Yes. A secondary dwelling can be added to a lot that has a single-family dwelling (not a two-family dwelling, also known as a duplex) in UR-8, NMU-8, TR-4, and SR-2 zoning districts.
Among other requirements, it can be up to 50% of the square footage of the primary dwelling (but no larger than 1,100 square feet), and it cannot be sited between the primary structure and an adjacent public roadway.
For more information, contact email@example.com or contact the Zoning Administrator at 828-419-9300, ext. 373.