In architecture, the assembly of buildings or their component parts at a location other than the construction site. Prefabricated units may include doors, stairs, window walls, wall panels, floor panels, roof trusses, room-sized components, and even entire buildings. While the concept and practice of prefabrication has been part of human experience for centuries, its modern sense dates from about 1905. This building method controls construction costs by economizing on time, wages, and materials.