- What it looks like
- Green or grey growth, thickest on north-facing slopes and under overhanging trees.
- What is actually happening
- Shade and damp. Croydon has heavy tree cover across Shirley, Selsdon, Purley and West Wickham, plus around 33,000 council street trees, so shaded slopes are common here.
- Why it matters
- Less than people are told. Moss itself rarely causes leaks. What it does do is shed into gutters and block them, and it holds moisture against the covering. Worth clearing, not worth panicking about, and be wary of anyone who leads with it.