Can I Build Garage Conversion in St. Louis, MO? (2026)

Converting an attached or detached garage into living space in St. Louis, MO is a popular way to add an ADU or additional living area without new construction. Garage conversion regulations in St. Louis require verification with the local building department. A key consideration: whether replacement parking is required for a garage-to-ADU conversion has not been confirmed — check with the building department.

Garage Conversion Rules in St. Louis

Garage Conversion Rules in St. Louis: Allowed: Status not confirmed — see official source. Replacement parking required: Status not confirmed — see official source. All garage conversions to habitable space require a building permit. The converted space must meet minimum habitable room standards (typically 7 ft ceiling height, egress window, insulation, and ventilation).

Costs & Fees

Garage conversion permit fees in St. Louis are typically based on project valuation. Contact the local building department through their official website for current fees. Conversion costs typically range $20,000–$80,000 depending on scope (permits, labor, materials, utility connections).

Timeline

Permit timeline: typically 2-6 weeks for plan check. Construction: 2-4 months for a typical garage conversion.

Next Steps

Next steps for converting your garage in St. Louis: 1. Determine if the conversion will be an ADU (separate unit with kitchen/bath) or additional living space. 2. Check replacement parking requirements for your zone. 3. Have a contractor assess structural requirements (ceiling height, foundation, utilities). 4. Submit plans and permit application to the local building department. 5. See the full ADU rules page for size limits and requirements if creating an ADU unit.

St. Louis Building Division (Community Development Administration)

Frequently Asked Questions