Answers · Materials and upkeep
How do I get moss off my roof?
The short answer
Low-pressure treatment and letting it die and weather off, not scraping and not pressure washing. Moss holds moisture against the shingle and its roots lift the edges, so it is worth removing — but pressure washing strips the granules and costs the roof more life than the moss would have.
Why moss matters more than algae
Algae is a surface stain. Moss is a plant with a root structure that holds water against the shingle and physically lifts its edges, which lets water under. On a shaded, damp slope it is a genuine maintenance item rather than a cosmetic one.
How it is done properly
- Treat with an appropriate solution applied at low pressure, protecting the landscaping below.
- Let it die and weather off over following weeks rather than scraping it.
- Remove what lifts away gently, working down the slope so nothing is forced under the shingles.
- Deal with the cause: trim overhanging branches, clear debris from valleys and gutters.
- Consider zinc or copper strips at the ridge, which release trace metal in rain and inhibit regrowth below.
Also asked
- Is roof cleaning worth paying for?
- On a shaded slope with established moss, yes, because the alternative is water held against the shingles. On a roof with light algae staining and no moss, it is cosmetic, and the money is better spent on gutters, flashing and an inspection.
General information about roofs and about hiring, not advice about your building. Roofing contractor licensing, permits, insurance practice and deductible rules are set state by state and province by province across the United States and Canada, so your own authority is the current answer.