What is Moss?

Definition

A bryophyte plant that establishes on roof surfaces in shaded, moist environments, particularly on north-facing slopes and under trees. Unlike algae, moss has rhizoid root-like structures that physically lift and separate shingle layers as the plant grows, causing significant physical damage over time. Moss retains moisture against the shingle surface, accelerating deterioration. Treatment with zinc or copper sulfate solutions or manufacturer-approved biocides is effective.