Render Turning Green
External render developing green algae or moss growth, making the walls look dirty and neglected.
What Is Causing This?
- 1North-facing or shaded walls staying damp
- 2Textured render trapping moisture and organic matter
- 3Trees and bushes close to the wall reducing air circulation
How Urgent Is This?
This is a cosmetic issue. It is not causing damage and can be addressed in your own time.
What Needs to Be Done
A rendering specialist will soft-wash the render with a biocide treatment to kill the algae and prevent regrowth. Pressure washing may damage the render and should be avoided on soft finishes.
How Much Will It Cost?
National average estimate
Labour: £850 – £2,233 | Materials: £417 – £1,267
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Prices are estimates based on typical UK rates. Actual costs depend on the specific issue, accessibility, and your location. All quotes from tradespeople on Tradesfolk are completely free.
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Ask a QuestionPlanning Permission Guidance
Some fixes for this problem may require planning permission or building regulations approval. Check if your project needs permission:
How to Prevent This
Trim back vegetation near rendered walls. Apply an algae-resistant coating after cleaning. Improve air circulation by cutting back overhanging branches.
Related Problems
Other Rendering Specialist Problems
Cracks appearing in the external render, ranging from hairline to wide splits that expose the masonry beneath.
Sections of external render detaching and falling from the wall, exposing bare brickwork or blockwork.
Damp patches visible on internal walls that correspond to areas of external render, especially after rain.
Pebbledash coating losing stones or whole sections detaching from the wall.