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What are Roof Shingles Made of?

asphalt roof shingles

What are roof shingles made of? How are shingles made? You might be surprised to hear that asphalt shingles are not entirely made of asphalt. The composition can vary, but asphalt shingles usually consist of mineral fiber and cementitious fillers. It has been revealed in studies that asphalt makes up only 5 percent to as much as 35 percent of the shingle. This material is also called ACM, or “Asphalt Containing Material.”

In this article, we reveal what other materials can be found in an asphalt shingle.

What are fiberglass roof shingles made of?

The fiberglass shingle production process includes a continuous sheet, which is the foundation on which the asphalt and other materials are put together. Asphalt roofing shingles can also be reinforced with a fiberglass mat, which is made from glass fibers connected with binders or stable resins. The fiberglass is put into large rolls at the mill, and then “unwound” when the roofing shingle production process starts.

What are asphalt roof shingles made of?

Asphalt is the basic water-resistant ingredient in asphalt shingles. This type of asphalt is an oil refining product which is processed to the high degree of hardness necessary for the shingle’s performance. The material then has to be “oxidized” by blowing air through the hot asphalt, which increases its viscosity.

This air blowing process has to be precise. After that, a fine mineral powder is mixed with the asphalt, which enables the installed shingle layer to be fire and weather resistant. This asphalt “coating” is pressed on the top and bottom of the fiberglass mat.


The most visible ingredient of asphalt shingles is the stone granule surfacing. Hard rock is crushed to a precise, granular size. Then the granules are applied to the part of the shingle that is not exposed.

The granules are then processed into various colors using ceramic firing to give them lasting colors on the exposed part. Some shingles can also include an algae-resistant granule that helps prevent discoloration caused by blue-green algae. Also, special “reflective” granules can be used to make shingles that are able to reflect a higher percentage of the sun’s energy. 


A thermally-activated asphalt sealant is applied to the roof shingles to connect the shingles on the roof. A material called laminate is used on multi-layer shingles to bond the shingle layers together at the time of production. 

These adhesives are specially made to ensure that they activate at particular temperature ranges, holding the bond through the installation process and during winds and other stresses.

Release film

Have you ever wondered what keeps the sealant from activating and sticking the shingles together when shingle packages are stored outside in the summer heat or a warehouse? 

This material is called “release film.” It does its job only while the shingles are sealed in the package. Once they’re installed, the film has no purpose and just stays on the shingle. 

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