Catawba County, NC Accessory Structures: ADU Rules (2026)

Section 44-631 sets a detailed standard for accessory dwelling units and guesthouses. Only a stick-built home meeting the building code, a modular home, or, on parcels inside the DWMH-O manufactured-home overlay district, a Class A or B manufactured home limited to a lineal family member or sibling's use, may serve as an ADU. Every ADU must meet the county division of environmental health's on-site sewage and well requirements, and a manufactured home only counts as a primary residence if the Catawba County Tax Office classifies it as real estate rather than personal property.

Only one accessory dwelling unit is allowed per deeded lot, and it must be clearly subordinate to the principal dwelling. The ordinance ties ownership together: the ADU and the principal dwelling must be owned by the same person, and that owner must live in one of the two dwellings or on an adjacent parcel, preventing use as a stand-alone rental unrelated to the main household. Size is capped by a floating formula: where the principal dwelling is stick-built or modular, the ADU cannot exceed 650 square feet or 50 percent of the principal dwelling's gross heated floor area, whichever figure is larger; where a manufactured home is the principal dwelling, the ADU must be smaller than the principal home's square footage outright.

ADUs must meet the zoning district's maximum height limit and the principal (not accessory) building setbacks, a stricter setback standard than typical accessory structures receive. Unless the ADU has its own separate road frontage, it must share a driveway with the principal structure, and it may be combined with a garage or workshop. S. 153A-123.