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While render can instantly improve and transform the appearance of your home, if it becomes damaged or stained, it can also quickly become an eyesore. As it is constantly exposed to the elements and pollution, it is normal for rendered surfaces to become stained and damaged over the years.

Green or black stains on render are some of the most common stains you will come across. But while these stains are unsightly, they can be removed with relative ease, and you can soon have your rendered walls looking as good as new.

Continue reading to learn more about green stains on render and how to remove them.

What Are the Causes of Green Stains on Render

The most common causes of green stains on render include:

Green Algae

Algae growth is the most common cause of green stains on your rendered surfaces. Algae thrive in damp conditions and can grow on most surfaces. Algae spores are airborne, so all they have to do is land on an outdoor surface where they grow and spread. Although algae isn’t technically a plant, just like plants, it does have the ability to photosynthesis, meaning that it can grow on surfaces that many other organisms can’t.

If there is heavy rainfall or if your home has a water leak, you may see green algae growing on your home’s exterior. The good news is that green algae is one of the easiest algae types to remove. If the algae is removed quickly, it does not pose a significant risk to the structure of your home.

Moss

Moss can be classified as plant life, and while it is most commonly found on roof tiles, it is slowly becoming more prevalent on rendered home surfaces. Especially during winter or wet weather conditions when the combination of moisture and the heat coming from inside your home combine to make the perfect growing conditions.

Like green algae, moss will not cause severe damage to your home if removed quickly, but it will make it look unsightly.

Green Mould

Green mould is another type of fungal growth that is sometimes used interchangeably with green algae.

Just like green algae and moss, it thrives in wet environments that don’t receive much sunlight. It can quickly spread across rendered surfaces after heavy rainfall, leaving a green stain in its wake.

Plant Life

Although it might initially have an aesthetic appeal, plants that grow near your home may cause damage to the structure, especially when the plants are wall-growing plants like ivy, Jasmine or bougainvillea. Once wall-growing plants start growing and working their way up your home, they can cause cracks in the render, leading to serious structural damage if left untreated.

Risks

Green stains are not a pretty sight, but even more importantly, they can cause significant structural damage to your home if left untreated.

These risks can include:

  • Excess moisture: Fungi growth, like algae, mould, and moss, is a sign of excess moisture being present. This excess moisture can penetrate the render and go through to the structure of the home, damaging the integrity of the walls and causing cracks and further render damage.
  • Other biological growth: Mould growth can result in a neverending cycle of dampness, which means they can encourage other biological organisms to grow, causing decay and damage to the render.
  • Render degradation: Fungi growth can damage the integrity of the render and paint on the surface of your home, leading to it crumbling and flaking.
  • Decreased property value: A clean, well-maintained home will always look more appealing than a run-down, stained one. Having green stains on your home is an eyesore and can make it more difficult to sell.

Removing the Stains

The most effective ways to remove green stains from rendered walls include:

  • Softwashing/low-pressure washing: One of the most effective and best ways to clean green stains off the render is by softwashing.Softwashing includes using a low-level pressure washer, hot water, and a biocide (algacide or fungicide) to remove the green stains. It is both gentle and effective and won’t damage the render or the structure of your home.
  • Handwashing: If the green stain is only spread over a small area, you can easily handwash it using a brush, water, detergent, or algaecide.
  • Steam cleaning: Hot steam can break down the organic growth on rendered surfaces. There are usually no chemicals involved – just hot steam and a little water.

Ways to Prevent Green Stains on Rendered Walls

The best ways to avoid getting green stains on your rendered walls include:

  • Regular maintenance: Cleaning your rendered walls every few months with a stiff, bristled brush, low-pressure water, and some gentle detergent ensures that you are removing any debris or organic growth before it spreads.If you notice any cracks or damage to the render, call a professional renderer to come out and repair it before the damage worsens.
  • Using an algaecide: Using an algaecide after you clean the render can prevent any regrowth of algae.
  • Protective render layers: Some protective primers can be applied on top of the render layers. These primers are water-resistant and can help to prevent algae growth.
  • Sun exposure: If you have multiple trees or plants surrounding your home, cut back as many as possible to ensure your home gets some exposure to the sun during the day. Sun exposure will help prevent moisture buildup, and the sun’s antiseptic qualities will help to fight algae growth.

If you keep having recurring problems with green stains on your rendered home, it is best to call the professionals. At Sydney Cement Rendering, we know the effective and quickest ways to safely remove green stains without damaging the render or your home’s structure.

Contact us at 0402 704 984 or visit our website: https://sydneycementrendering.com/ to find out more about what we offer! We take pride in being Sydney’s trusted rendering experts, providing our customers with the highest quality rendering services.