California ADU Regulations · Updated 2026

ADU Rules in California, City by City

California sets the floor. Cities can be more permissive — never more restrictive. Find your jurisdiction, learn what state law guarantees, and skip the guesswork.

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49 California cities · State law summary · 2026 updates

The California Baseline

Every city in California must allow at least this much. Local rules can only sweeten the deal.

How Many ADUs You Can Build

Single-family lots: at least one ADU plus one Junior ADU (JADU). As of 2026, lots may also add an additional 800 sq ft state-exempt detached ADU and a single-family conversion ADU.
Multi-family lots: as many detached ADUs as there are existing units, capped at eight. Up to 25% of the existing units (rounded down, minimum one) may be added as conversions of non-livable space.

Size & Height

Cities must allow at least 850 sq ft for a studio or one-bedroom ADU and 1,000 sq ft for two or more bedrooms.
An 800 sq ft ADU is exempt from local lot coverage, FAR, and front-setback rules — you can build one even if your lot is otherwise maxed out.
Detached ADU base height is 16 ft. It rises to 18 ft within ½ mile of major transit or on multifamily multistory lots, with up to 2 extra feet to match the main home’s roof pitch.
Attached ADUs may be up to 25 ft or the height of the primary home, whichever is lower.

Setbacks

4 ft minimum from rear and side property lines for any ADU at or below the height limits above.
Front-yard setback follows the underlying zoning — but the state-exempt 800 sq ft ADU may encroach if there is no other location.
Building separation between the ADU and other structures is set locally; most cities require 6–10 ft, some require none.

Parking

No replacement parking is required when a garage, carport, or driveway is removed to build an ADU (SB 1211, effective Jan 2025).
No parking is required at all if the ADU is within ½ mile of public transit (including bus stops), inside a historic district, attached to the primary home, or converted from existing space.
When parking is required, tandem and driveway parking inside setbacks is allowed.

Owner Occupancy

No owner-occupancy requirement for standard ADUs — the rule was made permanent in 2023.
JADUs require owner occupancy only if they share sanitation facilities with the main home (clarified in 2026 by AB 1154 / SB 543). A JADU with its own bathroom does not.

Permit Timelines

Cities must determine application completeness within 15 business days and approve or deny a complete ADU application within 60 days.
If the city silently misses a completeness deadline, the application is deemed complete by default.
Pre-approved plans must be acted on within 30 days. Coastal-zone permits get 60 days under AB 462.
AB 253 lets owners hire a certified private plan checker to force a decision in 10 business days when a city sits on a complete permit longer than 30 business days.

Impact & School Fees (SB 543)

No impact fees on ADUs 750 sq ft or smaller — and no impact or school fees on JADUs.
Above 750 sq ft, fees must be calculated proportionally to the size of the main home. Flat or arbitrary fee schedules are no longer allowed.
ADUs and JADUs under 500 sq ft do not increase assessable space for property-tax or school-fee purposes.

JADUs (Junior ADUs)

Up to 500 sq ft of interior livable space, carved out of an existing single-family home.
Cannot be used as a short-term rental.
A JADU cannot trigger sprinklers if the main home is not already sprinklered.

HOAs & Historic Districts

HOAs may impose reasonable objective design standards but cannot charge ADU-specific fees (AB 130).
Being inside a historic district is no longer enough to block ministerial ADU approval — only individually listed historic resources qualify (AB 1061).

What’s New for 2026

Key 2026 ADU Law Changes

AB 1154 / SB 543

JADUs capped at 500 sq ft of interior livable space; owner occupancy only when sanitation is shared; JADUs may not be short-term rentals.

SB 543 — Impact Fees

No impact fees under 750 sq ft. Above 750 sq ft, fees must scale with the ratio of ADU size to main-home size.

SB 543 — Permit Shot Clock

15-business-day completeness review, no new requirements after resubmission, 60-business-day final decision on disputes.

AB 462

60-day decision required on coastal-zone ADU permits. Disaster rebuilds may receive a certificate of occupancy for the ADU before the main home is finished.

AB 253

If a city sits on a complete ADU permit longer than 30 business days, the owner can hire a certified private plan checker to force a decision in 10 business days.

AB 920

Cities of 150,000+ residents must offer a centralized online permit portal for housing including ADUs (most must launch by Jan 1, 2028).

AB 1061

Historic-district overlays can no longer be used to block ministerial ADU review unless the property itself is individually listed.

SB 9 / SB 543 — Enforcement

If a city fails to file or fix its ordinance with HCD, the local rules become null and void and state law applies directly.

Find Your City

Each city page summarizes the most relevant local rules and links to the official jurisdiction.

ADU Rules in California, City by City

The California Baseline

Key 2026 ADU Law Changes

Find Your City

San Diego County

Los Angeles Region

Bay Area

Orange County

Inland Empire

Sacramento / Central Valley

Central Valley

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