Accessory Structures in Allen County, IN (2026)
4 rules for unincorporated Allen County, Indiana.
Verified from official government sources
ADU Rules
In unincorporated Allen County, the Zoning Ordinance allows one accessory dwelling unit (ADU) per residential lot. An integrated ADU inside a single-family home must be at least 300 square feet, and only one freestanding ADU is permitted where there is no integrated unit.
Accessory Dwelling Unit Rules in Allen County
Some RestrictionsAllen County Zoning Ordinance, Title 3 Article 2 (Zoning Districts)
If integrated into a single family detached dwelling, and if there is no freestanding accessory dwelling unit on the property; the integrated accessory dwelling unit shall be at least 300 square feet.
Shed & Carport Rules
In unincorporated Allen County, a detached accessory building such as a shed may not exceed 25 feet in height. On residential lots under two acres with on-site sewage, a new detached accessory building must be smaller than the primary building, and a shed generally requires an Improvement Location Permit.
Shed & Accessory Building Rules in Allen County
Some RestrictionsAllen County Zoning Ordinance, Title 3 Article 2 (District Development Standards)
On lots of less than two (2) acres served by an on-site sewage system, new detached accessory building square footage shall be less than the square footage of the primary building. Height (maximum): Accessory building 25 [feet].
Garage Conversions
The Allen County Zoning Ordinance has no separate garage-conversion permit. Converting a garage into living space or a second unit changes its use, so it must meet the district's dwelling and ADU standards (an integrated accessory dwelling unit must be at least 300 square feet) and needs an Improvement Location
Garage Conversion Rules in Allen County
Some RestrictionsAllen County Zoning Ordinance, Title 3 Article 2 (Zoning Districts)
If integrated into a single family detached dwelling, and if there is no freestanding accessory dwelling unit on the property; the integrated accessory dwelling unit shall be at least 300 square feet.
Tiny Homes
Allen County's Zoning Ordinance has no separate tiny-home category. A dwelling must meet its district's minimum standards. Temporary structures such as portable storage containers are capped at 90 days (120 with a Certificate of Use) and cannot be used as permanent housing.
Tiny Homes & Portable Structures in Allen County
Some RestrictionsAllen County Zoning Ordinance A.C.C. 3-4-3 (Temporary Accessory Structures)
A temporary storage or similar structure, including a portable storage container, shall be permitted in a residential district for up to 90 days without a Certificate of Use; if the applicant obtains a Certificate of Use then the structure may be permitted up to 120 days.
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