Los Angeles County, CA Accessory Structures: ADU Rules (2026)

Section 22.140.640 of the Los Angeles County Code implements Chapter 13 of Division 1 of Title 7 of the California Government Code for the unincorporated areas. In a Coastal Zone the applicable Local Coastal Program governs instead, and where Title 22 conflicts with the state ADU chapter, the state provision controls.

Lots in a Very High Fire Hazard Severity Zone cannot take an ADU unless the lot has two distinct, non-overlapping vehicular routes to a highway, each at least 24 feet wide excluding sidewalks and built to standards approved by Public Works. A lot with one access that fronts a highway and lets vehicles enter directly from it is exempt from that test. The state-exempt units in Subsection H skip the prohibition entirely.

Table 22.140.640-A sets the count. One single-family residence supports one ADU attached to or within the residence or an accessory structure, one detached ADU, and one junior ADU. A multi-family property supports ADUs equal to 25 percent of its principal dwelling units inside existing buildings, rounded up to the next whole number, plus two detached ADUs, and no junior ADU.

Size and height: an ADU must be at least 150 square feet with one habitable room of 70 square feet. The cap is 1,200 square feet, lifted for units entirely inside an existing residence or converted from an accessory structure expanded by no more than 150 square feet for ingress and egress. Height is 25 feet, though a Community Standards District or Specific Plan limit still applies as long as it allows 16 feet for a detached unit, 18 feet near major transit or on a multi-family lot. Within 200 feet of a scenic route the limit drops to the residence height or 18 feet, whichever is less.

Setbacks are four feet from rear, interior side and corner side lot lines. Conversions need no setback, and a unit of 800 square feet or less can enter the front setback when no ground-level alternative exists.

Parking is not required outside Very High Fire Hazard Severity Zones. Inside them, Chapter 22.112 applies unless an exception fits, such as no bedroom, a location within one-half mile walking distance of public transit, or a historic district. Replacement parking is never required when a garage or carport is demolished or converted.

Use restrictions bar separate sale except under Government Code section 66341, require rentals longer than 30 consecutive days, and prohibit home-based occupations inside the unit. Junior ADUs need an efficiency kitchen, a separate entrance, bathroom access, a recorded covenant, and owner occupancy; a corporate-owned lot cannot have one.