What are the Dark Streaks on My Roof?

Have you ever driven through a neighborhood and noticed dark streaks running down some of the roofs? Or maybe, you have recently noticed that your own roof is affected by these mysterious streaks, and you’re looking for answers.

You’re not alone! Dark streaks are an unsightly but common roofing issue, especially in parts of the country with higher humidity.

What causes dark streaks?

What surprises people is that the streaks aren’t caused by dirt or mold, but instead, algae. This specific type, known as gloecapsa magma, is a blue-green algae that grows on asphalt shingles and appears dark brown, gray, or black in color. This algae thrives in humid environments and spreads easily across roof surfaces. Gloecapsa magma can cause streaks on roofs in any part of the country, but the areas that are especially prone to this issue include the Pacific Northwest and the Southeastern United States.

Do dark streaks mean my roof is damaged?

Generally, you won’t notice algae growth on your roof until it spreads into longer, larger streaks. While algae growth usually does not pose an immediate threat to the structural integrity of your roof, it will cause deterioration of roofing materials over time if left untreated. The main concern most homeowners have is the negative effect that dark streaks have on the aesthetic and curb appeal of their homes.

So, if you have dark streaks on your roof, that typically doesn’t mean you’re in urgent need of a replacement, but you should plan to have your roof inspected and cleaned.

What should I do if my roof is affected?

If you notice dark streaks or any other moss or algae growth on your roof, call in the professionals to complete an inspection and removal. There are DIY remedies for cleaning and removing moss and algae, but doing it yourself can cause further damage to your roof if you’re inexperienced in dealing with roofing materials. And in some cases, cleaning or treating your roof on your own may void your warranty.

If you have dark streaks on your roof or any other roofing concerns, give Farha Roofing a call, and we’ll complete a free inspection!