ADU Rules: Altadena vs Los Angeles
How do adu rules rules compare between Altadena, CA and Los Angeles, CA?
Los Angeles has fewer restrictions than Altadena.
Altadena, CA
Los Angeles County
Altadena 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 in non-livable existing space.
View full Altadena 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 | Altadena | 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 (hillside) | - |
| 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.
Altadena FAQ
Who regulates ADUs in Altadena?
Altadena is unincorporated, so LA County Regional Planning regulates ADUs under LA County Code Title 22 §22.140.640, not a separate city ordinance.
Do hillside or fire rules apply to Altadena ADUs?
Yes. Altadena's hillside neighborhoods are in LA County's Very High Fire Hazard Severity Zone, requiring Chapter 7A ignition-resistant construction and Fire Code §325 brush clearance. Hillside-grading provisions of Title 22 apply on slopes steeper than 10%.
How big can my Altadena ADU be?
Under §22.140.640, a detached ADU on a single-family lot may be up to 1,200 sq ft; multifamily-lot ADUs have no maximum size cap. JADUs are capped at 500 sq ft.
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.
Compare other topics
See how Altadena and Los Angeles compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool