Algae & Moss Prevention and Cleaning for Asphalt Roof Systems

Worker is cleaning for algea & moss on asphalt roof systems

Unsightly stains that develop on your asphalt shingled rooftop can quickly do a lot more than negatively affect your home’s curb appeal. If not cleaned, things like algae and moss growth can start to damage the actual structure of your roof and the integrity of your shingles.

In the roofing business, it often rains when it pours, meaning any untreated damage can quickly lead to more issues with your roof. Fixing these issues is inconvenient and expensive, so preventing the problem before it becomes a bigger one is key in these situations. One way to ensure you don’t run into bigger issues caused by algae and moss buildup on your asphalt roof is to properly clean these stains. To help you, we’ve prepared a brief breakdown of how to keep your roof clear of both of these potentially damaging organic materials.

How to Remove Algae and Moss from roof naturally


Most of us are familiar with algae buildups in ponds, puddles of standing water and even some pools. For the most part, people recognize algae as a green, scummy substance, but the algae that appear on an asphalt roof is slightly different. Black algae are common on roofs throughout North America, particularly those that are built-in coastal areas such as Vancouver and the lower mainland. The black algae are actually protected from UV rays because of its colour, meaning it is hard to remove even when exposed to direct sunlight that would otherwise dry the algae out. The good news is that algae are not nearly as damaging to an asphalt roof as other substances like moss. Despite this fact, it can be very unsightly, especially if it grows in long black streaks across the roof.

You can discourage the buildup of algae on your roof by keeping trees from hanging their branches over the roof. You should also try to keep your roof free of any debris that can build up over time. The same goes for gutters, as the damp organic material that builds up is the perfect place for algae to develop. If algae do build upon your asphalt roof, the best way to get it cleared off is to clean it with a mixture of water and bleach.


Moss can spread a lot faster than algae and can cause a lot more structural damage if left unchecked. Moss is typically a green coloured and grows right over shingles, causing them to curl and have an increased risk of being blown off the roof. Animals, tree leaves and even the wind itself can carry moss spores right onto your roof, so it is important to keep an eye out for any buildups of organic materials left on your roof or in your gutters.

Like algae, moss can remove moss from the roof naturally by using a water and chlorine bleach solution. There are ways to remove moss naturally, but if you find there is a significant amount already on your roof, the best way to clear up the issue is with bleach. A 50:50 ratio of bleach to water should be sufficient to remove the moss and prevent its return for a period of time. Other than cleaning it directly, it is important to incorporate regular roof sweeping and gutter cleaning into your roof maintenance routine. Doing so will help your roof stay dry and intact, and it will extend its overall lifespan.

For more information about asphalt roof maintenance and how the experts at Taves Roofing can keep your roof clear and intact, be sure to contact Taves Roofing today.

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