![]() There are differing levels of paint quality for metal roofing-all affecting the price of the finished product. Yet, the paint is flexible enough to be later stamped or roll formed into the final roof shape-long panels, shingles, shakes, tiles or slate forms. The roofing material is painted when it is in flat sheet form in giant coils. Metal roofs that are painted use very sophisticated paint technology. ![]() They can also provide specific energy saving qualities. The paint finishes provide the aesthetic qualities that consumers want to see on their roofs. Most residential metal roofing has a paint coating applied to the outside of either the aluminum or steel plus metallic coating. In shoreline, non-saltwater environments both galvanized and Galvalume steel will provide a long lifetime of protection. Another factor to consider is how often the roof is rinsed with fresh water through rainfall. In many inland salt water situations steel with metallic coatings performs very well if there is not a lot of wave action - intercostal area of Florida and the Southeastern U.S., Puget Sound in Washington, etc. This will occur where there is a lot of wave action in salt water near the ocean. Salt EnvironmentsĪluminum is often preferred as a roofing material substrate in heavy salt spray environments. However, in many years of exposure testing Galvalume has proven to be up to three times more effective in preventing rust from appearing on the sheet steel.Īluminum sheet does not require a separate metallic coating barrier since aluminum oxide, when it forms is not noticeable in most cases. These are equivalent levels to G-90 galvanized product. Galvalume has a designation AZ-50 or AZ-55. G-90 will have 90 ounces of Zinc- 45 ounces on each side per 100 square feet of roofing sheet steel. The numbers G-40 G-60 and G-90 refer to the ounces of zinc per 100 square feet of sheet steel coated (top and bottom). The greater the number, the longer the protection against rust will last. This is in accordance with the Guidelines for Residential Metal Roofing published by the Metal Construction Association. For houses, the MRA recommends a minimum of G-90 be used. For agricultural applications, galvanizing levels called G-40 or G-60 may be used quite successfully. There are differing amounts of metallic coating used on sheet steel depending upon its final product application. When zinc is combined with aluminum to form Galvalume there is even more protection in most circumstances. Zinc is a more “active” metal than iron so it oxidizes first and forms a protective barrier - zinc oxide, before the iron (Fe) in the steel can become Ferric Oxide (rust). Metallic coatings “sacrifice” themselves to protect the iron (Fe) in steel from oxidation when exposed to the air and moisture is present. Galvalume or Zincalume: A mixture of aluminum and zinc.Galvanized: This is 100% Zinc in various thicknesses depending upon the product usage.There are two types of metallic coatings used: This is underneath and separates from any paint, which imparts color to the product. Metallic CoatingsĪll Steel Roofing has a protective barrier on both sides of the sheet called a metallic coating, which protects against rusting. Granular coated steel shingles, shakes, tile are a special category and are produced by stamping galvanized steel (26 gauge) then sprayed with an acrylic coating embedding granular stone then baked in an oven at the factory. 040 thicknesses designate aluminum residential metal roofing. These gauges are appropriate since most residential metal roofing applications are over a solid substrate.Īluminum roofing follows the same process except that it does not require the metallic coating step.ĭecimal thickness and ranges from. Steel residential roofing is made in thicknesses designated by gauge and is generally 24 to 26 gauge, with the higher gauge being thinner than the lower.
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