The owners of the Delta Gypsum building supply company in Wake Forest have confirmed plans to expand into the Queen City for the first time following its acquisition of Charlotte-based United Materials. United Materials, like Delta Gypsum, specializes in the sale and delivery of drywall products and materials for the commercial and residential building industries. It employs 19 people at its warehouse in Charlotte. Along with Delta Gypsum's six other warehouse and distribution locations in North...