Garage Conversions: Altadena vs South San Gabriel
How do garage conversions rules compare between Altadena, CA and South San Gabriel, CA?
Altadena and South San Gabriel have similar restriction levels.
Altadena, CA
Los Angeles County
Garage conversions to ADUs in unincorporated Altadena are governed by LA County Code Title 22 §22.140.640 and California Government Code §65852.2. No replacement parking is required when an existing garage is converted, and existing setbacks are grandfathered. Properties in Very High Fire Hazard Severity Zones also trigger Chapter 7A wildland-urban interface standards.
View full Altadena rules →South San Gabriel, CA
Los Angeles County
LA County allows converting existing garages to ADUs or JADUs in unincorporated areas under the ADU Ordinance. Garage conversions are the most affordable ADU option at roughly $80–$150K. Replacement parking is not required by state law.
View full South San Gabriel rules →Key Facts Comparison
| Fact | Altadena | South San Gabriel |
|---|---|---|
| Governing Code | LA County Code §22.140.640 | - |
| Replacement Parking | Not required | Not required |
| Existing Setbacks | Grandfathered | - |
| Fire-Zone Construction | Chapter 7A in WUI hillside | - |
| Permit Required | Yes — LA County building | - |
| JADU Max | - | 500 sq ft |
| Permit From | - | Public Works B&S |
| Cost Range | - | $80K–$150K typical |
| State Law | - | Gov. Code §65852.2 |
Highlighted rows indicate differences between cities.
Altadena FAQ
Do I need replacement parking if I convert my Altadena garage to an ADU?
No. Cal. Gov Code §65852.2 and LA County Code §22.140.640 prohibit the county from requiring replacement parking when a garage is converted to an ADU.
Are fire-resistant materials required for an Altadena garage conversion?
Yes, where the property is in a Very High Fire Hazard Severity Zone. Chapter 7A of the California Building Code requires ignition-resistant siding, eaves, vents, windows, and roofing in Altadena's hillside WUI areas.
Who handles the Altadena garage conversion permit?
LA County Public Works (Building & Safety) issues the building permit and LA County Regional Planning handles the ministerial ADU planning review under §22.140.640.
South San Gabriel FAQ
Can I convert my garage to a living space in unincorporated LA County?
Yes. Garage conversions to ADUs or JADUs are allowed under the ADU Ordinance. You need a building permit from Public Works and must meet current building code for habitable space.
Do I need to add replacement parking if I convert my garage?
No. California state law prohibits LA County from requiring replacement parking when a garage is converted to an ADU.
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