Galvanized Metal Roofing

Galvanized Metal Roofing

Englert’s nationwide team of architectural sales reps spend a considerable amount of time each year counseling architects on which standing seam metal roofing products and profiles might work best for their design projects.  One of the questions most frequently asked by architects is: What are the differences between  Galvalume and Galvanized Steel when used in roofing. It comes up so often, we thought we’d take a few minutes and use this week’s blog to explain those differences. First, a little bit of background. Galvalume® was invented by Bethlehem Steel in 1972. It is a trademarked name, but many people use it as a generic term to describe a metal roofing product consisting of  steel coil coated with a metal alloy. That alloy is 45% zinc and 55% aluminum and looks similar to galvanized steel, but the visible crystals are smaller and close together, giving it a smoother appearance.  Galvalume has a cousin, Galvalume Plus. The only difference is Plus has a thin, clear acrylic coating. Because Galvalume Plus can be roll-formed dry without vanishing oil, it is very easy to form and install safely. The combination of zinc and aluminum in Galvalume enhances both the positive and negative effects of aluminum.  Galvalume has barrier corrosion resistance and heat resistance similar to aluminized material and good bare edge galvanic protection and forming qualities like galvanized material. Consequently, Galvalume  and Galvalume Plus will resist rust, the elements and fire while providing a sturdy and protective covering. Galvalume® is more corrosion-resistant than galvanized steel, but because aluminum provides barrier protection instead of galvanic protection, scratches and cut edges are less protected.  Galvalume is offered in both bare and pre-coated versions. Most Galvalume®–like galvanized steel– is coated. But Galvalume has an excellent performance life in bare exposures as well.  Both galvanized steel and Galvalume® weigh 100 to 150 pounds per 100 square feet and contain about 35% recycled materials. The cost of Galvalume and Galvalume Plus are about the same as that of galvanized steel.The coating used on  Galvalume is very important because it is critical to the length and conditions of the entire warranty of the panel product. Coated metal roof panels have progressed from a single coat straight polyester paint system in the early years to Poly vinyl idene fluoride(PVDF)  acknowledged as the premium resin for coil coatings.  It is a kind of fluoride, a family that includes such well known products as Teflon and Halar.  PVDF resin has superior chalk resistance and gloss retention as well as stain and chemical resistance.  It is softer than polyester, making it highly formable without risk of cracking. Current pretreatments and primers along with superior paint coating have increased product warranties dramatically. However, some people only ask if there is a warranty not how many years the warranty lasts, and most people do not check to make sure that they are not getting the inferior straight polyester system. Straight polyester should really not be used for metal roofing and wall panel in today’s market. If you see there is a dramatic difference in the price of two painted Galvalume panels you are specifying, then the less expensive, less effective  kind of  coating should be suspected. Galvalume should not be used on, in, or around concrete or mortar. Concrete and mortar are highly alkaline environments. Bare Galvalume and painted Galvalume sheets suffer rapid corrosion when in contact with mortar and concrete. Bare Galvanized and painted Galvanized perform better in this type of environment. Neither Galvalume or galvanized substrate is warranted to be used, in or around animal confinement or agriculture. Bare Galvalume and coated Galvalume panels will very rapidly deteriorate when exposed to the corrosive agents of animal confinement.  But bare Galvalume and coated Galvalume panels have an outstanding corrosion resistance in a wide variety of general environments, including industrial, marine and even severe marine environments.  And Galvalume offers exceptional heat reflectivity, resulting in lower energy load on buildings and improved interior comfort. That pretty much summarizes the key features of Galvalume versus Galvanized.  In a nutshell, Galvalume is a proven metal roofing material because of its strength, outdoor corrosion resistance and longevity. If you have any other questions about Galvalume, contact an Englert architectural sales representative near you.
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Galvanized Metal Roofing

Unfortunately, not everything about galvanized metal roofing is ideal. This material does not last as long as other types of metal, it is more challenging to install than traditional materials and it is very heavy. As mentioned previously, the cost of galvanized metal roofing is also a big consideration for homeowners. While not as expensive as other types of metal roofs, galvanized steel is still a big investment, and it may not be suitable for those who plan to flip the home or sell within the next five years. On average, galvanized metal roofs can last 50 years or longer when properly maintained, but that still isn’t as long as some kinds of steel or aluminum roofs. Since galvanized metal weighs upward of one pound per square foot, the large sheets used in roofing can be incredibly heavy, and installation is not typically something that can be done without professional assistance.
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Galvanized Metal Roofing

Galvanization is a process where metals, typically steel and iron, are coated with a layer of zinc in order to reduce or eliminate the potential for rust. Therefore, galvanized metal roofing is any roofing material that has been treated with a layer of zinc in order to last longer and age without rust. In most cases, when someone refers to galvanized metal roofing, they are specifically referring to an inner metal layer of iron and carbon alloy steel that has been dipped in a hot zinc bath and is now coated with a thin layer of the material. While far from the most common roofing material available on the market, galvanized metal roofing is becoming increasingly popular as a solid investment for the future.
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Although galvanized metal roofs are more expensive than traditional shingled roofs, they bring with them a number of significant advantages including energy-efficiency, longevity, increases in resale value and design style. However, it is important to note that while galvanized metal roofing can seem pricey, it is still one of the most affordable metal roofs on the market, making it a smart choice for the savvy buyer. This style of metal roof can also be incredibly energy-efficient, especially in warm climates. By repelling rather than absorbing heat, it can help reduce the workload of the air conditioning system in the home and therefore reduce energy costs substantially. Thanks to the lifespan of metal roofs, investing in one can also increase the value of the home, which may be a benefit when the owner wants to sell one day in the future. Since galvanized metal roofing is covered in a layer of zinc, it will never rust, which is a huge benefit that is not always associated with metal roofs. Finally, galvanized metal roofs are attractive, and they are versatile enough to work on very contemporary houses as well as with more traditional or rustic structures.
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At Union Corrugating, we supply corrugated metal roofing and corrugated siding panels that are the original metal roofing and siding panels and are a traditional staple in agricultural metal roofing applications. Today, usage of galvanized corrugated metal roofing and corrugated siding panels has expanded beyond its rural roofing heritage, corrugated metal roofing and corrugated siding panels add a traditional look to roofs of many restaurants, retail establishments, and other commercial buildings.
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Many homeowners don’t realize that galvanized metal roofs can come in several variations, and these will affect both price and durability for the buyer. Thickness of the steel itself will be something to consider, and so will the thickness of the zinc coating. Generally, the thickness of the galvanized metal roofing as a whole will be referred to as its gauge, and that number might range from 20 to 30. The higher the gauge, the thinner the material will be, and the thinner the roof’s profile will be. For most residential homes, the gauge of galvanized steel roofing should be either 24 or 26. The thickness of the zinc coating is also important. A thin coating could result in rust over time, but a thick coating costs more and may be unnecessary. Homeowners typically want to look for a zinc coating thickness of G-90, which translates to 0.9 ounces of zinc used in the coating of every square foot of metal. Lower G-ratings are available, but these are not sufficient for homes and should be skipped, even if they have the potential to lower the price of the roofing project.
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Selecting metal panels made from high-quality materials is essential to the longevity and success of any metal roofing system—from the steel sheets to the fasteners. Although the quality of the paint system applied to metal roofing panels provides an essential level of protection (as discussed in our recent ‘Decoding Your Warranty’ blog series), not to be overlooked is the coating used on metal roofing panels. Two coatings are commonly used on steel sheeting in the metal panel industry today: Galvalume® and Galvanized. Both products are manufactured to adhere to carbon sheeting and provide a barrier that resists corrosion and enhances long-term water-tightness and durability, ensuring resilience through damaging weather conditions. But what exactly are the differences between Galvalume® and Galvanized?