Complete 2026 cost breakdown: construction, permits, financing, and expected rental ROI.
Calculate your Saint Paul ADU cost →Building an ADU in Saint Paul costs between $135,000-$270,000 for new construction, with per-square-foot costs averaging $130-$270. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $65,000-$155,000, while prefab/modular ADUs fall in between at $95,000-$220,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | $1,900-$3,200 |
| Impact Fees | $400-$800 |
| 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 Saint Paul — no obligation.
Get Saint Paul builder quotes →Permit fees in Saint Paul are $1,900-$3,200. The review timeline is 45-65 days, with plan check: 2-3 weeks. Impact fees are $400-$800. Pre-approved plans: Available.
| 1-Bedroom Rent | $1,300-$1,750/month |
| 2-Bedroom Rent | $1,650-$2,300/month |
| Annual Rental Income (est.) | $18,300/year |
| Payback Period (est.) | 11.1 years |
| Short-Term Rental | Permitted with license |
| Overall ROI Estimate | 7-9% annual return |
A typical ADU in Saint Paul generates approximately $18,300 per year in rental income based on average 1-bedroom rents. At an average construction cost of $202,500, the estimated payback period is 11.1 years — before accounting for the resale value the ADU adds, which an appraiser determines from comparable sales in Saint Paul 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 Saint Paul: $65,000-$155,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $95,000-$220,000.
3. Pre-approved plans — available in Saint Paul, 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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