The Importance of Longevity in Reflective Roof Coatings

Posted by Lubrizol Performance Coatings Team on 06/24/2020

Roofs have to protect the buildings underneath them from the elements. Roofs also have to perform well and maintain high performance protection over time under severe climate conditions. Critical to performance and longevity of the building is the roof coating.

There are many different materials that can be used to create or formulate a roof coating. The most common materials are bitumen-based, EPDM or TPO membranes. Most of these materials ensure long-lasting protection, but they have the disadvantage of needing roofing professionals to install them. They also lack one of the most important added values today: sustainability.

 

Sustainable Roofing

Sustainable roofing, in the case of roof coatings, can have multiple meanings, such as:

  • Easy and fast application to reduce complexity and labor hours.
  • Long-lasting performance to avoid costly and frequent re-application.
  • Ease of removal and disposal of materials in the case of unavoidable substitution.
  • Materials based on unregulated and user-friendly raw materials (i.e., water-based versus solvent-based, low emissions, etc.).
  • Energy savings/lower air conditioning costs by reducing the amount of heat coming through the roof and into the building. These “cool roofs” or “reflective roofs” are able to reduce the impact of UV on the roofs.

Reflective roof coatings limit heat absorption by reflecting the sun’s heat and then releasing it back into the atmosphere. This green technology has been shown to extend roof life as the first layer of UV and waterproofing protection, while also reducing expansion and contraction (thermal shock) of the roof. Most solar reflective coatings are white and are primarily based on acrylic or polyurethane resins.

 

Maintaining Reflectiveness

Achieving the appropriate level of reflectiveness in a newly applied white roof coating is easy. The difficult part is maintaining the reflectiveness inherent to a white coating year after year when the roof is exposed to the elements and pollution.

The reflective roof coating needs to remain smooth, clean and white to keep its reflective properties and not compromise the efficiency of the cool roof. The right resin with a strong resistance to attracting dirt is the key to achieving a longer lifespan, which is especially important in industrial areas or areas with higher-than-normal pollution. The membrane must also maintain its required elasticity, which is tricky to do while balancing the desired properties of being smooth, durable and offering dirt pick-up resistance.

 

Liquid Applied Membranes

A liquid-applied coating based on acrylic elastomeric polymer technology with white reflective pigments is commonly used for cool roofs. Over time, acrylic-based resins have demonstrated certain advantages over other reflective roof coating technologies, such as being easier to apply compared to solvent-based or two-component systems; having regulatory advantages compared to solvent-based systems; and, getting much closer to the performance of polyurethane-based systems that are able to create smooth, high-performing waterproofing systems.

Lubrizol has developed a number of resins with hybrid technology—acrylic polyurethane dispersions under the Carboset® Acrylic Resins brand name—that are able to balance performance (i.e., low water absorption and balanced mechanical properties for a wide range of climate conditions) and durability (i.e., aging and weather resistance). These resins enable smooth, elastic films that reduce dirt pick up to keep their reflectiveness and energy-saving qualities over time.

Contact us to learn more about the resins we offer that enable reflective roof coatings to deliver long-term performance.

Lubrizol Performance Coatings Team

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