What is the best method for removing moss from a roof?
Short answer. The most reliable method is to kill the moss first and remove it second: apply a labeled moss treatment on a dry day, give it days to weeks to die and loosen, then brush the remains downhill with a soft brush and let rain finish the job. Skip pressure washers and stiff scrapers, which strip shingle granules and can push water under the shingles.
Step by step
- Check the forecast. Pick a mild, dry day, with the rain-free period the product label requires after application.
- Protect plants and surfaces. Wet down and cover shrubs below the eaves, and keep runoff out of ponds, streams, and storm drains.
- Clear loose debris. Use a leaf blower or soft brush to remove leaves and pine needles so the treatment reaches the moss.
- Apply the treatment. Use a pump or hose-end sprayer, soaking the moss evenly. Avoid walking on wet, mossy shingles; work from a ladder where you can.
- Wait. Moss typically turns brown or orange over several days to a few weeks as it dies and loosens its grip.
- Brush downhill. With a soft brush on an extension pole, sweep dead moss down the slope, never upward under the shingle edges.
- Rinse gently. A garden hose at normal pressure, or simply the next few rains, clears the rest.
- Clean the gutters. Dead moss collects there and can clog downspouts.
Prevent the regrowth
Trim branches to let in sun, keep valleys clear, and consider zinc or copper strips near the ridge. Moss returns quickly to shaded, debris-covered slopes. See trees and your roof and moss and lichen on roofs.
When to stop and call someone
If the roof is steep, two stories high, or the shingles crack or break when brushed, stop. Brittle shingles are a sign the roof is near the end of its life, and no cleaning method will fix that.