Metal Roof Paint Systems: Kynar 500® vs. SMP

Once you’ve made decisions about your metal roofing material and contractor, the roof paint, or coating system, you choose might not seem like as difficult of a decision to make. But a roof is a long-term investment, and the paint/coating system is the difference between a roof that only looks good now and a roof that looks good for the long-term.

Before we compare specific paints, it’s important to understand some of the basic paint characteristics and terms used in metal roofing. If you’re totally new to paint systems for metal roofing, we’d recommend checking out this article from Construction Magazine Network for a good introduction to all things paint.

Paint Basics

All paints have three basic components:

• Pigment – the part of the paint that creates the color and reflects UV rays
• Resin – resin holds the pigment together and provides most of the film properties
• Solvent – this part of the paint will actually evaporate during the curing process

The composition of these three components have a direct correlation to paint performance. More specifically, these components have an effect on  film integrity, and the ability to resist fade, and chalk which are the biggest determining factors for how the paint will perform for your new roof.

Color sample on far left of each sequence represent standard/new. Center and right color samples reflect levels of fade over time from lesser quality coatings.  

When comparing roofing paint systems, there are three common types of paint in the metal roofing industry:

• Polyester (Good)
• Silicone Modified Polyester (Better)
• Fluoropolymer/PVDF (Commonly referred to as Kynar 500® (Best) 

Polyester (Good)

Polyester paints used to be the paint of choice in the 1980s. And while the low price of polyester paint might seem attractive to homeowners today, the performance of this paint type doesn’t compare favorably to other paint options.

Polyester paint is hard and resistant to scratches, but with no silicone in the paint it is prone to chalking. The lack of silicone also means that the new, glossy appearance of the paint fades quickly.

With the lowest price point today, polyester paints are also the lowest performing paints. So, while still available, polyester paint is the least popular option for homeowners using metal roofing today.  

Silicone Modified Polyester (Better)

Silicone Modified Polyester (SMP) paints are a middle of the road option  for metal roofs and offer a mid-level price point and mid-level performance.

This paint style typically contains 30% silicone in the resin portion of the paint (initially silicone levels were higher, but it was determined to be unnecessary to gain the desired performance). This means that there is a superior initial and long-term gloss to the paint compared to polyester paint systems. The silicone also allows for better resistance to fade and chalk than polyester counterparts. However, SMP paint systems still have lower performance than Kynar 500® systems.

There are two major drawbacks to SMP paint systems. First, the quality varies greatly between manufacturers depending on the type of pigment used (ceramic systems outperform organic and inorganic type systems). Second, because of the hardness of this style of paint, these paint systems can actually micro-fracture during metal roof panel manufacturing. Once fracturing occurs, the base metal is exposed to the elements, and rusting/failure can begin. At McElroy Metal, we use Thermoforming technology to reduce the risk of this phenomena. 

So, while SMP paint systems are better than polyester paint systems and are the most widely used, they aren’t the best metal roofing option available to homeowners today.  

Fluoropolymer/Kynar (Best)

Offering the best protection against fade and chalk, Flouropolymer/PVDF coatings are the industry’s best performing paint system.The trade name for this type of coating is Kynar 500®, and it is a chemical cousin to Teflon. To be classified as a Kynar 500® coating, the PVDF component (Polyvinylidene fluoride) must be 70% of the total resin content. While Kynar 500® paint systems are a bit more costly, they offer unparalleled performance.

Developed in the 1960s, Kynar was initially produced by a single manufacturer for use on historic and monumental buildings. However, over time more manufacturers began producing Kynar paint systems, and the price fell to a level that made it accessible to homeowners.

Kynar 500paint systems are a softer paint than SMPs so the paint is more flexible. This means that it is less likely to fracture during panel manufacturing than SMP counterparts. This paint style also offers superior chalk resistance, fade resistance, gloss retention and film integrity.

This building dramatically illustrates Kynar 500®'s superior performance. This building was built in two phases, nine years apart. Note, no color difference in the two halves of the roof. No fade! No chalk!

Comparing Paint Systems

When it comes to longevity and appearance, Kynar 500® clearly outperforms both polyester and SMP paint systems. Kynar 500® typically adds a bit more to the material pricing than either of the other options. However, keep in mind that this is only a reflection on materials pricing, labor pricing remains unchanged so the overall increase in price is often minimal. McElroy Metal is one of the only manufacturers that has taken a full-scale stocking position on Kynar 500® in the lighter gauges commonly used for residential roofing.

For the record, McElroy Metal sells both Kynar 500 and SMP coated panels so contractors that install McElroy Metal products have access to both coating systems. We highly recommend Kynar 500 coatings because we’ve seen outstanding results over the last two decades in both long-term performance and customer satisfaction. 

Learn More

View a full list of our Kynar 500 metal roof products, or contact us at any time to learn more about our roofing solutions.