Cleaning Moss & Algae Off Your Roof

Roofing Experts 9:27 am

Cleaning Moss & Algae off your roof

Everyone has seen moss, it grows on the surface in damp areas. It uses sports to reproduce and because it has no roots, it can spread on many surfaces, including your roof. Algae on the other had is typically an aquatic plant that grows in damp environments. Because moss and algae thrive and reproduce in damp and shady environments, they can reproduce and spread on a roof. It specifically appears on the north side of a roof, as the north side receives the least amount of sun, or under tree branches that overhang a roof. Over time, moss and algae can damage a roof and can cause it to degrade.

How to clean your roof of Moss and Algae

There are different ways to clean moss and algae off of a roof. You can physically remove the invasive plants with a long handled scrub brush, as long as you are careful with the shingles. You can also use a pressure washer but that may break sensitive shingles. With either method, you want to make sure you work down the roof, along with the shingles, not against. This will keep your shingles from breaking off or chipping.

You can also buy chemicals made specifically to kill moss and algae. Diluted bleach will also kill the plants. These chemicals can be placed on the roof or squirted onto the plants. However, these chemicals might drain off of the roof and affect plant life around your house. If you decide to use chemicals, make sure to wear protective gear; plastic gloves, eyewear, and a mask to block the chemicals from entering your airway.


To prevent the return growth of moss or algae, cut back any tree limbs that overhang the roof. This will allow more sunlight to reach the roof and less water to get trapped there. You can also install strips of copper or zinc coated sheet material along each side of the roof along the ridge. Copper is toxic to algae and moss cannot grow on metal as it absorbs heat and moss needs a damp environment to grow.

For more information, contact Eastbrook Construction today!