During the early 1970s, a handful of roofing contractors realized the potential of retrofit metal roof systems and pioneered the development of a new roofing market segment. These innovators used materials common to their businesses to adapt early metal roof systems to conventional low-slope roof systems. Many mistakes were made, but their successes built the basis for current retrofit metal roof systems.
Initially, framing systems used for retrofit metal roof systems were crude and simple. The basis for adding slope to a relatively flat roof was wood. Wood studs, rafters and sleepers were used and anchored to existing roof systems as necessary to provide slope and support. Wood stud framing gave way to wood trusses, steel-angled truss framing, steel stud framing and specialty steel framing established specifically for retrofit metal roofing applications.
In addition, manufacturers of pre-engineered metal buildings that had relationships with these pioneer roofing contractors began developing specific framing shapes and design data. Equipment was developed to produce cold-formed steel shapes for hat sections, posts and purlins, all of which still are the basis for current products that support retrofit metal roof systems.
As with most new products, methods for achieving desired goals and results vary among manufacturers and systems. For every solution to a problem, there is another solution that is equally correct. This is true in metal roofing and retrofit framing. Most metal roofing manufacturers have products, which may vary, that provide support and slope for their roof systems. Following is some general information about retrofit metal roof systems, as well as specific information regarding installation.