A material that has no apparent rigidity cannot, at first glance, support any load, but when the same material is bent, it acquires greater structural properties. Based on this principle, corrugating a steel sheet enhances its bending strength, with the result producing a structural panel.
Manufactured using steel of a higher grade than that used for conventional siding, the Honco structural panel is cold-formed on a fully automated production line.
The main corrugation provides the panel with overall stability during compression or bending. The smaller secondary corrugation ensures the local stability of each panel section. A groove on each side of the panel stiffens the connection between panels.
A study performed by the Metal Construction Association (MCA) on fifteen commercial buildings found that metal roofs (coated in an aluminum-zinc alloy) can last at least sixty years. The material analyzed, known as GALVALUME (aluminum, zinc and silicon alloy coated onto the panel) is the one we use in our buildings.
(Source: http://www.metalconstruction.org/index.php/media-center/press-releases/metal-roofs-can-last-60-years)