Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your San Bernardino ADU cost →Building an ADU in San Bernardino costs between $160,000-$280,000 for new construction, with per-square-foot costs averaging $200-$260. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $75,000-$140,000, while prefab/modular ADUs fall in between at $80,000-$150,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | $3,000-$12,000 estimated (building permit + plan check; varies by size) |
| Impact Fees | Waived under 750 sq ft (SB 13); proportional for larger units |
| Site Prep & Foundation | $10,000 – $35,000 |
| Framing & Structure | $15,000 – $45,000 |
| Plumbing | $8,000 – $20,000 |
| Electrical | $5,000 – $15,000 |
| HVAC | $3,000 – $8,000 |
| Interior Finishes | $15,000 – $40,000 |
Quotes for the same ADU commonly vary 20–40% between builders. Get up to 3 free quotes from ADU builders serving San Bernardino — no obligation.
Get San Bernardino builder quotes →Permit fees in San Bernardino are $3,000-$12,000 estimated (building permit + plan check; varies by size). The review timeline is 60 days mandatory for approval/denial of complete applications with an existing dwelling, with plan check: Included in the permit timeline; agency must respond within 60 days. Impact fees are Waived under 750 sq ft (SB 13); proportional for larger units. Pre-approved plans: Yes - Pre-Selected ADU Plans Program: Morning Glory (462 sq ft, 1BR) and Carnation (738 sq ft, 2BR).
| 1-Bedroom Rent | $1,300-$1,700/month |
| 2-Bedroom Rent | $1,700-$2,100/month |
| Annual Rental Income (est.) | $18,000/year |
| Payback Period (est.) | 12.2 years |
| Short-Term Rental | Subject to city/county ordinances; verify before planning |
| Overall ROI Estimate | 7-10 year payback |
A typical ADU in San Bernardino generates approximately $18,000 per year in rental income based on average 1-bedroom rents. At an average construction cost of $220,000, the estimated payback period is 12.2 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in San Bernardino and varies by market (often less than build cost).
1. Garage conversions save 40-60% vs new construction since the shell already exists. Average cost in San Bernardino: $75,000-$140,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $80,000-$150,000.
3. Pre-approved plans — available in San Bernardino, which can save $3,000-$10,000 in design costs and 2-3 months in review time.
4. State grants — California's CalHFA ADU grant (up to $40K) is currently paused; check calhfa.ca.gov/adu for status and your state for active programs.
5. Get multiple bids — ADU contractor pricing varies 20-40% for the same project. We recommend getting at least 3 quotes.
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