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 $125,000-$350,000 for new construction, with per-square-foot costs averaging $180-$400. These figures include design, permitting, site preparation, and construction. The most affordable option is a garage conversion at $95,000-$185,000, while prefab/modular ADUs fall in between at $150,000-$350,000.
| Cost Category | Estimated Range |
|---|---|
| Architectural Plans | $3,000 – $15,000 |
| Permits & Fees | Valuation-based (Sec. 33.04; schedule effective 2/25/2023): $1,499 for the first $100,000 plus $8 per additional $1,000, a plan-check fee of 65% of that, and the 0.05% state surcharge — about $3,200 on a $150,000 ADU and $5,300 on $300,000, before trade permits and any SAC. |
| Impact Fees | Minnesota cities do not charge development impact fees. The Metropolitan Council Sewer Availability Charge (SAC) may be assessed for a new ADU and is collected by DSI with the building permit; the 2026 SAC rate could not be verified from the Met Council site — confirm the SAC determination with DSI before you budget. |
| 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. We pass your request to up to 5 local builders serving Saint Paul, where we have them — free, no obligation.
Get Saint Paul builder quotes →Permit fees in Saint Paul are Valuation-based (Sec. 33.04; schedule effective 2/25/2023): $1,499 for the first $100,000 plus $8 per additional $1,000, a plan-check fee of 65% of that, and the 0.05% state surcharge — about $3,200 on a $150,000 ADU and $5,300 on $300,000, before trade permits and any SAC.. The review timeline is DSI does not publish an ADU review time; zoning and building plan review run through DSI Plan Review (651-266-9007). A separate sewer/water service, or a plumbing alternate request to connect through the house, adds a plumbing plan review., with plan check: 65% of the building permit fee (no plan-check fee on valuations of $1,000 or less); review time not published by DSI.. Impact fees are Minnesota cities do not charge development impact fees. The Metropolitan Council Sewer Availability Charge (SAC) may be assessed for a new ADU and is collected by DSI with the building permit; the 2026 SAC rate could not be verified from the Met Council site — confirm the SAC determination with DSI before you budget.. Pre-approved plans: None. Saint Paul has no pre-approved ADU plan program; DSI publishes information sheets on ADUs and the building code and on ADU sewer/water connections..
| 1-Bedroom Rent | $1,270-$1,630/month |
| 2-Bedroom Rent | $1,540-$1,980/month |
| Annual Rental Income (est.) | $17,400/year |
| Payback Period (est.) | 13.6 years |
| Short-Term Rental | Yes, with a licence: any stay under 30 days needs a Short-Term Rental Host licence from DSI, paid per unit and renewed yearly; a non-owner-occupied unit also needs a Fire Certificate of Occupancy, and hosts need $300,000. |
| Overall ROI Estimate | 5-11% gross rental yield on a $200,000-$350,000 detached ADU renting at $1,400-$1,900/mo (HUD FY2027 range), before taxes, vacancy, insurance and financing; a $95,000-$185,000 garage or basement conversion renting at $1,. |
A typical ADU in Saint Paul generates approximately $17,400 per year in rental income based on average 1-bedroom rents. At an average construction cost of $237,500, the estimated payback period is 13.6 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: $95,000-$185,000.
2. Prefab/modular ADUs offer predictable pricing and faster timelines. Average: $150,000-$350,000.
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. 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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