Sun Damage to Your Roof

While we often focus on the damage that wind, rain, and hail can do to roofs, over time that sunshine we all crave can be just as bad. 

Two Sources of Sun Damage

The sun can damage a typical roof in two ways: Ultraviolet radiation and thermal expansion. These factors are related and work in tandem to break down asphalt shingles. 

Ultraviolet Radiation

What is ultraviolet radiation and what, specifically, does it do to a roof? Often abbreviated to UV, ultraviolet radiation is basically light that is beyond our capability to see. A form of electromagnetic radiation, UV is light with a particular wavelength. Of all the light generated by the sun, roughly 10% is made up of the UV wavelength. Our atmosphere, which acts a lot like a roof for the planet, absorbs most of the UV light before it reaches the earth’s surface. The light hitting your roof on a sunny day is about 3% UV.

UV Damage to a Roof

When that little bit of UV hits a roof’s asphalt shingles, a chemical reaction starts to take place. While not a vigorous and explosive reaction, it will cause damage over time. The more sun a roof receives, the more that little bit of damage adds up. In short, the oily material in the asphalt shingles evaporates away bit by bit. That material both helps with a shingle’s waterproofing and flexibility. When it’s gone, the shingle will be less effective at repelling water and will become brittle and prone to cracking, which creates an even bigger water penetration issue.

Granules Protect against the Sun Damage

One of the main reasons asphalt shingles have granules is to scatter the light that reaches the roof. As shingles lose their granules over time, due to rain, wind, wear, and UV damage, the more light the shingles absorb. More absorbed light means more damage, and so the downward damage spiral continues.

Thermal Damage

Thermal damage is related to UV light. As the shingles absorb the light energy, they heat up. That heat causes them to expand. As they cool, they contract. This process is called thermal shock. As that cycle repeats over time, the different rates at which the different materials in a shingle undergo the process can cause them to separate.

Regular Maintenance and Inspections

A schedule of regular inspections and maintenance can help to lessen the overall potential for long-term damage. Let Vanguard inspect your roof and offer advice for repair or replacement. Contact us here.

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