Why is there moss on my roof and how do I get rid of it?

January 19, 2024

If you’ve noticed your roof taking on a green hue, or maybe can see the heavy growth of moss on your roof, you might be wondering why that happens. Moss, algae, and lichen can grow on most types of roof systems including tile, composition shingles, and wood shake. It grows in cool, damp environments, so it's likely that where you’re noticing moss growth on your roof it is cool, damp and shady. 

Moss does not grow via roots, instead it gathers its water and nutrients through its leaves. Moss spreads through seeds that can land on the roof via small animals such as squirrels or birds. Moss, algae, and lichen can be invasive and rapidly growing. It is not just the appearance that is a problem though. 

A roof system covered in moss can prevent proper ventilation and can prevent heat from escaping the attic. It can also trap moisture which leads to rot, bacteria growth, and mold growth. 

The presence of this type of growth can also drastically reduce the lifetime of the roof system. Not only does it physically eat away at the roof material, but it can also creep up underneath shingles and tiles, lifting them, and rotting away at the underlayment, causing leaks. 

Luckily, you can prevent these types of problems by hiring a knowledgeable roofing contractor. Attempting to remove moss, algae, or lichen from your roof can be incredibly dangerous, adding a slippery surface to an already dangerous job. Hiring a professional that knows how to navigate the roof system is imperative. It's also important to know how to safely remove the moss without damaging the roof system. For instance, some people may choose to pressure wash a roof, which can cause serious damage to a roof system. 

There are products such as “moss out” that a reputable roofing contractor can spray onto the roof that when left can kill the moss and prevent it from growing back. It is best to let this spray soak into the roof system. Once dead, the moss can be broomed off the roof surface. This procedure often does not remove the green hue from the roof surface that’s left by lichen, but it does kill the moss and prevents it from growing and damaging the roof system further.  

Moss, algae and lichen on your roof system is never something you should ignore. Properly maintaining your roof system, including removing moss growth is imperative to keeping your roof healthy and your home protected. If your roof needs maintenance, American Eagle Roofing is here to help!