Granule loss can be caused by a number of factors. Because some granules are not embedded in the asphalt during manufacturing, some granules come loose during packaging, transport, and installation. Some granules come off because of foot traffic, either during installation or periodic maintenance done on the roof. The kind of degranulation highlighted in the video below is due to a bad batch of shingles. Though fairly rare, it does happen. This is why it's imperative to choose a manufacturer that has extended warranties and a reputable contractor that has been in business at least 10 years. Unless the owner specifies differently, we use GAF and Certainteed. Both of these shingle manufacturers have been in business for more than a 100 years and offer the most comprehensive warranties in the business. They always stand behind their product, even when a bad batch is detected.
Billy Guyette - Montgomery native - roofing specialist