The Ideal Weather Conditions for Rendering?

Things don’t always go to plan when working on a construction site, and sometimes poor weather conditions can affect whether or not you’re able to start rendering. The current heatwave in the UK has meant that we’ve received many enquiries from renderers and homeowners about whether these are the best conditions for rendering, and we endeavour to give as much advice as possible to avoid situations where the render fails.

The ideal temperatures for installing render varies between manufacturers, however 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 this unprecedented heat wave should put a halt to all works, as we know that the daily temperatures have been well over 25. 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, as this is the most probable cause of the render drying out too fast. Render that has dried out too fast can result in cracking and damage, or even a patchy finish.

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 5am!). Start by applying render on a wall that is not exposed to sunlight, and 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 (it’s also much better for the installer to be out of the sun anyway – safety first!).

Another way to avoid cracking when the weather conditions for rendering are not ideal is to wet the walls before application, or even better apply the Water Based Primer. This 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 ensures that the substrate is prevented from absorbing too much water from the render and 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 Render. 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.

Rendering 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.

Mineral Render is a great option when it comes to applying thin coat render in colder conditions. This is because it’s a dry-mix render and is therefore much more quick-drying than our ready-to-use thin coat renders. It also has much faster drying times than our Monocouche Scratch Render because this is applied in a very thick layer, which increases its curing time.

Using a Render Accelerator in the colder weather is also excellent if you are installing our Silicone Silicate, Silicone or Acrylic Renders. Simply mix in 100ml of Render Accelerator per 25kg bucket of render and 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 for rendering are not ideal – it can be used even down to zero degrees. When you use the Winter Adhesive, you are ensuring that you have a strong and crack-free surface onto which you can apply your thin coat renders. By doing this, you increase your chances of achieving a great finish – even when the weather is not ideal!

We upload every Tuesday and Thursday, so stay tuned for more content all about our render and EWI systems.

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