Rules
Can you build an ADU in your Los Angeles backyard? The rules that decide
By cmoilchef · Updated octobre 17, 2026 · 2 min read
Usually, yes. California law lets most single-family lots add at least one ADU, caps the side and rear setback at 4 feet for new units, and exempts ADUs under 750 sq ft from impact fees. What actually decides your project is the lot: space, utilities, easements and hazard zones.
| Topic | What state law says |
|---|---|
| Side and rear setback | Max 4 ft for new ADUs |
| Size floor | 850 sq ft (1,000 sq ft if 2+ bedrooms) |
| Impact fees | None under 750 sq ft |
| Parking | Max 1 space; many exemptions |
| JADU | Max 500 sq ft, one per lot |
What is an ADU?
An accessory dwelling unit (ADU) is a small, separate home on the same lot as a single-family house. It has its own entrance, kitchen and bathroom. It can be detached in the backyard, converted from a garage, or built above an existing structure.
How big can it be?
Cities set their own maximum ADU size, but California does not let them set it below 850 sq ft, or 1,000 sq ft for units with more than one bedroom.
How close to the property line?
For a new ADU, a city cannot require side or rear setbacks greater than four feet.
Do I pay impact fees?
ADUs under 750 sq ft are exempt from local impact fees, and so are all junior ADUs. Larger ADUs can be charged fees in proportion to the size of the main home.
Do I need parking?
A city can require no more than one parking space per ADU. It cannot require any if the ADU is converted from existing space, is near transit or is in a historic district. It also cannot require replacement parking when a garage is converted.
What is a JADU?
A junior ADU (JADU) is a unit of up to 500 sq ft created inside an existing or proposed single-family home, including an attached garage. Each lot can have one.
What can still block a project?
State law sets the ceiling. The lot sets the limit: available space, utilities, easements, trees, slope, and fire or flood zones. This is what a feasibility check settles for your address.
Check your own lot.
Send your ZIP code and project type. We reply with a clear next step.
Sources
- California HCD, Accessory Dwelling Units fact sheet
- California Government Code §§ 66310–66342
General information, not legal advice. Local Los Angeles rules can add detail; verify with the city or a licensed professional.
Quick questions
Can I build an ADU on any lot in Los Angeles?
Most single-family lots can host at least one. The lot decides what fits, so check space, utilities, easements and hazard zones.
Can I turn my garage into an ADU?
Yes, in most cases. A city cannot require replacement parking when a garage is converted.
Are there fees?
ADUs under 750 sq ft are exempt from impact fees; larger ones are charged in proportion.
StructBuilder team, Los Angeles.