Asphalt shingles are most commonly found in climates with high temperatures like the southwest United States. As one of the most common roofing systems available, asphalt shingles provide cost savings and fire resistance at the same time. In high temperature areas the ability of asphalt to maintain its composition is the key indicator in its ability to prevent fires. What is Asphalt? Asphalt is created from bitumens from petroleum sources. It is commonly found in roofing, pavements, and roadways. In roofing, asphalt also acts as an adhesive for other roofing materials and as a water barrier. The most commonly thought of asphalt shingle, known as a multi-ply built up roofing, has been around for over 100 years. This roofing system contained asphalt shingles that were coated from the manufacturer and attached to the roof with a nail. Asphalt Shingles are Fire Resistant The shingles were constructed using a felt, like glass fiber mas, and pulled through an extremely hot coat of bitumen and other roofing material aggregates. The aggregate materials, usually a manufacturer specific, is what gives asphalt shingles their fire ratings. Generally speaking, many asphalt shingle roofing systems are categorized as Class A fire resistance, the top level of fire resistance. Asphalt Usage in Roofing Because asphalt serves as a “hot adhesive”, it literally glues ply sheets to the roofing substrate and to other ply sheets. In roofing repair, fleece-backed materials can be used in hot asphalt in order to “lay over” or cover-over old asphalt roofing applications. Asphalt can be applied by mop. However, proper temperature must be reached in order to balance viscosity. Mop applied asphalt should be 125cP (+/- 25°F). With a mechanical application, viscosity should be around 65cP (+/- 25°F). Standards Guiding Asphalt Roofing The most recent standard regarding the use in asphalt roofing was issued in 2010. Known as D7654, “Asphalt Used in Roofing”, measured by Dynamic Shear. This standard defines the softening point of asphalt or the point where asphalt starts to become more viscous. The softening points are measured at various temperatures and are used to classify asphalt shingles by type. The reason for finding the softening point of asphalt shingles also has to do with a phenomenon called “slippage”. Slippage occurs when coated sheets are laid on ply systems and additional weight from other shingles and shingle sheets created a downward force. The force is multiplied by the effect of gravity and creates a force in the magnitude and direction of the slope of the roof. Literally your shingles can slide down. Fiberglass mats are most commonly used today to prevent this issue. The roofing industry has also stopped the usage of soft asphalt grades. Asphalt grades for high temperature climates are usually type III or type IV. Schulte Roofing is a College Station roofing contractor with over 100 years of combined roofing experience. Schulte Roofing has been building asphalt shingle roofing systems in College Station, TX and surrounding areas for the last 18 years. To learn more about asphalt roofing and asphalt shingles, contact your local College Station roofing contractors today.
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