Pressure washing looks impressive but can lift tile coatings, drive water under sheeting, and blast paint off eaves. For most residential roofs, soft washing is safer and equally effective.
What soft washing actually is
Soft washing uses low-pressure water combined with biodegradable cleaning agents to lift moss, lichen, mould and grime from the roof surface. The chemistry does the work, not the pressure.
- Low pressure — safe on tiles, Colorbond® and paintwork
- Kills moss and lichen at the root, so it doesn't grow back as fast
- Won't drive water under roof sheeting
- Safer for solar panels and skylights
When pressure washing is appropriate
Pressure washing has its place — driveways, concrete paths, some hardstand surfaces. On a residential roof, it's almost always the wrong tool.
Signs your roof is ready for a soft wash
Common triggers Coast Flow sees on South Coast homes.
- Black streaks or green tint on the roof
- Lichen patches on tiles
- Visible moss in valleys or ridges
- Reduced solar output from panel shading
Key takeaways
- Soft washing is the safe default for residential roofs
- Pressure washing can strip tile coatings and drive water under sheeting
- Combine roof washing with a gutter clean for best results
- Ask what pressure and chemicals will be used before booking any roof clean