Everything You Need to Know About Shingle Granules

The vast majority of homes feature asphalt shingles on their roofs. Asphalt shingles are the most budget-friendly

roofing option. What's more, they're highly durable. They also come in many colors, shapes, and even dimensions.

However, unless you've ever inspected your roof closely, you might not realize the shingles feature a top coat of

mineral granules.

Continue reading to find out everything you need to know about these shingle granules.

Purpose of Shingle Granules

Roofers usually offer two types of asphalt shingles — fiberglass and organic. They both start with a mat base,

either fiberglass or organic felt, which manufacturers coat with asphalt. They top the asphalt with ceramic-

coated granules before running the mats through a series of presses, so the granules adhere to the sticky asphalt.

The granules serve two purposes. One purpose is aesthetic. They come in different colors, so the granules are

the method of changing the asphalt shingle color. The manufacturers might also choose to vary the colors, which

offers a richness of the surface. The granules are three-dimensional, so they add depth to the shingle surface as well.

The main purpose of granules, though, is utilitarian. They provide a hard outer layer to the shingles, which help give them their structural integrity. They also protect the asphalt from ultraviolet radiation. Without the granules, the asphalt shingles' lifespan would significantly decrease.

Composition of Shingle Granules

As noted, granules top both types of asphalt shingles. The manufacturers actually treat the granules separately before they coat the shingles with them.

Manufacturers start with natural stone. They crush and screen the stone to separate the granules by size. The manufacturers select specific percentages of the different granule sizes to create a blended mixture. The purpose of the mix is to ensure the granules interlock on top of the asphalt surface to provide maximum coverage.

After the crushing process, manufacturers create a slurry mixture of organic and/or inorganic pigments. They apply the slurry to the granules and bake the mixture at such a high temperature that the pigment is fused to the stone in a ceramic process. The manufacturers can then mix different colors of ceramic-coated granules to create the roofing look they want.

Causes of Granule Loss

The manufacturing process embeds the granules into the surface of the shingles. However, over time, the asphalt can lose some of its structural integrity. The bond between asphalt and granule becomes loose, and the granules can fall away. This situation happens on old roofs.

Granule loss can also occur on younger roofs. The main cause, then, is shingle damage. For instance, shingles can lose their structural integrity after a bad storm and shed some of their granules. Hail storms are especially noteworthy for causing granule loss. Another cause is moisture trapped inside the shingles, which causes them to blister and shed granules.

Identification of Granule Loss

You can identify granule loss in two ways. The first method is pretty obvious — you see the granules. They show up in roof gutters and at the bottom of downspouts. You may also just see them on the ground. The loss of a few granules is normal. You should become concerned if you have a large accumulation of granules.

The other method of identifying granule loss is to inspect the roof. If you feel comfortable, you can climb onto the roof and look closely at the shingles. Look for any balding patches. If you don't want to climb on the roof, look for new variegations in color on your roofline. Because the granules impart the shingle color, those variegations are a likely sign of granule loss.

Unfortunately, if you're experiencing widespread granule loss, you might be looking at full or partial roof replacement. Call your local roofers for an inspection and discussion of your next steps. HF Roofing Contractor Inc. can help you with all your roofing needs.

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