What Are Those Ugly Black Streaks on Roofs?

You take great pride in the beauty of your home until one day; you see unsightly black stains or dark spots on the roof. Now, what is that on my roof, and also where did that come from? You wonder, alarmed.

Here's an overview of what it is, why it happens, and how the best roofing companies can help you get rid of those unattractive asphalt shingle spots.

What Exactly Are Those Roof Stains?

These dark stains and obnoxious black stains on your roof may appear to be dirt, mold, soot, or mildew, but they are actually algae. Gloeocapsa magma, often known as blue-green algae, is the most prevalent kind.

Algae growth typically starts as little patches and then progresses to apparent streaks. But by the time the householder notices the algae, it has generally been out on the asphalt shingle roof for at least two months.

What's the Deal With the Dark Streaks?

Roof algae have a black pigment that acts as a protective coating, shielding them from the sun's UV radiation. That is the source of its unappealing blackish hue that ruins the roof colors. 

Gravity drags the algae down the asphalt shingle roof as it grows, generating distinctive dark streaks. These black stains on lighter roof colors can enhance indoor temperatures, resulting in higher cooling expenses.

Why Do Shingles Get Algae?

Algae spores can travel through the air. Winds, animals, and perhaps even your clothing can spread them. As these germs are airborne, they could spread rapidly over a neighborhood from rooftop to rooftop. Condos, apartments, and residential properties are all examples of this.

Why does it appear that roof algae are more prevalent today than it was 20 years ago? Asphalt shingles get their name because they are primarily constructed of asphalt (an oil-based material) and felt materials.

Most shingle makers have moved to shingles that contain asphalt but are made mainly of fillers like fiberglass and broken limestone, which stimulate algae growth. The crushed limestone filler is the primary feeding source for these algae.

Algae Growth on Shingles Gets Influenced by Weather

Even though the usage of inferior shingles has caused algae growth concern in practically every section of the United States, tropical, sunny, and damp climates tend to offer the friendliest circumstances for algae growth.

Roof streaks created by algae are still an issue in sections of the world with freezing seasons, such as the northeast or Midwest, but they also have a humid climate.

Roof algae upon the north side of the house are common in these algae-prone places. Why? Because the northern half of your house's roof is shadowed while the sun passes during the day. This shade collects moisture and creates an excellent habitat for algae to develop.

Roof algae are also caused by gutters that drain immediately onto the rooftop and overhanging trees. A dark or wet surface also stops the sun from rapidly drying the roof, which encourages growth.

Is Such Roof Algae Dangerous or Harmful?

Roof algae are neither toxic nor dangerous in and of themselves, but they can lead the barrier protection UV granules that coat roofing shingles to start to peel away over time, wearing out the shingles.

Fungus, which spreads through the air, can interact with algae on your asphalt shingle roof to become lichen. The algae and shingle filler are both foods for this lichen. Lichen, unlike algae, can grow roots, making it more difficult to eradicate than algae alone.

How to Keep Your Roof Free of Black Streaks

Is it possible to get rid of algae for good? "No," is the most straightforward answer. Roof algae might make you feel like you've caught a cold. Algae spores, like several cold viruses, are airborne and inescapable. You can address the symptoms, but you'll ultimately get a new algae problem, especially if others in your neighborhood have it on their roofs.

But don't give up! Cleaning and maintaining your roof will help prevent black streaks on your roof from recurring, just like washing your hands frequently and eating a healthy diet can help you from contracting a cold. Here are some suggestions for preventing roof algae:

  • Keep Your Roof in Good Shape

Tree limbs should be pruned to allow more sunshine to reach the roof and to reduce debris accumulation. As part of a routine maintenance program, any debris that accumulates on the roof should be removed by hand regularly. That creates an atmosphere that is less conducive to the formation of roof algae.

To ensure adequate water drainage, maintain gutters and downspouts clean and clear of blockages. Never allow an upper roof's gutters or downspouts to drain straight onto a lower roof; instead, extend the downspout from the higher roof into the lower gutter.

Gutters that drain onto a lower roof not only encourage algae growth but can also enable water to stagnate on your roof, causing shingles and the inner wood structure to rot. Hire the best roofing companies for regular inspections. 

  • Place a copper or zinc strip down the roof's side

Another frequent approach is to put copper or zinc strips beneath the column of shingles nearest to the roof's peak, leaving 2 to 4 inches of the metallic strip's lower edge open to the elements.

That suggests that the rainwater will wash down the building when it rains, killing whatever algae are lying there because the water will carry algae-killing chemicals from the metal.

While copper is more effective at killing algae, galvanized sheet metal is a more cost-effective alternative. Copper and galvanized metal come in a variety of widths and thicknesses. They should be accessible to the customers' home improvement store or on the internet. Many companies make zinc strips exclusively for removing roof algae.

Although copper or zinc strips can help, it's crucial to remember that they won't provide 100 percent protection. Whether it's raining or not, algae spores depend on humidity and moisture. Thus these strips will give an added layer of protection.

  • Purchase New Shingles

The best roofing companies have responded to the problem of roof algae by developing shingles that include copper, which is toxic to algae. It is not essential to change your roof shingles simply because you notice black stains, and you must be wary of any contractor who recommends roof shingle replacement as the only answer to your algae problem.

If your roof is older or in poor condition and needs to be replaced, you might want to consider this copper-infused shingle, but ensure you obtain the best and most extended guarantee. Homeowners who have had these shingles placed have reported varied results. The copper content in these shingles is not controlled and varies from one producer to the next.

Final Tips

Roof algae is unpleasant and seems prominent on lighter roof colors, but it's easy to remove, and there are a few things you can do to prevent those black streaks from reappearing on your roof.

Get in Touch With Our Team Today!

For more information, contact us today to speak with a True Quality Roofing team member.