5 county-level rules, plus city-specific rules for 2 cities in Kane County, Illinois.
Verified from official government sources
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.
Kane 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.
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.
Kane 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...
Kane County has no ordinance that specifically authorizes garage-to-living-space conversions. Because only one residence per lot is allowed and a converted garage cannot become a second dwelling, any conversion to habitable space needs a building permit and must meet the residential building code and off-street parking rules.
A carport is a detached or attached accessory structure and counts toward Kane County's two-detached-structure limit and combined floor-area caps (900 sq ft on lots up to two acres). It must meet accessory-building setbacks, cannot occupy more than 25 percent of a required yard, and needs a building permit.
Kane County Zoning Ordinance 25-5-9-2
No detached accessory building or buildings shall occupy more than twenty five percent (25%) of the area of a required yard for a principal building. ... Detached accessory buildings or structures shall be located no closer to any other accessory or principal building than five feet (5').
Kane County zoning has no tiny-home category and allows only one residence per lot, meeting the adopted building code. A tiny house on a foundation is treated like any dwelling; one on wheels is an RV and cannot be a permanent residence in unincorporated areas.
2 cities in Kane County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
See every category we cover for Kane County — parking, noise, fences, fires, animals, pools, and more.
Kane County Ordinance Hub →