There's something quaint and maybe even a bit romantic about a moss-covered roof. But as visually pleasing as a mossy roof may be, moss growth is actually terrible for your shingle roof. Here are a few key things you should know if your roof is covered in miss — or just starting to grow moss.
Moss eats away at shingle roofs.
You may have heard that moss does not have roots. This is technically true, but it does not mean that moss does not grow down into a roofing material. Moss does have structures called rhizoids which anchor it into the substance that it grows on. These rhizoids physically and chemically disrupt the shingles that they anchor themselves into. So, moss can and does cause shingle damage from the time it starts growing. Moss growth on the roof is therefore undesirable.
Roofers should remove moss.
When you see moss starting to grow, you may figure you'll just scrape it off, or maybe powerwash it away. But it's actually best to call a roofer to remove the moss. If you go about it too aggressively, which homeowners often do, you could do more damage to the shingles and remove too many granules from their surface. Roofers know how to gently remove moss. Usually, they will spray it down with roof-friendly herbicides, and let them kill the moss over a period of days. When the moss is dead, it dries out and is easy to remove with special brushes.
You can take steps to prevent future moss growth.
After having moss removed from your roof, you should not just sit back and wait for it to grow back. There are things you can do to keep it from growing back.
Your roofer might give the roof another good, thorough coat of herbicide to prevent new moss from taking root. They may also install zinc or copper strips across the roof. Moss does not grow well in the presence of zinc or copper. You can also work to clear any shade that might be cast on your roof. Moss loves to grow in the shade. This may involve removing or trimming back a tree.
Moss-covered roofs may look cool, but moss and roofs don't mix very well. If you want to protect your roof, having the moss removed is a good first step. Then, talk to your roofer about steps you can take to prevent the moss from coming back.