Published August 16, 2026
A detached ADU in Minneapolis or St. Paul costs $180,000 to $400,000 — roughly $340 to $520 per square foot for a 500–800 sq ft unit. An attached or above-garage ADU runs $140,000 to $280,000. A basement conversion ADU, where the shell already exists, can come in at $70,000 to $160,000.
Both cities allow ADUs on most single-family lots. That makes the Twin Cities one of the better ADU markets in the Midwest — and most homeowners still do not know it.
Cost by ADU type
| ADU type | Typical size | Cost | $/sq ft |
|---|---|---|---|
| Basement conversion | 500–800 sq ft | $70,000–$160,000 | $130–$220 |
| Attached (addition with own entry) | 450–700 sq ft | $140,000–$260,000 | $290–$400 |
| Above detached garage | 450–700 sq ft | $160,000–$280,000 | $320–$430 |
| New detached (studio/1BR) | 400–600 sq ft | $180,000–$310,000 | $380–$520 |
| New detached (2BR) | 650–850 sq ft | $250,000–$400,000 | $340–$470 |
| Garage conversion (no second story) | 400–600 sq ft | $95,000–$180,000 | $210–$310 |
Where the money goes on a 600 sq ft detached ADU
| Line item | Cost |
|---|---|
| Design, survey, engineering, permits | $15,000–$35,000 |
| Site work and utility trenching | $12,000–$30,000 |
| Frost footings and slab/foundation | $22,000–$45,000 |
| Framing, roof, exterior envelope | $55,000–$95,000 |
| Plumbing (new sewer/water tap) | $18,000–$40,000 |
| Electrical (often a new service) | $10,000–$22,000 |
| HVAC (usually mini-split) | $7,000–$14,000 |
| Insulation, drywall, interior finish | $40,000–$75,000 |
| Kitchen and bath | $22,000–$45,000 |
| Landscape restoration, walk, parking | $6,000–$18,000 |
The utility connections are the surprise line. Trenching a sewer lateral and water service to a backyard structure, plus a separate electrical service, routinely runs $30,000–$60,000 combined. Get a bid on that before you commit.
The rent math
Twin Cities ADU rents in 2026 typically run:
| Unit | Monthly rent |
|---|---|
| Studio ADU | $1,150–$1,600 |
| 1BR ADU | $1,350–$1,900 |
| 2BR ADU | $1,700–$2,400 |
On a $260,000 detached 1BR renting at $1,600, gross annual rent is $19,200. Net of taxes, insurance, and maintenance, call it $14,500. That is a 5.6% cash yield on cost, plus appraised value added to the property, plus a hedge against needing eldercare or adult-child housing later.
Compare that to a basement ADU at $120,000 renting for $1,350 — $11,800 net on $120,000 is a 9.8% yield. Basement conversions are almost always the better return; detached units are better living space and better resale.
Twin Cities rules you need to know
Both cities permit ADUs broadly on single-family lots, but the details govern feasibility:
- Owner occupancy requirements have been relaxed in Minneapolis — verify current rules with the city before you plan.
- Size caps are typically tied to a percentage of the primary structure or a hard square footage ceiling.
- Height and setbacks for detached structures, plus lot coverage limits (often 30–35% of the lot including the house and garage).
- One ADU per lot in most cases.
- Short-term rental rules are separate and stricter — do not assume an ADU can be an Airbnb.
- Alley access and parking requirements vary by ward and neighborhood.
Rules change. Verify current zoning with Minneapolis CPED or St. Paul DSI before you spend money on design.
Timeline
- Feasibility and zoning check: 2–4 weeks
- Design and engineering: 6–12 weeks
- Permit review: 6–14 weeks
- Construction: 4–7 months
Total: 10 to 16 months. Start the conversation a year before you want a tenant.
Frequently asked questions
How much does it cost to build an ADU in Minneapolis? $180,000 to $400,000 for a new detached unit. Basement and garage conversions run far less — $70,000 to $180,000.
Does an ADU add value to my property? Yes, both through appraised value and income. Appraisers in the Twin Cities increasingly use an income approach on ADU properties, which values the rent stream directly.
Can I finance an ADU? Common routes are a HELOC, cash-out refinance, construction loan, or renovation mortgage. Some lenders will count projected ADU rent toward qualification.
Is a basement ADU cheaper than a detached one? Substantially — often less than half — because the foundation, roof, and envelope already exist. The tradeoffs are egress requirements, ceiling height, and a shared entry.
We build detached, above-garage, and basement ADUs across Minneapolis and St. Paul. Start with a feasibility review — we will tell you what your lot allows before you pay for design.
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Frequently asked questions
How much does an ADU cost in Minneapolis?
A new detached ADU runs $180,000-$400,000. Above-garage units are $160,000-$280,000 and basement conversions are $70,000-$160,000.
Are ADUs allowed in Minneapolis and St. Paul?
Yes, both cities permit accessory dwelling units on most single-family lots, subject to size caps, setbacks, height limits, and lot coverage rules. Verify current zoning before designing.
What does an ADU rent for in the Twin Cities?
Roughly $1,150-$1,600 for a studio, $1,350-$1,900 for a one-bedroom, and $1,700-$2,400 for a two-bedroom in 2026.
How long does it take to build an ADU?
Ten to sixteen months total: 2-4 weeks feasibility, 6-12 weeks design, 6-14 weeks permitting, and 4-7 months construction.
What is the most expensive surprise in an ADU budget?
Utility connections. Trenching sewer and water to a backyard structure plus a separate electrical service commonly runs $30,000-$60,000.