles, CA
Los Angeles County
Los Angeles follows CA state ADU law (Gov Code §65852.2). Detached ADUs up to 1,200 sq ft. 4-ft side/rear setbacks. 16-ft height limit (18 ft near transit). Solar required. LADBS permits.
View full Los Angeles rules →Key Facts Comparison
| Fact | Castaic | Los Angeles |
|---|---|---|
| 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) | - |
| State Law | - | CA Gov Code §65852.2 |
| Max Size | - | 1,200 sq ft detached / 50% attached |
| Setbacks | - | 4 ft side/rear |
| Height | - | 16 ft standard / 18 ft near transit |
| Solar | - | Mandatory for new ADUs |
| Permit Fees | - | $3,000–$10,000 (LADBS) |
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).
Los Angeles FAQ
Can I build an ADU on my property in los Angeles?
Los Angeles follows CA state ADU law (Gov Code §65852.2). Detached ADUs up to 1,200 sq ft. 4-ft side/rear setbacks. 16-ft height limit (18 ft near transit). Solar required. LADBS permits.
What are the size limits for an accessory dwelling unit in los Angeles?
State Law: CA Gov Code §65852.2. Max Size: 1,200 sq ft detached / 50% attached. Setbacks: 4 ft side/rear. Height: 16 ft standard / 18 ft near transit.
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