A roof that sits in a shaded area could easily begin to be affected by moss. That’s a problem, because the moss can cause water to back up under the shingles, sending it off to places it doesn’t belong. This could result in damage to your roof sheathing or leaks inside your home. If cutting down trees to allow sunlight in is not possible or preferred, you’ll need to have the roof cleaned and the moss removed.
This Old House offers this helpful video on how to remove the moss.
The process isn’t complicated. It involves brushing as much of the mold off as possible, then treating the roof with a moss-killing solution. Some people also install a zinc strip at the peak of the roof. This may help prevent additional mold growth. While not difficult, removing moss on your own can be dangerous, and is best left to a professional unless your roof has a low pitch or is close to the ground. Fall is a good time to check for moss, so take a look now before blocked water freezes and does even more damage.