Is Moss on a Roof Harmful?

Dec 8, 2021 | Roofing

As a homeowner, you may be wondering if moss on a roof is harmful. Instead of going the long way about this question, let’s cut to the chase. Yes, moss on your roof can cause damage. While it looks beautiful in a forest and lining trees, it’s not something you want to find thriving on your roof as well.  



Why Is Moss on a Roof Bad? 

It might seem simple and harmless with its flowerless, fluffy look, but make no mistake — moss is an enemy to your roofing. Moss thrives in shady damp areas, and if it takes root on a roof, it will damage it. As it lays roots on the roof between the tiles or shingles and gradually pushes them apart, it’ll allow moisture into the attic space. A damp or leaking attic space can mean a lot of other problems which need fixing, such as bacteria, mold, and eventually big holes in the roof.  


getting rid of roof moss


How to Get Rid of Roof Moss 

If you have a problem with moss on your roof, there are three main ways to get rid of it. Using a garden hose, some will wash straight off, leaving a few parts that might still need to be hand scraped away. Don’t be hasty in reaching for a pressure washer. If there is any damage caused by the moss, you may make it worse and fill your attic with water.  

Moss powder is probably the most effective option for moss removal, but comes with the most cautions as it can harm wildlife and vegetation. It does kill moss very effectively, but should only be used with care to ensure it doesn’t get into the area surrounding your home. 

Diluted bleach will also kill moss. As with water, you may still need to scrape some stubborn bits away. Bleach may stain clothing and the tiles on your roof, so it is worth testing an area first before throwing bleach on the roof. You also need to be careful with the runoff and ensure no animals are around. 



How to Prevent Roof Moss

The best way to avoid having to remove moss is to prevent it from taking up roots on your roof in the first place. Keeping gutters clear of dead leaves, bits of dirt, and twigs will help prevent the growth of moss. If there are trees above or very close to the roof, trim them back so that they don’t drop onto the roof. This can also help prevent bird droppings on your roof. An extra step you can take is to place zinc strips on your roof that will wash a small amount of zinc over the roof every time it rains, though these will need to be replaced every year.  

As with any other type of roof maintenance, if you’re unsure, don’t hesitate to call in a roofing specialist such as Story Roofing. If you find that you are unable to clear away moss on your own, or you notice that the moss has already done damage to your roof, a roofing expert can help you repair the roof so that you can avoid bigger problems.