When I speak to home owners about Roof Cleaning I’m very open about the fact that the black streaks we normally treat is harmless and doesn’t effect the life of the shingles. The algae causing the black streaks on your roof is actually a cyanobacteria called Gloeocapsa Magma.
Moss or lichen on the other hand will cause damage to your roof if left untreated. Moss on a roof is caused by lots of moisture and lots of shade. The moss spores arrive on your roof carried by wind or animals and can easily spread throughout neighborhoods. Unlike algae, moss can be detrimental to asphalt shingle performance.
Moss can thrive on roofs because it’s a non-vascular plant that obtains water through its leaves and not through a root system. Here in North America, moss tends to grow on north facing roof planes that receive less direct sunlight and stay damp longer than south facing planes.
In addition, trees that overhang a roof constantly shade any sunlight and our humid coastal climate helps to holds in moisture and acts as a food source for moss. All these conditions create the perfect environment for moss. Cutting back trees is recommended if you have moss growing on your roof. This will let some sunlight in and prevent it from growing back once cleaned
According to the Asphalt Roofing Manufacturers Association, Moss can cause the leading edges of the shingles to lift or curl, which increases the risk of shingle blow-off during wind events. In severe cases, moss build-up can cause lateral water movement resulting in moisture damage to the roof deck or may even cause leaks.
The most effective method of cleaning algae and moss from a roof is with a strong antimicrobial mix of six percent liquid chlorine bleach and water. Cleaning moss from a roof requires more work then cleaning the algae causing black streaks normally encounter here in Hampton Roads Virginia.
Moss has to be manually brushed to remove the larger chunks before treating with the potent antimicrobial cleaning solution. Apply with a softwash sprayer and allow the solution to dwell on the roof surface for 15 to 20 minutes, and then rinse thoroughly with low pressure water. Be sure to take proper precautions to protect landscaping and surrounding areas from the chlorine bleach solution.
Do you have moss or those unsightly black streaks ruining the appearance of your home? Call your Softwash Super Hero to get a quote on bringing back your home’s natural appearance.