Denver CO Metal Roof Coatings: Why and When to Use It

This is a common scenario any highly reputable and professional Denver CO roofing contractor may have observed through all the years of working with property owners: when their metal roof gets rusty, Denver CO homeowners will go to their nearby supply store, purchase a bucket of metal roof coatings, and apply the coatings on the rusted roofing material.

True enough, this argument is solid. Metal roof coatings are efficient in reducing the further rusting and damage it can do to your roof. In fact, many metal roofing specialists encourage it. Metal Construction News talks about metal roof coatings as a "sacrificial layer" of sorts that help prevent long-term metal roof material exposure -- a key to its long lifespan and durability.

Metal Roof Coatings as Sacrificial Layers to Protect Roof

Metal roofs can be re-coated for a variety of reasons. Initially, they have a factory finish coating that may be galvanized, or Galvalume finished steel panels or fluoropolymer-based paint such as Kynar 500. However, as metal panels reach the end of their designed life expectancy, their coating becomes compromised.

"Regardless of the original finish, long-term exposure to the elements will deteriorate the protective finish," says Bob Arnold, vice president and general manager of Topps Products Inc., Stilwell, Kan. "Rust will begin to form and over time will compromise the structural integrity of the roof, and negatively affect the aesthetics of the building. All metal roofs expand and contract with temperature fluctuations. This allows the seams to open up and lets moisture enter the building envelope. Proper repair compounds and re-coating products will restore a metal roof to like-new condition, using the original substrate as its base." (continued)

Metal roof coatings offer a great number of advantages. The most recognizable of them all especially for any Denver CO homeowner is the low expenses they encounter and the advantages of a better roof they enjoy right after application.

Sherwin Williams has an excellent explanation as to how metal roof coatings enhance a metal roof's appearance, make them uniform especially for sheds using scraped-together metal roofing pieces, and improve on the overall base material's long-term performance. Read an excerpt that explains it below.

Exterior coatings

Exterior coatings further enhance a metal roof’s aesthetic and performance characteristics. To ensure uniform gloss, color, and thickness, a coil-coat process is the preferred application method for metal roofing. Using this method, the rolls of metal are painted prior to them being shaped into the roof panels. 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.

Exterior coatings for metal roofs are composed of four main elements: resin, pigment, solvents, and additives. 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.

The resins primary function in a paint formulation is to bind together all the components within the coating. It is the primary source for a coating’s durability and physical properties. Resin increases the physical strength and chemical resistance of the coating film, and allows the chemical reaction of the curing process.

Common resins used in the manufacture of paint coatings for metal roofing include: (Continued)

However, just like other roofing materials and additives, metal roof coatings are not infallible. They can fall short of expectations in some situations. There are case studies that indicate metal roof coatings aren't exactly the best choice when it comes to superior levels of roofing restoration, which points to roof repairs and replacements as a better option to improve the lifespan of a Denver CO residential property.

KTA University has a great case study that illustrates this point concisely. You can read an excerpt of their research below to help you learn more when or when not to use metal roof coatings to repair or restore your roof.

The Failure of Metal Roof Coatings

Coating problems on the church’s roof were observed just a few years after installation and the owner contacted a coatings consultant to investigate. The project specification called for “G90” galvanized steel sheet with a fluoropolymer coating system consisting of a primer and a finish coat with a total minimum dry film thickness (DFT) of 0.9 mils. The specified color was dark green.

A field investigation was conducted to evaluate the reported problems. A visual examination, as well as dry film thickness measurements and adhesion testing, were performed. The consultant observed that the green-coated roof panels had small areas of scattered rusting distributed over the roof’s surface. A typical rusted area was less than one-square-inch, with some larger areas measuring several square inches. Although the rusted areas were estimated to be approximately five percent or less of the total surface area of the roof panels, the rusted areas were scattered throughout and were readily visible from ground level. (Continued)

Therefore, if you see your roof is lightly rusted or damaged, you can use metal roof coatings to protect these areas from further issues. However, if a huge part of your roof has become affected by rust, it may be best to consult a professional with experience in metal roofing repairs and replacements. If you have yet to find a reliable one, you can count on Roper Roofing to help you. Learn more about what we can do for you by contacting us today!

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