Installing lime render and lime basecoat follows many of the same processes as other types of render. However, there are certainly differences in some of the procedures, and it’s worthwhile sharing some tips with you directly from our expert trio of Paul Christmas, Paul Harris, and Steven Wyllie.

Lime render has been a trusted material in building constructions for centuries, particularly prized for its breathability and flexibility. It is perfect for older buildings that need a sympathetic approach. Whether restoring a historic property or aiming for a natural finish on a new build, installing lime render can be immensely rewarding. However, it’s also a process that demands precision and patience.

1. Understand Your Materials

Before you begin, it’s crucial to understand the types of lime render available and which is suitable for your project. Lime render can generally be categorised into non-hydraulic lime, which cures slowly through carbonation with the air, and hydraulic lime, which sets through water and is more resistant to damp and freezing conditions. Your choice will depend on the existing construction, the environmental exposure, and the desired finish.

Paul Christmas: “EWI Pro’s Lime range is all non-hydraulic lime (NHL), so both the render sets through carbonation.”

2. Prepare the Surface Properly

Preparation is key in lime rendering. The surface you render must be clean, stable, and free of paint, dust, or debris. Use a stiff brush or a pressure washer to clean the surface thoroughly. If you’re applying render to a smooth surface, you might need to create a key for the render to grip onto. This can be achieved by attaching a metal lath or applying a spatter dash coat.

Paul Harris: “If you’re going to install some insulation, like mineral wool, make sure you lay down a very thin layer of Lime Basecoat to flatten the “fluffy” surface of the insulation board. This will help with adhesion.”

3. Mix the Render Correctly

Achieving the right consistency is vital for the application and longevity of lime render. Follow the manufacturer’s instructions closely. EWI Pro Lime Render and Basecoat come ready to mix with water; you’re looking for a maximum of 5 litres per bag. Use clean water and mix thoroughly until you achieve a creamy consistency. Avoid overmixing, which can lead to a quick setting of the lime.

Steven Wyllie: “This part is crucial, PPE. Lime in the eyes is no joke, as I say, so make sure you have your protective glasses and wear gloves. The pouring process of the dry material will release small lime dust particles, which are very harmful if they get in your eyes.”

4. Apply in Suitable Weather Conditions

Lime render should not be applied in extreme weather conditions. Ideal temperatures for rendering are between 5°C and 30°C. Avoid direct sunlight, strong wind, and rain during application and curing, as these can cause the render to dry unevenly and crack. If necessary, use temporary screens to shield the work area.

Paul Harris: “Lime has a slightly longer setting and curing process, so look for an extended period of good weather.”

5. Use the Right Tools

Use the correct tools for the best results. A hawk and trowel are essential for applying the render, and a float can be used to achieve a smooth surface. For textured finishes, you may require different tools, like a sponge or brush.

Steven Wyllie: “If you want a smoother finish, use a trowel rather than a sponge float.”

6. Apply Multiple Thin Coats

Lime render should be applied in several thin layers rather than a single thick coat. This technique helps to prevent cracking and allows each layer to cure adequately before the next is applied. Typically, two to three layers are applied: a base coat, a float coat, and a finishing coat. Each layer should be slightly thinner than the last.

Paul Christmas: “It’s not essential to apply several coats of EWI Pro’s Render and Basecoat, but it also doesn’t hurt!”

7. Cure the Render Slowly

Lime render requires time to cure, and it’s important not to rush this process. Keep the render moist after application by lightly misting it with water over a few days, especially in dry, windy conditions. This helps in the carbonation process and prevents cracking.

Paul Harris: “This is where your hessian comes in. You can wrap the wall with it and gently mist it with water, which helps to cure the render slowly.”

8. Regular Maintenance

Once cured, lime render can last for decades but requires maintenance. Regular inspections can help identify any cracks or wear. It’s breathable and should be maintained with breathable paints or limewash to preserve its moisture-handling properties.