ADU Rules: Santa Clarita vs Topanga
How do adu rules rules compare between Santa Clarita, CA and Topanga, CA?
Santa Clarita and Topanga have similar restriction levels.
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 →Topanga, CA
Los Angeles County
Topanga 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. Detached ADUs are capped at 1,200 sq ft; multifamily-lot ADUs have no maximum size under county rules. Topanga lies within the Santa Monica Mountains Coastal Zone, so a Coastal Development Permit also applies.
View full Topanga rules →Key Facts Comparison
| Fact | Santa Clarita | Topanga |
|---|---|---|
| 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 | - |
| Governing Code | - | LA County Code §22.140.640 |
| Single-Family | - | 1 ADU + 1 JADU per lot |
| Multifamily Detached | - | Up to 2 new + conversion ADUs |
| Coastal Permit | - | Required (Santa Monica Mtns LCP) |
| Side/Rear Setback | - | 4 ft (new construction) |
Highlighted rows indicate differences between cities.
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.
Topanga FAQ
Who regulates ADUs in Topanga?
Topanga is unincorporated, so LA County Department of Regional Planning regulates ADUs under LA County Code Title 22 §22.140.640, not a separate city ordinance.
Do I need a Coastal Development Permit for a Topanga ADU?
Yes. Topanga falls within the certified Santa Monica Mountains Local Coastal Program, so most ADU construction requires a Coastal Development Permit in addition to the building permit.
Can a Topanga 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).
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