More than 40 years after its development, galvalume roofing and siding panels are used everywhere. An estimated 80 billion square feet* of galvalume sheet steel now covers buildings in all kinds of climates and environments throughout the United States, Canada and Mexico, as well as Europe, Asia, India and Australia. As the popularity of galvalume steel roofing continues to grow among architects, contractors and building owners, these construction and design professionals frequently ask similar questions regarding the product's availability, performance, installation and maintenance. So, the following most frequently asked questions, along with their answers, are detailed to help you — the reader — with buying, installing and maintaining a galvalume roof.galvalume sheet is used for two broad categories of roofing: nonresidential and residential. For nonresidential roofing, bare or unpainted galvalume sheet is used for low slope, concealed fastener standing seam roofs (SSR) as a replacement for nonmetallic built-up, rubber and ballasted nonmetallic roofs and for steeper slope screw-down roofs with exposed fasteners. Prepainted galvalume sheet is mostly used for steep slope architectural roofing and mansards to enhance the appearance of the building using color, form and texture. Nonresidential roofs can be new or retrofit over both old steel and nonmetallic roofs. For residential roofs, prepainted galvalume sheet is generally used, although some architects and home owners use bare galvalume sheet because they like the look of its bright metallic surface. galvalume residential roofs can be new or retrofitted over old roofs.