This major group includes special trade contractors who undertake activities of a type that are specialized either to building construction, including work on mobile homes, or to both building and nonbuilding projects. These activities include painting (including bridge painting and traffic lane painting), electrical work (including work on bridges, power lines, and power plants), carpentry work, plumbing, heating, air-conditioning, roofing, and sheet metal work. Special trade contractors primarily engaged in activities that are clearly of a type specialized to heavy construction, such as grading for highways and airport runways; guardrail construction; installation of highway signs; underwater rock removal; and asphalt and concrete construction of roads, highways, streets, and public sidewalks are classified in Major Group 16.
Special trade contractors may work on subcontract from the general contractor, performing only part of the work covered by the general contract, or they may work directly for the owner. Special trade contractors for the most part perform their work at the site of construction, although they also may have shops where they perform work incidental to the job site.