Hendersonville, TN Accessory Structures: Garage Conversions (2026)

Garage conversions in Hendersonville are a change of occupancy under the Tennessee-adopted International Residential Code (currently the 2018 IRC with state amendments), so a building permit is required from the Hendersonville Building Codes Department. The new habitable space must meet IRC requirements for ceiling height (7 ft minimum in habitable rooms), light and ventilation, egress windows from sleeping rooms (minimum 5.7 sq ft openable, 24 in height, 20 in width, sill ≤ 44 in), smoke alarms and CO alarms, energy code insulation, and any new electrical/plumbing/HVAC must meet current code. If the conversion is to non-dwelling habitable space — home office, family room, hobby room — those are the only requirements. If the conversion ADDS a kitchen AND a separate entrance, the result is an independent dwelling unit, triggering ADU classification under Hendersonville Zoning Ord. Ch. 10.4: (a) if the converted garage is attached to the principal dwelling, it is an Attached Accessory Apartment — heated area ≤ 40% of combined area, occupancy limited to family or domestic employees, owner must occupy principal dwelling ≥75% of year, one front door per street frontage, recorded covenant required, no variance; (b) if the converted garage is detached, it is a Detached Accessory Dwelling — lot must be ≥ 30,000 sq ft, Conditional Use Permit ($250) required from BZA, located in rear yard behind rear plane of principal dwelling, 20 ft side/rear setbacks, design must match principal dwelling, size caps (1,200-1,800 sq ft tied to lot size). The general accessory-dwelling rules require at least 4 off-street parking spaces total (garage/carport spaces do NOT count) — so converting the only garage on a property typically requires adding a paved parking pad or driveway expansion to meet the 4-space minimum. Tennessee has no state preemption of local ADU/conversion rules.