Basement finishing turns an unfinished lower level into heated, lit living space with framed walls, insulation, drywall, a ceiling and flooring. This page covers the usual order of work, the code points that shape the rooms, and what to ask the people who quote it.
Before anyone frames a wall
Any active leaks or dampness should be fixed before finishing.
Next comes a floor plan. Towns around Milwaukee ask for more than a sketch. Menomonee Falls wants room dimensions and uses, the ceiling finish, and the locations of the furnace, water heater, sump crock, smoke alarm and carbon monoxide detector, and says a general picture of the rooms isn't enough [1]. Waukesha asks for an existing floor plan and a proposed one that shows egress window details, alarm locations, plumbing fixtures and ventilation [2].
The usual order of work
Inspections set the order. Cudahy's list runs rough framing before insulating, insulation before the wall and ceiling finish, and a final inspection before you move in [3]. Menomonee Falls does one rough visit for framing, electrical and plumbing, then an insulation inspection before drywall, then a final [1]. A typical sequence:
- Plans and permits
- Framing, then rough electrical, plumbing and ductwork
- Rough inspections
- Insulation and its inspection
- Drywall and ceiling
- Flooring, doors, trim and paint
- Final inspection
Code points that shape the rooms
- Ceiling height. Habitable rooms need 7 feet, with exceptions for low areas, beams and some bathroom fixtures [4]. See ceiling height and layout.
- Bedrooms. A basement used for sleeping needs two exits, and an egress window in each bedroom can serve as the second one [5]. See egress windows.
- Light and air. Waukesha's basement page lists window glass of at least 8% of a habitable room's floor area and 3.5% openable, unless there's mechanical ventilation [2]. State code, SPS 321.05, exempts habitable basement rooms other than bedrooms from the natural light rule, so ask your town which applies [6].
- Insulation. Menomonee Falls notes that state code doesn't allow a vapor barrier over insulation on masonry walls and that bottom plates must be treated lumber [1]. Greendale's checklist also says not to put a vapor barrier on below-grade walls [7].
- Alarms. Waukesha requires a listed carbon monoxide alarm with battery backup in the basement unless the home has no attached garage, fireplace or fuel-burning appliance, along with interconnected smoke alarms [2].
Choosing basement finishing contractors
The state ties building permits for houses and duplexes to two DSPS credentials: the company holds a Dwelling Contractor (DC) certification and has a Dwelling Contractor Qualifier (DCQ) on its team. An owner who lives in the house is exempt [8]. Trade rules vary by town. Waukesha lets only licensed plumbing and electrical contractors get those permits [2], while New Berlin lets an owner-occupant of a single-family home do their own plumbing and electrical [9]. In the City of Milwaukee, all electrical work needs a licensed contractor [10].
Questions worth asking:
- Who pulls each permit, and who books the inspections?
- Which trades are subcontracted, and are they licensed?
- Is the quote itemized by framing, insulation, electrical, ceiling, flooring and finish work?
- What's left out, such as HVAC changes, egress windows or a bathroom?
Cost
HomeGuide puts a full finish at $30 to $50 per square foot nationally [11], and Angi's 2026 national average is $32,000 [12]. See the cost guide for more.
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Sources
- Village of Menomonee Falls, Lower Level / Basement Remodel (fetched Nov 11, 2026) https://www.menomoneefalls.gov/653/Lower-Level-Remodel
- City of Waukesha, Residential Basement Remodel (fetched Nov 11, 2026) https://www.waukesha-wi.gov/government/departments/residential-basement-remodel.php
- City of Cudahy, Inspection FAQs. https://www.cudahy-wi.gov/departments/inspection/faqs.php
- Wis. Admin. Code SPS 321.06, Ceiling height (fetched Nov 11, 2026) https://docs.legis.wisconsin.gov/code/admin_code/sps/safety_and_buildings_and_environment/320_325/321/ii/06
- Wis. Admin. Code SPS 321.03, Exits (Register November 2024 No. 827; fetched Nov 11, 2026) https://docs.legis.wisconsin.gov/code/admin_code/sps/safety_and_buildings_and_environment/320_325/321/ii/03
- Wis. Admin. Code SPS 321.05, Natural light and natural ventilation (fetched Nov 11, 2026) https://docs.legis.wisconsin.gov/code/admin_code/sps/safety_and_buildings_and_environment/320_325/321/ii/05
- Village of Greendale, Basement Rec-Room Checklist for Plan Submittal (PDF) https://greendale.org/departments/inspection_services/docs/BASEMENT%20REC%20ROOM-PLAN%20REVIEW%20CHECKLIST-website.pdf
- Wisconsin DSPS, Dwelling Contractor Qualifier (DCQ), Building Permit Requirements (fetched Nov 11, 2026) https://dsps.wi.gov/a-z-professions-list/dwelling-contractor-qualifier-dcq/
- City of New Berlin, Recreation Rooms guideline (PDF, dated 08/26/2022) https://www.newberlin.org/DocumentCenter/View/500
- City of Milwaukee DNS, Does It Need a Permit? (fetched Nov 11, 2026) https://city.milwaukee.gov/DNS/permits/PermitChecklist
- HomeGuide, "How Much Does It Cost to Finish a Basement? (2026)," byline Feb 6, 2026. https://homeguide.com/costs/cost-to-finish-a-basement
- Angi, "How Much Does It Cost to Finish a Basement? [2026 Data]," Rachel Hoffman, updated Oct 29, 2026. https://www.angi.com/articles/how-much-does-it-cost-finish-basement.htm