5 county-level rules, plus city-specific rules for 1 city in Hamilton County, Indiana.
Verified from official government sources
Hamilton County's fast-growing cities zone their own land under IC 36-7-4, so ADU rules come from Carmel, Fishers, Westfield, or Noblesville, not the county. Carmel allows one guest house with cooking facilities only on lots of at least one acre.
Carmel UDO § 5.02(C)(4)
Guest House: One (1) Guest House with cooking facilities may be permitted as an Accessory Building on Lots containing not less than one (1) acre.
Sheds are governed by your city's zoning code, not the county. In Carmel, a detached accessory building must sit at least five feet from side and rear lot lines, top out at 18 feet, and requires an Improvement Location Permit.
Carmel UDO § 5.02(B)(1)(b)
When more than ten (10) feet away from a Principal Building, Accessory Buildings and Uses shall be set back a minimum of the greater of the following: [1] Five (5) feet, or [2] Easement plus three (3) feet.
Converting a garage to living space is a city zoning and building matter in Hamilton County, handled by Carmel, Fishers, Westfield, or Noblesville, not the county. A local permit and Indiana Residential Code compliance are required.
A carport is an accessory structure regulated by your Hamilton County city's zoning code, not the county. Carmel treats a carport as a detached accessory building: it needs a permit, must meet setbacks, and can only connect to the house by a roof.
Carmel UDO § 5.02(A)(4)
Accessory Buildings shall not be attached to the Principal Building, with the exception of an allowable uniform and continuous roof supported by customary supports or joists, and no other connection or attachment between the structures exists.
Tiny-home rules come from your Hamilton County city, not the county. Carmel's UDO requires every single-family dwelling to be at least 23 feet wide, and Indiana treats a tiny house on wheels as a recreational vehicle that cannot be lived in.
Carmel UDO § 5.04(A)
All single-family or duplex dwelling units shall be required to be constructed with a width of no less than twenty-three (23) feet.
1 cities in Hamilton County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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