What is insulated render?

We get plenty of people calling us to buy insulated render, but often they don’t understand exactly what that means. Insulated render does not mean insulation within the render itself, it is simply another way of saying a layer of insulation buried beneath the render. In the industry, the more commonly used term for this is external wall insulation, solid wall insulation or EWI.

There are many variations on this product available, but they all have one key thing in common: there is a layer of insulation fixed to the wall, and then a layer of render applied on top.

How is insulated render installed?

For most systems, a mineral wool or expanded polystyrene board is fixed to the wall with adhesive and mechanical fixings. This insulation sits on the outside of the wall and is usually 90-100mm thick, although there are other thicknesses available and we have seen people going up to a thickness of 200mm.It tends to be that the thicker you go, the better insulating benefits you will achieve. Our systems are comprised of EPS, Mineral Wool and Wood Fibre – so you can choose which insulation material depending upon your property and your personal preference. EPS is our most cost effective insulation material, Mineral Wool offers unparalleled fire resistance and Wood Fibre is fantastic if you are looking to be eco friendly with your insulated render. Read more about our different insulation materials here!

Many people use insulated render as a means of covering over their existing render; be it pebbledash or something other, we recommend installing 20mm of EPS over the existing render and then applying our thin coat renders on top. That way, you get a fantastically fresh looking property and you get the added benefit of increased thermal performance.

After installing the insulation boards onto the wall, the surface is prepared and a basecoat is then applied. A fibreglass mesh is run through the basecoat to add extra tensile strength, prevent cracks and and create a strong stable surface on which to apply the top coat. Lastly, a top coat of Acrylic, Mineral or Silicone Render is typically applied to create a quality finish. Our insulated renders come in a wide range of colours – we have special mixing equipment so you can choose any colour and we will mix it up for you!

As part of the job, plumbing is often adjusted to accommodate the insulation, and windowsills will often need to be adapted to allow the insulation to fit underneath. The whole process will take a couple of weeks on the average house, and you will end up with a very different looking property to when you started.

Typical components of insulated render

Although there are different systems available, a good insulation job will have the following as part of the system:

  • Insulation board made of EPS or mineral wool
  • Adhesive to fix the boards
  • Mechanical fixings to attach the boards
  • Base coat to apply on top of the boards
  • Mesh to lay into the base coat
  • Starter track and beading where appropriate to create clean, straight edges
  • Top coat to create a quality finish

If any of these products are missing from your insulation job, you should probably check that your installer is doing all the stages necessary.

Which is the Best Insulated Render Top Coat?

Acrylic Render: Acrylic is what most people think of when they think of insulated render top coat. It is most renowned for coloured render because it is so great at holding onto colour pigment (think of the vibrancy of acrylic paint). Acrylic render is very impact resistant, so if you have kids who love kicking footballs against your walls acrylic render is right for you!

Silicone Render: Currently, our top of the range insulated render top coat is our Silicone render. Silicone render offers unsurpassed breathability and vapour permeability (it will allow water vapour to escape through it, thereby preventing damp). The inverse of this is that it’s also hydrophobic, so there’s no chance of water getting in. Silicone render is also self-cleaning, so it’s definitely the top coat to choose if your house is situated in an area where there are lots of trees and plant life.

Silicone Silicate Render: Silicone Silicate is very similar to silicone in that it offers excellent breathability and vapour permeability. The only real difference between the two is that Silicone Silicate will only offer a limited amount of resistance to organic growth. It’s therefore better suited to properties that do not require a high level of self cleaning capabilities.

Mineral Render: Mineral render is a great choice if you live in a particularly harsh climate. Because of the fact that it’s fast drying, it can be installed in cold or humid conditions, nevertheless it does require painting with a silicone paint after it has dried to prevent the formation of lime bloom – which is essentially like a cement ‘disease’ which makes your house render appear patchy.

What does EWI Store offer?

EWI Store is one of very few retailers to specialise in external wall insulation. Where there are plenty of rendering suppliers out there, we really pride ourselves on our external insulation systems and have plenty of options to offer you in store and on our website. If you have any questions about how EWI works and if it might be right for you, or you have a technical question on how to install the systems, just give us a call and we will be happy to help.

Whilst you are here, you may want to check out our calculator. This tool allows you to get an immediate quote for your EWI materials, by simply inputting the size of your job.

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