Why Does Render Crack?
- Veramut
- 5 days ago
- 7 min read
Updated: 3 days ago
Cracked Exterior Wall Render Explained
If you live along the beautiful Dorset coast, you know the advantages of having a seaside property. Breathtaking views, fresh breezes, and a sense of calm you won’t find inland. But when it comes to looking after your home's exterior, the coastal climate can be unforgiving. One of the most common issues coastal homeowners face is cracking in the render on their walls.
These cracks aren’t just a cosmetic issue. They can allow water in, reduce insulation, and even lead to structural damage if left unchecked. But do not worry, the good news is that cracked render isn’t something you have to live with.
In this article, we’ll break down why render cracks appear in the first place, why properties are at risk, and what you can do to prevent them.
We’ll also explore modern, flexible rendering solutions, such as spray cork and silicone render, two advanced materials designed to withstand the challenges of coastal living. Let’s dive in and discover how you can keep your home looking great and protected for years to come.
Why Does Render Crack? Article outline:
1. Why Does Render Crack? Main Factors Causing Your Render to Crack.
As you can imagine, you are not alone wondering, "Is it normal for render to crack?". Yes, we know how frustrating and worrying render cracking can be, but understanding the root causes is the first step in prevention. Several factors contribute to why cracks appear in render, particularly in coastal areas like Dorset.
1.1. Natural Causes of Render Cracking.
Thermal Expansion and Contraction
Render materials expand and contract in response to temperature changes. In coastal areas, where the weather can shift rapidly between sunshine and chill, this movement is more pronounced. Over time, this causes stress on the render surface, leading to cracks.
Moisture and Salt Exposure
The salty sea air contains moisture and salts that can penetrate traditional renders, weakening their bond with the wall. Salt can also crystallise beneath the surface, exerting pressure and causing cracking.
Movement of the Building Structure
All buildings experience some degree of movement, especially in older properties. Shifts in foundations, settlement, or vibrations from nearby roads can stress rigid render layers, causing cracks.
1.2. Human and Material Factors.
While nature plays a big role in render cracking, especially in coastal areas, human decisions and the materials we use are often just as influential. In many cases, the issues stem not from the weather but from how the render is chosen, mixed, and applied. Here are the most common man-made causes:
Poor Application Techniques
One of the primary causes of render cracks is poor workmanship during the application process. Even the best materials can fail if they’re not applied correctly. Common mistakes include:
Inconsistent thickness
If the render layer is applied too thickly in some areas and too thinly in others, it won’t cure evenly. This imbalance leads to internal stress, which eventually causes cracking, especially under thermal expansion or moisture changes.
Insufficient surface preparation
Before any render is applied, the wall surface must be clean, dry, and structurally sound. Dirt, old paint, loose mortar, or damp patches can prevent proper bonding between the wall and the render. Without good adhesion, the render becomes far more likely to crack or fall away.
Skipping curing time
Renders need time to dry and cure at a controlled pace. Rushing this process (often in an effort to meet deadlines or beat the weather) can result in surface shrinkage and cracks.
Incorrect mixing
Getting the render mix right is more important than many people realise. Too much water can weaken the structure and make it prone to shrinkage, while too little water can lead to brittleness. Both extremes increase the risk of cracking over time.
Applying in poor weather conditions
Rendering in very hot, cold, or damp weather is risky. Wind and direct sun can dry the render too quickly, while cold or rainy conditions can interfere with bonding and curing. On the Dorset coast, where the weather can shift quickly, it’s vital to time the job well or use weather-resistant products.
Use of Inflexible Materials
Another common issue is the choice of materials that simply aren't designed to cope with the demands of a living, breathing building, especially in a coastal setting.
Cement-based renders
Traditional renders made from sand and cement are still widely used, but they come with limitations. These materials harden into a hard, brittle shell, which might look solid at first, but it doesn’t take much movement or weather stress for cracks to appear.
Low elasticity
Cement render lacks the flexibility needed to absorb the small shifts and expansions that buildings go through naturally. Even everyday factors, such as changing temperatures or slight ground movement, can cause stress fractures in these rigid surfaces.
Poor breathability
Many older render types also trap moisture within the wall structure, especially if applied to stone or solid brick homes without cavity walls. Over time, this trapped moisture can expand and contract with the temperature, a process that not only weakens the render but also encourages cracking from within.
2. How to Prevent Render Cracks.
2.1. Opt for the Right Rendering Material.
Not all renders are created equal, and if you live by the sea, flexibility and resistance to moisture and salt should be top of your list. Here are two modern options that are perfectly suited to coastal homes:
Spray cork is an innovative material made from finely ground cork mixed with a flexible binder. It's sprayed directly onto your walls, forming a lightweight, breathable, and highly elastic finish, ideal for withstanding coastal conditions.
It works well because cork naturally moves with your building, reducing the chances of cracks forming.
It’s water-resistant and breathable, so it keeps rain out, but still lets your walls breathe, which is key for preventing damp and mould. Helps to insulate your property by keeping the cold out and the warmth in, which can help lower energy bills. It also resists salt damage, unlike traditional renders, spray cork doesn’t deteriorate as easily from salty air.
Silicone Render
Silicone render is a modern, polymer-based system designed to handle everything the coast throws at your home, from salt spray to stormy winds. It stretches and moves with the structure, making cracks far less likely.
Stands up to weather, UV rays, and salt exposure. Silicone also allows trapped moisture to escape while keeping rainwater out. It looks great, longer, as it keeps its colour and finish for years with minimal upkeep.
2.2. Don’t Skip Proper Surface Prep.
This is where many rendering jobs go wrong. Before anything goes on your wall, the surface needs to be clean, dry, and free from any flaky paint, dust, or old material. Sometimes, bonding agents are also needed to help the new render grip properly. Good prep = a strong, long-lasting finish.
2.3. Use Experienced Professionals for the Job.
Even the best materials can fail if they’re applied incorrectly. That’s why it’s essential to work with a trusted, experienced rendering company, especially one that understands coastal homes and how to address the unique challenges they present.
They’ll know how to apply the product at the right thickness, in the right conditions, and allow proper curing time so it sets as it should. No shortcuts, no surprises.
Look for companies with:
Proven experience in coastal areas like Dorset
Great reviews and a strong portfolio of rendering projects
Use of premium materials like spray cork or silicone render
Transparent pricing and a focus on long-term performance
2.4. Keep an Eye on It.
Even with high-performance render, a little TLC goes a long way. Make it a habit to inspect your home’s exterior every year or so. Look for small cracks, stains, or signs of damp. Catching problems early can save you from more costly repairs down the line, and help your render last for decades.
3. Why Does Render Crack? The Key Takeaways.
Living on the Dorset coast is a joy, but it comes with challenges for your home’s exterior. Render cracks are common but not inevitable. By understanding why render cracks and investing in flexible, weather-resistant solutions like spray cork and silicone render, you can protect your home from the coastal elements and maintain its beauty for years to come. Choose the right materials and ensure a professional application. Your home deserves a render that can breathe, move, and withstand Dorset’s unique climate.
Get a Free Quote from Dorset’s Coastal Rendering Specialists
Have you noticed any cracks appearing on your walls, or are you concerned about your home’s exterior withstanding the coastal weather? Veramut Ltd is here to help. We specialise in flexible, weather-resistant rendering solutions, such as spray cork and silicone, perfect for homes in Dorset. Get in touch today for expert advice and a free, no-obligation quote. Let’s protect your property before small cracks turn into costly repairs.
Frequently Asked Questions (FAQs)
Q1: How long does spray cork render last?
Spray cork render is known for its impressive durability. When professionally applied, it can last 25 years or more, giving homeowners peace of mind that their render is applied to last.
Q2: Can silicone render be applied over existing cracked render?
It’s possible, but the old render must be inspected and any loose or damaged sections repaired or removed before applying silicone render.
Q3: Is spray cork environmentally friendly?
Yes, cork is a natural, renewable material harvested sustainably from cork oak trees.
Q4: How do I know if my home’s render is at risk of cracking?
Look for small hairline cracks, damp patches, or flaking. Early signs often appear before larger damage.
Q5: Can I apply these renders myself?
Both spray cork and silicone render require professional application to ensure correct thickness, adhesion, and finish.