ADU Rules in Cincinnati, Ohio

Accessory dwelling units have been legal in Cincinnati since October 2, 2023.

The current City Planning guidance says ADUs are permitted on properties that:

• allow single-family residential use; and
• contain a single-family dwelling.

Number of ADUs

Only one ADU per lot is permitted.

An ADU may be attached to the principal dwelling, located within converted space, or constructed as a detached permanent structure, subject to the zoning and building requirements.

Registration

All Cincinnati ADUs must be registered with the Zoning Administrator.

The City provides an online registration process and requires an owner acknowledgement/covenant process.

Occupancy Requirement

The property owner or a designated responsible person must reside in either:

• the principal single-family dwelling; or
• the ADU.

The City requires the applicable restrictive covenant/registration documentation.

Height

A detached ADU may not exceed 25 ft in height, subject to the code's rules for measuring height and the exception for conversion of an existing accessory structure.

Setbacks

A detached ADU is subject to the side- and rear-yard setback rules for accessory residential structures in the applicable zoning district.

A legally existing accessory structure may have different treatment when it is converted without expanding its footprint.

Parking

ADUs are exempt from additional off-street parking requirements, but any parking already required for the principal single-family dwelling must be maintained.

Short-Term Rentals

An ADU may be used as a short-term rental only if the City's separate short-term-rental rules and registration requirements are also satisfied.

Official Sources

City of Cincinnati — Accessory Dwelling Units

Cincinnati Zoning Administration

Cincinnati ADU Ordinance

Disclaimer: Confirm the current zoning district, registration rules, and building-permit requirements before constructing or converting an ADU.