How to Compare Roof Coatings

Reflective roofs keep buildings cooler.

When comparing roof coating products, you must know the type of roof you plan to coat. You should know the roof's condition and if this is its first coating. It's best to choose a roof coating during construction or roof repairs.

Metal Roof

Metal roofing usually comes factory coated, but you can coat it again after installation for added protection. Know the coating used on your metal roofing, if any, because silicone and acrylic products don't adhere well to each other. Most metal roof coatings are acrylic, aluminum, rubberized aluminum, white, polyurethane or polymer-based. When comparing these products, you should consider the roof's current condition, code requirements, budget and desired performance. Product performance may be waterproof or reflective, for example. You might also consider using a zinc-rich metal roof primer to increase adhesion and inhibit rust.

White, Reflective Coating

Many reflective roof coating products are Energy Star rated and approved for the program. Reflective coatings reduce energy used to cool buildings by 10 to 15 percent. A roof's surface temperature can be lowered by 100 degrees Fahrenheit when coated with an Energy Star approved reflective coating product. White, reflective roof coating products can be applied to nearly any existing roof material, including shingles and asphalt. Products with a high solar reflectance are sometimes called albedo. White roof coatings get dirty and weather more quickly than other roof coatings. For these reasons, it's generally preferred for flat roofs.

Rubber

Rubber roof coating products are a common choice for roof repair. Rubber products are waterproof, have high adhesive strength, hold up to extreme weather conditions and apply easily with a roller. This type of product can be used on tar, metal, concrete and other roofing materials. Rubber coatings also come in white for a reflective quality.

References

• Roof Coatings: Coatings for Today's Roof Systems
• Energy Star: Roof Products for Consumers
• Solar Estimate: Cool Roofs for Hot Climates
• Ames Research: Premium Elastomeric Roof Coatings