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Building Render Cracks – When to Worry

Building Render Cracks – When to Worry

14th April 2022

Cracks in building render are common, but when do they become a cause for concern? Here we look at building render cracks and how important they are.

What are Building Render Cracks?

Building render cracks form in the cement rendered finishes of external walls. These cracks are common, and many property owners overlook them or assume they aren’t significant. A prevalent train of thought is that if the cracks aren't on the inside, they aren’t problematic. Internal cracks could indicate serious issues such as subsidence.

Causes of Building Render Cracks

Render is vulnerable to cracking, particularly on walls facing south or southwest. Shrinkage or thermal movement in render or masonry can cause cracks to form in the render. Cracks often appear around windows and doors due to these being weaker areas that expand.

Inadequate preparation before render application could contribute to cracking as well as letting the render dry out too fast between coats. If the undercoat and topcoat of render do not bond correctly, this is another risk factor, as is a stronger render mix than the substrate.

When are Render Cracks a Cause for Concern?

There are several risks involved for property owners when they notice building render cracks. These include:


If the render cracks are not repaired, rainwater may penetrate the render. Once water gets behind the render, it can cause dampness in the internal walls. This may lead to more significant issues and health risks, such as mould and respiratory problems. Damp and mould are also tricky problems to combat once inside a building.

Ice Damage

During the colder months, freezing temperatures will bring ice. Water expands when it freezes, and this can cause the render to crack further and even fall away from the wall.


A small crack may seem harmless, but even the tiniest of gaps can allow water to enter a building. In some cases, properties are at risk of leaks if the cracked render is left untreated. This is a potential risk all year round with the ever-changing UK weather.

If you are worried about building render cracks, consulting a professional surveyor is the best way to address the situation. A professional, like TFK Surveyors, can look over the building and make sure you know about any risks.

if you want to know more about the property services we offer at Taylor Freeman Kataria, call us at 0208 5999911.

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