What Causes Roof Algae
Roof algae has specific causes, and a Amo homeowner benefits from understanding them. Here are the main ones.
Moisture
Algae thrives in moisture, so a roof that stays damp is more prone to algae growth. Algae likes moisture. Damp roofs are prone. It thrives there. It is a main cause. Drying helps.
Shade
Shaded areas of a roof, which dry slowly, are more prone to algae, especially under trees. Shade slows drying. Shaded areas are prone. Trees add shade. It encourages algae. It is a factor.
Humidity and Climate
Humid climates encourage algae, since the moisture in the air supports its growth. Humidity encourages algae. Moist air helps it. Climate matters. It is a factor. It affects how common it is.
North-Facing Slopes
North-facing slopes that get less sun often show more algae, since they stay damp longer. North slopes get less sun. They stay damp. They show more algae. It is common. It reflects the conditions.
What Causes Algae, in Short
Roof algae is caused by moisture since algae thrives where a roof stays damp, by shade since shaded areas that dry slowly are more prone especially under trees, by humidity and climate since humid air supports growth, and it often shows more on north-facing slopes that get less sun and stay damp longer.
Address the Causes With Us
Our Team inspects and cares for roofs across Amo and . Call for a free inspection of your roof.
One thing worth being clear about for Amo homeowners is that those unsightly dark streaks running down a roof are, in the great majority of cases, a type of algae rather than dirt or general staining. This algae grows on roofs and shows up as black or dark green streaks, and it tends to spread gradually across the roof over time, so streaks that start small can grow larger if they are simply left alone. Part of the reason it takes hold so readily is that it can feed on materials in the shingles, which gives it a foothold and lets it spread. It is worth knowing that this algae is not the same thing as moss, which is a thicker, green growth, so the two are distinct and are treated differently. As for what causes it, the common thread is moisture, since algae thrives wherever a roof stays damp. Shaded areas of a roof, which dry out slowly, are more prone to it, and that is especially true under overhanging trees that both cast shade and drop debris. Humid climates encourage algae as well, because the moisture in the air supports its growth. A very common pattern is for north-facing slopes, which receive less direct sun and therefore stay damp longer, to show noticeably more algae than the sunnier sides of the same roof. None of this means the situation is dire, but it does explain why the streaks appear where they do.