Black Mold On Slate Roof

What are those ugly black streaks on my roof.

Black mold on slate roof.

Commonly found in climates with warm humid summers it does no damage to the roofing but it certainly does looks bad. Like all tile however slate can be prone to mildew and mold particularly if it is installed in a high moisture area like a bathroom a basement or a kitchen. Slate is a sedimentary rock with miniscule layers that easily cleave. Believe it or not those black streaks only appear on roofs in certain areas of the country.

At best slimy black mold deposits are an eyesore. Those that tend to be the most humid furthermore they will only appear on the north side of the roof. Just because you can t see it however doesn t make it any less dangerous. Slate is one of the most durable and popular materials used in construction.

This quality is what distinguishes slate as a suitable roofing material. For this reason it works as well on a tiled roof as it does on a bathroom floor. Although these dark spots and ugly black streaks on your roof may look like dirt mildew soot or mold what they really are is algae. Once turned into roofing material slate absorbs water and can naturally de laminate during the freeze and thaw cycles of winter.

At worst they can pose serious health risks. Technically the black streaks on roofs are a form of algae known as gloeocapsa magma. That s why if. The black streaks are also known as black algae or roof mold.