What kind of moss brush should you use on a roof?
Short answer. Use a soft to medium nylon or polypropylene brush on an extension pole, never a wire brush or stiff deck broom, and always stroke downhill so you do not lift shingle edges. A brush works best after a moss treatment has killed the growth, when the dead moss loosens and sweeps off with light pressure.
What to look for in a roof moss brush
- Bristles: soft to medium synthetic bristles flex over the shingle texture without grinding off granules. If the bristles feel stiff in your hand, they are too stiff for shingles.
- Extension pole: a telescoping pole lets you reach from a ladder or the eave line instead of walking on slick, mossy shingles.
- Angled head: a head that can tilt keeps the bristles flat against the roof as you reach farther up the slope.
- Width: a moderate width is easier to control on a pole than a wide push broom.
How to brush without damage
- Treat the moss first and wait until it has browned and loosened, usually days to a few weeks.
- Work only on a dry roof; wet moss is slippery and clings harder.
- Brush in the direction water flows, from the ridge toward the eaves. Brushing upward drives bristles under shingle edges and can break their seal.
- Use light pressure and let the brush do the work. If moss will not come off, give the treatment more time instead of scrubbing harder.
- Rinse with a garden hose at normal pressure, then clean the gutters.
Tools that do more harm than good
Wire brushes, stiff deck brooms, metal scrapers, and rotary scrubbers strip the protective granule layer, exposing the asphalt to the Georgia sun. Pressure washers are worse. Some granule loss from brushing dead moss is normal; bare black patches are not.
For causes and prevention, see moss and lichen on roofs.