Accessory Dwelling Units (ADUs) have become one of the most popular housing solutions in San Diego. Whether you want to add a rental unit, house relatives, or create a flexible home office, ADUs carry both financial and practical benefits. But before you pour concrete or knock down an old garage, you need approvals from San Diego’s Development Services Department (DSD).
Getting that permit isn’t a one‑day job. The City requires precise documents, proper zoning compliance, and a review process that can stretch from weeks to months. Mistakes—sometimes simple ones—cause costly project delays. This guide breaks down the entire
ADU permit process in San Diego, explains common pitfalls, and provides practical ways to keep your project moving without setbacks.
Why ADU Permits Matter in San Diego
Housing Demand and Local Policy
San Diego struggles with rising housing prices and limited rental availability. ADUs are part of California’s state‑level response to expand housing without new large‑scale developments. Local governments, including San Diego, must allow ADUs under state laws. But they adapt requirements to match local zoning and infrastructure realities.
Legal and Financial Protection
Permits are more than legal paperwork. They ensure:
- Construction meets building codes
- Fire and safety standards are followed
- Insurance and financing remain valid
- You avoid fines, stop‑work orders, or future sale complications
Skipping permits now creates expensive headaches later—often when you least expect them.
Step‑by‑Step ADU Permit Process in San Diego
Step 1: Pre‑Design and Zoning Check
Before you draw a single floor plan, confirm that your property zoning allows an ADU. San Diego broadly permits ADUs in most residential zones, but codes specify:
- Maximum number of ADUs allowed per lot
- Setback distances from property lines
- Height restrictions
- Parking and access rules
A zoning verification early prevents later surprises. Think of this step as checking the map before a road trip. Without it, you’re lost before you start driving.
Step 2: Design and Documentation
Working With Professionals
Architects and designers familiar with San Diego codes are valuable. They prepare required plans and avoid basic mistakes. While it may look like an added cost upfront, their stamp of accuracy reduces corrections, saving months.
Standard Submittal Package
Most ADU applications in San Diego include:
- Site plans noting existing and proposed structures
- Floor layouts detailing living areas, kitchen, and bathroom
- Elevation drawings for exterior features
- Structural and mechanical notes
- Energy and efficiency compliance forms
- Utility connection diagrams
Missing even one of these elements can push your application to the “incomplete” pile. That’s the bureaucratic equivalent of detention.
Step 3: Submitting to Development Services
San Diego offers online submittal through its Development Services Department (DSD) portal. While you can still visit in person, online submission is the standard.
Review Timelines
Expedited Review: 2–4 weeks for smaller ADUs with complete documentation.
Standard Review: 2–3 months for detached ADUs, structural modifications, or properties needing variances.
Complex Review: 4–6 months if utilities or environmental considerations arise, such as Coastal Zone regulations or hillside safety reviews.
Few ADU applications pass in the first round. Staff often request clarifications or revisions. Common issues include:
- Incorrect measurements for setbacks
- Missing mechanical or electrical details
- Conflicts with utility infrastructure
- Incomplete stormwater management notes
Quick response to correction notices matters. Every week you delay corrections pushes your timeline back the same number of weeks.
Step 5: Plan Approval and Permit Issuance
Once your plans meet zoning, building, and utility standards, the City issues construction permits. At this point, you’re cleared to start building. Remember, this doesn’t mean the City is out of the picture. Project inspections continue during construction.
Step 6: Construction and Inspections
San Diego inspectors check work at critical stages:
- Foundation pour
- Framing
- Electrical and plumbing rough‑ins
- Final finish
Failing an inspection requires corrections before you move further. Always schedule inspections in advance—slots fill quickly. Waiting two extra weeks because you didn’t call on time can cripple project momentum.
Step 7: Final Approval and Occupancy
Once construction passes all inspections, you’ll receive final occupancy approval. At this point, your ADU is fully legal. You can rent it, house family, or use it however you planned.
The Most Common Mistakes ADU Owners Make
Even careful homeowners often underestimate the process. Here are the issues that delay most San Diego ADUs:
Q. Ignoring Local Code Differences
Ans: California passed ADU laws that loosen restrictions, but San Diego has additional layers. For example, coastal zone properties face stricter review. Assuming state law alone dictates rules can lead to rejected plans.
Q. Underestimating Utility Requirements
Ans: Many homeowners forget their current electrical, water, or sewer service may not handle an added unit. Upgrading services isn’t just expensive; it often requires separate city reviews.
Q. Incomplete or Rushed Documentation
Ans: Submitting “placeholder plans” wastes time. Staff return incomplete packages, and you lose weeks.
Q. Not Reviewing Parking Regulations
Ans: While some areas waive parking entirely, others still require spaces. Failing this requirement can sink a design.
Q. DIY Guesswork Without Professionals
Ans: Experienced contractors and designers pay for themselves by avoiding rejections. Attempting blueprint drawings in MS Paint may sound bold, but it won’t fly with the City.
Practical Tips to Avoid Permit Delays
Hire an ADU specialist familiar with San Diego Development Services review staff.
Submit a zoning verification early.
Double‑check parking, utility, and setback requirements.
Respond quickly and clearly to correction notices.
Bundle required documents together before submittal.
Schedule all inspections ahead of time.
Every day you save on the permit process accelerates your construction finish date.
What San Diego Property Owners Should Expect to Pay
Permit fees vary depending on ADU size and type. Expect:
- Smaller ADUs (400–600 sq. ft.): $4,000–$8,000 in permitting costs
- Larger ADUs (800–1,200 sq. ft.): $8,000–$15,000
- Detached multi‑story ADUs: $15,000+
These figures cover plan review, development impact fees (sometimes waived), and inspection costs. Budget both time and money. Treat the permit as an investment in project protection.
Case Study: A Delayed Garage Conversion
One San Diego owner converted a detached garage into a rental ADU. He submitted plans without checking utilities. Midway through review, DSD flagged that his sewer capacity was inadequate. He needed an upgrade costing $10,000 and three months of extra review. Had he checked utilities first, costs and delays would have been minimal.
The lesson is simple: don’t assume. Verify every element before submission.
Long‑Term Benefits of a Properly Permitted ADU
- Increases resale value by 20–30% in some San Diego neighborhoods
- Meets insurance, fire safety, and lending standards
- Provides legal rental income potential
- Avoids stop‑work orders, fines, and demolition risks
The upfront hassle of permits protects your long‑term interests.
Final Thoughts
Building an ADU in San Diego is rewarding but requires patience with the permit process. Don’t cut corners. Submit accurate plans, respect zoning, and invest in professional guidance.
Think of the process like surfing Pacific Beach. You can’t control the wave, but you can learn to ride it. Permitting may feel slow, but once approved, the payoff is real housing, real income, and long‑term property growth.
