An insurance letter about roof streaks or moss is tied to a specific policy and a specific request, not a general opinion about your roof. Before you clean anything, read the exact wording of the letter and any referenced policy language.
What the letter usually asks for
Most letters ask you to address a condition — black streaks, moss, or lichen — that the insurer believes affects the roof. Some request proof of maintenance. Note exactly what the letter asks for and by when, and whether it requires a particular method or contractor.
Never pressure wash a roof
High pressure can strip the protective granules off asphalt shingles and may void some manufacturer warranties. The black streaks are an airborne algae, not dirt — pressure will not kill it and can damage the shingles. Low-pressure roof washing treats the organism at the root.
Check your warranty too
Your shingle warranty may have specific language about cleaning methods and products. Read it before you act, because the wrong method could affect coverage independent of what the insurer wants.
Five-minute self-check
- Read the letter and note the deadline and exactly what is requested.
- From the ground, photograph the streaks, moss, or lichen.
- Look for lifted or curling shingles (a roofer issue, not a clean).
- Find your shingle warranty and check its cleaning language.
- Note any interior water stains that mean a leak, not a dirty roof.
Related reading
See our roof washing page and our post on moss and manufacturer instructions. Confirm your specific insurer and warranty requirements against your own documents.