What a finished basement adds
In the 2025 Cost vs. Value report, a basement remodel in the Twin Cities cost $52,745 on average and added $41,401 at resale, recouping 78.5%, above the national 71% (Cost vs. Value). The benchmark project is a 20-by-30-foot entertaining area with a wet bar and a 5-by-8-foot full bath (project descriptions). NAR's 2025 report puts basement conversion to living area at 71% cost recovered, with a homeowner Joy Score of 8.8 out of 10 (NAR 2025).
How the square footage counts
A finished basement adds living space, but it's counted separately from the main floors:
- Appraisals. Fannie Mae treats a level as below grade if any part of it is below grade, so finished basement rooms (even a walkout) aren't included in above-grade square footage or room count. But Fannie Mae also says those rooms "may add substantially to the value of a property," and appraisers report them on their own line and adjust for them (Fannie Mae Selling Guide).
- Listings. NorthstarMLS, Minnesota's MLS, reports "Above Ground Finished Square Feet" and "Below Ground Finished Square Feet" as separate fields (NorthstarMLS). It says finished areas need ceilings at least 7 feet high (6'4" under beams, ducts and other obstructions) and permanent, sufficient heat (NorthstarMLS).
- Bedrooms. NorthstarMLS requires a bedroom to meet local code to be listed as one, including an egress opening where required and permanent heat. A room that doesn't qualify can be listed as a den, office, flex room or bonus room (NorthstarMLS). See our egress window guide.
Permits
Minnesota's building code exempts only finish work like painting, flooring, cabinets and countertops from permits; framing walls and adding rooms need a building permit, and plumbing, electrical and mechanical work need their own permits (Minn. R. 1300.0120). St. Paul requires a plan with the basement layout, dimensions and labeled rooms before it issues a basement-finish permit (St. Paul DSI). West St. Paul requires inspections for framing, insulation, drywall and final (West St. Paul). New electrical work must be inspected (Minn. Stat. 326B.36), with a rough-in inspection before wiring is covered (MN DLI).
What Minnesota code requires
- Ceiling height. For alterations to an existing basement, Minnesota requires at least 6 feet 4 inches, including beams, ducts and other obstructions (Minn. R. 1309.0305, R305.2.1).
- Room size. Habitable rooms need at least 70 sq ft and at least 7 feet in any direction (R304).
- Egress. Altering an existing basement doesn't by itself trigger an egress window, but a new bedroom created in an existing basement needs one, unless the basement is sprinklered (R310.6).
- Smoke alarms. When work requires a building permit, smoke alarms must be brought up to new-home locations, including every level and basements, and interconnected (R314).
- Carbon monoxide alarms. Required within 10 feet of each room used for sleeping (Minn. Stat. 299F.51, R315).
- Fireblocking in stud walls and furred spaces at the floor and ceiling and at soffits, and ½-inch drywall on the enclosed side of any closet under the stairs (R302.11, R302.7).
- Heat. Habitable rooms need heat that can hold 68°F; portable space heaters don't count (R303.10).
- Foam insulation must be covered by a thermal barrier like ½-inch drywall (R316.4). See insulating basement walls.
Fix water first
University of Minnesota Extension: "Walls must be dry before insulating. Slabs must be warm and dry before carpeting." It recommends grading that slopes away from the foundation at least 1 inch per foot for 6 feet, at least one downspout per 50 feet of eave, and extensions that discharge at least 4 feet from the wall. Dehumidifiers treat symptoms but aren't a permanent fix, and an interior coating without drainage generally won't solve the problem long term (UMN Extension).
The Minnesota Department of Health recommends testing for radon before and after finishing a basement (MDH).
The order the work happens in
- Moisture and radon check, then design and permits.
- Framing, then rough-in plumbing, electrical and ductwork.
- Rough-in and framing inspections.
- Insulation and its inspection.
- Drywall, then doors, trim, flooring and paint.
- Fixtures and devices, then final inspection.
What it costs in the Twin Cities
Angi puts finishing a basement in Minneapolis at $33,536 on average, typically $19,000 to $65,000, or about $32 to $100 per sq ft (Angi Minneapolis). The Cost vs. Value benchmark with a wet bar and full bath is $52,745 (Cost vs. Value). Size, a bathroom, a bar, egress windows and ceiling work around ducts drive the range.
Where the money is best spent
- Dry first. Water problems ruin finished basements.
- A legal bedroom with egress and permanent heat, so it can be listed as one.
- A bathroom if there isn't one. See adding a basement bathroom.
- Permitted work. It's the law, and it gives buyers and appraisers confidence the space was done right.