Do I need a permit for garage conversion in Unincorporated Clay County?

Most likely yes. Garage conversion usually requires a permit in Indiana. Confirm the specifics with Unincorporated Clay County.

Under Indiana's Section R309.6, any habitable area in a detached garage or accessory structure must meet all applicable sections of the residential code and have an exit door or window as specified in Sections R310 and R311. Indiana's N1107.1 makes Sections N1107 through N1111 of the energy chapter control the alteration, addition, and change of occupancy of existing buildings, so newly conditioned space must meet the energy provisions that apply to that work. Under Indiana's R314.2.2 and R315.2.2, alterations or additions requiring a permit trigger smoke and carbon monoxide alarms as for new dwellings, except electrical work in existing rooms other than new or relocated bedrooms. Indiana's residential code deletes the IRC's permit, exemption, inspection, and fee sections (R105 and R108 to R114), so whether this job needs a permit is set by the local ordinance of the city, town, or county, not by the model IRC exemption list. Turning a garage into a bedroom, living room, office or apartment changes it to habitable space, which must meet the code for living areas, such as insulation, heating, ceiling height, light, and an emergency escape opening in any sleeping room. A conversion normally needs a building permit, and often electrical, mechanical and plumbing permits too. Zoning may also require you to keep off-street parking or limit a second unit, so check zoning before you design.