Why Oregon roofs grow moss
Shade, moisture, tree debris, limited drying, and rough roof surfaces create favorable conditions. Moss can hold water, obstruct drainage, and lift vulnerable material edges.
Avoid destructive cleaning
High-pressure washing can remove granules, damage wood fibers, force water into laps, and void product guidance. Use roof-appropriate methods and protect landscaping, gutters, siding, and runoff.
Reduce the conditions
Keep drainage paths clear, improve safe sunlight and airflow where appropriate, correct overhanging debris sources, and schedule routine inspections rather than waiting for heavy growth.