Roofs · 4 min read
Lichen and moss on your roof: why water-blasting is the wrong fix
Why high-pressure water-blasting damages roofs, and how a soft wash and treatment removes moss and lichen safely on Colorsteel and tile roofs.
- Moss and lichen hold moisture against your roof
- Water-blasting can strip coatings and erode tiles
- A soft wash plus treatment works gradually and lasts longer
Lichen and moss are common on Canterbury roofs, especially on shaded slopes and under trees. They look untidy, but the bigger problem is what they do to the roof underneath.
What lichen and moss do to a roof
Growth holds moisture against the surface. On metal roofs that can speed up wear on the coating, and on concrete tiles it slowly breaks the surface down. Moss also traps debris that ends up in your gutters.
Why water-blasting isn’t the answer
High-pressure water can strip the protective coating from metal roofing, erode concrete tiles and drive water under flashings. It also tends to leave the roots of the growth behind, so it comes back quickly.
How a soft wash works
A soft wash applies a cleaning solution at low pressure to kill moss, lichen and mould, then rinses the roof clean. A follow-up treatment keeps working after the visit, so remaining growth loosens and washes away with the weather.
What to expect
- Loose moss and mould come off on the day
- Stubborn lichen fades over several weeks as the treatment works
- Regrowth is slowed, so the roof stays cleaner for longer
- Your roof’s coating and tiles stay intact
Read more about our roof cleaning and treatment, or see how long roof treatments take to work.
Frequently asked questions
Does lichen damage a roof?
Yes, over time. It holds moisture and grips the surface, which wears coatings on metal roofs and breaks down concrete tiles.
Maidly looks after homes across Christchurch with eco-friendly methods and a 100% work guarantee on every service. Request a free quote.