Last updated: January 2026 · 8 min read
San Diego ADU / Accessory Dwelling Unit Guide
San Diego homeowners can add an Accessory Dwelling Unit (ADU) to expand property value and housing options. The Development Services Department (DSD) oversees ADU permits for residential properties meeting specific zoning and building requirements. Homeowners must submit detailed plans and meet local building codes to proceed.
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What Requires a ADU / Accessory Dwelling Unit in San Diego
San Diego ADUs must comply with strict municipal zoning regulations. Properties within residential zones can typically construct ADUs, with maximum size restrictions based on lot dimensions. Single-family residential lots under 10,000 square feet may construct ADUs up to 850 square feet. Larger lots might allow expanded unit sizes, contingent on specific setback and coverage requirements. Homeowners must demonstrate compliance with parking standards, typically requiring one dedicated parking space per ADU.
What Doesn't Require a Permit
Minor interior modifications not affecting structural integrity typically do not require full ADU permits. Repairs under $5,000 that do not alter electrical, plumbing, or structural components can proceed without comprehensive review. Small decorative changes, such as painting or replacing fixtures, remain exempt from DSD permitting processes. Homeowners should still consult the Development Services Department for definitive guidance on specific project scope.
ADU / Accessory Dwelling Unit Costs and Fees in San Diego
San Diego ADU project costs involve multiple fee components. The demolition fee stands at $205, while school fees are calculated at $4.08 per square foot. Additional expenses include mapping fees of $11.34 and mechanical permit costs determined during initial consultation. Total project expenses vary significantly based on unit size, complexity, and specific site conditions. Homeowners should budget for plan review, construction, and potential infrastructure upgrades.
How Long Does ADU / Accessory Dwelling Unit Approval Take
San Diego Development Services Department processes ADU permits through a multi-stage review mechanism. Initial plan submissions typically require 4-8 weeks for comprehensive evaluation. Complex projects involving significant structural modifications may extend review periods. Expedited review options exist for projects meeting pre-approved standard designs, potentially reducing processing time to 3-6 weeks.
Required Documents for San Diego ADU / Accessory Dwelling Unit
San Diego DSD requires comprehensive documentation for ADU permit applications. Mandatory submissions include detailed architectural plans, site surveys, structural calculations, and proof of property ownership. Digital submissions through the DSD Online Services portal streamline the initial review process. Professional drawings must demonstrate compliance with local building codes, zoning regulations, and setback requirements.
Step-by-Step Application Process
The San Diego ADU permitting process involves careful navigation of municipal requirements.
- 1
Initial Consultation
Schedule preliminary review with DSD to discuss project specifics and potential constraints.
- 2
Document Preparation
Compile comprehensive architectural plans, site surveys, and required technical documentation.
- 3
Online Submission
Submit complete application package through DSD Online Services portal.
- 4
Plan Review
Await comprehensive review and potential request for additional information.
- 5
Permit Issuance
Receive approved permit after successful document review and fee payment.
Required Inspections
San Diego ADU projects mandate multiple critical inspections throughout construction. Typical inspection points include foundation preparation, framing, electrical, plumbing, and final occupancy verification. Contractors must schedule inspections through the DSD, providing 48-hour advance notice. Successful completion of each inspection phase ensures compliance with municipal building standards.
Common Adu Permit Mistakes in San Diego
One of the most common mistakes homeowners make in San Diego is underestimating the complexity of the Adu permit process. Many assume it's a simple process, only to be caught off guard by the various requirements and fees. Failing to account for impact fees or not properly calculating the square footage can result in unexpected costs and delays. Another frequent issue is overlooking the need for a building permit for structural changes or utility connections. Homeowners who try to bypass the permit process altogether risk fines and having to redo work to meet code. To avoid these pitfalls, it's crucial to thoroughly review the DSD's Adu requirements and work closely with a licensed contractor who understands the local regulations.
Sample Adu Permit Cost Calculation
Let's walk through a sample cost calculation for an Adu project in San Diego. Suppose you're adding an 800 square foot Adu to your existing 1,500 square foot single-family home. Based on the fee data provided, the base inspection fee would be $7,833.94, and the base plan check fee would be $7,538.70. Since the total project size is under 3,000 square feet, the per-square-foot fees would not apply. However, you would still need to account for the mapping fee of $11.34 and the mechanical permit fee of $329.26 for the first unit. Additionally, the school impact fee of $4.08 per square foot would apply, but you would be exempt for the first 500 square feet. So the total school impact fee would be $1,226.40 (800 sq ft - 500 sq ft = 300 sq ft x $4.08/sq ft). With the 50% sewer and water discount, your total permit and impact fees would come to approximately $17,000. Remember, this is just an estimate, and actual costs may vary depending on your project specifics.
How San Diego Compares to Other California Cities
When compared to other major California cities, San Diego's Adu permit process has both similarities and differences. Like Los Angeles, San Diego offers fee waivers and discounts for smaller Adus, such as the impact fee waiver for units under 750 square feet. However, San Diego's per-square-foot fees for larger projects are generally higher than those in San Jose. For example, San Diego's inspection and plan check fees for residential new construction over 3,000 square feet are $3.93 and $3.82 per square foot, respectively, while San Jose's are $2.35 and $2.67 per square foot. The timeline for Adu permit approvals also varies, with San Diego typically taking 4-6 weeks, compared to 6-8 weeks in San Francisco. Additionally, San Diego's online permit application system, DSD Online Services, is more advanced than some other cities, streamlining the process for homeowners.
Recent Adu Permit Changes in San Diego
In 2024, San Diego's Development Services Department (DSD) implemented several updates to the Adu permit process. One significant change was the launch of a new online portal, allowing homeowners to submit applications and track the status of their permits entirely digitally. This has greatly reduced the processing time, with many Adu permits now being approved within 4 weeks. Additionally, the DSD has updated its fee structure, aligning with recent changes to California's building codes. For example, the school impact fee has been reduced from $4.08 per square foot to $3.50 per square foot, and the sewer and water discount has been increased from 50% to 60% for Adus under 750 square feet. These updates aim to make the Adu permitting process in San Diego more accessible and affordable for homeowners.
Tips for Faster Approval in San Diego
Successful ADU permit applications in San Diego require meticulous preparation. Ensure architectural plans precisely match zoning requirements and include comprehensive structural details. Anticipate potential DSD review questions by providing thorough, clear documentation. Professional drawings from licensed architects familiar with San Diego municipal codes significantly improve initial submission quality.
Frequently asked questions about San Diego adu permits
How much does a ADU / Accessory Dwelling Unit cost in San Diego?
Total ADU project costs range from $150,000 to $350,000, with school fees at $4.08 per square foot and a $205 demolition fee. Exact expenses depend on unit size, design complexity, and specific site conditions.
How long does it take to get a ADU / Accessory Dwelling Unit in San Diego?
The permitting process typically spans 4-8 weeks, with potential extensions for complex projects. Expedited reviews for standard designs can reduce processing time to approximately 3-6 weeks.
Can I apply for a ADU / Accessory Dwelling Unit online in San Diego?
San Diego DSD offers comprehensive online submission through their Digital Services portal. Homeowners can upload documents, track application status, and communicate with reviewers electronically.
Do I need a contractor for a ADU / Accessory Dwelling Unit?
While owner-builder options exist, most San Diego ADU projects require licensed contractors. Complex permitting and technical requirements often necessitate professional expertise to ensure regulatory compliance.
What happens if I build without a permit in San Diego?
Unpermitted ADU construction can result in significant penalties, including stop-work orders, retroactive permit fees, potential fines up to $5,000, and mandatory reconstruction to meet code standards.
What's the biggest mistake people make with Adu permits in San Diego?
The biggest mistake homeowners make in San Diego is underestimating the complexity of the Adu permit process and failing to account for all the necessary fees and requirements.
How do San Diego Adu permit costs compare to other cities?
Compared to other major California cities, San Diego's Adu permit costs are generally higher, especially for larger projects over 3,000 square feet. However, San Diego does offer fee waivers and discounts for smaller Adus, similar to cities like Los Angeles.
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Related Permits in San Diego
San Diego Building Department Contact
Development Services Department
1222 First Ave, San Diego, CA 92101