Over time, it is possible for roofs to suffer streaks and stains. If you are wondering why your roofing near Redmond has developed these unsightly discolorations, then keep reading to learn what might be causing them and how a professional roofer can help. 
Causes
Black streaks and stains that form on asphalt shingles are caused by a mold called gloeocapsa magma , or GM. This mold is a type of bacteria that survives through photosynthesis and feeding on the limestone filler used to make asphalt shingles. You may be wondering why you never noticed this type of roof stain while growing up. The reason for this is that asphalt shingles were once made of felt and asphalt. Today, this roofing material is created using limestone and fiberglass, which allows the mold to thrive. The staining typically develops on east- and north-facing sides of the roof because the GM enjoys cool, shady areas.
Risks
There is no consensus regarding the damage that GM may cause to a roof. Because of this, it is generally considered an aesthetic problem. This photosynthesizing fungus grows roots that wrap around the granules of the shingles, making it difficult to dislodge. Because scrubbing and aggressive washing can damage your roofing, professional cleaning is recommended. Staining can also be a result of moss growth, which can indeed shorten the lifespan of your roof and should be removed.
Removal
If you are considering cleaning your roof yourself, then consider some reasons why it is better to hire a professional. First, using a pressure washer or similar device on some types of roofing may damage the shingles and worsen the state of your roof. Second, working on a roof can be quite dangerous and can lead to devastating falls. For these reasons, the best way to handle a discolored roof is to hire a professional roofer. These contractors have the equipment and expertise needed to clean your roof shingles safely and properly.