4 Common Causes of Roof Stains

Man inspecting damaged roof

The roofing of your home is the first layer of protection against outdoor elements such as rain, sun, wind, and storms. In addition, a roof also serves an aesthetic purpose. It factors into the décor and appeal of the indoor atmosphere of your home.

Roof stains are a problem that affects both aspects of your roofing. They are an indication of a deeper problem that may be damaging the structural strength of the roof. At the same time, stains look awful and mar the aesthetic appeal of the roof. This is why it is important to identify the actual cause of roof stains and resolve it at the earliest.

Roof stains can be caused by various reasons. Here is a look at some of the most common causes of roof discoloration and stains.


Rust is a problem that metal roofs, or metal components in other roofs, may experience over the years. Rusting usually occurs when a section of the metal is exposed to water or moisture. As the metal components rust, they leave the brown rust-color deposit which may then be carried into the roof by rainwater. When you experience rust-colored roof stains, it is indicative of two problems – rust, and water seepage.

To resolve the first problem, you will need to thoroughly inspect the roofing to see which components have rusted. If the rust has been around for a time, it may have corroded the metal enough to compromise its structural integrity. In such a case, you may need to replace the flashing or another component that has rust on it. In other cases, surface rust can be removed and the metal restored with surface treatment.

The second problem is to identify how the rust set in, in the first place. As noted above, the metal component must have been exposed to water or moisture for rust-color discoloration to appear on your roofing. The solution to this is to find the source of this water leakage or seepage and take care of it.


Algae can grow into the structure of the roof due to the presence of heat and moisture. Limestone filler material, often used in asphalt shingle roofs, is a source of nutrients for the algae. Once it sets in, algae can quickly spread across the roof. It is visible in the form of black streaks along the roof. When you see roof stains of this kind, it is time to consult roofing professionals.

This is because the most common solution to stains caused by algae is to power wash the affected section of the roof. When you hire a contractor to remove algae, make sure the contractor chooses a water pressure that is safe for the roof.

Algae growth and the stains caused by it are typically not preventable. This is because conditions conducive to algae growth often exist in both residential and commercial roofs. The best you can do is to identify such growth in time and have it power-washed while it is still on a small scale.

Roofing Material

Roofing materials can deteriorate over time, causing them to lose their color. This color may then seep to the roof surface and cause discoloration and stains. The color of such stains typically depends on the type of material used. Asphalt shingles, for instance, will cause black stains when it breaks down at the end of its life span. Stains from a degrading metal roof may be of a different color.


It is also possible for outdoor debris such as leaves, fruits and seeds from trees, and bird droppings to leave stains on your roof. These stains can be quite extensive especially when a tree overshadows a portion of the roof. When stains on your roof are caused by such debris, the easy solution is to wash away the stains. If you don’t have the equipment, you can hire a professional contractor for the job.

Hiring a Reliable Roofing Company in Atlanta, GA

If you wish to have your roof inspected for stains and other problems, it is important to hire a reputable contractor. Here at Sentinel Exteriors, we have been offering a comprehensive range of roofing services to homeowners and businesses across Atlanta, GA. We take pride in ensuring a premium standard of service delivery and ensuring customer satisfaction in every job we undertake. Whether you want a new roof installation or the repair, service, or maintenance of an existing one, we have got you covered. Call us today to consult our experts and hire our services.


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