The Best Weather Conditions for Rendering

What are the Ideal Weather Conditions for Rendering?

Things don’t always go to plan when working on a construction site, and sometimes weather conditions can affect whether or not you’re able to start rendering. 

The ideal temperatures for installing render varies between manufacturers. For EWI Pro renders it is advised that the optimal temperature for applying the renders should be between +5 and +25 degrees Celsius.

This isn’t to say that an unprecedented heatwave should put a halt to all works, as we know temperatures can reach well over 25 degrees in the summer. Renderers simply need to be able to find ways to work around the heat, and the same goes for when the weather’s cold.

So here’s our advice on what to do when the weather conditions aren’t ideal for rendering!

Rendering in Hot Weather

We always advise not to use our materials in temperatures over 30 degrees. Most especially, we advise that if it’s a warm day it’s best not to render in direct sunlight. This is the most probable cause of the render drying out too fast. Resulting in cracking and damage, or even a patchy finish.

Tips for Rendering in direct sunlight

• Start before the sun has fully risen
• Apply to walls in the shade
• Apply a water-based primer
• Use covers to provide shade
• Embed Fibreglass Mesh to the system

An old trick that lots of renderers use is to start before the sun has fully risen (many of our installers start out at around 5 am!). Start by applying on a wall that is not exposed to sunlight. Then follow the sun around the building working on the walls that are in the shade. This allows you to continue to work in sunny weather, but prevents issues with the render drying out too fast in direct sunlight.

A Water Based Primer limits the absorptive capacity of the substrate. During hot weather, ordinary masonry will have dried out and the absorptive capacity of the substrate will be extremely high. Using a primer prevents the substrate from absorbing too much water from the render. Causing it to crack during the curing process.

For our thin coat render systems, we always advise the use of Fibreglass Mesh embedded within the basecoat layer. We also advise that mesh is embedded within the first layer of Monocouche. This is even more essential when the weather conditions for rendering are not ideal, as the Fibreglass Mesh increases the tensile strength of the whole system. So, when the render shrinks during the process of drying, the mesh will help to prevent cracking.

Working in Cold Weather

Cold weather means that the render may not dry out fast enough. If this is the case, the render may retain moisture for too long and thus become susceptible to damage from this trapped moisture.

When applying Silicone or Acrylic Renders in colder weather,  Render Accelerator is excellent for speeding up drying times. Simply mix in 100ml of Render Accelerator per 25kg bucket of render. You can gain faster drying times, reduced cracking and water retention in the winter.

When it comes to the basecoat layer, the Winter Adhesive has been specifically designed for use in colder temperatures when the weather conditions are not ideal – it can be used even down to zero degrees. When you use Winter Adhesive, you are ensuring that you have a strong and crack-free surface.  By doing this, you increase your chances of achieving a great finish – even when the weather is not ideal!