Story County, IA Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Story County, IA, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Facade requirement
- Garage doors removed, replaced with matching facade
- Eligible structures
- Must meet Table 86-2 bulk standards or be nonconforming
- Additions
- Must meet single-family dwelling bulk standards
- Still required
- Zoning permit, septic permit, 911 address
- Size cap
- 1,200 square feet gross floor area applies
Summary
Converting an existing garage or other accessory structure into living space for an accessory dwelling unit is allowed in unincorporated Story County only if the structure already meets the accessory-structure bulk standards in Table 86-2, and Section 86.04(3)(L)(5) requires every overhead or garage door on the converted portion to come out and be replaced with a matching facade.
(5) Conversion of Existing Accessory Structures. a. Existing accessory structures conforming to the bulk requirements for accessory structures in Table 86-2 , or that are legal nonconforming structures, shall be permitted to be converted to an accessory dwelling unit. Additions to a converted accessory structure shall meet the bulk requirements for a single-family dwelling in Table 86-2 . b. Overhead doors, or garage doors, shall be removed from structures being converted to Accessory Dwelling Units and shall be replaced with a new, matching facade. This requirement only applies to the portions of a structure being converted to living space for the accessory dwelling unit.
Full Breakdown
04(3)(L)(5) sets the rule for turning an existing accessory structure, including a detached garage, into an accessory dwelling unit. The structure qualifies for conversion if it already conforms to the bulk requirements for accessory structures in Table 86-2, or if it is a legal nonconforming structure; either way, any new square footage added onto the converted building has to meet the stricter bulk requirements that apply to a single-family dwelling in the same table, not the looser accessory-structure standards. Subsection (5)(b) then requires overhead doors or garage doors to be removed from any part of the structure being converted to living space and replaced with a new, matching facade, though that requirement applies only to the portion actually becoming living space, so a section of the building that stays a garage can keep its door.
04(3)(L): a zoning permit under subsection (1), a septic permit from the Environmental Health Department approved before that zoning permit issues under subsection (2), a separate 911 address under subsection (3), and the 1,200 square foot gross floor area cap and one-ADU-per-parcel limit under subsection (4), regardless of the fact that the space started out as a garage rather than new construction.
Violations & Fines
A garage-to-ADU conversion that skips the required door and facade change, the zoning permit, or the septic sign-off is enforced under Chapter 93 like any other Land Development Regulations violation: Planning and Development issues a written Notice of Violation with 30 days to correct, and an uncorrected violation can bring a County infraction citation carrying a civil penalty of up to $750 for a first offense and up to $1,000 for each repeat offense, or prosecution as a simple misdemeanor.
Frequently Asked Questions
Can I convert my detached garage into an accessory dwelling unit in Story County?
Do I have to remove the garage door when I convert it?
Does a converted garage still need a separate zoning permit?
Sources & Official References
Other rules in Story County
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