Kirkwood, MO Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Kirkwood, MO, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Governing section
- § 25-45(b)(2) and (5)
- Minimum lot area
- 15,000 square feet
- Max ADU size
- 750 sq ft, two bedrooms max
- Height cap
- two stories, never taller than main house
- Parking
- one extra off-street space required
- Enforcement
- $10-$250/day fine, Director of Public Services
Summary
Kirkwood lets homeowners convert a detached garage into an accessory dwelling unit under Zoning Code § 25-45(b), but the garage must be brought up to every ADU standard in the section, including the setbacks that apply to principal buildings, before the Director of Public Services will sign off. A converted garage cannot skip any requirement just because the structure already exists.
(2) Accessory dwelling units may be constructed within an existing dwelling unit (interior apartment) or as a separate or converted accessory structure (e.g., converted garage, carriage house, unit above a garage). ... (5) No existing accessory building can be converted to an accessory dwelling unit or modified to incorporate an accessory dwelling unit without meeting all the standards of this section, including the required setbacks.
Full Breakdown
Kirkwood's zoning code treats a garage conversion as one path to an accessory dwelling unit (ADU) under § 25-45(b), but it does not get a shortcut around the standards that apply to purpose-built ADUs. Subsection (b)(2) expressly allows an ADU to be built as a separate or converted accessory structure, naming a converted garage, carriage house, or unit above a garage as examples, so a detached garage is a recognized starting point. Subsection (b)(5) then closes the loophole: no existing accessory building, garage included, can be converted or modified to add an ADU without meeting all the standards of the section, including the required setbacks.
In practice that means the converted structure must sit on a lot at least 15,000 square feet in area (b)(8), serve only a single-family dwelling on that lot (b)(1), and cap out at 750 square feet of floor area with no more than two bedrooms (b)(9); floor area for a garage-based unit excludes the garage space itself. The building cannot exceed two stories or the height of the principal house (b)(6), and only one ADU total is allowed per lot (b)(7). An extra off-street parking space with direct, drivable street access is required beyond what § 25-65 already demands for the main house (b)(10).
Converting a garage without a building permit, or without meeting setbacks for principal buildings in the applicable district, exposes the owner to enforcement under Article XIII rather than a simple after-the-fact fix.
Violations & Fines
A garage converted to living space without meeting § 25-45(b)'s standards is a Code violation enforced by the Director of Public Services under § 25-99. Under § 25-100(b), the owner faces a fine of $10 to $250 per day the violation continues, or up to 10 days' imprisonment per day, rising to $100 to $500 per day for a repeat violation at the same property. Decisions may be appealed to the Board of Adjustment under § 25-25.
Frequently Asked Questions
Can I convert my detached garage into an accessory dwelling unit in Kirkwood?
How big can a garage-conversion ADU be in Kirkwood?
What happens if I convert a garage without a permit?
Sources & Official References
Other rules in Kirkwood
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