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

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

Under SPS 320.04(4), a building previously used for another purpose, such as a garage, must comply with the UDC upon conversion to residential use. Additions and alterations to a home built on or after June 1, 1980 must meet the UDC in effect at permit application (SPS 320.04(2)), which includes the SPS 322 insulation and window requirements for newly heated space. Wisconsin sets no statewide permit requirement for additions or alterations to existing homes; under SPS 320.09(2)(b) those permits are required where the local ordinance requires them, and in a municipality where DSPS has UDC jurisdiction building permits for additions and alterations are not required, though zoning and electrical permits may still apply. Wis. Stat. 101.645(3) requires a smoke detector in the basement and on each floor level of a dwelling, and Wis. Stat. 101.647(3) requires a carbon monoxide detector in the basement and on each floor level (except the attic, garage or storage area) of any dwelling with an attached garage, a fireplace or a fuel-burning appliance. 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.