ADUs in Los Angeles: what can you build?
An accessory dwelling unit can create housing for family, rental income or long-term flexibility. The right answer starts with the property—not a generic floor plan.
What is an ADU?
An ADU is an independent home on the same lot as a proposed or existing primary residence. It includes permanent areas for living, sleeping, cooking and sanitation. Common formats include a detached backyard home, attached addition, garage conversion or space created inside an existing house.
How many ADUs can a property have?
California’s March 2026 ADU Handbook says qualifying single-family lots must be allowed to combine certain unit types. In some cases this can mean an ADU created from existing space, one JADU and one newly constructed detached ADU. Multifamily properties use a different formula and may qualify for converted non-livable space plus detached ADUs.
| Property | Possible state-law path |
|---|---|
| Single-family lot | Existing-space ADU + JADU + detached ADU may be combinable when requirements are met. |
| Multifamily lot | Qualifying non-livable-space conversions plus detached ADUs under a separate formula. |
| SB 9 lot | Different unit caps may apply depending on whether a lot split occurred. |
How large can an ADU be?
Local rules may set size limits, but state law protects the ability to build at least an 850-square-foot ADU, or 1,000 square feet for more than one bedroom, subject to the applicable path. State law also protects an 800-square-foot option with four-foot side and rear setbacks from certain local limits. Some detached ADUs may reach 1,200 square feet where a compliant local ordinance does not set another maximum.
Will another parking space be required?
Parking cannot be required in several state-law situations, including certain sites near transit and qualifying conversions. Confirm the exact exemption before design; a map pin alone is not enough.
What does the permit process look like?
- Research zoning, legal records, easements and utilities.
- Compare conversion, attached and detached options.
- Prepare architectural, structural and energy documents.
- Submit through the correct City review process.
- Answer corrections and complete clearances.
- Build only after permit issuance and pass required inspections.
State law generally calls for approval or denial within 60 days after a complete application is received for a lot with an existing dwelling. Total project time may be longer because completeness, corrections and other agency reviews matter.
Fees, utilities and real project cost
ADUs of 750 square feet or less are generally exempt from local-agency impact fees under state law; larger units may have proportional impact fees. School fees and utility charges are separate. Real cost depends on access, foundation, grading, utility distances, fire requirements, finishes and existing conditions.
Start with a property review
A useful budget begins with the buildable option, utility plan and permit path.
Discuss your Los Angeles ADU