Moss growth on roofs in Portland, Oregon can cause damage to shingles and other roofing materials. Moss absorbs and retains moisture, which can lead to rot, leaks, and other types of damage. Moss can also make the roof heavy, putting extra strain on the structure of the building.

Additionally, moss can block gutters, causing water to back up and damage the roof. The moss itself can also be unsightly and may decrease the curb appeal of the property.