Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Santa Ana ADU cost →Building an ADU in Santa Ana costs between $130,000-$300,000 for new construction, with per-square-foot costs averaging $200-$360. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $75,000-$170,000, while prefab/modular ADUs fall in between at $100,000-$240,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | REPLACE THE GUESS WITH PUBLISHED FIGURES. Planning Division FY 2026-2027 Fee Schedule: Accessory Dwelling Unit Review $1,940.00; ADU Over-the-Counter Review $594.00; ADU Pre-Approved Plan Review $524.00. Certain applications also carry a 7% technology fee per transaction, and from July 1, 2026 a 2.5% credit/debit card processing fee. These are PLANNING fees only — building permit fees are additional and the city does not publish them ('Building permit fees vary according to the scope of work'; Permit Counter (714) 647-5800). |
| Impact Fees | TRUE BUT MISLEADING — add the capacity charge. The state 750 sq ft exemption covers impact fees, but NOT connection fees or capacity charges. Per the city's FY2026-27 impact fee document (OCSD Table A, effective 7/1/2026), ADUs are charged the Capital Facilities Capacity Charge at the AVERAGE DEMAND rate of $1,710.00 per 1,000 sq ft (or portion thereof), and the $6,588 minimum charge expressly does NOT apply to ADUs. Net effect: even a 400 sq ft ADU owes about $1,710. Separately, the city sewer connection fee is computed per fixture at $53.00 per fixture-unit value. School district fees are billed separately by the district. |
| 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 5 free quotes from ADU builders serving Santa Ana — no obligation.
Get Santa Ana builder quotes →Permit fees in Santa Ana are REPLACE THE GUESS WITH PUBLISHED FIGURES. Planning Division FY 2026-2027 Fee Schedule: Accessory Dwelling Unit Review $1,940.00; ADU Over-the-Counter Review $594.00; ADU Pre-Approved Plan Review $524.00. Certain applications also carry a 7% technology fee per transaction, and from July 1, 2026 a 2.5% credit/debit card processing fee. These are PLANNING fees only — building permit fees are additional and the city does not publish them ('Building permit fees vary according to the scope of work'; Permit Counter (714) 647-5800).. The review timeline is 60 days, with plan check: Standard city review. Impact fees are TRUE BUT MISLEADING — add the capacity charge. The state 750 sq ft exemption covers impact fees, but NOT connection fees or capacity charges. Per the city's FY2026-27 impact fee document (OCSD Table A, effective 7/1/2026), ADUs are charged the Capital Facilities Capacity Charge at the AVERAGE DEMAND rate of $1,710.00 per 1,000 sq ft (or portion thereof), and the $6,588 minimum charge expressly does NOT apply to ADUs. Net effect: even a 400 sq ft ADU owes about $1,710. Separately, the city sewer connection fee is computed per fixture at $53.00 per fixture-unit value. School district fees are billed separately by the district.. Pre-approved plans: WRONG — THE PROGRAM IS LIVE. 10 free downloadable pre-approved plan sets for DETACHED ADUs: 3 studio (Ranch, Spanish, Traditional), 6 one-bedroom (Ranch, Spanish, Traditional, Contemporary by Design Path Studio; Craftsman and Spanish by James Gartner & Associates), 1 two-bedroom (Contemporary). Each downloads as a ZIP with the required submittal documents. Planning fee drops to $524 vs $1,940 standard, and the city says an over-the-counter submittal 'may be approved in as little as one day.' ELIGIBILITY LIMITS: property must have a single-family dwelling; NOT in flood zone A or AE; NOT in a historic district; NOT in Heninger Park; must meet grading permit exemption requirements. Requires a recent title report (within 6 months) and a pre-submittal consultation via planning@santa-ana.org..
| 1-Bedroom Rent | $1,700-$2,300/month |
| 2-Bedroom Rent | $2,100-$2,900/month |
| Annual Rental Income (est.) | $24,000/year |
| Payback Period (est.) | 9.0 years |
| Short-Term Rental | Regulated; check city STR ordinance |
| Overall ROI Estimate | 7-10% annual return |
A typical ADU in Santa Ana generates approximately $24,000 per year in rental income based on average 1-bedroom rents. At an average construction cost of $215,000, the estimated payback period is 9.0 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Santa Ana 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 Santa Ana: $75,000-$170,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $100,000-$240,000.
3. Pre-approved plans — available in Santa Ana, which can save $3,000-$10,000 in design costs and 2-3 months in review time. See which cities offer pre-approved ADU plans.
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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