Durham, NC Accessory Structures: ADU Rules (2026)

Durham has adopted permissive ADU policies under UDO Section 5.4.2. One accessory dwelling unit is allowed per residential lot with a single-family or duplex primary dwelling. ADUs may be attached to the principal structure, detached in a separate building, or created through internal conversion of existing space. The maximum heated area is 1,000 square feet on a single story or 1,200 square feet total. The ADU floor area cannot equal or exceed the primary structure. In the RR district on lots of 4 or more acres, the ADU may be up to 50 percent of the primary dwelling size. No special use permit is required and no additional parking spaces are mandated. Density limits do not apply to ADUs. Detached ADUs follow accessory structure height rules while attached units follow primary structure height limits. ADUs are prohibited in Special Flood Hazard Areas and Future Conditions Flood Hazard Areas. North Carolina Senate Bill 495 enacted in 2025 further requires all local governments to allow at least one ADU per single-family lot statewide. Durham also ran a $1.75 million Forever Home Durham loan program to help finance ADU construction.