Springfield, IL Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Springfield, IL, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Code Section
- Zoning Ord. 155.068(a)-(b)(2)
- Detached garage to dwelling
- Prohibited
- Detached garage to office/business
- Prohibited
- Attached garage
- Treated as part of principal building; permit required
- Building permit
- Required for garage construction/alteration
Summary
Springfield's zoning code bars converting a detached garage or accessory building into a dwelling unit or a business: Section 155.068(b)(2) states no portion of such a structure may be used as a dwelling unit or for any business or office use. Converting an attached garage into living space is treated as altering the principal building and requires a permit.
(2) The maximum height allowed for any detached garage, accessory building, or structure in a residential zoning district is 18 feet. However, in no case shall any portion of a detached garage, accessory building, or structure be used as a dwelling unit or for any business or office use.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 82).
Full Breakdown
068. " This forecloses converting a detached garage into an apartment, office, or accessory dwelling unit. 068(a), considered part of the principal building and is therefore subject to all regulations applicable to the principal building; converting attached-garage space into habitable rooms must meet the principal-building setback, lot-area, and building-code requirements and requires a building permit. Springfield's building code requires a permit before construction or alteration of garages, and footings below the frost line are required for attached garages and larger detached garages. Because Illinois has not enacted statewide ADU preemption (HB 1813 remained pending as of 2026), there is no state override permitting a detached-garage-to-ADU conversion in Springfield. Owners wanting a second dwelling unit must pursue a variance or text amendment through the Planning and Zoning Commission.
Violations & Fines
Occupying a converted detached garage as a dwelling, office, or business violates Section 155.068(b)(2) and is subject to the zoning penalty cross-referenced at Section 155.999. Converting garage space without a building permit also violates the city building code and can trigger stop-work orders and after-the-fact permit fees.
Frequently Asked Questions
Can I convert my detached garage into an apartment in Springfield, IL?
Can I turn a detached garage into a home office or business in Springfield?
What about converting my attached garage into a living room?
Sources & Official References
Other rules in Springfield
Compare Springfield to another location·View the Illinois accessory structures overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.