Tag Archives: wall insulation

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 However, while pebbledash was vastly popular pre-1930, this aesthetic is now largely considered outdated, making render the go-to for creating a clean, modern look.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.

Replacing Pebbledash with Coloured Render

Pebbledash is perceived by many as an outdated look for a property; it was frequently used during the post-WW1 housing crisis as a means of covering up quickly-built, slap-dash properties. If you live in the UK, you are most likely to have come across a pebbledash building and, while it’s a durable building method, it’s definitely an acquired taste.

What is pebbledash?

The pebbledash effect is created by applying a layer of mortar (usually sand and cement) to an external wall and literally throwing pebbles at the wall. Pebbledash houses are still dotted all over towns and cities in the UK and can often have a somewhat dilapidated look. Over time, the pebbles can drop from the wall, leaving the mortar exposed to the weather and therefore vulnerable to absorbing water and causing damp issues. Also, due to its unpopularity, pebbledash can reduce the value of a property purely for its lack of aesthetic appeal. This is why coloured render is vastly more popular because it’s much nicer to look at. Our coloured renders can be customised to absolutely any colour of your choice and can be ordered online or over the phone!

How can I replace pebbledash with a coloured render?

While we’re not hating on pebbledash (much), you might want to consider re-rendering your property, whether you’re moving into a new home, updating the look of your current property or both. However, as one of our frequently asked questions here at EWI Store, we recognise that there is a knowledge gap on how to apply render on top of pebbledash. That’s why we’ve made this blog – to tackle the question for all you pebbledash homeowners!

The short answer is that, unfortunately, you cannot replace pebbledash with coloured render by applying coloured render directly on top of the pebbledash. Saying that, there are several ways around it that you may wish to consider. Here are some options.

Essentially, there are three possible options for removing pebbledash:

Option 1: Removing the pebbledash

The first option is to attempt to remove the pebbledash by hacking it off. However, the main downfalls to this option are that the brick underneath is at risk of being damaged, and there is no guarantee that you will achieve a smooth finish. If this is the best or only option for you, be very careful about who you hire to tackle the task; make sure they are experienced in removing pebbledash. If your pebbledash is forcibly removed, this can really damage the underlying wall and invalidate your house insurance. It’s also important to note that, even after all this, you still wouldn’t be free to apply coloured render directly on the wall. Building regulations stipulate that if you strip it right back to the original brick, then you’ll need to insulate before rendering with a coloured render.

Option 2: One Coat Dash Cover (OCDC) to cover up pebbledash

The second option is to use the One Dash Coat Cover (OCDC) to completely smooth over and cover up the pebbledash to achieve a clean slate. This product is specifically designed to be applied on top of pebbledash, and it can then be painted or rendered to achieve a modern appearance. The good thing about the OCDC is that it is breathable, so it will allow any trapped moisture within the underlying pebbledash to escape. It can also be applied up to 20mm in one pass (up to a maximum of 50mm), so it’s guaranteed to smooth over the pebbledash nicely!

Option 3: Insulate then render over pebbledash

A beneficial way of ridding the pebbledash look is by installing 20mm (or thicker, but the thicker you go, the more expensive) external wall insulation (EWI) boards over the top of your pebbledash. This is a great option because the EWI will give you added insulation, which can save you money on bills in the long run.

By installing EWI boards, you will also save time and money because hacking off the pebbledash won’t be necessary. Instead, you can simply secure insulation boards over the top of the pebbledash using adhesive and mechanical fixings. Once you have done this, you can apply the render of your choice on top of the insulation boards and achieve a far more pleasing outcome.

Which coloured render can I use to replace my pebbledash?

There are so many options for replacing your pebbledash with coloured render that it can be quite overwhelming. We want to give you a clear idea of what each coloured render can offer so that you can make the right choice to suit the needs of your property and your personal taste.

Thin Coat Coloured Renders to Replace Pebbledash

Thin coat renders are a great option for when removing your pebbledash and replacing it with coloured render. Because they are thin-coat, they offer a level of flexibility that ensures that your coloured render finish stays crack-proof for years to come. Thin coat coloured renders are also highly breathable, so they will help to prevent problems with damp and mould on your walls.

They also come in different grain sizes, which determines the textural finish that the coloured render will offer you – the bigger the grain size, the more textured the finish that you’ll achieve. If you have simply removed your pebbledash, then you may want to go for a larger grain size as this makes any imperfections in the basecoat less noticeable. Read our blog Coloured Render Cost Per M2 for an idea of pricing!

There are three options that you can choose for thin coat coloured renders:

  • Silicone render/Silicone Silicate render: Silicone Coloured Render is a premium, modern technology coloured render – which is available in hundreds of different colours. Silicone is a very popular choice because it offers hydrophobic properties – which means that it repels water, dirt and organic growth – so it probably requires about the same maintenance as pebbledash (very little). Silicone render is also super easy to apply because it comes ready to use, so you just apply it straight out the pot. (Read more about Silicone Render here).

 

  • Acrylic render: Acrylic Coloured render is very similar to silicone, except that it doesn’t provide the same hydrophobic properties. It’s a solid middle-ground thin coat render because it still provides the same flexibility, but it’s also great at holding onto colour pigment. This is a fantastic choice if you are looking to replace pebbledash with a coloured render. (Read more about Acrylic Render here).

 

  • Mineral render: Mineral Coloured render is a dry-mix, thin coat render. This is a very popular choice if you live in a cold or rainy climate (as many pebbledash homeowners do – Scotland, coastal homes!) because mineral render is extremely fast drying; you can’t apply other renders in cold/rainy temperatures because they take longer to dry. The only thing about this render is that you need to paint it afterwards with silicone paint to seal it in. This is because, if it’s left exposed to the elements, it can develop lime bloom due to the presence of Portland cement. (Read more about Mineral Render here)

Thick Coat Coloured Renders to Replace Pebbledash

Thick coat renders are far more traditional but, as the name suggests, they do lack flexibility and breathability because they are applied in a much thicker layer. Once you’ve removed your pebbledash, you can use our Monocouche Scratch Render. Note: thick coat renders aren’t suitable for application on top of insulation boards.

  • Monocouche scratch render: Monocouche scratch render is a thick coat, through-coloured render. It is more traditional, but does require extra work to install it. This is because the Monocouche needs to be applied in two passes for extra strength and cannot be applied in wet or humid conditions. Monocouche render then needs fibreglass mesh embedded within it to provide extra strength and flexibility (which means it will resist cracking) and then, once dried, it needs scratching back to achieve the desired texture. Read our blog Monocouche Scratch Render Cost Per M2 for an idea of pricing!

To conclude…

If you are a pebbledash homeowner, looking to re-render, or potentially even install EWI, then we have everything you will need. Check out our materials calculator or get in touch with us directly and we can point you in the direction of one of our fantastic approved installers!

Are you a fan of Pebbledash? Leave a comment below…

Let’s debate: pebbledash or no pebbledash? Leave a comment below with your opinion; is pebbledash outdated and ugly, or is it a relic from our past that we should preserve for traditional purposes? For those in favour of the pebbledash look, we might have something just for you. Check out our blog Pebbledashing: Dash Receiver or Cement Mix?

We upload a new blog post every Tuesday, so stay tuned for more EWI installation advice, tips for homeowners and product information!

 

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