Galvalume is ideal for metal roofing in Miami due to its outstanding durability, resistance to corrosion and rust, and performance under hurricane conditions. It can be used in today’s metal roof designs which are strong yet light weight and, unlike conventional roof systems, won’t crack and peel when subjected to the elements. It can be roll-formed into a variety of standing-seam panels as well as stamped into tiles and shingles. Galvalume® can also be factory painted and is 100% recyclable.
What is Galvalume?
Galvalume is basically sheet steel run through a molten bath of 55% aluminum and 45% zinc, after which the sheet is wrapped around a reel into a coated steel coil. It was developed in ‘72 by Bethlehem Steel which licensed several other steel companies to produce and market the product using its patents and technology. All of these products are the same Al-Zn coated steel using the same process and technology.
Residential and Commercial Roofing
Galvalume® sheet is used for three categories of metal roofing. There is, of course, residential and commercial roofing. It’s also used in industrial roofing, commonly known as structural. Structural panels are attached directly to a building’s steel frame. Commercial applications usually feature standing seam panels for steep slopes and mansards to enhance the appearance of the building. For residential roofs standing-seam panels are attached directly to the wood deck with the fasteners concealed by each successive panel. Pre-painted panels are often used but in Miami we are noticing the less expensive bare, mill-grade Galvalume® stays cleaner longer due to the zinc in its coating.
Before moving forward with a standing-seam Galvalume® metal roof homeowners in South Florida need to make sure their home is more than a half mile from salt water. From within that distance an upgrade to aluminum, stainless steel or copper is required, by Code.
Energy Efficient Metal Roofing
Galvalume® metal roofing has good heat and sunlight reflectivity when a light color or mill-grade is chosen, making its reflective surface excellent for hot climates. During the summer it makes buildings cooler by efficiently reflecting away sunlight and reducing the amount of heat radiated into the building. This good thermal reflectivity translates into energy savings by reducing cooling costs. Tests show that only half as much heat from solar radiation is transmitted into a building with a Galvalume® roof compared to galvanized, and almost one-third less heat compared to clay tile.
Galvalume® vs. Galvanized
Galvalume® sheet has been successfully used in metal roofing applications for more than 30 years; it has been evaluated in outdoor R&D tests for over 40 years. Based on these tests, in which corrosion weight losses were measured and compared with galvanized, Galvalume® sheet is projected to outlast galvanized sheet (with an equivalent coating thickness) in various atmospheres by up to nine times. Likewise, recent inspections of 82 low slope Galvalume® roofs up to 22 years old in the eastern U.S. confirms the R&D results. These roofs are in excellent condition and are projected to last 30 to 40 years before requiring maintenance.
Salt Water Advisory
It must be noted that in Florida the use of Galvalume is limited to at least one half mile from the coast or any body of salt water. At that point an upgrade is required (in order of cost) to aluminum, stainless steel, or copper.
Galvalume® Popularity Still Growing
More than 35 years after its development, Galvalume® is used almost everywhere. An estimated 40 billion square feet now covers buildings in all kinds of climates and environments throughout the world. The popularity of metal roofing in Miami continues to grow among architects, roofing contractors, businesses and homeowners.
This RMI Article includes excerpts from an article at steelroofing.com
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