How much is a permit to build an ADU in California?

Last Updated on June 14, 2025 by DYM Builders Group

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Key Takeaways:

• You need a permit to build an ADU in California—it’s required by law.
• Permit costs typically range from $2,000 to $20,000, depending on your city and ADU type.
• Smaller ADUs (under 750 sq ft) may qualify for fee waivers or reduced costs.
• Extra fees like utility connections, school, and inspection charges can add up—plan ahead.
• Using pre-approved plans and speaking with your city early can help save time and money.

Many people wonder about this because an ADU (Accessory Dwelling Unit) can add extra space or even rental income to a home. Before you start building, it’s important to know how much the permit will cost so you can plan your budget right.

Do You Need a Permit for an ADU in California?

Yes, you need a permit to build an ADU in California. There are different types of permits you might need, such as a building permit, electrical permit, plumbing permit, or zoning permit. These ensure that your ADU will follow laws and be safe to live in.

How Much Does an ADU Permit Cost in California?

The cost of an ADU permit in California usually ranges from about $2,000 up to $20,000 or more. The exact price depends on the city where you live, the size of the ADU, and what type of ADU you are building. For example:

City	Typical Permit Cost Range
Los Angeles	$5,000 – $9,000
San Diego	$4,000 – $7,000
San Francisco	$6,000 – $10,000

Smaller ADUs usually cost less to get permits for, while bigger and more complex units may have higher fees.

What Affects The Cost of an ADU Permit?

Several factors can change how much you pay for an ADU permit:

• Size of the ADU: ADUs smaller than 750 square feet often have lower permit fees or may be exempt from some fees.
• Type of ADU: Detached units that are separate from the main house usually have higher permit costs because more inspections and plans are needed. Attached ADUs or garage conversions are often cheaper.
• City or County Rules: Different cities and counties have their own pricing based on their costs and regulations.
• Special Areas: If your property is in a coastal zone or historic district, extra permits and fees might apply.

Are There Fee Waivers or Discounts Available?

Yes! California supports making ADUs affordable by offering fee waivers or reductions, especially for smaller units called Junior ADUs (JADUs) or ADUs under 750 square feet. Some cities offer waivers that can reduce fees by hundreds or even thousands of dollars. For example, some homeowners can get up to $2,500 in fee waivers for eligible ADUs. These discounts help more people build an ADU without paying high upfront costs.

Common Additional or Hidden Fees with ADU Permits

Be aware that besides the main permit fees, you might pay extra costs, such as:

• Plan Check Fees: Charges to review building plans.
• School Fees: Some areas charge fees that help fund local schools.
• Utility Connection Fees: Costs to connect water, sewer, gas, and electricity.
• Impact Fees: Fees charged to cover the cost of public services affected by new buildings.
• Inspection Fees: Charges for city inspectors who check the work during building.

These fees can add up, so include them in your planning.

Tips to Save Money and Time on ADU Permit Fees

Here are some ways to lower your permit costs and reduce delays:

• Contact your local building department early to understand their fees.
• Consider using pre-approved ADU plans to speed up the permit process.
• Building a smaller ADU or converting an existing space, like a garage, can save money.

FAQ

How much does an ADU permit cost in Los Angeles?

Around $5,000 to $9,000 depending on the project.

Do permit costs vary between cities? 

Yes, each city has its own fees.

What are impact fees? 

Charges to cover costs to public services like roads and parks.

Are permits cheaper for garage conversions?

Usually yes, because they reuse existing structures.

Can I build an ADU without a permit?

No, building without a permit is illegal and can lead to fines or having to remove the ADU.

Conclusion

Knowing the cost of permits helps you plan to build your ADU without surprises. Permit fees in California generally range from $2,000 to $20,000, but can vary based on where you live and the type of ADU. Make sure to check your local city or county building department for exact fee information and ask about fee waivers that might apply. Taking these steps will help you get the permits you need and make building your dream ADU easier and more affordable.

Ready to Learn More About ADUs?

If you’re planning to build an ADU in California, don’t stop here—there’s more to know! Check out our other helpful guides:

👉 How Long Does it Take to Build an Accessory Dwelling Unit (ADU)?
👉 How Much Does it Cost to Build an ADU?
👉 What is the New ADU Law 2025?
👉 How to Get an ADU Permit in California
👉 What is a State Exempt from ADU?
👉 Can My ADU Be Bigger Than My House?

Each blog dives into key topics that can help you save time, money, and stress during your ADU journey. Start exploring now!