ADU Rules: Altadena vs El Monte
How do adu rules rules compare between Altadena, CA and El Monte, CA?
Altadena and El Monte have similar restriction levels.
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 →El Monte, CA
Los Angeles County
El Monte Municipal Code Chapter 17.110 regulates Accessory Dwelling Units (ADUs) and Junior ADUs per California Government Code Sections 66314-66339. Detached ADUs may be up to 1,200 sq ft; attached up to 800 sq ft or 50% of the primary dwelling.
View full El Monte rules →Key Facts Comparison
| Fact | Altadena | El Monte |
|---|---|---|
| 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) | - |
| Code Section | - | EMMC Ch. 17.110 |
| Detached Max | - | 1,200 sq ft |
| Attached Max | - | 800 sq ft or 50% of primary |
| Max Per Lot | - | 2 ADUs + 1 JADU |
| STR Use | - | Prohibited |
| Building & Safety | - | (626) 580-2037 |
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.
El Monte FAQ
How big can an ADU be in El Monte?
Detached ADUs may be up to 1,200 sq ft. Attached ADUs up to 800 sq ft or 50% of the primary dwelling. Up to 2 ADUs and 1 JADU per single-family lot.
Can I convert my El Monte garage to an ADU?
Yes. Garage conversions to ADUs are permitted under California state law and El Monte's Chapter 17.110. A building permit is required.
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