GALVALUME sheet can be attacked by concrete and mortar. How are such attacked areas on GALVALUME roofing and siding best repaired?
The aluminum-zinc coating on GALVALUME sheet suffers fairly rapid corrosion in highly alkaline environments, such as concrete. The coating is attacked during the setting period when buried in concrete and can also be attacked from mortar splashes and droppings during masonry installation. The best repair for attack from mortar splashing is to cover the affected area with a protective coating. On bare GALVALUME roof panels, successful results have been obtained with Unilflex 500, an asphalt-based, fiber aluminum system available from Kool Seal, Inc. Repair of prepainted GALVALUME should done using the same type finish coats that are applied on the coil coating line. In all cases, the surface should be clean and dry and manufacturers’ instructions should be followed.