Statewide ADU basics (what California law guarantees)

Use these as your floor—cities can be more flexible but not more restrictive than state law.

Minimum size & types

  • At least one ADU up to 800 sf is allowed, regardless of FAR/lot coverage when other standards are met.
  • Max size commonly up to 1,200 sf (check local standards for larger lots).
  • JADUs up to 500 sf within a single-family home.

Source: California HCD ADU Handbook (updated Jan 2025). HCD ADU page

Setbacks & height

  • Reduced side/rear setbacks: typically 4 ft for new detached ADUs.
  • Existing structures converted to ADUs may keep existing setbacks.

Confirm with your city’s zoning code and HCD guidance.

Parking & occupancy

  • No parking required when within ½-mile of transit, in historic districts with certain conditions, or when converting existing space.
  • Replacement parking not required when converting a garage/carport to an ADU.
  • Owner-occupancy rules: ADUs generally not subject to owner-occupancy mandates; JADUs typically require it.

See HCD ADU Handbook and your city portal for current details.

💡 Tip: If a local ordinance conflicts with state law, state law controls. HCD regularly issues ordinance review letters—use them if your application gets stuck.

References: HCD ADU overview • HCD accountability & ordinance reviews

City specifics

Start with your city’s official portal for fees, submittal checklists, and any local incentives. We keep live links so you always land on the source of truth.

Los Angeles

Portal & guidance: LA City Planning ADU resources • Memo & FAQs (PDF): Development standards

Max sizeUp to 1,200 sf (state floor 800 sf). Check local lot/FAR rules.
SetbacksOften 4 ft side/rear for detached ADUs; verify hillside areas. {{verify locally}}
ParkingState exemptions apply near transit & for conversions.
Owner-occupancyADUs generally no requirement; JADUs typically require owner occupancy.
Fees{{verify locally: planning/building fees}}

Note: HCD issued a 2024 review letter on LA’s ADU ordinance—use if needed during review. See letter

San Francisco

Portal: SF Planning ADU page • Programs: ADU programs handout

TypesConverted, attached, detached; JADU up to 500 sf (owner-occupancy for JADU).
Setbacks/heightProject-specific; conversions may keep existing envelope. {{verify locally}}
ParkingState exemptions apply for conversions & near transit.
Fees{{verify locally: impact and permit fees}}

San Diego

Portal: Info Bulletin 400 (ADU/JADU) • Bonus program: ADU Bonus Program

Size150–1,200 sf per Bulletin 400 (see link).
HeightConforms to zone; single-dwelling zones generally ≤ two stories. See city guidance.
Bonus ADUsAffordable deed-restricted units can unlock bonus ADUs (especially within TPAs).
ParkingState exemptions apply; see checklist.
Fees{{verify locally: school/impact fees thresholds}}

Permit steps (California ADU)

  1. Confirm eligibility: Zoning, lot coverage/FAR, utilities. Save PDFs/screenshots from your city portal.
  2. Pick ADU type & size: Detached/attached/convert; target 800–1,200 sf per lot and setbacks.
  3. Site plan & drawings: Floor plan, elevations, utility notes, Title 24 energy calcs. {{verify city plan set list}}
  4. Submittal: Upload to city e-plan portal (if available); pay plan check fees.
  5. Corrections & approval: Respond to comments; check HCD letters if conflicts arise.
  6. Permit issuance & inspections: Pull building permit(s); schedule foundation, framing, MEP, final.
Match with builders Run financing options

FAQ

What’s the maximum ADU size I can build in California?
State law ensures at least one ADU up to 800 sf independent of FAR/lot coverage if other standards are met. Many cities allow up to 1,200 sf—check your city section above.
Do I need to provide parking for an ADU?
Often no. California waives ADU parking in several cases (e.g., within ½-mile of transit or converting existing space). Your city portal confirms specifics.
Do ADUs require owner-occupancy?
Generally not for ADUs (city policies vary over time); JADUs typically require owner-occupancy. Verify locally before you apply.
How long does permitting take?
Plan review timelines vary by city and workload. Typical first-cycle reviews run 2–8 weeks; total time depends on corrections and scope. {{verify locally}}
Can I add more than one ADU?
Certain lots and multifamily properties can support multiple ADUs under state law. Check your zoning/city portal and any bonus/incentive programs.
Where do I start?
Read the state basics, jump to your city section, and follow the permit steps. When ready, match with builders.