JADU Permit Costs and Fees

Building a Junior Accessory Dwelling Unit (JADU) can be more affordable than a full ADU, but homeowners often ask: How much does it cost to get a JADU permit, and what fees should be expected?

Understanding the full financial picture upfront — and using a preapproved ADU plan, a professional ADU blue print, and permit ready ADU plans — helps avoid unexpected surprises.

Main Costs for JADU Permitting

1. Permit Application Fees

Every city charges a fee to process a JADU permit application. Typical costs range from $1,000 to $5,000, depending on:

• City or county location

• Size of the JADU

• Complexity of construction

Choosing a permit ready ADU plan can sometimes lower plan check fees if review times are reduced.

2. Plan Review Fees

Plan review covers the city’s review of:

• Site plans

• Floor plans (your ADU blue print)

• Structural calculations

• Energy compliance documents

Plan review fees typically run $500 to $2,000.

3. School Impact Fees

In most cases, JADUs under 750 square feet are exempt from school impact fees under California law.However, always verify with your local school district to confirm.

4. Utility Connection Fees

• In many cities, JADUs can use existing utilities without major new fees.

• If separate water meters, sewer lines, or electrical panels are needed, additional costs apply.

Using preapproved ADU plans often helps pre-plan for shared utility setups, minimizing costs.

5. Other Potential Fees

Some jurisdictions may require:

• Sewer capacity charges

• Traffic mitigation fees (rare for JADUs)

• Environmental review fees (in special zones)

These fees are less common but should be checked during early research.

How Preapproved Plans Save Money

Using preapproved ADU plans and permit ready ADU plans can save homeowners money by:

• Reducing design and architectural costs

• Speeding up plan check approvals

• Avoiding costly redesigns during review

Investing in a detailed ADU blue print aligned with city requirements also minimizes corrections.

Real-World Example

A homeowner in Marin County used a preapproved ADU plan to convert an attached garage into a JADU. By submitting a complete package with a detailed ADU blue print, total permit costs were under $2,800 — significantly less than a new detached ADU permit would have cost.

Common Mistakes to Avoid

• Assuming all JADU permits are free

• Forgetting utility connection fees

• Submitting incomplete plans and triggering re-review fees

• Designing without energy compliance, requiring costly fixes later

Final Thoughts

Understanding JADU permit costs early on allows homeowners to budget wisely and move confidently through the process. At ADUnest, we specialize in helping homeowners prepare accurate ADU blueprints, access preapproved ADU plans, and create permit ready ADU plans that minimize costs and speed up approvals.If you have any questions about JADU permit costs, feel free to leave a comment below — the ADUnest team is here to guide you through your project!