Tag Archives: silicone

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.

 

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    Can you paint over K Rend?

    Is your house currently rendered in K Rend? Has it been a while since your house was rendered? Is it looking a bit dull and dirty? If this sounds all too familiar, then it might be time to consider refreshing the façade of your property. Simply painting over the render might sound like the most obvious way to achieve this, but there’s slightly more to it than that. This blog unpacks how to go about painting over a property rendered in K Rend but not before explaining what K Rend is to help you identify the type of render on your property in case you’re not sure.

    What is K Rend?

    Due to its renown, K Rend is often confused as the umbrella term for all types of render when, in fact, it is a brand of render. Here at EWI Store, we stock K Rend Silicone K1 Monocouche Render and K Rend Silicone TC15 Topcoat. K Rend Silicone Render is water-repellent, polymer-modified and self-coloured, meaning it is available in a variety of colours so you can achieve your desired coloured finish.

    How long does K Rend last?

    While K Rend looks fantastic upon application, it can eventually look a bit grubby due to prolonged exposure to the elements. If you can see black, red or green streaks anywhere on the façade, this is a sign of biological growth and an even bigger sign that it simply needs a good clean; a simple jet wash should do the trick. It is vital to get rid of any biological growth before painting over the render as it can continue to grow under the paint, defeating the purpose of refreshing the face of the property. Nonetheless, too high pressurised water can cause damage to the surface of the property, so it is worth considering hiring a professional to clean it for you.

    How can I paint over K Rend?

    Once your property is clear of dirt and biological growth, it can be painted. However, while it is possible to paint over K Rend with standard masonry paint, it is advised to consult with a professional who can recommend more compatible paints as masonry paint can compromise the render system. For instance, our Silicone Paint works with our Silicone Render to offer advanced breathability, flexibility and durability, which can also be tinted to match the very same colour as the current façade or to absolutely any colour you like, including any RAL and NCS colour. If you need assistance, you can contact our experienced technical team here!

    The verdict…

    So, to answer the question at the beginning, you can paint over K Rend. However, some factors need to be considered before doing so, such as the condition of the render before painting (does it need a good clean?) and the type of paint to use over K Rend (which should be discussed with a professional). Once these factors have been considered, your property can be given a lovely refresh! Don’t forget that you can contact our knowledgeable team regarding any other questions you have, or fill in the form below to send your request.

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      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!

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        Can You Paint Over Silicone Render?

        Have you had your Silicone Render for quite some time now? If so, you might be wondering how best to give it a little refresh. Here at EWI Store, we’re often asked how Silicone Render can be maintained to continue to exude a stand-out finish. Although Silicone Render has advanced self-cleaning properties, that doesn’t mean that it’s not completely susceptible to gathering dirt over time. To solve such, a gentle clean with a jet wash is perfect now and then however, houses that are likely to become dirty more easily – that is, those on busy roads or in highly-vegetated areas – may need to be painted over. That said, you might be wondering whether you can use standard masonry paint on top of Silicone Render. The simple answer is, while no one can stop you from doing so, it is highly recommended to use Silicone Paint instead. Keep reading to find out why.

        Why use Silicone Paint on top of Silicone Render?

        Silicone Render is a specialist, breathable render product ideal for application on external wall insulation systems where a breathable insulant, such as Mineral Wool, is being used. Therefore, while you technically can use standard masonry paint on top of Silicone Render, we recommend that you use Silicone Paint because it is also highly breathable. A standard masonry paint might not have such breathable properties which would completely nullify the render system’s ability to allow water vapour to pass through its surface, while a breathable Silicone Paint would work with the Silicone Render to continue to offer optimum performance.

        The best thing about our Silicone Paint is that it is available in thousands of colours. If your current render system is coloured and you’re afraid that you won’t find a colour to match, never fear – our Silicone Paints can be tinted to absolutely any shade! That way, not only will the Silicone Paint still cater to your taste, but it will also freshen up the entire façade of the property and extend its lifespan.

        How to apply Silicone Paint onto Silicone Render

        Before you apply Silicone Paint to your render, there are a few preparatory steps that must be taken to ensure a flawless finish. First, you’ll need to clear the render of any dirt or grime. If the walls have been painted previously, you’ll need to remove any flaking paint using either a jet washer or a wire brush. Also, be sure to apply tape to areas that need protection from the paint, such as window and door frames.

        Silicone Render is incredibly flexible and therefore highly unlikely to crack. However, if you notice any minor cracks, these too need to be filled.

        We recommend applying the paint using a standard brush and roller, starting at the top and working your way downwards to catch the paint as it drips and runs. Silicone Paint can be applied in multiple coats, so once the first is dry (after about 12 hours), you can go over it with as many coats as desired. However, beware that – if your render has a finer grain size – the more coats of Silicone Paint you apply, the less visible the grain size will become.

        So, if you’re looking to paint over your Silicone Render, look no further than Silicone Paint. Silicone Paint is the perfect solution for allowing your render system to continue to offer optimum performance, refresh the façade of your property and extend the façade’s lifespan. If you’re looking for a complete guide on how to maintain your render finish, be sure to check out our blog on how to look after your render finish here. As usual, if you have any questions, do not hesitate to contact us or comment below!

         

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          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.