Metal roof systems are available for virtually every structure
and design. In centuries past, before the Industrial Revolution,
soft, malleable metals (such as lead) that could be installed
using skilled labor and hand tools were used. With the
availability of steel and aluminum, along with mechanized
forming and application equipment, metal became cost-effective
for both non-structural and structural applications. Evolution
of Protective Coatings for Steel When metals are in contact, one
metal (zinc) will give up electrons and oxidize while the
current generated will prevent oxidation of the other metal
(steel). This mechanism extends the structural life of products
made from galvanized steel. A patent on zinc-coated steel
(galvanize) dates back to 1837. In roofing, corrugated zinc-
coated steel provides a utility type roof, generally used on
small roof areas and overhangs with through-fastening to
structural supports. Using an alloy of zinc and aluminum
(Galvalume) greatly increased the durability over zinc