Can I build an ADU on my property in Los Angeles?

You can build one ADU, attached, detached or converted from something already standing, plus one junior ADU of up to 500 square feet inside the house. State law protects an 800 square foot ADU with 4-foot side and rear setbacks and at least 16 feet of height. No local lot-coverage rule, floor-area ratio, open-space requirement or minimum lot size can be used to block that.

You can convert space that is not currently livable, like storage rooms, garages or a boiler room, into ADUs, up to 25 percent of the number of units already there. On top of that, a 2024 law allows up to eight detached ADUs on a lot with an existing multifamily building, capped at the number of units already on it. On a lot with a proposed multifamily building, the limit is two detached units.

Drawings that meet code, energy-code paperwork, and compliance with hillside grading and very-high fire severity zone rules. Fire sprinklers only if the main house has them. Historic districts get design review but cannot simply refuse an ADU.

In November 2024 the California Department of Housing and Community Development formally found the City of LA's ADU ordinance out of step with state law in 17 separate ways, including leaving out the 18-foot height allowance, limiting lots to a single ADU and imposing an owner-occupancy requirement the state has since banned. Where the city's ordinance conflicts with state law, state law wins. If a plan checker tells you something is not allowed, that is worth checking rather than accepting.