This subsector comprises establishments primarily engaged in the construction of buildings. Buildings are distinguished by their primary function, such as residential, commercial and industrial. Establishments may produce new construction, or undertake additions, alterations, or maintenance and repairs to existing structures. The on-site assembly of precast, panellized, and prefabricated buildings and construction of temporary buildings are included in this subsector. Part or all of the production work for which the establishments in this subsector have responsibility may be subcontracted to other construction establishments – usually specialty trade contractors.