Rendering in the winter requires careful attention and correct procedures to ensure appropriate use of the materials. Working against the weather can present a challenge, especially when work is suspended due to poor conditions.

At EWI Pro, we specify that our materials should typically be used at temperatures no lower than +5°C, however, we do have a few solutions to ease the challenges that winter presents.

Scaffolding

Ensuring that your work is protected against the weather is essential. Appropriate coverings (usually polythene sheeting) should ensure that frost does not settle on the product surface overnight, water cannot be allowed to get in and harsh winds must be blocked out.

Remember that the sheeting should hang far enough away from the substrate that it won’t disturb the product on the wall and won’t allow wind to get behind it. This is essential for ensuring that the all-important setting process is not disrupted.

Heating

Heating can play a crucial role in successful rendering during winter, especially when you’re dealing with low temperatures and high humidity. There are two primary types of heaters often used in this context: indirect-fired (IDF) heaters and electric fan heaters.

Indirect-fired (IDF) heaters are particularly effective for large-scale rendering projects. They work by burning fuel outside the air stream that is being heated, thus providing warm, dry air without introducing combustion by-products (like carbon monoxide) into the work environment. This makes IDF heaters a safer option, especially in enclosed or poorly ventilated spaces. They’re also known for their efficiency in heating large areas evenly, which is crucial for consistent curing of the render.

Electric fan heaters, on the other hand, are more suited for smaller or more confined spaces. These heaters work by passing air over heated electric elements and then using a fan to distribute the warm air. They offer the advantage of being relatively portable and easy to set up. However, they typically don’t have the same heating capacity as IDF heaters and can be less efficient in very large or open spaces. Another point to consider is that electric fan heaters can increase the ambient air temperature more rapidly, which can be beneficial in quickly raising the temperature to a suitable level for rendering.

Using the right materials

Winter Adhesive

If the weather is particularly bad, consider using materials that are designed for poor weather. The Winter Adhesive is ideal for this time of year; it’s completely frost-proof and waterproof and can be used at temperatures down to zero degrees. You can use this adhesive as both a basecoat and for fixing EPS insulation boards. Therefore, you reduce waste on site.

Mineral Render

Mineral Render is slightly different to the traditional thin coat render. It’s not a ready-mix topcoat; instead, Mineral Render requires mixing with water before application. It contains cement, which is what makes it more fast drying, but the only downside to this is that it doesn’t provide a decorative finish on its own.

Mineral Render needs painting with Silicone Paint afterwards to provide a decorative finish and provide a hydrophobic surface. This seals the render against water ingress and efflorescence.

Render Accelerator

EWI Pro’s Render Accelerator is able to cut drying times. One small bottle can be poured into one bucket of render and thoroughly mixed. The accelerator does not need any time to activate so does not slow down work.

Temperatures

With the exception of the Winter Adhesive, most of our materials can only be used in temperatures between +5°C and +25°C. Attempting to apply our products at the wrong temperatures will most likely lead to failure during the setting process.

The main issue is avoiding freezing overnight temperatures. The only way to do this is to keep a sharp eye on the weather forecast and make sure any work is applied and drying well before any frost is due.

At EWI Pro we do not recommend rendering in the rain, or even rendering if there is any rain forecast before the materials have completely dried. If any doubt, seek advice from our technical team.