Granules make up the entire outer layer of asphalt shingles, making them an important component. In addition to providing color and texture, granules protect the asphalt layer from UV damage. In today’s post, local residential roofing company Hinkle Roofing shares a closer look at asphalt shingle granules.
What Are Asphalt Shingle Granules Made Of?
Asphalt shingle granules are made of crushed rock that’s sifted to a certain grain size then mixed with ceramic granules. This granule mix can then be mixed with other ingredients for color and other features. For example, copper granules can be added into the mix to create resistance to blue-green algae.
How Asphalt Shingles Are Made
Asphalt shingles begin their life as wide sheets of fiberglass, which are fed into rollers and soaked in hot asphalt as they pass through. These sheets are soaked twice, then coated with powdered limestone to enhance flexibility. The granule mixture is then machine-pressed on one side of the still-wet sheets. Multiple nozzles for applying granules may be used to create “blends” or color transitions. Powdered stone and adhesive strips are then applied to the sheets before they’re trimmed, packed, and shipped to the asphalt shingle and metal roof contractors that ordered them.
What Happens When Granules Erode?
Asphalt or bitumen is vulnerable to damage caused by UV rays, which roofs are constantly exposed to every day. Without granules, a bare asphalt-soaked fiberglass sheet would crack or split in a few years’ time. Granules provide an opaque layer that blocks direct sunlight and helps prolong the roof’s service life.
The layer of asphalt shingle granules get worn out over years of exposure to weather. This is why one of the most common signs of an aging roof is its “balding” shingles. This is easily noticeable on roofs with relatively light color: eroded spots would appear black where the asphalt layer is exposed. Most roofs are warranted against premature wear — that is, eroding granules within its warranty period. However, if the worn-out roof is beyond its expected life span, it’s more practical to get a new roof than have it repaired.
Hinkle Roofing is the leading asphalt shingle and metal roofing contractor serving the Birmingham area for over 110 years. Give us a call at (205) 964-9677 or fill out our contact form to schedule an appointment.
