“Asphalt shingles are one of the most widely used roofing materials in market today” . The primary purpose of asphalt in roofing materials is to waterproof them. It can also hold the granules in place and add to the overall strength of the shingles used for roofing . This lightweight roofing material does not lack in durability either. And their relatively cheap cost makes them a favorite among home owners. And to add to all these advantages, they are very easy to install too . But asphalt shingles are not very resilient to drastic climate changes. If the surrounding temperature changes quickly, then asphalt shingles are more vulnerable to cracks or tears. Even with all the technological advancements that have affected asphalt shingles, they are still one of the weakest roofing materials available .
Manufacture and Components
Roofing shingles are available in a variety of forms in the modern market. They differ by their look, aesthetic feel, characteristics, and their application in different environments. They range from the traditional three-tab, organic, felt shingles to the most modern architectural and designer shingles. Roofing shingles are manufactured by combining or layering different varieties of materials.
For making the conventional three-tab, organic, felt shingles, the felt is first impregnated with saturated asphalt. This felt is then coated on the either side of the shingles. The coating on the exposed side is thicker than the reverse side. Granules are added to the exposed side to make a strong bond between the shingle and coating asphalt while the reverse side is applied with a backing dust to avoid the shingles sticking together during shipping as a bundle. Different components of asphalt shingles are 1. Asphalt: The asphalt needed for roofing shingles need to have excellent weathering characteristics. This is essential to meet the 15 year life expectancy of roofing shingles. The asphalt should be capable of withstanding drastic changes in temperature. It should be able to bend considerably (according to temperature variations) without breaking. “A durable asphalt will be pliable and slow to harden” . The asphalt used for roofing materials are obtained as a byproduct of crude oil refining. 2. Organic felts: The use of asphalt alone does not determine the durability and strength of any roofing material. The reinforcements used have an important role to play in the material’s performance to change in weather. Organic felts are formed by a combination of virgin wood pulp and recycled celluloid products. The base felt is saturated with the help of a bituminous saturating agent which is then passed through a coating section where filled asphalt is applied on the reverse side and top side of the sheet .
Organic felts undergo dimensional changes after absorbing moisture from the atmosphere. This is one of the major disadvantages of using organic felts. But they can be avoided by ensuring 1. Proper felt saturation and 2. Heavier coatings on felt. 3. Fiberglass felts: The disadvantages of organic felts related to moisture absorption can be avoided by using fiberglass felts. They have excellent moisture resistance but lack in crack resistance. They are created by a process very similar to the manufacture of paper. Glass fibers are blended with a binding resin (such as formaldehyde) to give a strong and flexible material . Their tensile strength and tear resistance can be changed by various other treatments as well as using different binders or resins. 5. Asphalt Sealant and Backing Dust: The shingles are sealed using asphalt sealant after it is thermally activated. The sealant used should be appropriate for the roofing shingles. This is ensured to avoid blow offs during strong winds. Backing dust has no other purpose than to avoid the sticking-together of shingles during shipment. This is ensured to avoid stains that are usually found on shingles.
Types of shingles: Comparison
Two major types of shingles available today are three-tab shingles and architectural shingles. They differ from each other in all of the major properties including durability, looks, and cost. Three-tab shingles are the most common and the oldest type of roofing shingles available today. The shingles used in three-tab roofing are of same dimensions and shapes . Therefore, the three-tab shingles have only one flat layer and are lighter than architecture shingles.
In contrast to the properties of three-tab shingles, architectural shingles are more durable and more aesthetically pleasing than three-tab shingles. This is because of the “dimensional” look they possess. Architectural shingles get their dimensional look by using shingles of different sizes and shapes for roofing. One interesting turn over from this dimensional look is the durability of architectural shingles. That is, by using shingles of different shapes and sizes, architectural shingles become heavier and thicker than three-tab shingles. Their thickness warrants a greater durability than that of three-tab shingles. This makes them highly resistant to strong winds too.
But all the aforementioned advantages come with a cost. They are highly priced than the conventional three-tab shingles available in the market. Many companies are also providing specialty shingles with added features like energy savings and designer shingles. The energy saving shingles is specially crafted to provide high insulation to temperature for efficient interior air conditioning. It is for sure that roofing shingles have not yet finished their evolution stage.
References
Architectural Shingles vs 3 tab Shingles. (2016). Retrieved March 15, 2016, from Roofpedia: http://roofpedia.com/architectural-shingles-vs-3-tab-shingles/
Asphalt Roofing Shingles. (2016). Retrieved March 13, 2016, from CertainTeed: http://www.certainteed.com/products/roofing/more-info/asphalt-roofing-shingles.aspx
McNurty, R. A. (2000, December). Asphalt Roofing Shingles. Retrieved March 15, 2016, from RCI-Online: http://www.rci-online.org/interface/2000-01-mcnulty.pdf
Types of Roofing Shingles. (2016). Retrieved March 13, 2016, from Roofpedia: http://roofpedia.com/types-of-roofing-shingles/
Types of Shingles. (2016). Retrieved March 13, 2016, from Roofpedia: http://roofpedia.com/types-of-roofing-shingles/
