Bloomington, IN Accessory Structures: ADU Rules (2026)

The Unified Development Ordinance (Title 20) authorizes accessory dwelling units at Section 20.03.030(g)(5), an Accessory Use available in most of the City of Bloomington's residential and mixed-use districts per Table 03-1 (Allowed Use Table). The Generally subsection, Section 20.03.030(g)(5)(B), sets the baseline: an ADU has to be accessory to a single-family or duplex dwelling that is the principal use on the same lot, only one ADU is allowed per lot, and an ADU cannot contain more than two bedrooms. An attached ADU tops out at eight hundred forty square feet under Section 20.03.030(g)(5)(D), matches the primary dwelling's maximum height, and has to meet the same setback the primary dwelling meets in its zoning district.

A detached ADU is capped under Section 20.03.030(g)(5)(E) at eight hundred forty square feet or the maximum accessory-structure footprint allowed by Section 20.03.030(g), whichever is less, cannot exceed twenty-five feet in height, cannot extend closer to the street than the existing primary dwelling, and must sit back at least five feet from any side or rear property line. Utilities have to connect to the public water main and sanitary sewer under Section 20.03.030(g)(5)(C), unless the primary dwelling already uses a septic system permitted under Monroe County Health Department standards.

The Owner Occupancy subsection, Section 20.03.030(g)(5)(G), requires either the primary dwelling or the ADU to be occupied by the property owner, backed by an affidavit filed with the Planning and Transportation Department and, under Section 20.03.030(g)(5)(H), a deed or title restriction recorded with the Monroe County Recorder barring the ADU from being sold separately from the primary unit. Any unit used as a rental has to register with the Department of Housing and Neighborhood Development (HAND).