Concrete is a popular building material known for its durability and versatility, but over time, you may notice that your exterior concrete surfaces start to develop unsightly staining. This discoloration isn’t just a cosmetic issue — it indicates the presence of harmful microorganisms like mold, mildew, and algae, as well as contaminants like dirt and organic debris. Understanding why concrete changes color can help you protect your surfaces with targeted maintenance plans that include the right concrete cleaning method.
Here’s a quick breakdown of what microorganisms might be causing the different stain colors on your concrete surfaces:
- Black stains are often caused by a cyanobacteria called Gloeocapsa magma. It thrives on concrete that is in damp, shady conditions.
- Green stains typically result from Cladophora or Chlorophyta algae, which also grow in moist, shady conditions. Moss and mildew may also add to green discoloration.
- Brown stains are generally left behind from tannins in leaves, rust from nearby metal surfaces, or certain soil-borne algae.
Left untreated, these contaminants trap moisture against the concrete, which can accelerate degradation and create slip hazards.
The most effective way to remove these contaminants is by investing in professional concrete cleaning services, particularly soft washing. Unlike high-powered pressure washing, soft washing uses cleaning solutions specifically designed to target these microorganisms and slow their regrowth. This means your surfaces are restored to their original color and also remain clean and safe for longer.
If the concrete surfaces around your property exterior are showing black, green, or brown stains, our team would be happy to come assess them and provide a quote for professional concrete cleaning. Reach out today to learn more or get scheduled!