ADU type
Detached, attached, conversion, garage conversion, multifamily conversion, and JADU paths can follow different city and state rule branches.
California ADU basics
California ADU Requirements
California ADU law creates important statewide protections, but the useful answer still starts with the address. Use this guide to understand the rule categories, then run the ADU Check to match them to a city and lot.
Primary keyword
California ADU requirements
Protected path
At least 800 sq ft can matter
Common setback
4 ft side / rear baseline
Best first step
Check the address
Requirement map
The ADU basics homeowners should check first
The wrong shortcut is asking whether ADUs are allowed in California. The better question is which rule branch applies to the property and whether a city or state path controls the decision.
Size and layout
State law creates protected ADU paths, but the practical unit size still depends on city rules, lot context, existing buildings, and the ADU type.
Setbacks and placement
Side and rear setbacks are central to ADU planning. Front setbacks, fire access, overlays, and existing structures still require address-level checks.
Parking
California limits when local agencies can require ADU parking, but the answer still depends on project type, location, and the local review path.
Fees
Permit fees, impact fees, utility charges, and plan-check corrections are separate questions. Fee assumptions should be checked against the city schedule.
Source trail
Official HCD guidance and city source pages should stay visible so a homeowner can tell the difference between statewide rules and local implementation.
Free ADU Check
Turn statewide requirements into an address-specific path.
The address check matches jurisdiction, property type, ADU type, and stored city rules so a statewide guide becomes useful planning context.
Run free address check- Confirm the property jurisdiction and whether the city or county receives the ADU application.
- Match the user-selected project type to a stored ADU rule path.
- Separate city rules from California State ADU protections.
- Identify where parcel facts, overlays, fire review, utilities, or existing structures still matter.
- Use official source links before spending on plans, contractor pricing, or permit filing.
City rule examples
California rules still need city context
Start with the statewide requirements, then open the city rule page for source-backed local implementation.
Los AngelesLos Angeles CountyRead city ADU rulesSan DiegoSan Diego CountyRead city ADU rulesSan JoseSanta Clara CountyRead city ADU rulesSan FranciscoSan Francisco CountyRead city ADU rulesOaklandAlameda CountyRead city ADU rulesSacramentoSacramento CountyRead city ADU rulesLong BeachLos Angeles CountyRead city ADU rulesAnaheimOrange CountyRead city ADU rules
Top questions
California ADU requirements FAQ
Start with ADU type, maximum size, minimum size, side and rear setbacks, height, parking, owner-occupancy or deed restrictions, fees, and the city review path. The address decides which of those rules actually matters.
California HCD guidance describes protected ADU paths where local standards cannot block at least an 800 sq ft ADU with four-foot side and rear setbacks. That is a legal floor to check, not a full parcel-specific approval.
Yes. State law creates protections, while cities administer permits, publish local standards, and apply objective rules. HomeFeasible keeps city and state rule paths separate so a report can show the difference.
No. A Junior ADU is a smaller unit type connected to the primary dwelling path, with different size and occupancy details than a detached or attached ADU.
Often not, but the answer depends on the project and local path. California law limits parking requirements in several ADU cases, while city and parcel facts still need review.
Run the address check first. It confirms jurisdiction, selected ADU type, source-backed city rules, and where a parcel-specific review is still needed.
Source notes
This guide summarizes official California HCD ADU guidance and HomeFeasible's source-backed city-rule workflow. It is planning research, not city approval, legal advice, or a parcel-specific buildability decision.
Canonical URL: https://homefeasible.com/california-adu-requirements