finding is based on the use of a strapping system of four inches between the plywood and "cool-color" metal on top, which provides an air gap between the plywood roof sheathing and the metal. Cool-color metals are light, reflective colors, like white. The study went on to say that re-sealing and insulating air ducts in the attic will save even more money. Metal roofing is also lightweight, creates little stress on the load bearing roof support structures and can be installed on top of an existing roof. A lightweight roof is very useful for large and or old structures, as it helps to maintain the overall structural integrity of the building. Despite its light weight, metal roofing provides increased wind resistance when compared to other roofing materials. This is because metal roofing systems use interlocking panels. Metal Roofing Sheets are also resistant to any kind of attack by pests and insects. Disadvantages The disadvantages of metal roofs include the noise created from rain hitting the roof, large hail may leave dents, and, in snowy areas, the tendency of snow to easily fall off the roof and onto pedestrians or property. Material types Metal roofs are sometimes made of corrugated galvanized steel: a wrought iron–steel sheet was coated with zinc and then roll-formed into corrugated sheets. Another approach is to blend zinc, aluminum, and silicon-coated steel. These products are sold under various trade names like "Zincalume" or "Galvalume". The surface may display the raw zinc finish, or it may be used as a base metal under factory-coated colors. Standing seam metal roof Standing seam metal roofs come in sheets up to 30+ feet long and widths of 12", 14", 16", or 18" inches. The standing seam is typically 1.5" or 1.75". They are more expensive upfront for installation and material costs but last longer than Asphalt shingles, over the 50+ year lifespan they are less expensive than asphalt shingle roofs. They require less maintenance than corrugated metal roofs because of the exposed fasteners on that roof. Mechanically seamed Mechanically seamed roofs are seamed together using a roof seamer and can be either single lock or double lock seamed, meaning they can be folded under once to be seamed together or folded under twice for extra weather protection. This is the most expensive of the three types but is the most weather resistant. Snap locked with fastener strip One side of the