What is the advantage of pre-engineered buildings? After the drawings have been approved, https://www.hrsinfrastructure.com/pre-engineered-building ( pre-engineered buildings ) are frequently built in just a few weeks. Lower Cost: The systems approach results in significant cost savings in terms of design, manufacture, and on-site erection. Expansion Flexibility: Buildings can simply be lengthened by adding extra bays. Larger spans: Buildings can be supplied with clear spans of up to 80 meters.