Contractors and supervisors, other construction trades, installers, repairers and servicers supervise and coordinate the activities of various tradespersons, installers, repairers and servicers classified in the following minor groups: Bricklayers and Insulators (7232), Concrete finishers, tilesetters and plasterers (7310), Roofers, Glaziers, Painters, decorators and floor covering installers (7311) and Building maintenance installers, servicers and repairers (7320). They are employed by a wide range of establishments; places of employment are indicated in the unit group descriptions. Contractors may be self-employed. This unit group also includes prefabricated product installation and service contractors and proprietors of some repair and service establishments.