Accessory Dwelling Units (ADUs) have transformed San Diego's housing landscape. Whether you're looking to house aging parents, create rental income, or add space for a home office, an ADU can be a smart investment. This guide covers everything you need to know about building an ADU in San Diego in 2026.
What is an ADU?
An ADU is a secondary housing unit on a single-family residential lot. In San Diego, ADUs can be:
- Detached ADU: A standalone structure separate from your main house (up to 1,200 sq ft)
- Attached ADU: Built onto your existing home with a separate entrance
- Garage Conversion: Converting an existing garage into living space
- Junior ADU (JADU): A smaller unit (up to 500 sq ft) within the existing footprint of your home
San Diego ADU Regulations in 2026
California's ADU laws have become increasingly homeowner-friendly. Key regulations for San Diego include:
Size Limits
- Detached ADUs: Up to 1,200 square feet
- Attached ADUs: Up to 50% of existing home square footage (minimum 800 sq ft allowed regardless)
- JADUs: Up to 500 square feet
Setback Requirements
ADUs must be at least 4 feet from side and rear property lines. This is significantly less restrictive than previous requirements, making ADUs feasible on more properties.
Parking
If your property is within half a mile of public transit (which includes much of San Diego), no additional parking is required for your ADU. Otherwise, one parking space may be needed.
Owner Occupancy
As of 2025, there's no owner-occupancy requirement for ADUs in California. You can rent both your main house and ADU without living in either.
How Much Does an ADU Cost in San Diego?
ADU costs in San Diego vary significantly based on type, size, and finishes. Here's what to expect in 2026:
| ADU Type | Cost Range | Cost per Sq Ft |
|---|---|---|
| Garage Conversion | $80,000 – $150,000 | $200 – $350 |
| JADU (500 sq ft) | $60,000 – $100,000 | $120 – $200 |
| Attached ADU | $150,000 – $250,000 | $300 – $400 |
| Detached ADU (new construction) | $200,000 – $350,000 | $350 – $450 |
What's Included in These Costs?
- Architectural plans and engineering
- Permit fees (typically $5,000–$15,000 in San Diego)
- Site preparation and foundation
- Framing, roofing, and exterior finishing
- Electrical, plumbing, and HVAC
- Interior finishes (flooring, cabinets, fixtures)
- Utility connections
ADU Rental Income in San Diego
San Diego's rental market makes ADUs financially attractive. Current market rates for ADUs:
- Studio/1BR ADU (400-600 sq ft): $1,800 – $2,400/month
- 1BR ADU (600-800 sq ft): $2,200 – $2,800/month
- 2BR ADU (800-1,200 sq ft): $2,800 – $3,500/month
At these rates, a well-designed ADU can generate $25,000–$40,000 in annual rental income, often paying for itself within 8-12 years while also significantly increasing your property value.
The ADU Building Process
Step 1: Feasibility Assessment
Before investing in plans, verify your property can accommodate an ADU. Consider lot size, existing structures, utility access, and neighborhood restrictions (some HOAs have ADU limitations).
Step 2: Design and Architecture
Work with an architect or design-build contractor to create plans that maximize your space and budget. San Diego requires ADUs to be compatible with your neighborhood's character.
Step 3: Permit Application
Submit plans to the City of San Diego Development Services Department. California law requires cities to approve or deny ADU permits within 60 days. Include:
- Site plan showing ADU location
- Architectural drawings (floor plan, elevations)
- Structural engineering
- Title 24 energy calculations
Step 4: Construction
Once permitted, construction typically takes 4-8 months for a detached ADU. Garage conversions can be completed in 6-12 weeks.
Step 5: Final Inspection
The city conducts final inspections for structural, electrical, plumbing, and mechanical systems before issuing a certificate of occupancy.
Should You Build an ADU?
An ADU makes sense if:
- You have sufficient lot space (minimum 200 sq ft for the structure itself)
- You can finance the construction (through savings, HELOC, or construction loan)
- You want long-term rental income or multi-generational living
- Your property is in a desirable rental area of San Diego
Ready to explore ADU options for your property? Contact Subworkit Contracting for a free feasibility assessment and estimate.
Ready to Start Your Project?
Contact Subworkit Contracting today for a free consultation. We serve San Diego County.