Moss and Your Roof: What You Need to Know

Feb 21, 2017

Moss can make rocks appear rustic, but when found on a rooftop, the plant is a problem. As a homeowner, it’s important for you to understand the issues surrounding rooftop moss growth. Knowing what moss can do to your roof and how you can prevent this damage can help you take care of your property and prevent roof leaks.

Moss Growing Conditions

Moss grows best in damp, cool, shady environments. The plant can be most often found on properties with a lot of large, old trees and wooded areas. The northern side of a roof is usually the most vulnerable to moss growth because this is the part of the home that gets the least direct exposure to sunlight in the northern hemisphere.

Moss Damage Causes

Moss traps moisture onto the roof and prevents it from drying. Moss also causes the shingles to deteriorate by curling up the edges and growing underneath. Over time, an untreated moss problem can cause water damage under the sheathing. The more established a moss colony becomes, the more damage occurs and the more difficult the plant is to remove.

Moss Removal Solutions

The best way to remove moss from your roof is to take action as soon as the moss has begun to grow. Inspect your roof regularly to look for tiny growths of moss around the corners and edges of the shingles. Moss often appears in small clumps.

Remove moss by carefully scrubbing it with a long-handled scrub brush, taking care not to hurt your shingles. A power washer will do the same job, but it has a higher chance of causing damage. Diluted bleach can also kill moss, but apply it sparingly—the runoff might harm any plants that grow under your eaves. If you’re applying chemicals like bleach, make sure to wear protective clothing, including gloves.

Moss growth starts small but can spread quickly, especially in spring and fall when temperatures are mild and rainfall is common. If your home has had a moss problem in the past, check for moss every year in the late spring and mid to late fall.

Moss Prevention

After moss has been removed, there are many ways to help prevent the return of moss on your property:

  • Clean your gutters. Your home’s gutters carry away moisture and keep your roof dry. When your gutters are clogged, this can slow roof drainage and lead to moss problems. Clean your gutters on a regular basis throughout the year to prevent these problems.
  • Cut away overhanging branches.  Overhanging branches can drop rain and moss spores onto your roof, and can reduce air flow around your roof, thus preventing the roof from drying after rainfall. Cutting back overhanging branches can help make conditions around your roof less favorable for moss growth.
  • Reduce shade. Moss prefer shade. Thinning the trees around your property and avoiding planting trees that will shade your home can help keep your roof in the sunlight.

Following the tips above can help prevent a moss problem from occurring and is especially important if you’ve had moss problems on your roof in the past.

Moss Assistance

Installing zinc strips, copper strips, or galvanized flashing along the ridge of your roof can also help prevent moss from returning. Run off from the strips or flashing releases tiny particles onto the roof that effectively kills the moss and keeps it away. These items can work for years or decades, depending on the product used.


If you have questions about your roof, call Advantage Roofing and Home Exteriors in Cincinnati. We can give you expert advice and provide repairs when necessary. To find out more, contact us.