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Part 3: Roof Coatings: Steps for Adhesion Tests
By Thomas A. Westerkamp
September 2010 -
A facility's age does not create an impossible challenge for managers trying to meet the provisions of key programs, codes and standards requirements for cool roof coatings. For example, a 75-year-old museum in California achieved LEED-EB: O&M certification, in part, by recoating the existing roof with an SPF base and applying a white, solar-reflective, acrylic topcoat. Since the coating expands as it dries, it fills cracks, seams, and flashing joints to form an impervious coating. As a result, the system increased the museum's energy efficiency.
When specifying coatings, managers also need to consider the condition of the substrate and the coating application process.
For these reasons, besides checking a product's cool roof rating, managers also need to test it to ensure a high-quality result before committing to a non-compliant solution. Among the characteristics managers can choose to test for are adhesion, coating thickness, contaminants, discontinuity of the coating through missed or thin spots, humidity and atmospheric tests, and surface-preparation tests.
Adhesion testing provides a revealing example. In this test, installers apply a coating to a 6- by 6-inch test area, both with a primer and without, to determine if a primer is necessary, instead of simply applying the coating over the old substrate. The procedure for one adhesion test involves these steps:
Adhesion is good if some coating remains on the substrate when the test strip comes off. If pulling the tab results in exposing a clean substrate, the adhesion is weak, and the coating will not provide the required energy efficiency or sustainability.
Thomas A. Westerkamp is president of the Work Management Division with Westerkamp Group LLC.
Roof Coatings: The Energy Connection
Part 1: Roof Coatings: LEED, Energy Star and the Cool Roof Rating Council
Part 2: Roof Coatings: What is the Annual Savings Potential?