Wausau, WI Accessory Structures: ADU Owner Occupancy (2026)

28(6)(e). The lead requirement is owner-occupancy: the principal building must be owner-occupied, meaning the property owner has to live in the main house, not merely own the property and rent out both structures to tenants. The section also prohibits splitting ownership of the two units: the accessory dwelling unit shall not be sold separately from the principal dwelling, keeping the ADU legally tied to the main home as a single real estate parcel rather than becoming an independently sellable property. Size is capped at whichever is smaller: the maximum size of an accessory dwelling unit shall not exceed 75 percent of the principal dwelling's floor area, up to a maximum size of 800 square feet, so a large principal home does not unlock an unlimited ADU.

The remaining clauses in (e) push the ADU toward visual conformity with the main house: its appearance must not be significantly altered so the property still reads as a single-family home, and its exterior finish material, roof pitch, exterior trim, projecting eaves, and window proportion and orientation must all match those of the principal dwelling. Together these standards mean a Wausau homeowner converting a garage or building a detached ADU has to both live on-site and match the new unit's exterior to the house next to it, not just meet a size limit.