Building Materials (Wholesale)" is a subdivision of the SIC Code 5031 that encompasses companies involved in the wholesale distribution of building materials such as lumber, plywood, millwork, wood panels, roofing materials, insulation, drywall, cement, bricks, and other construction supplies. These companies purchase large quantities of building materials from manufacturers and then sell them to retailers, contractors, and other businesses involved in the construction industry. The industry plays a crucial role in the construction sector by providing the necessary materials for building homes, commercial buildings, and infrastructure projects.