San Diego, CA · Garage Conversion ADU
San Diego Garage Conversion ADU Cost in 2026: $90K–$180K All-In
The cheapest, fastest path to a permitted ADU in San Diego. Convert a 1-car or 2-car garage into a 250–500 sq ft 1-bedroom rental in 4–6 months for 35–50% less than a new detached build.
Get 3 Free San Diego Garage-Conversion QuotesCost Ranges by Garage Size
| Garage size | Low | Mid | High | Notes |
|---|---|---|---|---|
| 1-car (~250 sq ft) | $70,000 | $95,000 | $130,000 | Studio layout, single bath, kitchenette |
| 1.5-car (~350 sq ft) | $85,000 | $115,000 | $150,000 | 1-bedroom + full bath, full kitchen |
| 2-car (~450–500 sq ft) | $110,000 | $145,000 | $180,000 | Roomy 1-bedroom or efficient 2-bedroom |
| Tandem 2-car (~500–600 sq ft) | $120,000 | $160,000 | $200,000 | Long, narrow layout; design constraints |
All-in pricing includes design, permits (~$8K–$12K San Diego DSD), structural reinforcement, full insulation to Title 24, electrical sub-panel, plumbing, HVAC mini-split, finishes, and utility separation. Excludes landscaping and driveway repair.
What's Specifically Included
San Diego Permit + Build Timeline
| Phase | Typical Duration |
|---|---|
| Design + structural plans | 3–5 weeks |
| San Diego DSD permit review | 8–14 weeks |
| Structural reinforcement + slab work | 2–3 weeks |
| Framing infill + MEP rough-in | 3–5 weeks |
| Insulation, drywall, finishes | 5–8 weeks |
| Final inspection + Certificate of Occupancy | 1–2 weeks |
| TOTAL (design → C of O) | 22–37 weeks (~5–9 months) |
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San Diego Garage Conversion ROI
Sample scenario: 2-car garage conversion at the mid-range price point.
| Total project cost (mid) | $145,000 |
| 20% down (cash or HELOC) | $29,000 |
| Loan principal (80%) | $116,000 |
| Estimated rate (May 2026) | 7.5% (30-year) |
| Monthly payment | ~$811 |
| Estimated rent (1BR, 400–500 sq ft) | $1,950–$2,500/mo |
| Net cash flow (mid rent − payment) | +$1,400/mo |
| Payback period (cash-on-cash) | ~5–7 years |
San Diego Garage Conversion Red Flags
- Bid is below $80K for a 2-car garage — almost guaranteed change orders
- Contractor doesn't include structural engineering report in scope
- Contractor says "no permit needed" — illegal conversions can't be insured or rented legally
- Slab moisture test is excluded — California requires it for habitable space
- No Title 24 compliance plan — required for permit + utility hookup