Accessory Structures in Kane County, IL (2026)
2 county-level rules, plus city-specific rules for 2 cities in Kane County, Illinois.
Verified from official government sources
ADU Rules
Unincorporated Kane County allows only one residential building per zoning lot, so a standalone accessory dwelling unit (second house) generally is not permitted by right. Detached structures may only be accessory, non-dwelling uses. A second dwelling requires a rezoning or special use through the Development Department.
ADUs and Second Dwellings in Unincorporated Kane County
Some RestrictionsKane County Zoning Ordinance 25-5-5
Except in the case of a planned unit development, not more than one residential building shall be located on a recorded zoning lot, and not more than two (2) detached structures accessory to a dwelling shall be located on a recorded or zoning lot.
Shed & Carport Rules
In unincorporated Kane County, detached accessory buildings such as sheds are limited to a combined 900 square feet on lots of two acres or less, and 1,800 square feet on lots between two and five acres. Sheds must meet yard setbacks; a building permit is required.
Shed Size and Setback Rules in Unincorporated Kane County
Some RestrictionsKane County Zoning Ordinance 25-5-9-5
On lots of two (2) acres or less in size, none of the detached accessory buildings or structures shall exceed a combined total of nine hundred (900) square feet in total floor area under roof. On lots greater than two (2) acres in size but less than five (5) acres in size, none of the detached buildings or structures shall exceed a combined total of one thousand eight hundred (1,800) square fee...
Accessory Structures by City in Kane County
2 cities in Kane County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
All Kane County ordinances
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