How to Safely Remove Moss From Your Roof

Moss on a roof is more than just an eyesore; it is a moisture-trapping sponge that slowly pulls the granules off your shingles and forces water beneath them. When you see green patches, you are looking at a system that is actively compromising the structural integrity of your roof by holding dampness against the surface long after the rain has stopped. Done well, removal is a low-pressure affair that favors chemistry over force. You never want to power wash asphalt shingles, as you will strip away the protective mineral coating that gives them their lifespan. Instead, focus on killing the organism at the root and letting the elements finish the job.

1. Sweep the slate clean. Use a soft-bristle broom to gently sweep away loose leaves, branches, and pine needles. Work from the top ridge down toward the gutters to avoid lifting the shingle edges.
2. Brew the killer blend. Combine a roof-safe moss cleaner or a mixture of one part oxygen bleach to three parts water in a pump sprayer. Ensure the mixture is well-diluted to protect your siding and landscape plantings.
3. Saturate the target. Spray the affected areas starting from the top and working down, saturating the moss thoroughly. Keep your movements steady to ensure even coverage without soaking the eaves excessively.
4. Let chemistry work. Allow the cleaning solution to sit for 30 to 45 minutes, or as directed by the manufacturer. You will see the moss begin to lose its vibrant green color as it reacts to the chemical.
5. Brush away the dead. Once the moss has turned brown and died, use your soft-bristle broom to gently brush the dead material off the shingles. Use light strokes to avoid damaging the shingle surface.
6. Clear the channels. Flush your gutters with a hose to clear out any dislodged moss and cleaning solution residue. Ensure the downspouts are clear so water drains away from your foundation.