Should roof moss and gutter cleaning be handled together?
Short answer. Yes, and in that order: treat and remove the moss first, then clean the gutters, because dead moss loosened from the roof washes down and clogs gutters and downspouts. Use a low-pressure treatment and gentle removal rather than a pressure washer, which strips the granules that protect the shingles.
Why they go together
Moss grows where roofs stay shaded and damp, usually the north slopes and areas under trees. The same trees fill the gutters, and clogged gutters keep the roof edge wetter, which helps moss creep down to the eave. Treating one without the other tends to bring both problems back.
The right sequence
- Treat the moss on a dry day with a product labeled for roofs, applied at low pressure. Protect plants below and follow the label.
- Wait. Most treatments need days to weeks for the moss to die and loosen.
- Remove gently. Light brushing downhill, or letting rain wash it off. Never scrape or pressure wash, which lifts shingle edges and blasts off granules.
- Clean the gutters and flush the downspouts after the moss has come off.
- Look for damage. Thick moss lifts shingle edges and holds water against the decking.
Keeping both away
- Trim limbs to let in sun and air.
- Zinc or copper strips near the ridge slowly release metals that discourage regrowth below them.
- Keep gutters flowing so the eave dries out between rains.
Who does what
Moss treatment and gutter cleaning are cleaning services. Robust Roofing does not offer either, but a roof inspection afterward tells you whether the moss did harm. See moss and lichen on roofs, black streaks and algae on the roof and trees and your roof.