About Galvalume® Sheet Roofing

Frequently Asked Questions

More than 50 years after its development, and more than 150 million tons of global production, GALVALUME roofing and siding panels are used everywhere.  On an area basis, 150 million tons correspond to more than 300 billion square feet of GALVALUME sheet steel; this covers buildings in all kinds of climates and environments throughout the United States, Canada and Mexico, as well as Europe, Asia, India, Australia, and around the world. 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 homeowners 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.

Generically, the metal alloy coating’s composition is 55% aluminum-45% zinc alloy coated sheet steel developed by Bethlehem Steel and sold commercially under the trademark GALVALUME, starting in June 1972. Bethlehem Steel later licensed other major.. Read Full Answer

Like galvanized, GALVALUME sheet steels is made by a "continuous hot dip" metal coating process. Cold rolled steel coils are welded end-to-end and processed continuously on the coating line at speeds up to 600 feet per minute. The uncoiled steel is f.. Read Full Answer

GALVALUME sheet is an ideal material for roofing because of its extraordinary outdoor corrosion resistance and heat reflectivity which results in its long service life and helps keep the inside of the building cooler. It can be readily rollformed int.. Read Full Answer

GALVALUME sheet is made to meet ASTM Specification A792. This specification covers several requirements, including coating weight. AZ50 and AZ55 are the English unit coating weight designations indicating that, respectively, 0.50 ounces per square fo.. Read Full Answer

GALVALUME sheet has good heat and sunlight reflectivity. Its bright, white reflective surface makes it an ideal material for roofing. During the summer it makes buildings cooler by efficiently reflecting away sunlight and reducing the amount of heat .. Read Full Answer

Leaking conventional, flat nonmetallic roofs are the biggest problem on nonresidential buildings for architects and building owners. Conventional roofs made with organic materials deteriorate even under normal environmental conditions. They embrittle.. Read Full Answer

A GALVALUME SSR is an ideal system for retrofit roofing. Its light weight makes it suitable for retrofit applications over any old, leaking, conventional, nonmetallic roof system. Retrofitting is accomplished by installing to the existing roof struct.. Read Full Answer

Regarding warranties, a purchaser needs to consider the two types of GALVALUME roofs that are used – structuraland architectural systems. Structural systems are those, such as SSR, that are installed directly on the roof structural system (i.e., pu.. Read Full Answer

GALVALUME sheet has been successfully used in roofing applications for more than 50 years; it has been evaluated in outdoor R&D tests for well over 60 years. Based on these tests, in which corrosion weight losses were measured and compared with g.. Read Full Answer

Wood or steel decking is normally used for prepainted GALVALUME architectural roof systems on both residential and nonresidential applications, but it is not recommended to install the panels in direct contact with the decking. Instead, 30 pound felt.. Read Full Answer

By far, fiberglass roll insulation is the most commonly used insulation for GALVALUME steel roofs on nonresidential buildings. It can be used in any of the available thicknesses to give the required insulation value. One of the main benefits of retro.. Read Full Answer

Because GALVALUME sheet does provide long life, flashing should be used that will provide a life commensurate with that of GALVALUME sheet. For bare GALVALUME sheet roofs, GALVALUME sheet flashing is preferred, although aluminum flashing is also acce.. Read Full Answer

There are several variations of concealed fastener systems. For low slope structural systems, panels are overlapped and lockformed or snapped together at the seams and held down with clips, one end of which is overlapped in the seam and the other end.. Read Full Answer

The aluminum-zinc coating on GALVALUME sheet suffers fairly rapid corrosion in highly alkaline environments, such as concrete. The coating is attacked during the setting period when buried in concrete and can also be attacked from mortar splashes and.. Read Full Answer

Direct contact with the concrete footer is not recommended for either bare or prepainted GALVALUME sheet. Water can accumulate at the crevice between the GALVALUME panel and the footer, causing corrosion at the cut edge. Ideally, sill plates should b.. Read Full Answer

From a practical standpoint, the life of a prepainted GALVALUME panel is dictated by the performance of the paint film, i.e., appearance as affected by conditions of fade, chalk and peel, and the life of the paint film is determined by the type of pa.. Read Full Answer

Contact with pressure-treated wood or, for that matter, any wet lumber is not recommended for either bare or prepainted GALVALUME sheet. Treated lumber contains chemicals that protect the wood when buried in soil. Direct contact between wet treated l.. Read Full Answer

The best way to buy a GALVALUME steel roof is through the roof panel manufacturers. The major manufacturers have regional sales offices and manufacturing plants throughout North America. They also have qualified and affiliated contractors who are tra.. Read Full Answer

The many benefits offered by new and retrofit GALVALUME standing seam roofs (SSR) over traditional nonmetallic roofs translate into both direct and indirect cost savings. A retrofit GALVALUME SSR installed on a lightweight structural system over an o.. Read Full Answer