Contrary to what you might think, asphalt shingles are not made entirely of asphalt. The composition varies with each manufacturer, but most of the content of asphalt shingles is mineral fiber and cementitious fillers. In some studies, it has been revealed that as little as five percent to as much as 35 percent of shingle content is actually asphalt. This material is known as ACM, or “Asphalt Containing Material.”
Organic shingles are composed of waste paper saturated in asphalt, which makes it waterproof. A perfunctory layer of asphalt is then applied as an adhesive along with ceramic granules to protect the shingles from UV rays. While the name may imply they are eco-friendly, organic shingles aren’t made up of materials that are necessarily environmentally friendly, in fact, they are not being made at all anymore due to their lack of fire resistance at only a class C fire rating.
Algae-resistant shingles may also be available. In this case, some of the granules contain a leachable coating, which is ceramically coated and designed to protect your roof from the discoloration caused by algae. The paper-based quality of organic shingles consequently makes them more prone to fire damage.
Fiberglass shingles are manufactured in nearly the same way, yet contain less asphalt. In this case, wet, random-laid fiberglass is bonded with urea-formaldehyde resin, which is then coated in asphalt followed by the superficial layer of adhesive, and finally the ceramic granules. Fiberglass shingles resist fire far better than the old organic shingles ever did.
If these shingles become old and begin to decompose, the material can become potentially dangerous, requiring proper care in removal. Fiberglass reinforcement was devised to replace the method of reinforcing paper roof tiles with asbestos. Over the years, the roofing industry has worked to stop using asbestos material altogether and have sought out other products simulating the appearance of asphalt shingles.
A metal roof that looks like asphalt shingles is one such example. It is crucial that a roofing contractor carefully investigates before beginning a roof repair or replacement. Asbestos, historically, has been a good choice for reinforcing shingles due to the hardy nature of the mineral as it weathers moisture, heat and wear and tear through the years. However, the dangers of asbestos have been known for years, so standards and requirements of handling this material have been developed for the roofing industry. Every roofer should be aware of this, and needs to follow the safety requirements of the removal of decomposing shingles to avoid health risks associated with asbestos.