This minor group comprises building maintenance installers, servicers and repairers, including residential and commercial installers and servicers; general building maintenance workers and building superintendents; pest controllers and fumigators; and other repairers and servicers. They are employed by companies specializing in specific product installation and service; water filtration and distribution plants and waste treatment plants; gas distribution companies; pest control companies; and product specialty repair shops and service establishments; or they may be self-employed.