When rendering a property's exterior, the choice of material is crucial for both aesthetic appeal and the longevity of the wall finish. Lime render and cement render are two of the most common types of materials used in the UK, each with its benefits and drawbacks. This blog explores the differences between lime and cement render, helping you decide the best option for your property.
Lime render
Lime render stands out for its unique properties that cater to the well-being of a building's structure, especially in older or historic properties. Originating from a blend of lime, water, and aggregates like sand, this traditional material has graced the exteriors of buildings for centuries, offering a breathable coat that significantly aids in moisture management within walls.
Breathability
One of the paramount benefits of lime render is its ability to allow moisture to permeate and evaporate away. This breathability is crucial for maintaining healthy walls, especially in older buildings constructed without modern damp-proofing techniques. By allowing moisture to escape, lime render prevents the accumulation of dampness within walls, safeguarding against the structural issues and mould growth that moisture can cause. This characteristic is particularly vital in the UK, where damp climates consistently challenge building maintenance.
Aesthetics
Beyond its practical benefits, lime render also brings aesthetic versatility. It can be applied in various textures and finishes, from smooth to coarse, catering to various architectural styles and preferences. Moreover, when lime renders age, it gracefully develops a patina that adds character and depth to a building's appearance. This natural ageing process can enhance the visual appeal of heritage properties, blending seamlessly with their historical context.
Sustainability
However, the advantages of lime render extend beyond the physical to the environmental. Lime is a more sustainable material than its contemporary counterparts, such as cement. During the curing process, lime render absorbs carbon dioxide from the atmosphere, undergoing a carbonation process. This not only contributes to the strength and durability of the render but also reduces the carbon footprint. The production of lime is less energy-intensive compared to cement, further enhancing its eco-friendly credentials. Yet, the adoption of lime render comes with considerations of cost and skill. The material itself, alongside the expertise required for its application, can be more costly than other rendering options. Its application is an art requiring skilled tradespeople familiar with traditional building techniques. Additionally, lime render takes longer to cure than cement-based products, necessitating patience and careful planning to ensure longevity and effectiveness. [gallery size="medium" ids="73863,73862,73865,73864,73867,73866"] Lime Basecoat and Lime Render in action in the EWI Pro Training Centre
Cement render
Cement render has become a staple in modern construction, valued for its robustness and versatility across various building types. This popular rendering option is composed of a mixture of cement, sand, and, in some mixes, a small proportion of lime to enhance workability and reduce the likelihood of cracking. Its appeal lies in its physical strength and durability, as well as its cost-effectiveness and adaptability to various architectural aesthetics.
Durability
The primary advantage of cement render is its exceptional durability. Once applied, it forms a hard, resistant surface that stands up well against environmental elements, from harsh weather conditions to everyday wear and tear. This resilience makes cement an ideal choice for buildings in areas exposed to severe weather. The solidity of cement render also enhances the structural integrity of buildings, providing an additional layer of protection against physical impacts.
Cost
Cost efficiency is another significant benefit of choosing cement render. Compared to other rendering materials like lime, cement render is generally more affordable regarding the raw materials and the labour costs associated with its application. This makes it popular for larger projects or property owners working within tight budget constraints. The straightforward mixing and application process makes it cost-effective, allowing for a quicker project turnaround without compromising quality.
Aesthetics
Cement render also boasts considerable versatility in terms of aesthetics. It can be finished in various textures, from smooth to patterned, and painted in any colour, offering endless possibilities for customisation. This adaptability enables property owners to achieve a wide range of looks. This ranges from contemporary sharpness to a more traditional or rustic appearance. Furthermore, innovations in cement render compositions have led to the development of coloured and textured renders, reducing the need for subsequent painting and offering even more options for personalisation. However, the choice of cement render comes with consideration. Its lower breathability than lime render can pose challenges in older buildings, where trapped moisture may lead to damp issues. Moreover, cement render is less prone to cracking than pure cement due to the addition of lime or plasticisers; it can still crack if the building settles or is subject to thermal expansion. This necessitates careful application and, in some cases, ongoing maintenance to ensure the render remains in optimal condition.
Lime render vs Cement render - which one is better for your project?
Compatibility with older buildings
Lime render's compatibility with older buildings starkly contrasts with cement render's limitations in such environments. The breathability of lime render allows moisture to move freely through the wall, preventing the build-up of dampness and related structural damage. Cement render, on the other hand, can trap moisture within walls due to its lower permeability. This can lead to damp problems and deteriorate the condition of historic masonry, making cement a less suitable option for heritage buildings or those constructed with traditional materials.
Environmental impact
The environmental implications of choosing between lime and cement render are significant. Lime render's production process is inherently more eco-friendly, emitting less carbon dioxide than cement's energy-intensive manufacturing. Additionally, lime's ability to reabsorb CO2 during the carbonation process renders it carbon neutral over its lifecycle. Cement render, by contrast, contributes significantly to CO2 emissions without the capacity to offset this impact. Consequently, it is a less sustainable choice for environmentally conscious projects.
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Lime cycle - https://www.lime.org.uk/community/the-lime-cycle/lime-and-its-production.html[/caption]
Flexibility and aesthetic qualities
The natural flexibility of lime render dramatically reduces the risk of cracking that is prevalent with cement render. Cement render's rigidity, while providing strength, does not well accommodate building movement or thermal shifts. Ultimately, this leads to cracks that require repair to maintain structural integrity and aesthetic appearance. Lime render, adaptable to the subtle shifts in building structure, maintains its integrity over time, preserving the building's aesthetic without the frequent maintenance cement render might necesitate.
Healthier living environments
Lime render contributes to healthier indoor environments by regulating humidity levels, and reducing mould and mildew growth potential. This is a stark difference from cement render, which, due to its lower breathability, can create conditions that foster mould growth by trapping moisture. The ability of lime render to allow walls to breathe protects the building's structural health and promotes better indoor air quality, making it a preferable choice for living spaces.