How do you remove moss and lichen from a roof?
Short answer. Kill both with a roof safe treatment, then remove the moss gently once it loosens. Lichen clings much tighter, so after treatment it is usually best to let rain and weather wear it off over months rather than scraping, which tears granules off the shingles.
Why lichen is harder than moss
Lichen is a partnership between a fungus and an alga or cyanobacterium. It bonds tightly to the shingle granules, grows slowly and survives dry spells. Moss, by contrast, sits on top and loosens readily once dead.
Removing moss
- Apply a roof safe moss killer on a dry day, following the label.
- Wait for the moss to brown and loosen, often days to a few weeks.
- Push it off by hand or with a soft brush, always downslope. Let rain do the rest.
Removing lichen
- Treat the lichen with the same kind of product; some labels list lichen specifically.
- Do not scrape. Dead lichen often stays visible for months but fades and loosens over time.
- Repeat treatment if it is still growing after a season.
What to avoid
- Pressure washers, wire brushes and metal scrapers.
- Walking on wet or freshly treated shingles.
- Letting chemicals run into gardens, ponds or storm drains.
Preventing both
- Sunlight and airflow: trim branches over the roof; see trees and your roof.
- Clean valleys and gutters; see pine needles and leaves on the roof.
- Zinc or copper strips near the ridge.
After heavy growth is gone, look for bald spots where granules are missing. Those areas age faster in Georgia sun. More in moss and lichen on roofs.