- Sometimes the moss can be cleaned without any additional cleaning agents. Using a firm brush on a long handle, brush the shingles in a downward manner, breaking apart and removing the roof moss. Do not brush upward toward the top of the roof, as this can tear and lift shingles, causing an even larger problem. When needed, wet the area with a light misting of clear water, then continue brushing.
- Choosing the right bleaching agent is essential. Chlorinated bleach should not be used, as it can discolor the roofing and also damage vegetation on the ground when it is rinsed off the roof. Chlorinated bleach can also expedite damage to gutters and downspouts, because it will speed up the corrosion process. Oxygen bleach is a better solution, and can be purchased at any home improvement or hardware store. The oxygen bleach usually comes in a powdered form, which must be mixed with water. Follow the usage instructions on the package, which will typically direct you to use a spray bottle attachment that can be twisted onto the garden hose. This will stream the water and oxygen bleach onto the roof, where you will let it sit for 20 minutes. Then scrub with a brush in a downward motion and the moss will easily be removed. For tough areas, repeat this process as needed. When all moss has been removed, rinse with a stream of clear, cold water to remove any remaining residue. It is best to follow this process on an overcast day when sun is not in direct contact with the roof. Sun beaming onto the roof can dry the bleach before it has time to work and break apart the moss.