National Coatings Blog

Part 1: The Basics of Roof Coatings

Posted by Nicole Gale on Tue, Oct 30, 2018 @ 08:50 AM

AcryShieldPailnolowtempflexWhat Roofs Can Be Coated?
Roof coatings can be applied to new construction, aged and failing roofs as a restoration system and for minor repairs and preventative safeguarding as a maintenance system.

The coatings can be applied over a wide range of roof substrates including:

  • Asphalt
  • BUR
  • Concrete
  • EPDM
  • Hypalon
  • Metal
  • Mod Bit
  • PVC
  • Single-Plies
  • SPF
  • TPO

What Does “Highly Reflective Roof Coating” Mean?
There are three main components that are measured to determine if a roof coating is highly reflective.

  1. Solar Reflectance: The amount of solar energy/UV rays that is reflected away from the roof, back into the atmosphere. The higher the solar reflectance is of a coating, the less heat is able to be absorbed by the building.
  2. Thermal Emittance: The relative ability of a roof to emit (or release) heat that has been absorbed.
  3. Solar Reflectance Index or SRI: A calculation method using reflectance and emittance values to determine the roof's overall capacity to refuse solar heat. The higher the SRI value is, the greater ability the coating has to reject solar heat absorption, maintaining a cooler temperature inside the building. 

What Types of Roof Coatings are Available?
The most common roof coatings available are acrylic coatings, asphalt coatings, polyurethane coatings, and silicone coatings. 

How are Roof Coatings Applied?
Roof coatings are applied by spray, brush or roller methods. Learn more: 5 Common Roof Coating Application Issues to Avoid.

What Does Low Slope Mean?
As defined by ASTM Standard E 1918-97, a low-sloped roof has a surface with a slope of 2:12 inches or less versus a steep-sloped roof which has a slope greater than 2:12 inches.Low sloped roofs are sometimes referred to as a flat roof; however, the pitch on a low-sloped roof is greater than that of a flat roof, which is 0 inches to 2 inches. Low-sloped roofs are designed with some pitch, to allow water to flow off the rooftop into a proper drainage system.  Learn more about roof slope here.

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