Published August 16, 2026
Converting a Twin Cities garage into a legal, rentable apartment runs $75,000–$150,000. It rents for $1,200–$1,900 per month. That is a 5–9 year payback — the best ratio of any conversion we do in Minnesota.
Where the money goes
| Line item | Twin Cities range |
|---|---|
| Foundation / frost footing correction | $8,000–$25,000 |
| Framing, roof tie-in, exterior | $12,000–$25,000 |
| Insulation to code (walls R-20+, ceiling R-49) | $6,000–$12,000 |
| Electrical service and rough-in | $8,000–$16,000 |
| Plumbing — water, sewer, trench to main | $12,000–$30,000 |
| HVAC (mini-split is standard here) | $5,000–$9,000 |
| Kitchen | $9,000–$22,000 |
| Bathroom | $9,000–$18,000 |
| Flooring, drywall, paint, trim | $10,000–$20,000 |
| Egress windows | $4,500–$9,000 |
| Permits, SAC, survey, plans | $8,000–$18,000 |
The three things that decide feasibility
1. The slab and footings
Most Minnesota detached garages sit on a floating slab with a shallow thickened edge — nowhere near the 42-inch frost depth required for a heated, year-round dwelling. You either underpin the perimeter or pour new footings. This is the single most common budget-killer.
Check this before you fall in love with the project.
2. Utilities
A dwelling unit needs its own water supply, sanitary sewer, and adequate electrical service. If the main is on the street side and the garage is on the alley, you are trenching the full lot depth. Every 30 feet matters.
The Met Council SAC charge for a new dwelling unit is a fixed, non-negotiable fee — commonly $2,500–$5,000 in the metro. It is not part of your contractor's bid.
3. Zoning
You need the lot to allow an ADU or a second dwelling unit. Both Minneapolis and St. Paul generally do. Suburbs vary widely — Edina, Bloomington, and Woodbury each handle this differently, and some require owner occupancy.
Insulating a Minnesota garage conversion
This is not optional and it is not cheap to do right:
- Walls: R-20 minimum. 2x6 with dense-pack, or 2x4 with continuous exterior foam.
- Ceiling/roof: R-49. If there is no attic, closed-cell spray foam in the rafter bays is the only practical path.
- Slab edge: rigid foam at the perimeter. Skipping this is why converted garages feel cold at the floor forever.
- Air sealing: the old overhead door opening is the biggest leak. It needs to be framed, sheathed, sealed, and insulated as a real wall.
Non-conforming alternatives that cost far less
If a full apartment does not pencil, these still add value:
| Use | Cost | Rent / benefit |
|---|---|---|
| Heated office or studio (no kitchen/bath) | $25,000–$45,000 | No SAC, no second unit zoning |
| Heated gym / workshop | $18,000–$35,000 | Fastest, simplest |
| Bedroom suite connected to the house | $45,000–$80,000 | Adds a bedroom to the count |
The honest read
If your garage has a frost-depth foundation and the utility trench is short, this is the strongest return in Twin Cities residential construction. If it is a floating slab 80 feet from the main, a basement or attic ADU inside the house will beat it every time — same rent, half the cost.
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Frequently asked questions
How much does it cost to convert a garage into an apartment in Minnesota?
$75,000-$150,000 for a legal, permitted, year-round dwelling unit, driven largely by foundation depth, utility trenching, and insulation to Minnesota code.
Do I need new footings to convert a garage in Minnesota?
Usually yes. Most detached garages sit on a floating slab, and a heated year-round dwelling requires footings at the 42-inch frost depth.
What is the SAC charge?
The Metropolitan Council Sewer Availability Charge, a per-dwelling-unit fee commonly $2,500-$5,000 in the Twin Cities that is separate from your contractor bid.