Not always. The R-2 zone district allows both single-unit and two-unit (duplex) residences. However, in order to have a legal duplex on an R-2 zoned property, a minimum of 12,500 square feet of lot area with 100 feet of lot width is required. A single-unit residence in the R-2 zone district requires 9,000 square feet of lot area with 75 feet of lot width. Conversion of a single-unit residence to a duplex requires building permits, as well as zoning approval.