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Silicone Render Problems: Understanding and Troubleshooting Common Issues

Updated June 28, 2023
Fixing Silicone Render Problems: UK Homeowner's Guide

Silicone render has gained popularity as an external wall finish due to its durability, weather resistance, and low maintenance requirements. However, like any construction material, it can encounter certain problems over time. In this comprehensive guide, we will explore common silicone render problems, understand their causes, and provide effective solutions to address them. By identifying and resolving these issues, homeowners in the United Kingdom can ensure the longevity and visual appeal of their silicone-rendered surfaces.

Understanding Silicone Render

Before we delve into the problems, let's have a brief understanding of silicone render. Silicone render is a type of render that contains silicone additives, which enhance its flexibility, water repellency, and resistance to algae and fungal growth. It is typically applied as a decorative finish on external walls.

Common Silicone Render Problems

1. Cracking

Cracking is a common issue that can occur in silicone render. These cracks may appear as fine hairline fractures or larger fissures, compromising the appearance and performance of the render. Several factors can contribute to cracking, including:

  • Insufficient preparation of the substrate before applying the render.
  • Movement in the underlying structure, such as settlement or expansion/contraction.
  • Inadequate curing time for the render.
  • Poor application techniques or incorrect mixing ratios.

2. Blistering

Blistering refers to the formation of bubbles or raised areas on the surface of the silicone render. This issue can be unsightly and may affect the overall integrity of the render. Common causes of blistering include:

  • Trapped moisture within the render during application.
  • Inadequate drying or curing time.
  • Application of the render in direct sunlight or on hot surfaces.
  • Use of incompatible or poor-quality materials.

3. Discoloration

Discoloration can occur in silicone render, leading to variations in colour or unsightly patches. Several factors can contribute to discoloration, such as:

  • Exposure to environmental pollutants, such as air pollution or organic matter.
  • Poor-quality or contaminated render materials.
  • Insufficient cleaning and maintenance of the render.
  • Incompatibility with certain cleaning agents or chemicals.

4. Algae and Fungal Growth

Algae and fungal growth can develop on silicone render surfaces, particularly in damp or shaded areas. This can lead to the formation of green or dark patches, affecting the appearance of the render. Factors contributing to algae and fungal growth include:

  • Moisture retention on the surface of the render.
  • Lack of proper ventilation and sunlight exposure.
  • Presence of organic matter or dirt on the surface.
  • Environmental conditions conducive to growth, such as high humidity.

Troubleshooting Silicone Render Problems

Now that we have identified common problems, let's explore potential solutions to address them effectively:

1. Cracking Solutions

  • Ensure proper preparation of the substrate, including thorough cleaning and removal of loose material.
  • Apply a suitable primer or basecoat to enhance adhesion and flexibility.
  • Use appropriate techniques for applying the silicone render, following manufacturer guidelines.
  • Allow sufficient curing time between coats and in different weather conditions.
  • Monitor and control moisture levels during the application and drying process.

2. Blistering Remedies

  • Identify and address the source of moisture, ensuring proper ventilation and drying conditions.
  • Thoroughly inspect the surface and carefully remove any blisters or raised areas.
  • Allow the affected area to dry completely before applying a new layer of silicone render.
  • Ensure proper mixing of materials and follow manufacturer guidelines for application.
  • Consider applying a breathable topcoat or sealant to prevent future blistering.

3. Discoloration Fixes

  • Regularly clean the silicone render surface using mild detergent and water.
  • Test any cleaning agents on a small, inconspicuous area before applying them to the entire surface.
  • Use gentle scrubbing or pressure washing techniques to remove dirt and pollutants.
  • Consider applying an anti-algae or anti-fungal treatment to prevent growth and discoloration.
  • Consult with professionals for specialized cleaning solutions or restoration techniques, if necessary.

4. Algae and Fungal Growth Prevention

  • Improve ventilation and sunlight exposure in affected areas to discourage growth.
  • Regularly clean the surface to remove organic matter, dirt, and debris.
  • Apply a suitable anti-algae or anti-fungal treatment to prevent growth.
  • Consider applying a breathable topcoat or protective coating to inhibit moisture retention.
  • Address any underlying moisture issues to minimize the recurrence of algae and fungal growth.


Silicone render offers numerous benefits for homeowners in the United Kingdom, but it is important to be aware of potential problems that may arise over time. By understanding common issues such as cracking, blistering, discoloration, and algae/fungal growth, homeowners can take proactive measures to address and resolve these problems effectively. Proper preparation, quality materials, adherence to manufacturer guidelines, and regular maintenance are key to ensuring the longevity and aesthetic appeal of silicone-rendered surfaces. Remember, early identification and timely action are essential in preserving the integrity and beauty of your home's exterior.


Richard Renderman, your trusted rendering expert at MidRender, is passionate about the art of rendering. With years of experience,he crafts…

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