ADU Permitting 101: Everything You Need to Know + Top California Markets

Thinking of building an Accessory Dwelling Unit (ADU)? You’re not alone. California has led the charge in making ADUs faster and easier to permit, but the process still varies by city. This guide walks you through the statewide permitting process, then drills down into top markets where ADUs are booming, with local insights you can’t get anywhere else.

📋 Permitting Overview: What Every Homeowner Needs to Know

California has passed a series of laws since 2017 to reduce red tape and make it legally easier than ever to build ADUs. But you still need two core approvals:

1. Planning Review (Zoning Compliance)

• Verifies compliance with: lot coverage, setbacks, height limits, fire access.
• In some cities, this step is now automatically bundled into the building permit.

2. Building Permit

• Technical review of construction drawings for safety, accessibility, energy compliance (Title 24).
• Often includes reviews from multiple departments (structural, electrical, public works).

✅ State law requires cities to approve or deny a complete ADU permit within 60 days. If they don’t, it’s deemed approved. (CA Gov Code § 65852.2)

💰 Typical ADU Permit Fees in California

CityAvg Permit FeesNotesLos Angeles$8,000–$15,000Impact fees waived for ADUs <750 sq ftSan Diego$4,000–$10,000Offers permit-ready ADU plan setsSan Jose$7,500–$14,000Online permit portal streamlines processOakland$4,000–$9,000Allows prefabs and streamlined conversionsSan Francisco6–9% of build costOffers permit fee waivers for certain ADUs

Source: Local planning departments, 2024 ADU ordinances

🔥 Top ADU Markets in California — and What Makes Them Different

🏙️ 1. Los Angeles

• Why it’s hot: Massive housing demand + state support = ADU boom
• Permit Notes:
  • LADBS offers Express Permit service for garage conversions
  • Allows up to 2 ADUs per lot on multifamily properties
  • ADU Standard Plan Program available (ladbs.org)

🌴 2. San Diego

• Why it’s hot: Loosened parking rules, strong prefab incentives
• Permit Notes:
  • Offers Permit-Ready ADU Designs to fast-track applications
  • Minimal or no impact fees under 750 sq ft
  • Sandiego.gov/adu

🏡 3. San Jose

• Why it’s hot: High incomes, large lot sizes, and city investment in ADUs
• Permit Notes:
  • Online submission + real-time portal updates
  • Offers ADU consultant hours for free
  • SanJoseCA.gov/ADU

🌁 4. San Francisco

• Why it’s hot: High land value = high ROI for every added square foot
• Permit Notes:
  • Two-stage process: Planning Approval Letter → Building Permit
  • Partial permit fee waivers through 2024
  • Supports ADUs in historic buildings
  • sfplanning.org

🌲 5. Oakland & Berkeley

• Why it’s hot: Pro-housing city councils, strong support for modular
• Permit Notes:
  • ADUs allowed by-right in most residential zones
  • Many cities offer design and permit templates
  • Streamlined “conversion ADU” track for garages and basements

🏘️ 6. Sacramento

• Why it’s hot: Affordable land, flat topography, and a growing ADU pilot program
• Permit Notes:
  • Waived impact fees for ADUs <750 sq ft
  • Offers pre-reviewed prefab designs
  • ADU feasibility map available online

🛠️ Pro Tips to Streamline Your ADU Permit

• Use Pre-Approved Plans: Cities like LA, San Diego, and Oakland offer standard plans that skip initial design reviews.
• Apply Online Where Possible: Most major cities have digital portals for plan submittals and fee payments.
• Bundle Your Permits: Some cities allow you to combine planning and building approvals in one package.
• Hire a Local Pro: Use designers and consultants familiar with your city’s quirks to avoid redlines and rework.

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