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Roofing Shingles
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Wind damage
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Consider the condition s a roof must endure. First there is the intense heat
of the sun, which scorches the surface of the roof and raises rooftop temperatures 50-75 F
above ambient temperature. The sun's rays are relentless, especially during the early afternoon
hours. In addition to the heat, the sun is the source of ultraviolet radiation, which has been
shown to degrade and accelerate the aging of the asphalt layers of the shingle. If not for the
protective layer of colored granules, roofing shingles would fail very quickly. Other factors
such as moisture, pollution and physical effects (roof traffic, hail, snow loads, tree limbs
etc.) all contribute to the aging and degredation of roofing shingles.
Seasonal and weather changes can also play a role in the aging of asphalt roofing shingles. For
example, consider the common situation in which the roof is bathed in the intense heat of the
summer sun. On such a day the rooftop may reach temperatures in excess of 160 F. Now imagine a
cold front sweeping through the area, bringing with it the violent thunderstorms that are a
common occurence during the sweltering days of summer. Almost instantaneously the rooftop
temperature drops 60-100F as it is pounded with a summer shower. Thermal shocks such as this
cause the rock deck beneath to expand and contract, placing a strain on the shingles. Year
after year this process is repeated, resulting in cyclic fatigue on the shngles.
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Comp. style ridge caps after 10 years.
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In addition to all the climatic and external variables that can impact the performance of the
roof, consider the internal factors that negatively influence the performance of roofing
shingles. Research has confirmed that an improperly ventilated air space inhibits air movement
and under most circumstances increases moisture content in comparison with properly vented
attic air spaces. Heat shortens the shingle's life and moisture causes deck movement and/or
deterioration, which ultimately affects the performance of shingles.
As you can see, the roofing environment is a hostile one with many factors influencing the
longevity of roofing shingles. The natural aging process begins as soon as the shingles are
installed on a roof. Day after day the shingles are exposed to the elements - sun, rain, heat
and cold. A roof never has a "good day."
Asphalt is one of the primary ingredients in roofing shingles. Its purpose is to provide the
waterproofing integrity for the roof. Secondarily, the asphalt holds the colored granules in
place and contributes to the overall strength of the shingle. Asphalt, which is derived from
petroleum, contains oils that provide ductility and pliability to the shingles. During the
lifetime of the shingles these oils begin to rise to the surface, where they are washed away
by rainwater. In an attempt to restore equilibrium, new oils surface and the washing process
continues. Also the intense heat of the roof oxidizes or hardens the asphalt over time.
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