Resin increases the physical strength and chemical resistance of the coating film, and allows the chemical reaction of the curing process. It is the primary source for a coating’s durability and physical properties. The resins primary function in a paint formulation is to bind together all the components within the coating. The pigment particles are suspended within the resin, and the mixture is then reduced to a liquid form, providing an easy application to a metal surface. These pre-painted sheets of steel or aluminum can be cut, slit-formed, corrugated, profiled, and molded into shingles, shakes, curves, and various shapes for distinctive architectural designs.Įxterior coatings for metal roofs are composed of four main elements: resin, pigment, solvents, and additives. Using this method, the rolls of metal are painted prior to them being shaped into the roof panels. To ensure uniform gloss, color, and thickness, a coil-coat process is the preferred application method for metal roofing. This 55/45 percent aluminum-zinc alloy coating functions both as a sacrificial and a barrier coating, with its zinc providing protection on exposed edges or scratches and its aluminum providing a barrier to corrosive media.Įxterior coatings further enhance a metal roof’s aesthetic and performance characteristics. Another type of coating is an aluminum-zinc alloy composed of 55 percent aluminum to 45 percent zinc it is produced in either AZ50 or AZ55 coating weights. This type of coating is a zinc-based metal covering that comes in either G60 or G90 of zinc of the total area covered and is a sacrificial coating.Ĭoatings containing a five percent aluminum-zinc alloy also serve as a sacrificial coating. Galvanized coatings are metallic coatings most popularly used to protect metal roofs from corrosive media. There is little attack by the corrosive media on the barrier-type coating. Barrier protection is intended to repel the corrosive media. Eventually, this sacrificial coating will be completely corroded away, leaving the bare steel to rust. Sacrificial protection involves having a protective metallic coating that gets attacked by corrosion, instead of the steel. You May Also Like Free e-book explores high-strength steel for Chicago high-rise The metal roofing substrate can be protected from corrosion with one of two types of protective metallic coatings: sacrificial and/or barrier protection. Localized corrosion can lead to pitting, cracking, and eventual fractures, causing leakage or more serious failure of building components. Design features include photovoltaic (PV) power and insulated standing-seam metal roof panels with a copper finish.Ĭorrosion can affect the structural integrity and durability of roof metals and alloys. Located in Modesto, California, Beckwith Veterinary Hospital’s 1300-m2 (14,000-sf) facility used green building strategies to save resources and promote sustainability. Steel and aluminum are amongst the most recycled materials in the world with more than 50 percent of steel supply in the United States and 40 percent of the aluminum supply in North America being produced through recycled sources. Steel’s strength and durability throughout its service life, as well as its lifecycle cost, make it an attractive investment. In weight, pound for pound, steel is economical metal roofing. Steel and aluminum are both used in the manufacture of metal roofs, with the former being the most common. The lightweight system also makes them easier to transport and install, further saving on time, as well as financial and environmental costs. A metal roof can be one-eighth the weight of other roofing products, placing a lighter load on the structure and foundation and extending the life of the entire building. Metal roofs can be designed to withstand extreme weather conditions and are more fire-resistant than other roofing materials such as wood or asphalt. Their materials contain recycled content and are 100 percent recyclable at the end of their useful life. Metal roofs can last longer than most non-metal roofing products. In addition to directly benefiting the building owners and occupants, these roofs also assist in benefiting the surrounding community by mitigating the urban heat island effect. These are critical to the panel’s weather and corrosion resistance, color retention, and overall longevity.įinished with the proper coating system, ‘cool’ metal roofs can also help reduce a building’s carbon footprint, energy consumption, and cooling/heating loads. The performance of the assembly’s panels depends on the metal substrate, metallic layer, and exterior coating. Recognized as sustainable, durable building components, metal roofs are used in various applications. Photos courtesy Kingspan Insulated Panels/Valspar
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