Rendering the façade of your property is not entirely straightforward. As such, many problems can occur. These problems are either functional or visual, but all have their solutions and ways to prevent them. Whilst functional problems are naturally worrying, visual problems can leave you feeling disheartened. The process of refreshing your façade is not altogether cheap. Therefore if the finish is not what you envisioned, there will be issues. In today’s blog, we examine the different types of visual problems and how to fix them.
What visual problems occur on façades?
Efflorescence is when water seeps through the wall and dissolves minerals. As the water evaporates from the surface of the render, these minerals are left behind and form a white, powdery residue. Depending on the severity, efflorescence can be a cosmetic issue or indicate potential structural problems, like a faulty damp-proof course or high groundwater levels.
Efflorescence can often be removed by mechanically cleaning the surface using a stiff brush or pressure washing. However, it’s important to identify and address the source of water infiltration to prevent its recurrence. This may involve repairing cracks, improving drainage, or addressing other issues causing moisture penetration.
Mould and algae
Typically, these thrive in damp and shaded conditions. Mould might appear as black or dark green splotches, while algae often have a green or red appearance. Besides being unsightly, if left untreated, mould can lead to health problems for residents and cause the render to fail over time.
Treating mould and algae typically involves cleaning the affected areas with a mildewcide or fungicide, followed by proper ventilation and moisture control. In some cases, it may be necessary to remove and replace the affected render if the infestation is severe.
Fine hairline cracks can occur due to natural shrinkage as the render dries. However, larger cracks often indicate more serious issues. Problems such as structural movement, incorrect render mix (too much cement, for example, can make the render too rigid and therefore prone to cracking), or poor application techniques can be expensive to fix.
Small hairline cracks can be repaired using flexible sealants or patching compounds specifically designed for exterior use. Larger cracks may require more extensive remediation, such as cutting out and replacing the damaged render or addressing underlying structural issues.
Peeling or flaking
Render peels or flakes off if the original substrate is not properly prepared, if the wrong type or amount of bonding agent is used, or if the render dried too quickly (often due to applying in direct sunlight or high wind conditions). Render can also peel or flake due to a poor mechanical key.
To fix the peeling or flaking render, the loose or damaged areas need to be removed, and the surface should be properly prepared. This may involve repairing the substrate, applying suitable bonding agents, and reapplying a fresh layer of the render using proper techniques.
This refers to visible streaks or patches that appear on the surface of the render. It’s typically caused by moisture, often condensation, which allows for the migration of substances from the substrate or within the render itself. This can leave visible outlines of the underlying structure’s features.
Ghosting is often difficult to eliminate completely, but improving ventilation and addressing moisture issues can help reduce its appearance. Regular cleaning and maintenance of the render surface may also help minimise the visibility of ghosting.
Damp patches can appear if the render allows water to penetrate. This could be due to cracks, poor-quality render, or issues with the building such as leaking gutters or pipes. Dampness can lead to more serious problems like mould, structural damage, and internal water damage. There are different forms of moisture, including penetrating and rising dampness.
Identifying and addressing the source of moisture infiltration is crucial to resolving dampness issues. This may involve repairing leaks, improving drainage systems, applying waterproof coatings, or installing additional moisture barriers.
Bubbling or blistering
If moisture gets trapped under the surface of the render, it can cause the render to lift away from the wall, forming bubbles or blisters. This is typically due to poor application technique, allowing water to get behind the render — evaporation forces the embedded moisture out of the wall.
Bubbles or blisters in the render may indicate trapped moisture. The affected areas should be carefully inspected, and if necessary, the render may need to be removed, and the underlying substrate repaired or replaced before reapplication of render.
Dirt and pollution can cause staining over time, as can certain vegetation types. Rust stains can occur due to metal fixtures on the façade. Moreover, black stains can occur due to pollution or mould. Render staining often occurs around the building’s plinth. The type of staining will tend to be dirt splashback and manifests in the render looking yellowed. Specially designed renders like Mosaic Render combat this staining.
Stains can often be removed through cleaning techniques such as pressure washing or using appropriate cleaning agents. If the staining is persistent, it may be necessary to consider stain-resistant coatings or surface treatments.
UV radiation can cause the colour pigments in the render to break down over time, causing it to fade. Some colours are more prone to this than others, especially deeper, more vibrant colours. However, specially designed silicone renders have resistance to UV radiation. Therefore, their colour does not fade.
Fading cannot be reversed, but it can be addressed by repainting or applying a fresh coat of render with UV-resistant pigments. Choosing fade-resistant render materials and pigments can also help prevent future fading.
If the render hasn’t appropriately bonded to the underlying wall or there is structural movement, areas of the render can detach from the substrate. This is a serious issue as large render pieces can potentially fall off, posing a safety risk.
Addressing render detachment involves identifying the underlying causes, such as poor bonding or structural issues, and implementing appropriate remedial measures. This may include removing and reapplying the affected render, reinforcing the substrate, or addressing any structural movement.
Let us know below if you’ve encountered any of these issues and if we can help!