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

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified August 2026

ADU rules in Los Angeles County, CA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

Max floor area: 1,200 sq ft
Min floor area: 150 sq ft
Rear and side setback: 4 ft
Max height (detached on SFR/MFR lot): 25 ft
Parking required outside fire hazard zone: None
Application decision deadline: 60 days

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in California under recent ADU streamlining laws. The Los Angeles County, CA rules below cover local size, height, and setback requirements.

Summary

Detached ADUs in unincorporated LA County are capped at 1,200 sq ft and 25 feet tall, require a 4-foot rear and side setback, and are prohibited in Very High Fire Hazard Severity Zones unless the lot has two separate vehicular access routes.

City-specific rules exist: El Monte, Carson, South Gate, Santa Clarita, Pasadena, Lancaster, Palmdale, Lakewood, Norwalk, Inglewood, Burbank, Compton, Long Beach, Glendale, Santa Monica, Downey, Pomona, and Los Angeles have their own adu rules rules that differ from Los Angeles County's county-level regulations. If you live in one of those cities, check the city-specific page instead.

G.Accessory Dwelling Unit Development Standards. 1.Accessory Dwelling Units. a.Floor Area. i.Minimum. An accessory dwelling unit shall have a minimum floor area of 150 square feet, with one habitable room with a minimum floor area of 70 square feet. ii.Maximum.(1)General.(a)The maximum floor area of an accessory dwelling unit shall be 1,200 square feet... b.Height. i.The maximum height of an attached or detached accessory dwelling unit on a lot with an existing or proposed single-family or multi-family residence shall be 25 feet. c.Required Yards. iii.Notwithstanding any contrary provisions in this Title 22, a four-foot setback is required for an accessory dwelling unit not described in Subsection G.1.c.ii, above:(1)Any new accessory dwelling unit...shall be at least four feet from the rear, interior side, and corner side lot lines.

Source: LA County Planning – ADUView official code

Full Breakdown

The minimum ADU floor area is 150 sq ft with at least one habitable room of 70 sq ft. ADUs may not be sold separately from the primary residence. Short-term rental (under 30 days) of an ADU is prohibited. No parking is required for ADUs outside Very High Fire Hazard Severity Zones. The county must act on a complete ADU application within 60 days. A single-family lot may have one attached ADU plus one detached ADU, plus one junior ADU.

Violations & Fines

Unpermitted ADUs are subject to zoning enforcement under Chapter 22.242; illegal short-term rental of an ADU is also enforceable under Title 7.

Frequently Asked Questions

Can I build a 1,500 sq ft detached ADU?

No: the maximum floor area is 1,200 sq ft for a standard detached ADU.

Can I Airbnb my ADU?

No. ADUs may only be rented for periods of more than 30 consecutive days.

Do I need to add parking when building an ADU?

Not outside a Very High Fire Hazard Severity Zone. Within such zones, exceptions apply (e.g., the ADU has no bedroom, or is near transit).

Sources & Official References

[1]Los Angeles County Code of Ordinances (Municode)

Other rules in Los Angeles County

Shed & Carport RulesFew Restrictions ADU Rental RestrictionsSome Restrictions ADU Owner OccupancySome Restrictions Garage ConversionsFew Restrictions Noise Ordinances: Aircraft NoiseSome Restrictions Noise Ordinances: Barking DogsSome Restrictions Noise Ordinances: Vehicle NoiseSome Restrictions Parking Rules: Towing & Impound RightsSome Restrictions Parking Rules: Curb Color RulesSome Restrictions Parking Rules: Loading ZonesSome Restrictions

All Los Angeles County rules

How Los Angeles County compares: Easiest Cities to Build an ADU·California rules heatmap·Compare Los Angeles County to another location·View the California accessory structures overview

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