The three kinds
Detached ADU. A separate small house in the backyard. This is what most people picture.
Conversion ADU. A garage, pool house or part of the main house turned into a separate home with its own entrance. Usually the fastest and cheapest, because the structure already exists.
Junior ADU (JADU). Up to 500 square feet inside the main house, with its own entrance. It can share a bathroom with the house, and the owner must live in one of the two.
What decides what fits
- Lot size and shape. Where the house sits, how deep the backyard is, and whether a car can’t reach the back.
- Zone. Single-family and multifamily zones both allow ADUs. On properties with apartments, SB 1211 allows up to eight detached ADUs, but no more than the number of existing units.
- Fire zone and hillside rules. Very high fire hazard areas and some hillside streets have extra requirements.
- Utilities and easements. Sewer location, power lines and recorded easements can rule out parts of a yard.
Check your property
ADUCheck is our free property report for Southern California. Enter an address to see the zone, the size of the property, which kinds of ADU fit and where, the fees, the pre-approved plans that work there, and the fire hazard zone. The report is free on screen with no account. Real estate agents can add a property card to a listing.
You can also look up the zone yourself on ZIMAS, the city’s zoning map.
Pre-approved plans
The Los Angeles Department of Building and Safety keeps a library of ADU designs it has already reviewed for code. Choosing one shortens plan check; city staff still check how it sits on your property. There were 55 approved plans listed in October 2026.
When an ADU isn’t the best use
In multifamily zones such as RD1.5, a property may allow several full houses on their own parcels rather than one ADU. Find out whether yours does.
Questions people ask
Do I have to live on the property?
Not for an ADU; California law says owner occupancy can't be required. A junior ADU (JADU) is different: the owner must live in the JADU or the main house, with some exceptions.
How big can an ADU be?
Cities can't cap an ADU below 850 square feet, or 1,000 square feet with more than one bedroom, and must allow at least an 800 square foot ADU with 4-foot side and rear setbacks. A JADU is up to 500 square feet, inside the existing home.
Do I need to add parking?
Often not. No parking can be required for an ADU within half a mile of public transit, in a historic district, or converted from existing space, and a garage you convert doesn't have to be replaced.
How long does the permit take?
The city must approve or deny a complete ADU application within 60 days, or it is deemed approved. Using one of LA's pre-approved standard plans shortens plan check.
Can I sell the ADU separately?
Only where the city has adopted an ordinance allowing it, or in limited nonprofit cases. Check before you plan around it.