3 Reasons Your Residential Roofing is Discolored

Algae Stains

If you notice black streaks along the northern slopes of your roof, you may be dealing with algae stains. Algae stains on your new roof can’t be prevented, but they can be power washed away by a licensed contractor. Just make sure that the contractor you hire uses low water pressure with a detergent safe to use on your roof.

Algae love to feed on the limestone filler found in asphalt roof shingles and can even appear in relatively new roofs. Unless you hire an experienced roofing contractor to power wash the algae away, it will continue to feed on the limestone until it merges with fungus to form lichen. Unlike algae, lichen can’t be easily removed. Algae can also trap moisture in residential roofing, causing water damage.

To combat algae, some local roofers have started mixing copper or zinc in with the colored stone surface. When it rains, the copper or zinc particles activate to prevent algae from growing. However, these algae-resistant shingles are only covered under warranty for less than 10 years. Asphalt roof shingles typically last between 15 and 30 years.

Rust Stains

Metal roofing is susceptible to rust over time. This is why it’s important to invest in roof maintenance every 3 years or whenever you first notice a problem.

Red or brown stains on your roof indicate rust, which can be caused by a compromised metal chimney, roof flashing, or other metal element. Rusted roof flashings will need to be inspected to ensure no water is seeping through your roof. Metal chimneys will also need to be checked for holes.

To stop the flow of iron oxide, you will first need to determine the source of the rust. (Usually, the culprit is a rusted roofing nail.) In most cases, you will be able to treat rust stains with vinegar. Oxalic acid can be used for deep staining. Be sure to exercise proper safety precautions when working with these solutions and while being on residential roofing.

Asphalt Bleed-through

If your roof has reached the end of its lifespan or the materials are inferior, you may notice black streaks across your asphalt shingle roof. One of our roofing contractors will be able to determine if this is the cause of the black roof stains.

When asphalt shingles start to break down, the black pigment from the asphalt is allowed to come up to the surface. Roofing contractors call this asphalt bleed-through. As soon as you notice the signs of asphalt bleed-through, you should consult with a roofing contractor to see if replacement is necessary. Keep in mind that asphalt bleed-through can look a lot like algae stains because they are both black discolorations of the roof.