Garage Conversion Adu San Diego
Garage Conversion ADU in San Diego: The Complete Guide (2026)
Converting your garage into an ADU is the most affordable way to add a rental unit or extra living space to your San Diego property. With California's ADU-friendly laws and San Diego's high rental demand, garage conversions offer an excellent return on investment.
See our complete ADU builder cost guide for San Diego for detailed 2026 pricing.
A garage conversion ADU in San Diego typically costs $80,000 to $150,000—significantly less than building a detached ADU—because you're working with an existing structure that already has a foundation and walls.
Garage Conversion ADU Costs in San Diego
| Project Scope | Cost Range | Timeline |
|---|---|---|
| 1-Car Garage (200-250 sq ft) | $60,000 - $100,000 | 8-12 weeks |
| 2-Car Garage (400-450 sq ft) | $90,000 - $150,000 | 10-14 weeks |
| 3-Car Garage (600+ sq ft) | $120,000 - $180,000 | 12-16 weeks |
What's Included in a Garage Conversion
Required Work
- Insulation: Walls, ceiling, and floor to meet California Title 24 energy requirements
- Electrical upgrade: New panel or subpanel, outlets, lighting, dedicated circuits
- Plumbing: Kitchen sink, bathroom (toilet, shower, sink), water heater
- HVAC: Mini-split system or ducted heating/cooling
- Windows: Egress windows for bedrooms, natural light requirements
- Flooring: Raise and level the floor (garages slope for drainage)
- Drywall: Fire-rated drywall on shared walls with main house
- Kitchen: Cabinets, countertop, appliances, ventilation
- Bathroom: Full bath with shower required for ADUs
Optional Upgrades
- Separate entrance and address
- Private yard or patio space
- Washer/dryer hookups
- Upgraded finishes (quartz counters, tile floors)
- Smart home features
San Diego Garage Conversion Requirements
Building Code Requirements
- Ceiling height: Minimum 7'-6" (most garages meet this)
- Floor area: At least 150 sq ft (efficiency) or 220 sq ft (1-bedroom)
- Egress: Emergency escape window in sleeping areas
- Fire separation: 1-hour fire-rated wall if attached to main house
- Parking: Not required to replace lost garage parking
Permit Process
San Diego has streamlined ADU permits. The typical timeline:
- Plan preparation: 2-4 weeks
- Plan check: 4-6 weeks (expedited options available)
- Permit issuance: 1-2 weeks
- Construction: 8-16 weeks
- Final inspection: 1-2 weeks
Rental Income Potential
San Diego garage conversion ADUs generate strong rental returns:
- Studio (200-300 sq ft): $1,200 - $1,800/month
- 1-Bedroom (350-450 sq ft): $1,600 - $2,400/month
- 1-Bedroom+ (500+ sq ft): $2,000 - $2,800/month
At $1,800/month, a $100,000 garage conversion pays for itself in under 5 years while adding significant property value.
Garage Conversion ADU Cost Per Square Foot (2026)
For 2026, a garage-to-ADU conversion in San Diego runs $250–$350 per square foot for most attached single-car garages — a 400 sq ft conversion typically lands at $100,000–$140,000 all-in, while a larger two-car garage (500–600 sq ft) reaches $125,000–$180,000. Because the shell, roof, and slab already exist, conversion still runs roughly 30–40% less than building a detached ADU from the ground up ($300–$450+/sq ft in 2026). The biggest cost swings come from the garage slab condition (foundation reinforcement), electrical service upgrade (many 1960s–70s garages need a panel upgrade), and whether the ADU gets a separate gas/water meter.
San Diego Garage Conversion Permit Process (Step by Step)
Converting a garage into a legal ADU in San Diego requires a building permit through the City’s Development Services Department: (1) floor plan and Title 24 energy compliance drawings, (2) plan submittal — California requires cities to review ADU permits within 60 days, (3) corrections cycle, (4) permit issuance and construction. Plan check and permit fees for a garage conversion typically run $8,000–$15,000 in San Diego. Since 2023 state law (AB 68/AB 881) allows garage conversions without adding parking spaces and without owner-occupancy requirements through 2027. Call (858) 434-7166 and Cali Dream Construction will pull your garage’s permit history and quote the full conversion, permits included.
Garage Conversion vs. New ADU Construction
| Factor | Garage Conversion | New Detached ADU |
|---|---|---|
| Cost | $80K - $150K | $150K - $350K |
| Timeline | 3-4 months | 6-12 months |
| Size Limit | Existing footprint | Up to 1,200 sq ft |
| Yard Impact | None | Uses yard space |
Why Choose Cali Dream Construction
Cali Dream Construction has completed dozens of garage conversion ADUs throughout San Diego County. We handle everything from design and permits to construction and final inspection.
Our garage conversion services include:
- Free feasibility assessment
- In-house design and engineering
- Complete permit processing
- Full construction management
- Fixed-price contracts with no surprises
Ready to turn your garage into rental income? Call (858) 434-7166 for an in-person planning session. Or try our Garage Conversion Calculator for an instant estimate.
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Phone: (858) 434-7166
License: CSLB #1054602 | Serving San Diego & North County
Related Articles
- ADU Cost Guide
- ADU Permit Process
- Adu Rental Income Potential San Diego
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