With its widespread use and essential purpose, it's not uncommon for homeowners to encounter areas of render that need repair. From hairline cracks to delamination, we’ve picked out five common rendering repairs at home.  

Rendering is commonly seen on domestic properties. A bit like plaster, it’s a coating that’s applied, usually to the exterior surface of the house, to protect the building against the elements and to create a decorative finish. It’s sometimes used in interiors, but that’s usually for decorative effects. 

1. Hairline cracks in render 

Cracks are a common repair at home, and they can be caused by many factors.  

What causes hairline cracks in render? 

  • Movement of the property 
  • Temperature changes 
  • Poor application of the render 
  • Shrinkage of the render whilst drying 
  • Moisture 

Repairing hairline cracks in render 

While hairline cracks may seem like a minor issue and can often be repaired by using an exterior filler, it’s important to check and assess if there are any other underlying issues.

 

2. Blown/hollow render 

If you’re seeing cracked or bulging areas of render or bits of render that are falling away, the render may be blown.  

What causes hollow or blown render? 

The main cause is water from cracks or an inadequate damp proof course getting trapped behind the render. With changes in temperatures, the water expands when it freezes, pushing the render away from the wall. 

If left, it could lead to damp inside the property or damage to the bricks and exterior walls.  

3. Staining and discolouration of render 

There are many factors that can contribute to staining or discoloured patches forming on your rendering.

Common causes of stained or discoloured render 

  • Algae and moss growth 
  • The weather 
  • Pollution 
  • Rust 
  • Poor application leading to moisture ingress 

Treating stained or discoloured render 

Many stains can simply be cleaned through washing with a mild detergent, but professional or specialised treatments and services are available depending on the cause and extent of the staining and discolouration.  

4. Render delamination 

Delamination of render refers to any type of peeling, cracking or even flaking of the rendering, so blown or hollow render would also fall into this category.  

What causes render delamination? 

It’s often due to poor application of the render, specifically where the initial surface preparation isn’t done correctly, perhaps the render isn’t mixed correctly, or it’s applied in adverse conditions, so it’s dried out too quickly.  

5. Large cracks and holes in the render 

Affected by similar factors to the hairline cracks and delamination, larger cracks and holes in render can be caused by many issues: 

  • Moisture 
  • Structural issues 
  • Poor application techniques 

Repairing cracks and large holes in render 

While the underlying cause will need to be assessed, the cracks and holes themselves can often be fixed using an exterior filler. Unlike the hairline cracks, the repair process is more involved for larger cracks and holes, requiring cleaning, preparation, filling and match finishing of the area.  

As you can see, some rendering repairs are simple DIY fixes when armed with the right know how and tools, while others will require a thorough assessment of the issue and may need underlying problems addressing with the help of a professional.  

Ready to tackle your own rendering repairs? Gain the skills you need with our focused 5-day hands-on introduction to rendering course.