written by: Finn Orfano
• edited by: Lamar Stonecypher
• updated: 2/21/2010
Asphalt shingles can be placed effectively over the existing roof. Nevertheless, it is recommended that if the existing roof layers exceed three, the old roofing structure is removed totally before fixing new shingles. Roof defects include thermal tearing, loss of granules, and curling.
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Basics of Asphalt Roofing Shingles
Asphalt shingles are basically a roofing material for residential applications that is widely being used globally. The asphalt roofing profile shingles are popular because of their relatively low cost, suitable characteristics as roofing materials, and simplicity in installation. These roofing materials are available in numerous styles and colors, and are durable. The cost of roofing asphalt materials is influenced by the shingle type, location of site, building height, roof slope, and access to the location. The types of roofing materials used are fiber glass, organic, and zinc roofing materials. The roof slope is important during roof installation to ensure that rain water does not remain standing on the roof. Therefore, standard roof slope should be maintained according to the roof specifications.
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Types of Asphalt Roof Shingles
Asphalt shingles are available in numerous types. However, the popular kinds are the fiber glass and organic. There characteristics are as under:
Fiber Glass: These roofing shingles have a fiber glass strengthening mat that is produced to the shingle shape. The mat is produced from fiberglass bonded with resin. The mat is covered with asphalt that includes mineral fillers. The purpose of the glass fiber mat is reinforcement, and is not used for waterproof. The asphalt ensures water proof of the shingles. Fillers are used to facilitate the fixing of the asphalt with the mat. The asphalt seals the small voids and holes in the mat making it waterproof. After cooling, adhesive asphalt is utilized for the mat covering. Subsequently, the ceramic particles are embedded. Fiberglass shingles withstand fire better than the organic or paper mats. Fiberglass reinforcement was developed as a substitute of asbestos paper that was used for roofing shingles. Glass fiber shingles are generally preferred because of their lower cost, and simple manufacture process.
Organic Shingles: These shingles contain an organic felt material that is usually asphalt saturated paper for waterproof. A top coat of adhesive asphalt is spread and the ceramic granules are subsequently embedded. The ceraminc granules are added for the protection of the shingles from the sun, since its ultra violet rays are harmful for asphalt, and deteriorate it rapidly. Gravel is also used on roofs for these reasons. Granules are also used for aesthetic reasons. Organic shingles hold more asphalt than the glass fiber shingles, due to which their weight is more, and durability is better. However, the excessive asphalt makes the organic shingles less environmental friendly. The organic shingles are more vulnerable to fire damage.
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Life of Asphalt Roof Shingles
The lifetime of asphalt shingles depends greatly on the environment. Shingles used in cooler climates tend to last longer, compared to those fitted in the warmer regions. Thermal shock affects the shingles significantly. Thermal shock is the adverse reaction when ambient temperatures change radically in a short period. In some regions, there is a drastic difference between the day and night temperatures that may cause a thermal shock. Roofing materials are not capable to contract or expand on such temperature changes. Consequently, the materials start to crack. Subsequently, the entrance of water is facilitated, and the roofing materials are subject to further deterioration. Constant water existence will allow development of fungus on the roofing materials. Furthermore, during cold temperatures, water seeps into the roofing cracks, and freeze at low temperatures. On water expansion due to freezing, the cracks are enlarged. Therefore, the roofs have slopes to prevent water accumulation. The life of roofing materials is increased by arranging suitable water shedding. Furthermore, proper ventilation of roofs extends the life of asphalt shingle roofs.