Asphalt shingles have an outer layer of granules that protect them from damage caused by ongoing exposure to sunlight. Sometimes, shingles will shed their granules, and you’ll see them in the gutters or on the ground by your home. Is this something to worry about?
In today’s post, Sterling Exteriors, a top local roofing contractor, explains what causes asphalt shingles granules to fall off and why, most of the time, this is something you shouldn’t be worried about.
How Asphalt Shingles Are Manufactured
The asphalt shingle manufacturing process begins as rolls of backing material several feet wide are fed into rollers, some of which are in place to adjust the slack, which allows workers to ensure continuous flow of material into the machine.
Most asphalt shingles nowadays are made with fiberglass backing material, which is a composite. “Traditional” or “organic” backing material is made from pulped recycled fabric and paper. Asphalt shingles made with organic backing material are less flexible than fiberglass, but this construction adds more stiffness to the finished roof.
The sheets of backing material pass through a cascade of hot liquid asphalt, which soaks into the material and makes it more durable and water-resistant. The asphalt-soaked sheets are cooled by fans before undergoing a second asphalt soak. This time, the hot asphalt is mixed with powdered limestone, a substance that’s similar in composition to the tar that’s applied on traditional built-up flat roofing systems.
The second to last step in the process is the application of granules. Asphalt shingle granules are made of ceramic and crushed rock. The granules vary in color depending on the batch being manufactured. Some products feature a single color, while others have multiple blends or shades. Others still may contain specialty components like copper granules for algae resistance or may have reflective properties for energy efficiency. Shingles with reflectivity help reduce the heat absorbed through the roof, keeping the attic cooler on hot days.
The granules are pressed on one side of the still-wet backing material using rollers before being dusted by powdered stone and covered with sheets of polyurethane. Finally, a heat-activated adhesive is applied to the other side of the uncut sheets (which reinforces the fasteners during installation) before being fed into trimming machines. Traditional three-tab shingles comprise a single layer of material, which means they’re sent to be packed after one trim. Laminate or “architectural” shingles feature two layers of shingles cut differently to emulate a layered, hand-cut look. The shingles are then counted, packed and prepared for shipping to contractors.
What Causes Loose Asphalt Shingle Granules?
During the manufacturing process, granules are pressed onto the backing material and become embedded as the backing material is cooled. It’s not uncommon for some of the granules to come loose from the roofing surface after installation. If you see some granules in your gutter troughs a few months after installation, you don’t have to worry; it’s normal. Most of the granules will stay on the shingles under normal conditions.
Setting aside normal wear and tear, there are other reasons why your asphalt shingle roof would lose its granules. If you find a greater amount of granules in the gutters, it may be caused by one or more of the following:
Hail or Impact Damage — Damage caused by hail or airborne debris like rocks or large branches can dislodge granules from the roofing surface. You will need to have a roofing contractor inspect your roof to determine the extent of the damage, as some insurance providers may not pay for repair costs if they deem the damage to be merely “cosmetic.” However, some asphalt shingle products are rated for impact resistance, and may be eligible for repairs under warranty.
Blisters — Asphalt shingle blisters are caused by a manufacturing defect in which moisture is trapped in the asphalt during the soaking process described above. These pockets of moisture expand after exposure to heat from the sun, which results in blisters that separate the granule layer from the asphalt-soaked backing material. Like minor impact damage, insurance providers generally do not pay for asphalt shingle blister repairs, as this is considered cosmetic damage. However, as it is a manufacturing defect, the factory warranty may cover the replacement of the affected shingles.
Incorrect Installation — Asphalt shingles are supposed to be installed with specific nail patterns. If the roofer hammers roofing nails in the wrong place, the shingles can fold when hit by wind, resulting in creases that loosen the granules on the outer surface. This is one of many reasons why you should hire an experienced roofing contractor with top-notch credentials, including manufacturer certification. You won’t have to worry about such problems if the roof is installed by a trained professional. In addition, credentialed roofing contractors like us offer workmanship warranties in the unlikely event that your roof suffers damage from installation mistakes.
Tree Branches — Tall trees near your roof need to be regularly trimmed to avoid roofing damage. Sharp branches may scrape the rooftop and dislodge granules from the roofing surface. They can also poke holes in the roof, which can lead to roof leaks. Ideally, there should be about 10 feet of clearance between the outermost tree branches and the roofing surface. If you’re not sure how to cut tree branches without harming the tree, hire a local arborist.
Loss of Adhesion — Sometimes asphalt shingle granules come loose because they lose adhesion to the asphalt layer. This is more common on roofs built with low-quality asphalt shingles. It can also occur if the installer uses product way beyond its expected shelf life. This is yet another reason why you should hire credentialed roofing contractors, as we source our materials straight from the factory.
Old Age — If your roof is over 20 years old, you shouldn’t be surprised if you’re finding a lot of granules in the gutters. At this point, some of the shingles will start curling and cupping, which are both indicators of old age. The layer of granules will begin separating from the backing material. At this stage, you need to plan for a roof replacement.
Other Things That You Can Do to Minimize Granule Loss
With the exception of old age and manufacturing defects—things that are out of your control—most of the causes as cited above can be addressed, even prevented, by investing in a quality roof. This includes finding a credentialed and licensed contractor that offers quality products and warranties that cover both materials and workmanship. Adhering to a regular inspection and maintenance routine, as prescribed by your roofing contractor, can also help address granule loss if signs are spotted early on.
Sterling Exteriors is your leading provider of residential and commercial roofing systems. Give us a call at (513) 685-8055. You can also fill out our contact form to schedule an appointment. We serve customers in Cincinnati, Loveland and Newtown, OH.
