scratch render, thick coat render

In previous blogs we’ve taken a look at our thin coat renders (Acrylic, Mineral and Silicone) so this week let’s delve into the details of the thick coat render that we offer here at EWI Store: Monocouche scratch render! 

Monocouche scratch renders traditionally signified a move away from the sand and mortar render, to a more modern render of a higher technology. This is due to the fact that they are made with white Portland cement rather than the ordinary grey cement (which, until painted, is aesthetically unappealing).

Traditionally, renders could not be coloured because unfortunately the colour pigment would not adhere to their greyish cement base colour. But with the addition of the white Portland cement which creates a white base, manufacturers were able to add colour pigment to achieve a more customisable render finish to decorate their homes.

The benefit of this is that colour is also evenly distributed throughout the mixture (it’s through coloured), so if your render were to chip or crack slightly then it wouldn’t be an enormous eyesore where you could see the grey cement under the crack.

How is Monocouche Scratch Render Applied?

You can apply the EWI-090 Monocouche scratch renders to a range of different substrates, although in some cases the substrate may need priming so as to control the level of water absorption. We have a range of primers available for different substrates and renders!

Monocouche scratch render is a dry-mix render, which means it isn’t ready to apply straight out the bag. Preparing the render for use is easy, you just need to mix each 25kg bag with roughly 5.5 litres of water using either a mechanical mixer or manually with a paddle mixer for about five minutes until it’s fully combined.

Here at EWI Store we really recommend that to get the best out of our products they need to be applied correctly. Applying Monocouche scratch render isn’t a particularly easy DIY job, so we advise that you hire a professional to carry out the job. We have a huge list of installers who would be able to help you, so give us a call if you are interested!

In terms of the application process, Monocouche render is a thick coat render which needs applying in two passes, with fibreglass mesh embedded within it during the first pass. So you apply the first layer at a thickness of 9-10mm and allow it to go off slightly. The second pass is then applied on top at a thickness of 8mm. Once both layers have cured, around 2mm of the render is scratched back with a render scratch float.

The reason that we use fibreglass mesh for thick coat renders is because it contributes towards the prevention of cracking (your house expands and contracts slightly during colder and warmer months) and thus helps hold the render system together. So you can be extra sure of its strength and longevity!

What Properties does Monocouche Scratch Render Offer?

Our Monocouche render comes in a wide range of colours, and it’s virtually maintenance-free once it has been installed. As long as it’s applied correctly, Monocouche scratch render is very hard wearing. It also offers a high level of vapour permeability, helping to prevent any ingress of water. Renders really need to be vapour permeable because trapped water and moisture causes damp and mould to permeate through to the internal walls. If you have an EWI system, water can be really detrimental to its structural integrity.  The EWI-090 Monocouche scratch render should guarantee you with a sturdy 10-year finish.

Monocouche Scratch Render vs. Mineral Render

It’s great to get an idea of how a render works in comparison with other available renders on the market to help with the decision making process. Both Monocouche scratch render and Mineral render are dry-mix renders, so we thought we would compare them side by side to assess which one comes out on top and give more of a clear idea of what they can both offer (check out our blog ‘What is Mineral Render?‘ for more details on Mineral Render!).

As we know, Monocouche render is a thick coat render. Mineral render, on the other hand, is thin coat. Mineral render is great if you live in a rainy, cold or humid climate because it is really fast drying which prevents it being damaged by the weather during the drying process. It then needs painting over with silicone paint to seal it in, which adds to its longevity and prevents the formation of lime bloom. Monocouche does take longer than mineral to dry, but the plus side is that it doesn’t require painting with silicone paint afterwards.

Another of the main differences between the two renders is their flexibility. Over the summer months, the external walls of your house expand slightly due the the thermal mass that they are storing. In contrast to this, in the winter months the opposite effect occurs: the house contracts. This is of course only minimal (a couple of millimeters only), and yet this can have a pronounced effect on your render system in terms of cracking and weather damage.

Thin coat renders are great because they are applied (as the name suggests) in a thin layer. The thinner the layer, the more flexible your render is going to be and therefore the more resistant to cracks during expansion and contraction. However, not all hope is lost for the Monocouche in this regard, because the fibreglass mesh embedded within the render layers does create an added level of tensile strength which holds the render together and prevents cracking.

In terms of price, mineral render does come out more expensive per bag in comparison to the monocouche render. However, as we know the monocouche does require the additional cost of the fibreglass mesh, and mineral render also requires painting with silicone paint afterwards. So, you may end up paying a more premium rate for mineral render but you do get the additional security of the silicone paint on top of the render. 

Interested in exactly how much you’re looking at to install Monocouche Scratch Render? Check out our blog post ‘Monocouche Scratch Render Cost per m2’.

We are always happy to answer any further technical questions about our render systems, so drop us a call or an email if you are interested in them!

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