Published on 02/06/2024 by Site Manager
Modern cement render is incredibly hard and brittle. While this might sound like a benefit, it's actually the primary reason it fails on traditional masonry. When a building moves—as all buildings do—cement render cracks. These cracks allow water to enter, but because cement is non-breathable, the water becomes trapped against the stone or brick. In winter, this water freezes, expands, and causes the face of the masonry to 'spall' or blow off.
Lime render acts as a sacrificial layer. It is softer than the underlying brick or stone, meaning any stress or movement is absorbed by the render rather than the building's structure. If it does crack, it's easily repaired, and more importantly, it allows the wall to dry out rapidly through its surface.
There is a common misconception that lime is less durable than cement. However, examples of lime render exist that are hundreds of years old and still performing perfectly. When applied correctly by specialists, a lime render system will outlast a cement one, precisely because it works *with* the building rather than against it.
While the initial cost of lime rendering is higher than cement due to the specialist labor and material costs, the long-term savings are significant. You avoid the catastrophic damage to masonry that cement causes, and you reduce the need for frequent, expensive damp remediation projects in the future.
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