Moss on the roof: why it destroys tiles and when to clean it
Moss on the roof is not (just) a cosmetic issue. It is a structural problem in slow motion.
What moss does to tiles
Moss works like a sponge: it holds water on top of the tile for weeks. That constant moisture wears the material down, and the roots of the moss get into the joints and hairline cracks; with the cycles of heat and cold, the tile lifts and cracks. The result: leaks, rotting roof timbers, and repairs that cost thousands.
The warning signs
- Green or black patches you can see from the street
- Tiles with “cushions” of moss in the joints
- Gutters that clog with bits of moss
- Damp patches on the attic ceiling
Cleaning is more than washing
Washing removes the existing moss, but if you stop there, it comes back within months. The step that makes the difference is the anti-moss (algicide) treatment applied at the end: it kills the spores and delays regrowth. Lichens (the orange crusts) are even harder and need their own method. And the pressure has to be controlled: old tiles are fragile.
How much it costs
The price of a roof depends on access and height, so we give a tailored quote from photos or a visit. It is always a fraction of the cost of replacing rotten timbers. Learn more about the service →