# ADU Laws in San Diego 2025: Complete Guide to Building Your Accessory Dwelling Unit
Thinking about building an ADU in San Diego? Here's everything you need to know about permits, costs, and regulations.
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What is an ADU?
An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family residential lot. In San Diego, ADUs are also called:
- Granny flats
- In-law suites
- Backyard cottages
- Casitas
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San Diego ADU Rules (Updated 2025)
Size Limits
| ADU Type | Maximum Size |
|----------|-------------|
| Detached ADU | 1,200 sq ft |
| Attached ADU | 50% of main home or 1,200 sq ft (whichever is less) |
| Junior ADU (JADU) | 500 sq ft (within existing home) |
Setback Requirements
- Rear setback: 4 feet
- Side setback: 4 feet
- No setback required for conversions of existing structures
Parking
- No additional parking required for ADUs in San Diego!
- This changed in 2020 and makes ADUs much more feasible
Height Limits
- Detached ADU: 16 feet (can be taller in some zones)
- Attached ADU: Must match main home height
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How Much Does an ADU Cost in San Diego?
| ADU Type | Cost Range | Timeline |
|----------|------------|----------|
| Garage Conversion | $80,000 - $150,000 | 3-4 months |
| Prefab/Modular ADU | $150,000 - $250,000 | 4-6 months |
| Custom Built ADU | $200,000 - $400,000+ | 6-12 months |
Cost Breakdown:
- Design & Permits: $10,000 - $25,000
- Foundation: $15,000 - $30,000
- Construction: $150 - $400 per sq ft
- Utilities hookup: $10,000 - $30,000
- Landscaping: $5,000 - $15,000
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ADU Benefits for San Diego Homeowners
1. Rental Income
Average ADU rent in San Diego: $1,800 - $3,000/month
- Annual income potential: $21,600 - $36,000
- Can offset mortgage significantly
2. Property Value Increase
ADUs typically add 20-30% to property value
- $500K home → Could become $650K with ADU
3. Multi-Generational Living
- Housing for aging parents
- Space for adult children
- Guest accommodations
4. Work From Home Space
Perfect home office that's separate from main living areas
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San Diego ADU Permit Process
Step 1: Pre-Application Meeting (Optional)
Meet with city planning to discuss your project
Step 2: Submit Plans
- Site plan
- Floor plan
- Elevations
- Structural calculations
Step 3: Plan Review (60-90 days)
City reviews for compliance with codes
Step 4: Permit Issued
Pay fees and receive building permit
Step 5: Construction + Inspections
Build ADU with required inspections
Step 6: Final Inspection
Certificate of occupancy issued
Total timeline: 6-12 months from start to finish
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San Diego ADU Financing Options
1. Home Equity Loan/HELOC
Use your home's equity to fund construction
2. Construction Loan
Converts to permanent mortgage after build
3. Cash-Out Refinance
Refinance existing mortgage and pull cash for ADU
4. ADU-Specific Loans
New products designed for ADU construction
5. CalHFA ADU Grant Program
Up to $40,000 for qualifying homeowners
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Popular ADU Designs in San Diego
1. Modern Studio (400-500 sq ft)
- Open floor plan
- Murphy bed
- Compact kitchen
- Great for rentals
2. One-Bedroom (600-800 sq ft)
- Separate bedroom
- Full kitchen
- Living area
- Most popular choice
3. Two-Bedroom (900-1,200 sq ft)
- Family-friendly
- Two full baths
- Premium rental income
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Why Choose Cali Dream Construction for Your ADU?
✅ Full-Service: Design, permits, construction
✅ Local Expertise: We know San Diego codes inside and out
✅ Transparent Pricing: Fixed bids, no surprises
✅ Quality Built: Craftsmanship that lasts
✅ On-Time Delivery: We meet our deadlines
Our ADU Process:
- Free consultation and site visit
- Custom design based on your needs
- Handle all permits and approvals
- Build your ADU with regular updates
- Final walkthrough and handover
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Get Started on Your San Diego ADU
Ready to add an ADU to your property? Let's talk about your options.
📞 Call: (858) 434-7166
📧 Email: team@calidreamconstruction.com
🌐 Website: calidreamconstruction.com
Free consultations for San Diego County homeowners
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