Many different elements work together to create the overall product quality performance you can expect from post frame wall and roof panels. The two most significant elements that impact post frame metal panel product quality are: substrates and paint.
Metal Panel Substrate
One of the most obvious elements contributing to the quality of metal panels is the metal itself. Most metal panels are produced from two different types of steel: Galvanized or Galvalume. In both cases, the base steel receives a coating. Galvanized substrates are coated with a zinc alloy and Galvalume substrates with an alloy of zinc plus aluminum. Both have their advantages. Let’s start by looking more closely at Galvanized substrates.
Zinc levels are a critical difference in galvanized panels. It’s important to remember that higher levels of zinc provide greater protection against panel corrosion. G100 and G60 are two commonly used Galvanized substrates. These designations relate to the total amount of zinc contained on both sides of the panel surfaces. G100 products contain 1.0 ounces of zinc for every one square foot of panel, while G60 substrates contain 0.6 ounces of zinc.
While at first blush, that difference doesn’t appear to be significant, nothing could be further from the truth. G100 products contain 66% more protective zinc than a G60 substrate. This difference has a direct correlation to panel longevity. Consequently, you should expect both lower cost and performance from the G60 products. Lastly, Galvanized substrates are most often the preferred substrate choice for animal confinement situations.
Over four decades of testing and field applications have shown that Galvalume delivers superior corrosion resistance compared to Galvanized panels and is the preferred substrate for projects where long-term performance is essential. (See chart below)
Galvalume's performance has been so superior that steel mills actually warrant the Galvalume substrate (or metal) against perforation caused by corrosion. Similar steel mill warranties simply do not exist for Galvanized substrates. Therefore, it’s crucial to remember that a Galvanized product will not offer a mill-provided substrate warranty, and a Galvalume product will likely provide a 25-year substrate warranty.
National vs. Regional: National manufacturers typically offer both Galvanized and Galvalume panels within their product offering, where regional manufacturers tend to pick one or the other. Regionals tend to simplify their product offering for a couple of reasons. First, they often don’t have the storage space for multiple substrates. Secondly and perhaps more importantly, keeping inventory to a bare minimum offers considerable overhead savings, which is vital to their low-cost business model. Let’s look at an example to illustrate this point further.
At McElroy Metal, we inventory three different substrates: G-90, G-100, and Galvalume. We inventory G-90 for unpainted projects and inventory G-100 painted for our customers that need a galvanized substrate with a painted finish. But for the bulk of our business, we stock Galvalume substrates with two different paint systems.
We have chosen to inventory three different substrates to offer the widest number of options to our customers. Conversely, most regional manufacturers offer only one substrate. By selecting only one substrate to offer (compared to our three), regional manufacturers can effectively reduce their inventory costs by two-thirds over national manufacturers like McElroy Metal.
Summary: Ultimately, understanding your preferred substrate is a critical step in any discussion regarding regional and national manufacturers. If you’re looking for higher-end substrates and multiple options, you are almost always better served with a national manufacturer. If, however, price is your dominant buying decision with quality being less critical, then a regional manufacturer could be the better choice for you.
Post Frame Metal Panel Paint
Paint: The second prominent element affecting metal panel quality is the paint, or coating, applied on top of the substrate. Coatings consist of three primary ingredients: pigments, binder/resin, and solvents.
- Pigments are the coating ingredients responsible for color. Paint is created when the pigment is dispersed into the binder/resin.
- The resin is what holds or binds the pigment together and protects the coating from UV degradation. Higher quality resins provide the greatest protection against panel chalk and fade. Conversely, coatings produced from lower quality resins are more apt to fade and chalk. These failures occur when the binder breaks down and no longer holds the pigment together.
- The third primary coating ingredient, solvents, is responsible for ensuring the paint has the desired viscosity to be correctly applied. Solvents disperse the pigment. When the coating is applied, the solvent evaporates, allowing the resin and pigment to create the desired layer of coating and dry. In the case of metal roofing and siding, the solvent evaporates (burns off from heat) during the coil coating process.
The three most common resins for metal roofing and siding are Polyester, Silicone Modified Polyester (SMP), and PVDF (commonly known by the Kynar 500® trade name). These coatings have a well-defined good, better and best performance rating.
Polyester coatings are on the low-end of the quality spectrum and are most often utilized for interior applications, such as liner panels or interior design accents. They represent the “Good” value in our Good/Better/Best comparison.
Silicone Modified Polyester (SMP) is an improvement over straight polyester coatings and represents an alternative between Polyester and Kynar 500 coatings. While the same pigments can be used in all three coating types, the resin systems are very different and attributable to their different performance levels. SMP resins are better than those used in Polyester systems but lower quality than those used in Kynar 500 systems. As a result, SMP systems can be subject to conditions known as fade and chalk, often within just a few years of installation. Fading occurs when the environment attacks the pigment portion of the paint system.
Chalking occurs when environmental conditions cause the degradation of the resin. As the resin degrades, it takes on a whitish appearance called chalk. See photos above and below for a visual depiction of fade and chalk.
Consequently, it is important to note that SMP performance simply cannot match the long-term performance of Kynar 500 coatings; hence it’s a “Better” system but not the “Best” system.
PVDF (Kynar 500) coatings, however, provide the “Best” protection available against fade and chalk.
National vs. Regional: Quality-focused national manufacturers, like McElroy Metal, routinely offer both SMP and Kynar 500 coatings. While the cost difference between the two isn’t significant, they realize that not all projects require the top-of-the-line quality of Kynar 500 systems. By stocking both paint systems, many national manufacturers allow their contractors and ultimately end customers options in both the “Better” & “Best” categories of our Good/Better/Best scenario.
Conversely, much like regional manufacturers tend to offer only one substrate, they routinely also provide only one paint system. Most often, regional manufacturers opt for the middle-of-the-road SMP paint systems or the “Better’ criteria. Again, this decision fits nicely into their low-cost/low inventory business model. On occasion, regional manufacturers may indicate they offer Kynar 500 coated products; however, few (if any) of them stock the material in 29 gauge thicknesses common for post frame construction.
Summary: So which is best? Only you can decide that. If cost wins every time, you’re likely better off with a regional manufacturer. But suppose you want the option of picking SMP for a project today and Kynar 500 for one tomorrow, or long-term quality and curb appeal (like enhanced fade and chalk protection) is important to you. In that case, a national manufacturer is most likely your better choice.
This blog post series and the companion e-book are designed to educate you on the differences between regional and national manufacturers to help you decide which supplier type makes the most sense for you.
Feel free to contact one of our experts if we can answer any questions!
Since 1963, McElroy Metal has served the construction industry with quality products and excellent customer service. The employee-owned components manufacturer is headquartered in Bossier City, La., and has 14 manufacturing facilities across the United States. Quality, service and performance have been the cornerstone of McElroy Metal’s business philosophy and have contributed to the success of the company through the years. As a preferred service provider, these values will continue to be at the forefront of McElroy Metal’s model along with a strong focus on the customer.