What are the green/Black patches or coloured marks on my render, how do I remove it?

Green, black or other coloured marks on render are often caused by algae growth. Algae spores can settle on almost any external surface, including glass, plastic and render, and thrive in damp conditions. Areas shaded by trees, shrubs or nearby buildings are particularly susceptible, as they remain moist for longer periods.

To remove algae growth, the surface can be cleaned using a suitable specialist cleaner, such as SPS Envirowall's Antimoss treatment. Always follow the manufacturer's instructions when applying cleaning products.