Discoloration of a roof can be a mystery. You may have noticed that the color of your roof has changed over time, leaving you wondering what is causing it and how to fix it. This article discusses why your roof is discolored and how to address the issue. 

Algae Growth

Algae growth is a common cause of roof discoloration, particularly in areas with a humid climate. The blue-green algae is usually the culprit behind those streaky black stains on your roof. The algae discolor your roof by leaving behind a dark, hardy coating when they die, resulting in those unsightly black streaks you see. This coating allows the algae to withstand harsh winter weather and reflect UV light, enabling their survival and continued growth. Over time, as more algae die and leave behind their protective coating, the discoloration on your roof can become increasingly noticeable.

Addressing algae growth on your roof is crucial, not just for aesthetic reasons but also for the longevity of your roof. The algae hold moisture against the roof surface, which over time, can damage the shingles and shorten the lifespan of your roof. Therefore, if you notice black streaks on your roof, remove the algae as early as possible to prevent further damage.

Sun Exposure

The sun's ultraviolet (UV) rays can cause significant damage to your roofing materials over time, leading to discoloration. This is especially true for roofs with darker colors, as they absorb more of the sun's harmful UV rays, which can accelerate the aging process of your roof. 

The heat from the sun can cause your roofing materials to expand and contract, a process known as "thermal shock." Over time, this constant cycle of expansion and contraction can cause your roofing materials to crack, warp, or fade in color. Certain types of roofing materials, such as asphalt shingles, are more susceptible to this type of damage. The granules that coat these shingles can be loosened and washed away over time, revealing the underlying material and giving the roof a discolored appearance.

Lastly, sun exposure can also lead to "chalking"—a white, powdery substance that forms on the surface of certain roofing materials. This chalking is a result of the degradation of the roofing material's protective layer caused by prolonged exposure to the sun. Over time, this can lead to a noticeable discoloration of your roof, adding to the faded appearance caused by the loss of granules from the thermal shock.

If you notice that your roof is discolored, you should take steps to protect it from further damage. Contact a local roofing contractor to learn more.