Looking for a basement contractor in Ballwin, MO? Describe your project once and up to three basement contractors who work in Ballwin and St. Louis County get back to you with a quote. It's free and there is no obligation.
Ballwin is home to about 31,036 people (2024 Census Bureau estimate), a shrinking community (−2.1% since 2020). With 3,416 people per sq mi, it is a suburban area. Full basements are common here and often the cheapest way to add living space.
Ballwin at a glance
- Population (Census Bureau estimate, 2024)
- 31,036 (−2.1% since 2020)
- Rank in Missouri
- 21st of 938 cities and towns
- Land area
- 9.1 sq mi
- Population density
- 3,416 people per sq mi (suburban)
- Type
- City (Ballwin city)
- Main county
- St. Louis County
What to check before hiring in Ballwin
- Moisture first: waterproof before finishing.
- Egress: in Missouri, a basement bedroom needs an escape opening.
- Radon: test before you finish.
- Price drivers: size, bathroom, ceiling height, finishes and egress.
Useful official resources
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ICC: International Code Council
Official information and guidance.
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EPA: radon
Official information and guidance.
Services available in Ballwin
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Basement finishing
Framing, insulation, electrical, drywall and flooring of a basement, with permit.
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Basement bathroom or rental unit
Bathroom, kitchenette or legal basement unit with egress and plumbing.
Frequently asked questions in Ballwin
How much does basement finishing cost in Ballwin, MO?
It depends on size, bathroom and finishes. Describe your basement: contractors who serve Ballwin reply with a quote.
How long does it take?
Often several weeks.
Can I rent it out?
Only if local rules allow an accessory unit; check zoning.
Which basement contractors will contact me?
Up to three independent basement contractors who serve Ballwin and the surrounding area, chosen for the service you need. Your details are shared only with your consent.
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2024) and Gazetteer Files (public domain), imported on 10/31/2026. Figures describe the incorporated place or county as published; they are shown for information only.