A Complete Guide to ADU Costs in San Diego (2026)
Building an Accessory Dwelling Unit (ADU) in San Diego is one of the smartest investments you can make as a homeowner. Whether you want rental income, multigenerational living space, or increased property value, understanding ADU costs upfront is essential for planning your project.
- Climate and materials: varies by neighborhood -- coastal areas get marine layer, inland valleys hit 90s+ in summer
- Typical homes: everything from Victorian in Bankers Hill to 1960s ranch in Tierrasanta to modern in North Park
- Permitting: City of San Diego Development Services Department (DSD) on Fifth Avenue -- 6-10 weeks standard plan check
In San Diego County, a complete ADU typically costs between $150,000 and $400,000, with most projects ranging from $200,000 to $300,000 for a 600-800 square foot unit. Here's everything you need to know about ADU costs in San Diego.
ADU Cost Breakdown by Type
Detached ADU (New Construction)
| Size | Cost Range | Cost per Sq Ft |
|---|---|---|
| 400 sq ft (Studio) | $120,000 - $180,000 | $300 - $450 |
| 600 sq ft (1 Bed) | $180,000 - $270,000 | $300 - $450 |
| 800 sq ft (2 Bed) | $240,000 - $360,000 | $300 - $450 |
| 1,200 sq ft (Max) | $360,000 - $540,000 | $300 - $450 |
Garage Conversion ADU
Converting an existing garage is the most cost-effective option, typically costing $80,000 to $150,000. You save on foundation and framing costs, but still need electrical, plumbing, insulation, and finishes.(See also: adu construction in La Mesa)
In our 200+ completed projects across San Diego County, this is one of the most common issues that comes up during planning.
Junior ADU (JADU)
A JADU is created within your existing home (500 sq ft max) and costs $50,000 to $100,000. JADUs require less permitting and can share bathrooms with the main house.(See also: adu construction in La Mesa)
What's Included in ADU Construction Costs
Hard Costs (70-75% of Budget)
- Foundation: $15,000 - $35,000
- Framing: $20,000 - $40,000
- Roofing: $8,000 - $20,000
- Electrical: $10,000 - $25,000
- Plumbing: $15,000 - $35,000
- HVAC: $8,000 - $15,000
- Kitchen: $15,000 - $40,000
- Bathroom: $10,000 - $25,000
- Flooring: $5,000 - $15,000
- Windows/Doors: $5,000 - $15,000
Soft Costs (25-30% of Budget)
- Permits: $5,000 - $15,000 (varies by city)
- Architectural Plans: $5,000 - $15,000
- Engineering: $3,000 - $8,000
- Utility Connections: $5,000 - $20,000
- Impact Fees: Waived in most San Diego jurisdictions through 2026
San Diego ADU Regulations (2026)
California's ADU laws make San Diego one of the best places to build. Key rules include:(See also: adu construction in Vista)
- Size limits: Up to 1,200 sq ft for detached ADUs, 800 sq ft for attached
- Setbacks: 4-foot rear and side setbacks
- Height: Up to 16 feet (detached), 25 feet if near transit
- Parking: Not required if within 1/2 mile of public transit
- Owner occupancy: Not required for new ADUs (through 2025)
- Impact fees: Waived for ADUs under 750 sq ft
ADU Rental Income Potential in San Diego
San Diego ADUs command strong rental rates due to our housing shortage:
- Studio (400 sq ft): $1,500 - $2,000/month
- 1-Bedroom (600 sq ft): $2,000 - $2,800/month
- 2-Bedroom (800 sq ft): $2,500 - $3,500/month
With rental income of $2,000-$3,000/month, most San Diego ADUs pay for themselves in 7-12 years.
- Skipping the soil report -- San Diego has expansive clay in many areas requiring engineered foundations. $2,000 now prevents $30,000 later
- Ignoring Fire Department access -- ADU must be within 150 feet of a hydrant or you need sprinklers ($5,000-$8,000)
- Underestimating utility trenching -- sewer, water, gas, electrical 50+ feet to a backyard ADU: $15,000-$25,000
- Not researching rental market first -- a studio in Carlsbad gets $1,800-$2,200/mo, same unit in Alpine might only get $1,200-$1,500
How to Finance Your San Diego ADU
- Home Equity Loan/HELOC: Use existing home equity at competitive rates
- Cash-Out Refinance: Refinance your primary mortgage for ADU funds
- Construction Loan: Short-term financing that converts to permanent loan
- CalHFA ADU Grant: Up to $40,000 for pre-development costs
Why Choose Cali Dream Construction for Your ADU
Cali Dream Construction has built over 100 ADUs throughout San Diego County. We handle everything from design to permits to construction, making your ADU project simple and stress-free.
Our ADU services include:
- Free site evaluation and feasibility assessment
- In-house architectural design
- Complete permit processing
- Full construction management
- Transparent fixed-price contracts
Ready to explore ADU options for your property? Call us at (858) 434-7166 for a free consultation, or try our ADU Cost Calculator for an instant estimate.
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