Rock Island County, IL Accessory Structures: Shed & Carport Rules (2026)
Shed permit rules in Rock Island County, IL, also referred to as storage shed, backyard shed, or accessory building regulations, set size limits, setbacks, and when a building permit is required.
Key Facts
- Side/rear setback
- 5 feet in AG/SE/R districts
- Lot coverage cap
- 30% of lot area, any district
- Height limit
- 15 feet in Residential Districts
- R-district size cap
- Cannot exceed house's footprint
- Corner lots
- Same setback as principal building
- Penalty
- $25-$200 per offense, § 154.999
Summary
In unincorporated Rock Island County a shed, detached garage or other accessory building needs a 5-foot setback from the side and rear lot lines in the AG, SE and R districts. County-wide, accessory structures cannot cover more than 30% of the lot, and on R-district lots they cannot exceed the primary house's ground-floor footprint or 15 feet in height.
No accessory building or buildings shall be erected in any required court or yard. When erected in a side yard in an AG-1, AG-2, SE-1, SE-2, or any R District, the accessory building shall maintain a five-foot setback. When erected in a rear yard in an AG-1, AG-2, SE-1, SE-2, or any R District, the accessory building shall maintain a five-foot setback. In any zoning district, accessory buildings shall not occupy more than 30% of the lot area, and in any R District, it or they shall not exceed the total ground floor footage of the primary structure, except for swimming pools, and shall be a distance of five feet from any lot line that adjoins an AG-1, AG-2, SE-1, SE-2, or any R District. Accessory buildings in all Residential Districts shall not exceed 15 feet in height, except that an accessory building used in part or wholly as a dwelling for domestic employees of the owners or of the tenants of the principle building shall not exceed two stories or 25 feet in height.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2025 S-1: Supplement contains: Local legislation current through Ord. 2024-12-A, passed 12-17-2024; and State legislation current through 2024 Illinois Legislative Service, Pamphlet #6).
Full Breakdown
039 sets the accessory-building rules that apply outside the cities. No accessory building can go in a required court or yard, and any one erected in a side or rear yard in the AG-1, AG-2, SE-1, SE-2 or R districts must keep a five-foot setback. Across every district, accessory buildings together cannot occupy more than 30% of the lot area, and on any R-district lot they cannot exceed the ground-floor square footage of the house itself, except swimming pools are excluded from that cap. Height in Residential Districts tops out at 15 feet, rising to two stories or 25 feet only if the structure is a dwelling for domestic employees and meets the principal building's open-space rules.
On a corner lot, subsection (F) requires the accessory building to observe the same setback as the principal structure. Subsection (E) bars building any accessory structure on an SE-2 or R lot before the principal building itself is built. to 2-acre lots up to no size limit past 15 acres. 020(C): no permit for a use of land or building may issue until the Administrative Officer has examined the application, and any certificate issued in conflict with the chapter is void.
Violations & Fines
Violating any provision of Chapter 154, including the accessory-building setback, coverage or height limits, is punishable under § 154.999(A): a forfeiture of not less than $25 nor more than $200 per offense plus prosecution costs, with up to 30 days in the County Jail if the forfeiture and costs go unpaid. Each day the violation continues counts as a separate offense, so an unpermitted or oversized shed left standing accrues daily exposure.
Frequently Asked Questions
Do I need a permit for a shed in unincorporated Rock Island County?
How big can my shed be on a residential lot?
How tall can a shed or detached garage be?
What setback applies if my shed is on a corner lot?
Sources & Official References
Other rules in Rock Island County
How Rock Island County compares: Shed Permit Requirements by City·Compare Rock Island County to another location·View the Illinois accessory structures overview
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