Possible causes
- Shaded or north-facing roofs that stay damp
- Overhanging trees
- Rough-textured concrete tiles that hold moisture
Warning signs
- Thick moss on tiles and ridges
- Moss clumps in gutters
- Tiles lifting where moss has built up underneath
Typical solutions
- Careful removal by hand
- Clearing gutters and downpipes
- Repairing any tiles damaged underneath
When to call a roofer
When moss is blocking gutters or lifting tiles. Pressure washing can damage tiles, so it isn't recommended.
This is general guidance. The cause of any roof problem can only be confirmed by inspecting the roof.