Moss on asphalt shingles grows into the shingle, lifts the edges, and traps moisture that works the seal strip loose. Before you clean, check the shingle manufacturer's instructions — the wrong method can affect your warranty.
Why the manufacturer matters
Some shingle warranties specify approved cleaning methods and products. Using pressure washing or an unapproved chemical could affect coverage, even if it removes the moss. Read your warranty language before you act.
Never pressure wash
High pressure can strip the protective granules and may void warranties. Low-pressure application of a roof-safe solution kills the moss at the root; heavy moss may need a follow-up as it dies and releases over a few weeks.
Lifting edges are a roofer issue
If the moss has already lifted, cracked, or curled the shingles, that is damage, not staining. A clean will not re-seal lifted shingles — that is a roofer's repair.
Five-minute self-check
- From the ground, photograph the moss clumps and where they are.
- Note whether shingle edges are lifted or curled.
- Find your shingle warranty and check its cleaning language.
- Check for interior water stains that mean a leak.
- Decide if the moss is light (a clean) or heavy (a roofer may be needed).
Related reading
See our roof washing page and our post on black streaks on the roof.