Tag Archives: monocouche

Applying Render to OSB

How one should go about applying render to OSB is a question that we get asked on a near-daily basis. The simple answer is that applying render directly onto the OSB is not an ideal situation – it’s important to remember that at the end of the day, OSB is wood.

Nevertheless, there is a solution for rendering OSB, and we’re going to talk you through the best way you can do this!

Rendering OSB: Render Carrier Board

When rendering any substrate, especially when rendering OSB, consideration needs to be taken as to the suitability of the substrate for the materials that you are using. OSB is not completely waterproof and will inevitably absorb water from the basecoat, which can cause the wood to warp, eventually hindering structural integrity.

To avoid this, the best solution is to use a render carrier board. However, the render carrier board needs to be attached to battens, rather than to the OSB directly. This is because the two separate fabrics (the RCB board and the OSB) need ventilation between them to allow moisture to escape, and to avoid a situation where water builds up between the two materials. An air gap between the two is therefore necessary for the reduction of condensation.

The best course of action is to:

  • First, staple a breather membrane onto the OSB substrate – this will help prevent the build-up of condensation on the surface of the wood.
  • Next, install timber battens on top of the OSB (the positioning of the battens will depend upon the size of the render carrier board you are using).
  • Once these are in place, you can secure the render carrier boards onto the battens with wood screws.

The spacing of the boards will depend on the type of render carrier board you are using, but generally, you would leave 4-5mm between each board.

After the boards are in place, the gaps between them need to be covered over by a render carrier board tape. We recommend a tape that is breathable with a self-adhesive membrane, so it will prevent water vapour from gathering in the gaps between boards.

Basecoating the Render Carrier Boards

Render carrier boards don’t require priming because they are specially designed for being rendered, so you can go straight into applying the basecoat with no problems.

Although it is possible to use the 220 Basecoat Adhesive, we recommend using the 225 Premium Basecoat as a basecoat for extra strength and breathability. At this stage, the necessary beading required for the structure is sunk into the basecoat along with fibreglass mesh – remember to overlap each strip of fibreglass mesh by about 10-15cm.

Allow the basecoat to set for a period of 24-48 hours, before priming the basecoat with a Render Primer. The type of primer you use will depend upon the type of render, for example, if you were to render using Silicone Render (we recommend this one for buildings that require a high level of breathability), you would need to use our SiSi Render Primer. This can be painted on and then left to dry for 12 hours.

Rendering the Basecoat Layer

After all that essential preparation of the OSB and RCB boards, you are finally ready to render. Using our ready-to-use Silicone Render, apply it onto the substrate using a trowel. The render should go on at a thickness that matches the chosen grain size – for example, if you’ve chosen a 1.5mm grain size finish, then you should apply the render at 1.5mm thick.

Once distributed across the surface, rub up the surface of the render with a plastic render float to bring out the texture and achieve a consistent finish, then leave to dry for 24-48 hours. 

Struggling to chose a Silicone Render colour from our selection? Order a colour sample here.

 

Want to learn more? Come to one of the EWI Pro training centres!  More information found in the video below.

 

    Approved Installers Request Form

    Your Name*

    Your Email*

    Your Number*

    Your Postcode

    Additional Information

    I would like to receive news and offers from EWI Store

    Monocouche Render vs. Silicone Renders

    As you might have noticed, we offer a variety of advanced render systems here at EWI Store, the most popular being monocouche and silicone. Both monocouche and silicone render provide a decorative finish on the external walls of a property whilst also improving its thermal comfort. The result of the external appearance, however, greatly depends on the type of render chosen. In this blog, we discuss the main differences between monocouche and silicone render so that, if you are torn as to which one to choose for your renovation, we can assist in the decision-making process!

    Monocouche Render

    There are a wide variety of monocouche renders available on the market; here at EWI Store, we stock EWI Pro, K-Rend and Enewall. The key characteristic of monocouche render is that it is a through-coloured, thick-coat render. Monocouche render is very often compared to sand and cement render because it contains cement however, it is very different in terms of texture and characteristics.

    Monocouche render tends to offer a chalkier finish than other renders. To provide the finished facade, the render is usually scraped to create a pitted effect. Available in a range of colours (natural and bright), it’s a very popular choice for homeowners who are looking to create a chalky, flat finish.

    Silicone Render

    Silicone render is a highly flexible, breathable and durable render that comes ready to use in 25kg buckets. Unlike monocouche render, silicone render is a thin-coat render, meaning it is applied very thinly on top of a reinforced basecoat. Although readily available in a standard white, silicone render can be tinted to absolutely any shade. Here at EWI Store, we have specialist tinting equipment that enables us to match to any RAL, NCS or Pantone colour, meaning we can cater to absolutely any taste. Silicone render can be used as a standalone system straight onto brick or applied onto external wall insulation boards to provide a decorative finish.

    One of the main advantages of silicone render is that it is crack-resistant. The silicone properties within the render, coupled with the way it is applied, means that it is far less likely to crack than monocouche render.

    Now that you know the difference between monocouche and silicone render, you might be wondering how much each cost to install. If so, we’ve got you covered: check out our blogs on monocouche scratch render cost per square metre here and coloured render cost per square metre here to get an idea as to how much you’re looking at.

    We offer a variety of advanced silicone-based renders, including Nano Drex Silicone Render, Premium Bio Silicone Render, Silicone Render and Silicone Silicate Render. If you’re interested in trying any of these, be sure to give us a call and our lovely Sales Representatives will be happy to help!

    If you’re looking for an approved installer to carry out the work for you, fill out the form below and we will be in touch. We upload blog posts every Tuesday and Thursday, so keep up to date with our blog and social channels to find out more!

      Approved Installers Request Form

      Your Name*

      Your Email*

      Your Number*

      Your Postcode

      Additional Information

      I would like to receive news and offers from EWI Store

      Sand and Cement, Monocouche and Silicone Render: Which is best?

      Of the 28 million properties in the UK, a large proportion are rendered, or at least coated, with some form of protection like pebbledash. However, while pebbledash was vastly popular pre-1930, this aesthetic is now largely considered outdated, making render the go-to for creating a clean, modern look. In this blog, we investigate why render is so popular and the best products to create an incredible finish on your property or home.

       

      Originally, UK properties were built with either brick or block. Over time, however, the mortar fusing the bricks together would break down due to natural weathering. Replacing the damaged mortar – known as re-pointing – is incredibly time consuming and, as such, very expensive. Therefore, a feasible alternative to re-pointing a property is to apply render. Render acts as a protective layer for a property; not only does it disguise the existing damaged mortar, but it provides a new facade for the brickwork, offering a clean, modern finish.

       

      Traditionally, sand and cement render – typically six parts sand, one part cement and one part lime – was applied to the surface of a property. This render would be applied at a thickness of about 20mm and be coated with paint to complete the aesthetic. As with mortar however, the issue with these traditional renders was that, over time, they would crack due to the natural movements of the buildings by season, expanding in the summer months and shrinking in the winter months. While the addition of lime was intended to provide flexibility to adapt to such movements, the render was still not flexible enough to withstand these movements, causing hairline cracks. Such cracks cause further issues as they would provide an entry point for water to travel behind the render system and, as such, cause it to come away from the wall.

       

      In the 90s, several manufacturers introduced a render known as “monocouche”, French meaning “one coat”. Monocouche render is easier to use than sand and cement render as it is premixed, typically four parts sand and one part cement with various other additives; all you need to do is add water. It is applied at a similar thickness to sand and cement render however, once applied, it is scraped to provide a chalkier finish. Monocouche render always uses white Portland cement as the binder; the white base allows for the manufacturer to add a coloured pigment to the render, meaning it does not require paint on top. As such, monocouche became increasingly popular in the 2000s, becoming the go-to product for those looking to render their properties.

       

      Again, monocouche render ultimately comes with its downfalls. Firstly, as with sand and cement render, the thickness of monocouche render means that it cannot withstand the seasonal structural movements of the building, therefore causing cracks which again create an entry point for water. Secondly, while monocouche looks fantastic on application, it becomes a hot bed for algae growth as it encounters water. The biological growth on the monocouche can quickly lead to discolouring so, while it initially looks great, it quickly starts to look messy and requires a lick of paint to keep it looking fresh.

      Then, in early 2000 came silicone renders – sometimes referred to as thin-coat renders – from Eastern Europe. Silicone render fundamentally differed from sand and cement render and ultimately replaced monocouche render. As opposed to a 20mm-thick render, the silicone render maxed out at 7mm and consisted of two main layers: a 4-6mm cementitious basecoat with embedded fibreglass mesh, and a silicone render topcoat typically at 1.5mm thick, although 0.5mm, 1mm, 2mm and 3mm grain sizes are also available. The fibreglass mesh in the basecoat is vital; it provides the render system the ability to flex with and absorb a building’s natural movements, making it crack-resistant – the defining factor and main benefit of silicone render.

       

      Much like paint, silicone renders can also be tinted to any colour, providing infinite design options to apply to your property or home. Monocouche renders do come in various colours however, since pigments need to be added in the factory, they are very limited. So, if you need to match a specific colour – for instance, RAL-7016 anthracite grey – then silicone render is the obvious choice as it can quickly be tinted to match the required colour.

       

      What’s more, silicone renders are hydrophobic, meaning that they possess self-cleaning properties which repel water. This means that, whenever it rains, the rain carries away any dirt particles from the render system, so the facade stays cleaner for longer. The EWI Pro Premium Bio Silicone render also has added slow-release biocides within the render, helping to prevent biological growth, which is especially useful if the render is being applied in areas of high vegetation.

       

      Finally, unlike sand and cement and monocouche renders, silicone renders are lightweight, meaning that they are ideal to use in conjunction with external wall insulation systems. The weight of sand and cement and monocouche renders can pull the face of the insulation away and are therefore not recommended to be applied on top of insulation materials.

       

      As this blog has established, render technology has changed significantly over the last 30 years. Whether you have a property that has existing damaged render that needs an upgrade, or even a new build like an ICF or a timeframe building on which you desire an advanced render system, then look no further than silicone render. With a silicone render system, you can rest assured that the facade will not crack over time and will likely stay much cleaner than either sand and cement or monocouche render, therefore providing a render system that will last for years to come.