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California ADU Laws and Rules (2026)

San Diego County · City-by-city guides

Planning an accessory dwelling unit in California? Start with the jurisdiction that reviews your property. State law sets a baseline, while local standards, site conditions and overlays affect the plans you can submit. These guides bring together source documents, permit steps and a visible review date for five San Diego County cities.

Start from the state floor below, pick your city, then check what the rules mean for your specific lot in the Studio. Build a budget with the California ADU cost guide, then compare rent and payback scenarios in the free ADU cost calculator.

Before you choose a floor plan

  1. Confirm your permitting jurisdiction. A San Diego mailing address does not by itself establish that City of San Diego rules apply. For unincorporated properties, start with the County of San Diego ADU program.
  2. Read your city guide and check the linked official sources for coastal, fire and other site restrictions. The guide is a starting point, not a parcel approval.
  3. Compare a smaller and larger ADU in the calculator, then ask a designer or builder to price site work, utilities and the fees that apply to your lot.

California ADU laws: the state floor every city builds on

  • 1 ADU + 1 JADU per single-family lot, ministerial approval, 60-day decision
  • At least 850 sq ft (studio/1BR) and 1,000 sq ft (2+ BR); 800 sq ft exempt from coverage, FAR, and lot-size rules
  • 4 ft max side/rear setbacks; no setback for conversions of existing structures
  • No minimum lot size; max 1 parking space (waived near transit); no replacement parking ever
  • No owner-occupancy requirement for standard ADUs; no impact fees at 750 sq ft or less (other fees separate)

Sources: California HCD ADU Handbook (March 2026); HCD Accessory Dwelling Units policy page.

City guides — San Diego County's five largest cities

  • ADU Rules in San Diego (2026)

    The county's bonus-program city: extra ADUs beyond the state minimum, preapproved plans, and the two big overlays — coastal zone and fire hazard maps.

    Updated 2026-10-10 · 9 answered questions

  • ADU Rules in Chula Vista (2026)

    The predictable-permit city: preapproved standard plans with flat-fee review, a 30-day minimum rental rule, and hillside soils review in the east.

    Updated 2026-10-10 · 7 answered questions

  • ADU Rules in Oceanside (2026)

    The ordinance impact-fee relief city, with a coastal development permit layer over much of town while coastal ADU rules await certification.

    Updated 2026-10-10 · 7 answered questions

  • ADU Rules in Escondido (2026)

    The handbook city: plain-English handout numbers and a literal submittal checklist, no coastal zone, and an Article 70 update moving through 2026.

    Updated 2026-10-10 · 7 answered questions

  • ADU Rules in Carlsbad (2026)

    The specific-standards city: named Coaster stations for 18-foot height relief, a parking waiver that reaches bus stops, and a coastal permit for most ADUs in the Coastal Zone.

    Updated 2026-10-10 · 8 answered questions

These are the rules. Here is what they mean for your lot.

Enter your California address to see rent, build-cost, and payback estimates for your specific parcel. Free to explore — no account needed for your first address.

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