There are several reasons why renders used in the UK often fail and are subject to algae growth, cracks, and delamination. Some of these factors include:

  1. Climate and environmental conditions: The UK experiences a relatively damp and humid climate with frequent rainfall. This can lead to an increase in moisture penetration into the render, providing an ideal environment for algae growth. Temperature fluctuations also contribute to the expansion and contraction of the render, causing cracks and delamination over time.
  2. Incorrect application: The improper mixing of materials, incorrect application techniques, or inadequate surface preparation can all result in a compromised render system. This increases the likelihood of cracks, delamination, and algae growth.
  3. Material quality and compatibility: The use of low-quality or incompatible materials in the render system can cause premature failure. It is crucial to select materials that are compatible with the specific substrate and environmental conditions.

The use of polymer-silicate-based systems could be beneficial compared to acrylic and silicone systems for the following reasons:

  1. Breathability: Polymer-silicate-based renders offer superior breathability, which allows moisture to evaporate from the building envelope more efficiently. This reduces the risk of algae growth and minimizes the potential for trapped moisture to cause cracks or delamination.
  2. Durability: Polymer-silicate-based renders are known for their high resistance to weathering, which makes them less susceptible to degradation over time. This results in a longer-lasting, more durable finish that is less prone to failure.
  3. Alkali resistance: Polymer-silicate-based systems are highly resistant to alkalis, which helps prevent algae growth by creating an unfavourable environment for its development. This contributes to a cleaner, more aesthetically pleasing facade.
  4. Compatibility: Polymer-silicate-based renders are well-suited for use with mineral substrates and insulation materials, such as mineral wool, which enhances their compatibility with various building systems.

In conclusion, polymer-silicate-based render systems offer several advantages over acrylic and silicone systems, including improved breathability, durability, alkali resistance, and compatibility. These qualities can help mitigate common issues such as algae growth, cracks, and delamination experienced in the UK’s challenging climate and environmental conditions.

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