Author Archives: Anna Hindley

Silicone Render

Silicone Render

Silicone Render  Basecoat

Silicone Render beading

What is Silicone Render?

There are many different types of render on the market, all with different properties. The range includes older sand-cement style renders, to scratch renders, and thin coat renders. Silicone Render is a ‘thin coat render’, which means that it is applied on top of a basecoat at just a few millimetres thick. Silicone render is becoming ever more popular these days, so in today’s blog post we’re going to explaining a little bit about it.

Why choose Silicone Render?

There are many big advantages to using silicone Render – there really is little competition when it comes to quality of finish. Let’s take a look at some of the major advantages:

  • Silicone is breathable – Where cement and acrylic renders completely seal off the wall and prevent it from breathing, silicone is very breathable.
  • Silicone is self coloured – Unlike other renders that must be painted after curing, silicone render has the colour mixed into it, meaning just one coat and the job is done. Having the render pre-coloured means that it lasts longer and won’t show if it is scratched, as the colour runs through the whole top-coat. (for an idea of the cost of silicone render per square metre, read our dedicated blog post here)
  • Silicone is easy to apply – Where other renders have a painting stage, thin coats can be done in just a few hours on a properly prepared wall. Despite a slightly higher cost, your job will be done in much less time than a traditional render.
  • Above all else, silicone looks great! It leaves the property looking like a new house.

How is it applied?

Silicone is a one-application thin coat render. It is dead easy for a qualified renderer to apply this render to a fully prepared wall. On a typical wall, a basecoat should be applied to create a strong, stable and level surface with which to render. Once the base coat has dried, the silicone can be applied using a plastic float to create a thin and smooth finish.The thickness of the silicone top coat should be the same as the grain size of the render. So a 1.5mm Silicone Render will be 1.5mm thick on the wall. The layer has to be applied in one go on each elevation otherwise you could end up with patches and lines where the render has been joined.

If you are interested in downloading an install guide you can click here. 

Different types of Silicone Render

You will have noticed that we offer several types of Silicone Render:

  • EWI-040 Silicone Silicate Render
  • EWI-075 Silicone Render
  • EWI-076 Premium Bio Silicone Render
  • EWI-077 Nano Drex Silicone Render

All of these renders are manufactured by EWI Pro who specialise in this type of thin coat render.

There are 3 key characteristics that all silicone renders display, they are hydrophobic (repel water),  they are breathable and they are flexible and as you go down the list (i.e. from EWI-040 to EWI-075 and so forth) the renders show higher levels of these characteristics so basically you are getting a better product.

What does Silicone Render cost?

Each of the silicone renders has a different price point which you can see below, but it is worth mentioning that all silicone renders are going to cost more than acrylic render, because you are getting a vastly superior product. 

Typically though, since a bucket of the 1.5m grain render covers 10m2, when you consider the other products required like basecoat and mesh, you are going to be paying between £10 – £15 per m2 – which is comparable to monocouche / scratch renders. 

 

How much thin coat render do you need for a typical house?

This is going to come down to the area of wall you are looking to cover. The render comes in 25kg pre-mixed buckets, and each bucket at our standard 1.5mm finish will cover around 8 square metres of wall. For an average semi-detached house of say, 80m, you are looking at around 10 buckets of render. If you go for a finer grain size of 1mm, the render will go further, covering 11-12m of wall each. Thicker 2mm render will cover less area, so you need to take this into account when you are working out the quantities you need.

Who makes Silicone Render?

There are several brands available on the market, but we recommend the Silicone renders from EWI Pro . As mentioned the specialise in Silicone renders and also they are well priced and offer all of the advantages we have mentioned above. Plus we offer colour tinting and next day delivery on this product.

Where can I purchase Silicone Render?

You can buy our EWI Pro Silicone Render via our store – just click on the item below AND as a little thank you for visiting our website, simply use the code ‘SiliconeR’ at checkout to get a 15% discount to Silicone Render applied to your basket.

Can I get Silicone Render in cream, grey and magnolia?

The great thing about EWI Pro Silicone Render is that there is a huge range of colours available to choose from. You can order a free colour chart, pick your colour and this will be mixed up and sent out to you the next day in most cases, using our own delivery drivers, not couriers.

You can buy EWI Pro Silicone Render online, in-store or by giving us a call. For any further questions, we are always happy to help so leave a comment down below!

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Materials Required for Insulating Below the DPC

1. Priming Below the DPC:

If you’re installing your XPS insulation system below the DPC of a brickwork substrate it will need priming with the Water Based Primer. We recommend applying this to the substrate by roller or brush. However, if you are rendering onto a very smooth substrate then we recommend applying the EWI-310 Universal Primer, as this contains aggregates which will provide a rough surface for the basecoat to adhere to. Ensuring that your substrate is adequately prepared is essential to ensuring that your render system will last.

Coverage rates:

5 litres covers 15-30m2 depending on the substrate.

Drying times:

1 coat takes 4 hours to dry.


3. Preparing the Adhesive

Because the DPC area is so prone to damp, we recommend the use of Aquabase as this is a highly water-resistant basecoat/adhesive. Aquabase a very versatile, dual-purpose product that can also be used in the subsequent basecoat layer. The adhesive is applied to the entirety of the back of the board using a notched trowel. 

Coverage: 

1 x 25kg bag covers 4/5m2

Drying times: 

24-48 hours


4. Applying the XPS Insulation Boards

XPS insulation boards are ideal for below the DPC because they offer a closed-cell structure which makes them more waterproof and impact-resistant. We sell XPS by the square metre in a range of thicknesses. For insulating a solid brick wall the general recommendation to reach building regulations is to opt for a 110mm thickness. A really flat surface will need to be achieved while mounting the boards to ensure a smooth topcoat. We recommend using a spirit level to regularly check that everything is flat. 

Coverage:

1m2


5. Installing the fixings

EWI Pro recommends that you install one fixing per corner, with an additional two in the middle of the insulation board. Plastic fixings should be used with the XPS insulation system as they significantly reduce thermal bridging. The fixings are available in a wide range of lengths to accommodate different thicknesses of insulation.

Coverage:

Plastic pin fixings are the recommended fixing for XPS insulation. These come in boxes of 200 or 100 depending on the length.


6. Applying the Beading:

Beading is essential for reinforcing external areas that are more prone to damage, for example, the corners and the areas around windows and doors. The required beads will depend on the property and which particular areas need reinforcing. We have a broad range of render beads that should be selected and applied as necessary, our beads are uPVC and are designed to be embedded within the basecoat layer. For real security against condensation and cold spots, you may also want to use a foam tape in between the starter track and the top of the insulation boards.


7. Applying the Basecoat:

For insulating below the DPC with XPS insulation, we recommend using the EWI-226 Aquabase in the basecoat layer again for added protection against damp and water penetration. 

Coverage rates:

1 x 25kg bag covers 4/5m2

Drying times:

24-48 hours


8. Priming the Basecoat:

A render primer should be used to increase the adhesion of the render to the basecoat and can be tinted to match the colour of your render for increased opacity. The type of primer will depend on the type of render you are using. When using Mosaic Render, we recommend using the Mineral & Acrylic Primer which comes in two different bucket sizes.  

Coverage:

1 x 7L bucket covers 20m2

1 x 21L bucket covers 60-70m2

Drying times:

12-24 hours


10. Applying the Render Topcoat:

Once the primer is dry, the render topcoat can be applied. We recommend using the EWI-050 Mosaic Render as this is very durable and waterproof, which makes it perfect for below the DPC. Mosaic Render is available in a range of colours to achieve a unique finish. 

Coverage:

1x25kg bucket covers c. 3-4m2

Drying times:

24 hours (+)


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What Size Bead Do I Need For a Thick Coat Render?

Choosing the correct beads is essential to ensuring that your render system looks crisp and sharp at every angle, while also remaining impact resistant and structurally sound. 

We’ve put together a list of beads that are ideal for use with thick coat renders such as the Enewall Scratch Render, which is a monocouche that is designed to be applied in two passes.

Corner Bead Without Mesh

Our corner beads are available with or without mesh. The key difference between the two is that typically you’d use a corner bead without mesh for scratch renders and thick coat renders. The corner bead below is available with a 6mm, 11mm or 14mm nose depending upon the thickness that you’ll be applying the render at.

The main point of the corner bead is to get a crisp edge at 90-degree angles. This can be particularly tricky when applying really thick renders.

Bellcast Bead

The bellcast bead is designed to create a clean, reinforced line where the render finishes. It can also be used at the bottom of the wall to provide a drip, which directs water away from where the render finishes. This lessens the risk of water penetration and helps to keep the render at the bottom of the wall clean and damp-free.

Bellcast bead is great for two-coat renders, as it’s available in 11mm. Once embedded into the first pass of the two-coat render, the bead will help to create a nice sharp edge at the bottom of the wall.

 

Render Movement Bead

Render movement bead is ideal for use where you have a large expanse of render (over 12m). It is used for render only systems and is installed vertically along the wall to prevent the render from cracking. Essentially it enhances the tensile strength of the render system. 

Render movement bead should be embedded within the first pass of the render.

Blue Fibreglass Mesh

Although this isn’t technically a bead, we’ll give it a mention because it’s great for thick coat render systems. Blue Fibreglass Mesh offers a wider mesh weave which is fantastic at enhancing the tensile strength of a thick coat render system. As we know, thick coat renders may look great but they are less flexible than thin coat renders, which means that it’s harder to make sure that you don’t get hairline cracks. 

Embedding a Blue Fibreglass Mesh within your thick coat render will massively help to ensure that your render finish remains crack-free for years to come. We can’t recommend it enough if you’re looking for extra stability.

Those are just a few of the beads that we offer for thick coat render systems. If you’re looking for a bit more information about what beads should be used where give our technical team a call!

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EWI Store Aylesbury

EWI Store Aylesbury Branch

Pop along to our Aylesbury branch for all your insulation and render requirements!

Our conveniently located Aylesbury branch has the same expert staff and variety of brands that you’ve come to expect from our London branch.

Pop in today for the best prices and the best service.

Click the map below for details on how to find us.

Visit our new branch in Aylesbury

Unit 22

Faraday Road

Bicester Road Industrial Estate

Aylesbury, HP19 8RY

01296 821067

Why shop with EWI Store?

We take a whole-system approach to external wall insulation, stocking all the materials required to help installers achieve a stand-out result. Our selection of products is constantly growing as we strive to offer our customers the best possible choice of materials from trusted manufacturers and established brand names.

Whatever your plans, pop into one of our branches to pick up high quality materials. Alternatively, order with us online or over the phone and we’ll get them delivered to your home, building project or workplace.

In stock now…

  • EWI Pro
  • Kingspan
  • Jablite
  • K Rend
  • Weber
  • Parex
  • EcoTherm

…and more!

 

insulating a detached house

How to Insulate a Detached House

Choosing the Right Insulation for Detached Houses

As with any installation, insulating a detached house first involves choosing the type of insulation that you want to use. This decision can depend upon a number of factors, whether it’s based on the thermal performance of the material or how suitable it is for your particular property. Here are the salient points for each of our insulation materials:

Kingspan K5

  • Thermal conductivity: 0.020 (W/mK)
  • This is much more expensive than EPS, but a lesser thickness is required to reach the same U-values (60mm of K5 vs. 90mm of EPS). Great for if you are lacking external space.

EPS (Expanded Polystyrene)

  • Thermal conductivity: 0.032 (W/mK)
  • Cost effective, lightweight and with excellent performance. Our most popular insulation board.

Mineral Wool

  • Thermal Conductivity: 0.036 (W/mK)
  • Manufactured by Rockwool, our Mineral Wool insulation is completely non-combustible, breathable and with acoustic insulating capabilities.

Wood Fibre

  • Thermal conductivity: 0.038-0.043 (W/mK)
  • Breathable, natural and very eco-friendly. This is ideal for timber-frame houses.

XPS (Extruded Polystyrene)

  • Thermal conductivity: 0.038 (W/mK)
  • More expensive than EPS, but with better compressive strength and greater resistance to water. Installers tend to use XPS for insulating below the DPC, with EPS above the DPC.

Insulating the chimney breast

With a detached house, you’ll often find that the house has a chimney breast that will require externally insulating. If the chimney breast is in-use or is likely to be in the future, then it needs to be insulated using Mineral Wool insulation. This is because Mineral Wool is completely non-combustible, so when the chimney gets very hot during use your external wall insulation system remains completely safe.

Extending the Roof Line

Whether it’s detached or semi-detached, many installations involve extending the roofline to ensure that the roof adequately overhangs the insulation. If this isn’t the case, verge trim needs to be used to ensure that the system is completely watertight.

Verge trim is installed underneath the soffit to extend the overhang of the roof and ensure that water runs directly off the front of the system, rather than running down the back. If water manages to get behind the system it can cause serious damage, which needs to be avoided. Verge Trim is, therefore, an essential item to prevent this.

Insulating Above a Porch Roof

Detached houses often have a porch roof or a secondary roof where there is a ground-floor extension. On these properties, lead flashing tends to be applied to the area where the wall meets the roof. When insulating a detached house that has a porch roof, it’s essential that the lead flashing is re-installed on top of the insulation to prevent water gathering underneath where the insulation meets the roof. The lead flashing will enable the water to run directly down the wall and off the roof without causing any issues.

Insulating Bay Windows

If you’re insulating a detached house with a bay window, there are a few ways you can do this. Unfortunately, starter track isn’t designed for bay windows, but you can adapt your uPVC Starter Track to fit the bay window by cutting slits in the base so that it will bend to fit the wall.

Sometimes the bay window sill does not have enough of an overhang in order to house the EPS insulation. In this situation, you have two options: you can either extend the window sill so that the EPS will fit underneath, or if the window sill is wide enough you can use a 60mm Kingspan K5, which will offer the same thermal performance as the EPS.

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polymer render

What is Polymer Render?

Polymer render is essentially just a term for a render that contains ‘polymers’ as part of its ingredients. Different polymers can give the product different characteristics, often enhancing flexibility and increasing weatherproofing capabilities. The technology behind polymer renders is fairly new, but they are steadily starting to overtake the common sand and cement render in terms of popularity. In today’s post, we’re going to explore the different types of polymer renders within the EWI Pro range, and explain a little bit about the different characteristics that they offer.

Benefits of Polymer Renders

  • Hydrophobic
  • Elastic
  • Highly adhesive
  • Typically through-coloured
  • Pre-mixed
  • Vapour permeable (depending on the type of render)
  • High impact resistance

EWI Pro Polymer Renders

EWI Pro offers a range of polymer renders. We often refer to these as ‘thin coat renders’ due to the method of application. Thin coat polymer renders are applied in an incredibly thin layer directly onto a basecoat layer. The EWI Pro polymer renders that we sell all come pre-coloured and ready-to-use in 25kg tubs. They also contain grains (in a range of sizes to choose from) so that you can decide on the type of textured finish that you want.

Because of the fact that it contains silicone, Premium Bio Silicone Render falls into the category of polymer renders. The silicone within the render means that it is highly flexible, vapour permeable and also in the case of the Premium Bio, extremely hydrophobic and self-cleaning. This is ideal for areas where there is a high level of vegetation and a bigger risk of organic overgrowth.

Silicone render can be considered as the next step down from the Premium Bio in terms of performance. This is our classic render, offering vapour permeability, flexibility, and self-cleaning capabilities. Silicone render is a classic choice for a premium, long-lasting finish.

Silicone Silicate render is our best value polymer render in terms of the level of performance it offers. This is a hybrid render, as it is a mixture of both silicone and silicate and subsequently offers the same level of breathability as our other silicone-based renders but with less of a self-cleaning effect.

Our acrylic polymer render differs from our silicones. It’s extra UV resistant, so it will retain colour pigment really nicely, and it’s also great for impact-resistance. Acrylic render is a standard classic choice and is great if vibrancy in colour is an important factor. However it does lack the vapour permeability that the silicones provide, so this is probably something to consider for long-term performance.

Reinforcing Polymer Render

All of our polymer renders the need to be applied on top of a reinforced basecoat. Fibreglass Mesh is embedded within the basecoat at the application stage to enhance the tensile strength of the whole system. Therefore, the render alone without this basecoat reinforcement layer will not provide a long-lasting finish.

It’s also important to apply these renders onto a completely smooth surface because they are applied at a thickness that matches the chosen grain size (so between 1-3mm), so any slight unevenness in the substrate behind will be completely visible underneath the render.

Polymer modified renders are without a doubt the future of rendering, so give us a call if you’re interested in having this type of render installed on your property!

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Materials Required for Mineral Wool External Wall Insulation

1. Priming the Substrate:

If you’re installing your Mineral Wool insulation system onto a brickwork substrate it will need priming with the Water Based Primer. We recommend applying this to the substrate by roller or brush. However, if you are rendering onto a very smooth substrate then we recommend applying the EWI-310 Universal Primer, as this contains aggregates which will provide a rough surface for the basecoat to adhere to. Ensuring that your substrate is adequately prepared is essential to ensuring that your render system will last.

Coverage rates:

5 litres covers 15-30m2 depending on the substrate.

Drying times:

1 coat takes 4 hours to dry.


2. Installing the Starter Track

When it comes to starter track, you have two options. Opt for aluminium starter track with a clip-on stop bead if you are looking to cut down on costs. Alternatively, if you want to ensure that thermal bridging is kept to an absolute minimum, we recommend using uPVC starter track. Both are available in a range of widths to house different thicknesses of insulation and are drilled into the wall above the DPC.

Coverage rates: 

UPVC starter track is available in 2m lengths.

Aluminium starter track is available in 2.5m lengths.


3. Preparing the Adhesive

Mineral Wool insulation is much heavier than EPS and therefore requires the use of EWI Pro’s strongest adhesive, the EWI-225 Premium Basecoat. This is a very versatile, dual-purpose product that can also be used in the subsequent basecoat layer. The EWI-225 is also breathable and therefore will not interfere with the vapour permeability of the Mineral Wool.

The adhesive is applied to the back of the board using the dot and dab method. This will allow you to get a nice flat surface for the render topcoat. 

Coverage: 

1 x 25kg bag covers 4/5m2

Drying times: 

24-48 hours


4. Applying the Mineral Wool Insulation Boards

Mineral Wool insulation boards are high-performance and very effective. We sell Mineral Wool by the pack in a range of thicknesses. For insulating a solid brick wall the general recommendation to reach building regulations is to opt for a 110mm thickness. Mineral Wool can be tricky to install as you can’t rasp away imperfections (unlike EPS). A really flat surface will need to be achieved while mounting the boards to ensure a smooth topcoat. We recommend using a spirit level to regularly check that everything is flat. 

Coverage:

1m2


5. Installing the fixings

EWI Pro recommends that you install one fixing per corner, with an additional two in the middle of the insulation board. Metal fixings should be used with the Mineral Wool insulation system as they will support the weight of the boards. The fixings are available in a wide range of lengths to accommodate different thicknesses of insulation.

Alternatively, for advanced fire-safety, we recommend the use of our metal lamella firebreak fixings. These are great for insulating high-rise structures.

Coverage:

Metal pin screw fixings are the recommended fixing for Mineral Wool insulation. These come in boxes of 200 or 100 depending on the length.

7 fixings are required per m2.


6. Applying the Beading:

Beading is essential for reinforcing external areas that are more prone to damage, for example, the corners and the areas around windows and doors. The required beads will depend on the property and which particular areas need reinforcing. We have a broad range of render beads that should be selected and applied as necessary, our beads are uPVC and are designed to be embedded within the basecoat layer.


7. Applying the Basecoat:

For Mineral Wool external wall insulation systems, we recommend using the EWI-225 Premium Basecoat again for the basecoat layer, as this saves on material waste. EWI-225 should be applied at a thickness of 6mm.

Coverage rates:

1 x 25kg bag covers 4/5m2

Drying times:

24-48 hours


8. Embedding the Mesh:

Fibreglass Mesh is embedded within the basecoat for extra reinforcement. This will ensure the system remains crack resistant.

Coverage rates:

1 x 50m2 roll covers 42.5m2 when overlapped

Our standard mesh is sold either by the m2 or in rolls of 50m2.


9. Priming the Basecoat:

A render primer should be used to increase the adhesion of the render to the basecoat and can be tinted to match the colour of your render for increased opacity. The type of primer will depend on the type of render you are using. For a Silicone Silicate system, we recommend using the SiSi Render Primer which comes in two different bucket sizes.  

Coverage:

1 x 7L bucket covers 20m2

1 x 21L bucket covers 60-70m2

Drying times:

12-24 hours


10. Applying the Render Topcoat:

Once the primer is dry, the render topcoat can be applied. We recommend using either the Premium Bio Silicone Render, Silicone Render, or Silicone Silicate Render. These are intended for creating a decorative finish; they are through-coloured with grains suspended within the mixture in a range of different sizes to achieve the desired texture.

Premium Bio Silicone is our highest performing render, offering advanced self-cleaning capabilities that tackle any signs of organic growth on the substrate, and extra UV resistance for a long-lasting finish. Silicone Render is the ideal choice for a quality long-lasting finish as it has nano-silicone particles which are great for maintaining a clean facade. Silicone Silicate is excellent value, also offering vapour permeability. All of these options are highly flexible, so are ideal for ensuring that there are no problems with cracks.

Coverage:

1.0mm grain size: 1x25kg bucket covers c. 10m2

1.5mm grain size: 1x25kg bucket covers c. 7-10m2

Drying times:

24 hours (+)

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Materials Required for Kingspan K5 External Wall Insulation

1. Priming the Substrate:

If you’re installing your Kingspan K5 insulation system onto a brickwork substrate it will need priming with the EWI-301 Water Based Primer. We recommend applying this to the substrate by roller or brush. However, if you are rendering onto a very smooth substrate then we recommend applying the EWI-310 Universal Primer, as this contains aggregates which will provide a rough surface for the adhesive to adhere to. Ensuring that your substrate is adequately prepared is essential to ensuring that your insulation system will last.

Coverage rates:

5 litres of EWI-310 Water based primer covers 15-30m2 depending on the substrate.

20kg of EWI-310 Universal primer covers approximately 50m2 depending on the substrate.

Drying times:

1 coat takes 4 hours to dry.


2. Installing the Starter Track

When it comes to starter track, you have two options. Opt for aluminium starter track with a clip-on stop bead if you are looking to cut down on costs. Alternatively, if you want to ensure that thermal bridging is kept to an absolute minimum, we recommend using uPVC starter track. Both are available in a range of widths to house different thicknesses of insulation, and are held in place with screws positioned at 300mm centres. The starter track is installed on the wall just above the DPC.

Coverage rates: 

UPVC starter track is available in 2m lengths.

Aluminium starter track is available in 2.5m lengths.


3. Preparing the Adhesive

Kingspan K5 insulation is heavier than EPS and therefore requires the use of EWI Pro’s strongest adhesive, the EWI-225 Premium Basecoat. This is a very versatile, dual-purpose product that can also be used in the subsequent basecoat layer. 

The adhesive is applied to the back of the board using either the perimeter and dabs method or by using a notched trowel to cover the whole of the board. Both of these can be seen in the picture below – however we recommend using the first method if the underlying surface is not perfectly flat as the adhesive will be able to absorb these inconsistencies in the wall. 

 

The boards are staggered (like a brick pattern on a wall) and also are interlocked at corners. 

Coverage: 

1 x 25kg bag covers 4/5m2

Drying times: 

24-48 hours


4. Applying the Kingspan K5 Insulation Boards

Kingspan K5 insulation boards are high-performance insulation boards, offering far better thermal insulating properties than EPS or mineral wool. We sell Kingspan K5 by the board in a range of thicknesses. For insulating a solid brick wall the general recommendation to reach building regulations is to opt for a 60mm thickness. Kingspan K5 can be tricky to install as you can’t rasp away imperfections (unlike EPS). A really flat surface will need to be achieved while mounting the boards to ensure a smooth topcoat. We recommend using a spirit level to regularly check that the boards are being applied flat on the wall. As mentioned, applying adhesive around the perimeter of the K5 board allows you to absorb imperfections within the wall surface. 

Coverage:

0.72 m2 per board.


5. Installing the Fixings

EWI Pro recommends that you install one fixing per corner, with an additional two in the middle of the insulation board. Metal fixings should be used with the Kingspan K5 insulation system as they will support the weight of the boards. The fixings are available in a wide range of lengths to accommodate different thicknesses of insulation, but we recommend the fixing is at least 40mm longer than the thickness of the insulation to ensure it gets a decent hold in the brick or block. 

Coverage:

Metal pin screw fixings are the recommended fixing for Kingspan K5 insulation. These come in boxes of 200 or 100 depending on the length.

7 fixings are required per m2.


6. Applying the Beading:

Beading is essential for reinforcing external areas that are more prone to damage, for example, the corners and the areas around windows and doors. The required beads will depend on the property and which particular areas need reinforcing. We have a broad range of render beads that should be selected and applied as necessary, our beads are uPVC and are designed to be embedded within the basecoat layer.


7. Applying the Basecoat:

For Kingspan K5 external wall insulation systems, we recommend using the EWI-225 Premium Basecoat again for the basecoat layer, as this saves on material waste. EWI-225 should be applied at a thickness of 6mm – this can be achieved using a 10mm notched trowel.

Coverage rates:

1 x 25kg bag covers 4/5m2

Drying times:

24-48 hours


8. Embedding the Mesh:

Fibreglass Mesh is embedded within the basecoat for extra reinforcement. The fibreglass mesh gives the K5 external wall insulation system strength and flexibility – ensuring the system remains crack resistant for years to come. 

The mesh comes in 50m long rolls and is 1m wide. The mesh is marked at each end and this shows the overlap that you should be achieving when embedding mesh across the wall surface.

Coverage rates:

1 x 50m2 roll covers 42.5m2 when overlapped

Our standard mesh is sold either by the m2 or in rolls of 50m2.


9. Priming the Basecoat:

A render primer should be used to increase the adhesion of the render to the basecoat, and can be tinted to match the colour of your render for an increased opacity. The type of primer will depend on the type of render you are using. For a Silicone render system, we recommend using the SiSi Render Primer which comes in two different bucket sizes. This render can be applied with either a roller or a paintbrush. 

Coverage:

1 x 7L bucket covers 20m2

1 x 21L bucket covers 60-70m2

Drying times:

12-24 hours


10. Applying the Render Topcoat:

Once the primer is dry, the render topcoat can be applied. We recommend using either the Premium Bio Silicone Render, Silicone Render, or Silicone Silicate Render. These are intended for creating a decorative finish; they are through-coloured with grains suspended within the mixture in a range of different sizes to achieve the desired texture.

Premium Bio Silicone is our highest performing render, offering advanced self-cleaning capabilities that tackle any signs of organic growth on the substrate, and extra UV resistance for a long-lasting finish. Silicone render is the ideal choice for a quality long-lasting finish as it has nano-silicone particles which are great for maintaining a clean facade. Silicone Silicate is excellent value, also offering vapour permeability. All of these options are highly flexible, so are ideal for ensuring that there are no problems with cracks.

To learn more about the EWI Pro renders head over to ewipro.com

Coverage:

1.0mm grain size: 1x25kg bucket covers c. 10m2

1.5mm grain size: 1x25kg bucket covers c. 7-10m2

Drying times:

24 hours (+)


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Materials Required for EPS External Wall Insulation

1. Priming the Substrate:

A brickwork substrate tends to be very porous, and so it will need priming with the Water Based Primer. We recommend applying this to the substrate by roller or brush. However, if you are rendering onto a very smooth substrate then we recommend applying the EWI-310 Universal Primer, as this contains aggregates which will provide a rough surface for the basecoat to adhere to. Ensuring that your substrate is adequately prepared is essential to ensuring that your render system will last.

Coverage rates:

5 litres covers 15-30m2 depending on the substrate.

Drying times:

1 coat takes 4 hours to dry.


2. Installing the Starter Track

When it comes to starter track, you have two options. Opt for aluminium starter track with a clip-on stop bead if you are looking to cut down on costs. Alternatively, if you want to ensure that thermal bridging is kept to an absolute minimum, we recommend using uPVC starter track. Both are available in a range of widths to house different thicknesses of insulation, and are drilled into the wall above the DPC.

Coverage rates: 

UPVC starter track is available in 2m lengths.

Aluminium starter track is available in 2.5m lengths.


3. Preparing the Adhesive

The EWI-220 creates a strong, long-lasting adhesion, securing the boards to the substrate for years to come. There are a couple of options when it comes to choosing your EPS adhesive:

  • EWI-210: a standalone adhesive for EPS. Not to be used in the basecoat layer. (mix each bag with 6.3l of water).
  • EWI-220: a multi-purpose basecoat/adhesive for EPS, can also be used in the basecoat layer with mesh. (mix each bag with 5.8l of water).
  • EWI-221: a multi-purpose basecoat/adhesive for EPS, ideal for use in the winter months at temperatures down to 0 degrees. (mix each bag with 6.3l of water).

The adhesive is applied to the back of the board using the dot and dab method. This will allow you to get a nice flat surface for the render topcoat. 

Coverage: 

1 x 25kg bag covers 4/5m2

Drying times: 

24-48 hours

(also available in bulk)


4. Applying the EPS Insulation Boards

Our EPS insulation boards are lightweight, easy to install and very effective. We sell EPS by the square metre in a range of thicknesses. For insulating a solid brick wall the general recommendation to reach building regulations is to opt for a 90mm thickness. Graphite EPS tends to develop an oily outer layer, so it’s important to rasp it to get rid of this and ensure that the basecoat adheres properly. Rasping also offers the added benefit of enabling you to smooth out any imperfections in the surface. 

Coverage:

1m2


5. Installing the fixings

EWI Pro recommends that you install one fixing per corner, with an additional two in the middle of the insulation board. Plastic fixings should be used with the EPS insulation system as they significantly reduce thermal bridging. The fixings are available in a wide range of lengths to accommodate different thicknesses of insulation.

Coverage:

Plastic pin fixings are the recommended fixing for EPS insulation. These come in boxes of 200 or 100 depending on the length.

7 fixings are required per m2.


6. Applying the Beading:

Beading is essential for reinforcing external areas that are more prone to damage, for example, the corners and the areas around windows and doors. The required beads will depend on the property and which particular areas need reinforcing. We have a broad range of render beads that should be selected and applied as necessary, our beads are uPVC and are designed to be embedded within the basecoat layer.


7. Applying the Basecoat:

For EPS external wall insulation systems, we recommend using the EWI-220 EPS Basecoat for the basecoat layer, as this saves on material waste. TThe EWI-220 and EWI-221 contain reinforcing fibres, which guarantee a longlasting finish.

Coverage rates:

1 x 25kg bag covers 4/5m2

Drying times:

24-48 hours

(also available in bulk)


8. Embedding the Mesh:

Fibreglass Mesh is embedded within the basecoat for extra reinforcement. This will ensure the system remains crack resistant.

Coverage rates:

1 x 50m2 roll covers 42.5m2 when overlapped

Our standard mesh is sold either by the m2 or in rolls of 50m2.


9. Priming the Basecoat:

A render primer should be used to increase the adhesion of the render to the basecoat, and can be tinted to match the colour of your render for an increased opacity. The type of primer will depend on the type of render you are using. For a Silicone Silicate system, we recommend using the SiSi Render Primer which comes in two different bucket sizes.  

Coverage:

1 x 7L bucket covers 20m2

1 x 21L bucket covers 60-70m2

Drying times:

12-24 hours


10. Applying the Render Topcoat:

Once the primer is dry, the render topcoat can be applied. We recommend using either the Premium Bio Silicone Render, Silicone Render, or Silicone Silicate Render. These are intended for creating a decorative finish; they are through-coloured with grains suspended within the mixture in a range of different sizes to achieve the desired texture.

Premium Bio Silicone is our highest performing render, offering advanced self-cleaning capabilities that tackle any signs of organic growth on the substrate, and extra UV resistance for a long-lasting finish. Silicone render is the ideal choice for a quality long-lasting finish as it has nano-silicone particles which are great for maintaining a clean facade. Silicone Silicate is excellent value, also offering vapour permeability. All of these options are highly flexible, so are ideal for ensuring that there are no problems with cracks.

Coverage:

1.0mm grain size: 1x25kg bucket covers c. 10m2

1.5mm grain size: 1x25kg bucket covers c. 7-10m2

Drying times:

24 hours (+)


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How to Remove Render

There are a number of reasons people choose to remove the render from their homes. Whether it’s cracked sand and cement render that is causing problems with damp, or old dilapidated pebbledash that just looks tired and outdated. There are a few things that you can do to either remove the render or cover it over, so keep reading for our best advice!

Removing Existing Render 

Old render will need removing with traditional tools, such as a hammer and chisel. There is some specialist equipment on the market today, but if you don’t have access to these then standard tools will do the job. 

Using this method to remove the render means that you have to be really careful not to damage the underlying substrate, as this could create more work for you later down the line when you need to repair it. Any damage to the underlying substrate also means that you will most likely need to re-render the wall, and you may even need to use a levelling coat to get the substrate nice and flat again. 

Hiding Render with External Wall Insulation 

If removing the render puts the building at too much risk, then your next option is to install external wall insulation boards on top. As long as the existing render is sound and stable (i.e. not likely to fall off the wall) then this method is a great means to an end. 

You can make this as cheap as possible by merely using a 20mm thick EPS insulation board, which won’t do much for the energy efficiency of the building but will certainly help provide a flat surface for re-rendering. Alternatively, if you want to go all out then you could install 90mm and reap the rewards.

For this method, you will need to buy fixings that go through the insulation board and far enough back that they penetrate the actual brickwork/blockwork underneath. Once the boards are in place, a thin coat coloured render should be applied on top as a means of protection against the weather. 

Using the One Coat Dash Cover to Cover over Pebbledash

One Coat Dash Cover (OCDC) is a quick and easy solution to covering over pebbledash instead of removing the render itself. It’s a lightweight, lime-based basecoat which can be applied up to 50mm thick in two passes. This means that if the pebbledash is waterlogged, it will be able to dry out naturally as OCDC is very breathable and won’t trap the water. 

You can finish OCDC in any way that you like, whether you choose to use a thin coat render, lime render or a traditional masonry paint, it’s important to use breathable materials to allow any trapped moisture to escape.

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Top Tips for Preventing Cracked Render

There’s no doubt about it that cracked render can be incredibly disappointing and frustrating, especially for homeowners that have just had their houses re-rendered. There are many reasons as to why render cracks (we’ve previously covered it in this blog post).

As a renderer, it’s important to ensure that all your bases are covered so as to prevent cracking and achieve a long-lasting finish. In today’s post, we’re going to be giving our best installation tips to ensure that cracked render is a thing of the past. 

Prevent Cracked Render with Substrate Absorptivity Tests

The first step in any render installation is to check the absorptive capacity of the substrate. This is an essential step because porous substrates can absorb water out of your render very quickly, which can then affect its adhesion and, you guessed it, cause cracked render. 

The substrate absorptivity test that we recommend is to wet the wall with water and check the rate at which it is absorbed. You don’t want the substrate to be over-saturated with a low absorptive capacity, because this will mean that the render won’t stick, but equally you don’t want it to immediately absorb the water.

If your substrate is highly absorptive, then we recommend lightly dampening the walls with a fine mist of water and then performing the test again. Be careful not to oversaturate the walls. 

Use the Right Primer

Following on from this, a good primer is essential for limiting the absorptive capacity of the substrate, making sure that it is stable and thus preventing cracked render. We recommend using the EWI-301 Water Based Primer, or the EWI-302 Deep Penetrating Primer which is ideal for newbuild brick and blockwork.

A good primer will work to ensure that the substrate doesn’t absorb too much water from your materials. If you use the EWI-310 Universal Primer, then this also contains quartz aggregate which helps to create a mechanical key to aid adhesion.

Reinforce with Fibreglass Mesh

We recommend the use of Fibreglass Mesh in all of the render systems that we offer. Whether it’s a Monocouche render or a thin coat render system, you can embed the mesh in the first pass or within the basecoat layer. 

Fibreglass Mesh enhances the tensile strength of the render, keeping it nice and sturdy so that it can withstand any movements within the building structure and therefore resist cracking. The mesh is cut into strips and overlapped on all sides so that there are no gaps where cracks can form.

If you want to take the crack resistance up a notch, then we highly recommend using Panzer Mesh within your system, as this is incredibly high strength.

Don’t Forget Your Beading

We sell lots of different types of beading, all designed to be embedded within the render to reinforce certain areas. For example, our Corner Bead helps to provide a nice sharp finish at the corners of the render system while also providing this area with reinforcement against impacts. 

The slight difference here is that our thin coat render system beads tend to have a mesh wing to spread the reinforcement across a larger surface area, whereas the scratch render beads have just the hard uPVC without the mesh. 

Other types of bead: 

Movement Joints

Movement joints need to be reinforced using a render movement bead.  These are used where there is a large expanse of render (more than 12m). It’s installed vertically and is embedded within the basecoat layer to stabilise the render and ensure that any cracking is prevented. 

Stress Patches are Essential

Areas above and below openings (around windows and doors) need to be reinforced with strips of Fibreglass Mesh to distribute and resist stresses. The mesh should be cut into strips that extend past the stress patch by at least 50cm. It should be embedded in the middle of the basecoat or the first pass.

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best render to use in winter

The Best Render to use in Winter

Rendering in winter is a challenge that all professional renderers face. Choosing the right materials that can be used in low temperatures is particularly tricky, especially when there is an expensive risk of render failure.

We have a range of solutions for making sure that nothing can go wrong even in the winter months, so keep reading to find out about the best renders to use in winter!

Using Mineral Render in Winter

Mineral Render is a great choice for winter installations. It’s essentially the dry-mix version of our thin coat renders; it has grains within the render and it’s applied in a very thin layer. The only thing that makes this render different is the fact that it contains portland cement, which enables it to dry a lot faster than our other thin coat renders.

Faster drying times in winter are essential, as temperatures drop overnight, and wet render exposed to freezing conditions leads to render failure. Mineral Render does require painting with Silicone Paint, but despite the added cost of this it’s a much more effective material to use in the winter months.

Using the Winter Adhesive

The Winter Adhesive is a basecoat designed for use down to temperatures of zero degrees. That means that it’s perfect for those winter months when the weather is miserable and work is continuously stalled due to low temperatures.

The basecoat is essentially the same as the EWI-220 EPS Basecoat Adhesive in that it can be used as an adhesive for securing EPS insulation boards to a substrate, so the plus side is that it also helps to enable the installation of EWI in cold climates.

Using the Render Accelerator in Winter

Winter installations tend to be all about drying times, and the render accelerator really helps with this issue. It’s essentially an additive that you mix into your ready-mix render before applying as normal – the accelerator speeds up the process of drying before the wet render can be affected by the weather.

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Types of Rendering Mesh

Orange Fibreglass Mesh – Thin Coat Render

An integral component in both EWI and render systems, the orange mesh is ideal for embedding within the basecoat layer to improve the crack-resistance of the system. The mesh is cut into vertical strips and is embedded into the basecoat layer using the flat-edge of a trowel. Each strip will need to be overlapped by 10-15cm along all edges.

EWI Pro’s Orange Mesh is a strong and flexible 165g fibreglass reinforcing mesh. It works by increasing the overall tensile strength of the underlying basecoat so that any movements or fluctuations within the underlying substrate will not cause cracks. 

The fibreglass material that the mesh is made from is resistant to water, alkali and age damage, which means it’s the most long-lasting solution for crack-resistance. This particular mesh is designed for thin coat render systems as it has smaller holes within its structure. This is because, in thin coat render systems, the basecoat is applied in a thinner layer of around 6mm,  which means that less basecoat needs to be pulled through the holes of the mesh in order for it to sit within the middle of the basecoat layer. 

Blue Fibreglass Mesh – Thick Coat Render

The blue mesh that we stock is designed to be installed with thick coat renders. This can be anything from your traditional sand and cement to your monocouche renders. The blue mesh is more heavy-duty than orange and has larger holes to enable the user to pull more material through during the process of embedding it into the render. 

The blue mesh is also ideal for if you’re using EWI Pro’s lightweight basecoat, as this can be applied up to 25mm thick in one pass. Again, the mesh helps to ensure that the render topcoat remains intact and crack-free, ensuring a long-lasting finish.

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Where To Get an External Wall Insulation Quote

Try Out The Materials Calculator For a Free Quote

The External wall insulation materials calculator is a quick and easy online tool that provides you with a quote for the cost of the materials required for your project.

To complete the materials calculator, all you need to do is simply provide the details of the type of property you have, the square meterage, the type of insulation material that you want and the type of render. 

Once you’ve filled in all your details, you’ll be provided with a list of the external wall insulation materials as well as a quote. It’s incredibly easy to complete and takes only a couple of minutes, so definitely check it out for an accurate external wall insulation materials quote.

Request an EWI Pro Approved Installer

Getting a quote for external wall insulation materials is one thing, but the actual cost of labour is another. 

At EWI Store we have a database of approved installers who have completed the EWI Pro training course and who we recommend to interested homeowners.

If you’re looking for someone trustworthy to do the work for you, we strongly suggest opting for an approved installer, as they will be familiar with our materials, their work will be top quality and will adhere to our high standards.

When you get in touch with us to request an approved installer, we’ll typically give you the details of three installers who work within your area. They can then provide you with an external wall insulation quote and you can choose the installer that you feel suits you best. If you’re looking for an installer, fill out the form below and we will be in touch!

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What to Tell Your Neighbours Before Installing EWI

Telling your neighbours about building work can always be a bit of a tricky conversation. External wall insulation involves a few weeks of work on the exterior of your property and you can expect that during that time there may be a little disruption, especially if you live in close quarters with your neighbours. 

Going through the installation process will mean that your home is a more comfortable temperature during the winter and summer months, your heating bills are reduced and the external appearance of your property is updated and improved. No doubt it’s worthwhile for you, but your neighbours may not see it that way, so we’ve put together a brief list of things that you will need to inform them of prior to the commencement of the works. 

Parking may be more difficult

This is especially the case if your property or your neighbour’s property doesn’t have a driveway. Installers will often drive vans and materials will usually be delivered in a Luton van, so warn your neighbour that parking may be tricky for the duration of the installation.

It will probably be noisy at times

Erecting scaffolding, hammering and drilling in fixings and all the other details that go into an EWI installation all have one thing in common: noise. 

External wall insulation isn’t the noisiest job you could be having done (knocking down walls and building an extension would be much worse), nevertheless it’s likely to be a little bit busier and noisier in the area.

We recommend you inform your neighbours a couple of weeks in advance so that they know to expect it. The increase in noise will very likely occur during working hours, so you can reassure them that it won’t be going on late into the evening. 

There will be some dust and mess

Depending upon how simple the installation is, it’s likely there will be a level of dust and mess. EWI is installed using dry-mix adhesives which are very dusty before they’re mixed with water. Insulation off-cuts are also a common occurrence during an installation; EPS, in particular, can be quite messy when it’s cut with a knife as the polystyrene tends to disintegrate. Similar to the basecoat and adhesives, the render topcoat can drip so the installer should take precautions to protect the area surrounding the property. 

Scaffolding will likely be required

Unless you live in a bungalow it’s highly likely that scaffolding will be required to complete your project. Scaffolding is quite an eyesore so it’s courteous to warn your neighbours of its expected presence. If you live in a semi-detached home your neighbours will be particularly affected by the presence of the scaffolding and so will need to be notified in advance. 

The works are expected to last for at least two weeks

One of the best things about installing EWI is that the work shouldn’t take more than a couple of weeks to complete. Most of the delays are caused by drying times (e.g. you have to wait 24 hours for the adhesive to dry before you can install the fixings). The only thing that can cause delays is poor weather conditions, but other than this the whole process is quick and relatively easy.

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Celotex GA4000 Internal Insulation

If you’re in the process of renovating your home, or you’re simply looking for ways to reduce your energy bills by making your home more energy-efficient, internal insulation is always the best place to start. 

Whether it’s your loft, floors or walls that require insulating, we have one product that can do all of the above.  

Celotex PIR Internal Insulation Board

Introducing the Celotex GA4000 internal insulation board! A PIR insulation board with a rigid core and aluminium foil facings on both sides, Celotex GA4000 is a highly versatile product that can be used for a range of internal applications.

The awesome thing about this type of insulation board is that it is available in such a vast array of thicknesses (the GA4000 goes from 50 to 100mm), so you can choose a size that is suitable for the amount of space that is available within your home. Furthermore, if you’re worried about the environmental friendliness of PIR/foam insulation materials, the Celotex GA4000 boards are also very eco-friendly, having been manufactured with no environmentally hazardous blowing agents.

Where is Celotex GA4000 Used?

The Celotex GA4000 boards are designed for use throughout your building project, as they are very easy to handle and install. Typically, this type of insulation board is targeted at cut-to-fit areas such as between rafters and joists. This enables users to achieve lower U-values using just a single sheet of insulation. According to the manufacturer’s website, Celotex GA4000 can be used in the following areas:

  • Flat roofs
  • Pitched roofs
  • Ground floors including solid concrete, block and beam, suspended timber joist and with underfloor heating.
  • Timber frame walls
  • Steel frame walls
  • Retrofit on solid wall masonry and timber structures

Thermal Performance of Celotex Insulation

Celotex GA4000 PIR insulation boards are some of the best performing internal insulation boards on the market. With a thermal conductivity of 0.022 W/mK, the insulation boards are designed to eliminate thermal bridges and effectively slow down the rate of heat loss, offering buildings long-term energy savings.

Celotex GA4000 – Available at EWI Store!

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Is External Wall Insulation Safe?

Customers often call us to ask whether external wall insulation is safe to install on their homes. EWI Pro systems are BBA approved, which means that they have been rigorously tested by the British Board of Agrément, who have deemed that they are safe and suitable for installation onto UK homes.

Cladding materials have had a lot of negative press recently, being the source of heated debates over how trustworthy certain materials are. While external wall insulation can be classed as a type of cladding, it’s worth noting that it is completely different to rainscreen cladding – the material that resulted in the Grenfell fire tragedy. 

In today’s blog post we’re going to be discussing how our external wall insulation systems have been designed to ensure the highest level of safety. 

Securing External Insulation Boards – Dual Fixing

The EWI Pro system is designed so that the external wall insulation boards are fixed to the substrate using the dual-fixing method of both adhesive and mechanical fixings. This ‘belt and braces’ design ensures the stability of the system so that in the unlikely event that the adhesive fails, the fixings are still there to hold the boards up. 

The EWI Pro system also consists of two adhesives of different strengths. For example, our Premium Basecoat (EWI-225) is our strongest adhesive and so is always used with Mineral Wool insulation boards which are much heavier. Alternatively, the EPS Basecoat (EWI-220) is ideal for use with lightweight foam insulation boards such as EPS and XPS. Ensuring that the adhesive is of the correct strength for the weight of the insulation board is essential for a safe and secure system. 

Fire Safety of External Wall Insulation Materials

How fire safe your system is will greatly depend upon the type of insulation that you choose. 

Rockwool Mineral Wool boards are rated as Euroclass A1 non-combustible and are therefore the safest insulation material that you can have installed on your property. The Rockwool insulation boards work to contain the fire and prevent it from spreading throughout the building. As well as this, they don’t release toxic emissions or smoke when exposed to fire.

The EPS system has been designed in such a way so that in the event of a fire the EPS would simply melt within its cement-based plaster enclosure. The mechanical fixings would support and hold the structure in place, so although the system wouldn’t withstand the fire, it wouldn’t contribute towards the spread of it.

Wood Fibre, on the other hand, is known to char rather than burn. You’d think that being wood it would go up in flames very easily, however, timber burns very slowly and this charring effect actually creates an oxygen barrier which helps to slow down the spread of the flames.

Fibreglass Mesh for Reinforcement

We often talk about the use of reinforcement mesh in the context of ensuring that the render topcoat doesn’t crack. However, Fibreglass Mesh plays an important role within the external wall insulation system, enhancing its tensile strength to keep the boards securely tied to the wall.

Fibreglass Mesh strips are embedded within the basecoat layer and are overlapped by 10cm across each edge. This creates an added layer of reinforcement that spans across the entire surface area of the system.

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Should You Switch From Cavity Wall Insulation to External Wall insulation?

Cavity wall insulation vs. external wall insulation is an age-old argument that leaves people wondering as to what the best option is. It started as cavity wall insulation being solely for people who have houses with cavities (obviously), and external wall insulation was for people with solid wall houses.

Cavity wall insulation dominated the market as being the primary solution because most people had houses with a cavity wall. However, these days the world has gone energy-saving mad (which is a good thing!) and people want extra-extra super-insulated houses without having to spend too much money.

There’s a lot to be said for both types of insulation, and ultimately the decision will come down to what is right for your budget and your particular property. With cavity wall insulation’s history of poor installation and resulting damp, people tend to become concerned with the risks involved with this type of insulation. Nevertheless, it’s important to remember that both types of insulation have the potential to go wrong and need to be installed by qualified professionals.

We’ve put together a quick guide on the advantages and disadvantages of both cavity and external wall insulation.

Advantages of Cavity Wall Insulation

  • Will not affect the external appearance of the property
  • Does not require the loss of internal space
  • Cavity wall insulation reduces your energy bills – it can save you £100-200 a year on your heating bills.
  • Keeps your house warmer in the winter
  • Reduces your carbon footprint
  • Very quick and easy to install
  • Cheaper than external wall insulation

Disadvantages of Cavity Wall Insulation

  • Risk of poor installation from underqualified installers
  • Has been known to trap moisture and cause damp when poorly installed
  • Restriction on the amount of insulation that can be installed (dependent upon the size of the cavity) therefore less effective than EWI
  • Not suitable for all buildings (i.e. solid walls).

Advantages of External Wall Insulation

  • Requires no internal space
  • Can massively improve the look of a property due to the decorative topcoat
  • No restriction as to how much insulation you can install (you can get up to 200mm+)
  • Therefore no restriction on how much energy you can save
  • Certain insulation materials (i.e. Rockwool) have soundproofing capabilities as an added advantage
  • Regulates the thermal comfort of the home
  • Unlikely to cause damp and condensation when installing properly
  • No thermal bridges – continuous insulation
  • Prolongs the life of the building by protecting its exterior walls
  • Can increase the value of the property in terms of its energy efficiency and external appearance
  • Low maintenance
  • Virtually any property can have it installed

Disadvantages of External Wall Insulation

  • More expensive than cavity wall insulation due to the number of materials required and the higher level of skill needed to install it
  • Requires skill to install it to ensure it is safe and won’t cause problems, so you need to be careful of who you hire
  • Can be difficult to get planning permission for older properties, as it creates a completely new exterior
  • It may need occasional maintenance to ensure the render topcoat looks fresh

Should You Switch From CWI to EWI?

If you already have cavity wall insulation installed and it’s not as effective as you would like it to be, then you can certainly install external wall insulation as well. Essentially by doing this, you’ll be achieving two layers of insulation, and any thermal bridges within the existing cavity wall insulation will be erased by the EWI. Cavity wall insulation and external wall insulation together will achieve maximum effectiveness.

The downside is that you can’t have one without the other. Trying to install EWI onto an empty cavity wall will achieve very little, as the air within the cavity will just be heated up before escaping.

What it comes down to is what’s best for your property and your budget. If you’re looking for a bit more advice on the subject then give our technical team a call and we can talk you through the options for your home.

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How Much Does Rendering Cost?

The cost of having your house rendered can vary depending upon several factors. First, the type of render you opt to have installed will make a difference in the overall cost of the project. Secondly, the size of your property will dictate the amount of material required, so naturally the larger the property the more expensive it will be. 

We always recommend getting a quotation from at least 3 installers prior to going ahead. This way you can compare prices and find an installer that you trust. If you need help finding trustworthy installers in your area, give us a call and we can put you in touch! We have a database of installers who have undergone our rigorous training course and who we recommend to other customers like you.

One of the biggest cost-conscious decisions you will need to make is the choice of render. We’re going to talk you through a range of options and explain the benefits of each. 

Sand and Cement Render

Sand and cement render is the cheapest option available, and as such it’s possibly one of the worst choices in terms of longevity. Sand and cement render is an incredibly inflexible material that cannot withstand the slight fluctuations that a building naturally makes because it’s applied in such a thick layer.

The second issue with sand and cement render is that it’s not breathable and can very easily become waterlogged once cracked. Essentially what this means is that once water gets into the material it will struggle to evaporate out and will eventually cause damage (i.e. blown render or penetrating damp on the internal walls).

Monocouche Render

Monocouche render is the next step up from sand and cement, costing around £12 bag. Rather than coming as separate ingredients that the installer needs to mix on-site (i.e. the sand and cement), the monocouche render comes readily prepared in one bag, all it needs is mixing with water. 

The key benefit of the monocouche is that it’s through-coloured so there’s no need to paint it afterwards. Unlike sand and cement render, which is perfectly smooth, monocouche provides a natural stone-effect finish as it is scratched back to create a textured effect.

One downside to the monocouche render is that again it’s applied in a thick layer, which makes it more likely to crack. Modern technology has enabled us to produce breathable monocouche renders, however once the render cracks it still becomes very difficult to regulate the movement of moisture in and out of the substrate.

Acrylic Render

Acrylic render is somewhat different from the previously mentioned renders, as it is classed as a ‘thin coat render.’ Acrylic is the cheapest of our entire range of thin coat renders, coming in at just £29.97 ex. VAT per bucket. The render itself is applied in a very thin layer of 1-3mm (depending upon the grain size), on top of a reinforced basecoat which is around 6mm thick. This means that the maximum total thickness of the render system is 9mm – far less than your average 15mm+ for sand and cement. The thinness of the render means that it is far more flexible and able to compensate for any movements within the underlying substrate, so the chance of cracking is massively reduced. Thin coat renders come ready to use straight out of the bucket; they are through-coloured in a range of shades (much like paint) and are applied by trowel.

Acrylic render is a non-breathable thin coat render, but out of all the thin coat renders it is the most impact resistant.

Silicone-Silicate Render

Once you start getting into the ‘silicones’ category, you’ll notice that prices begin to rise due to its greater performance. Silicone Silicate is a hybrid silicone thin coat render, costing £52.45 ex. VAT per bucket. This is our best value thin coat render due to the performance it offers at the price point it comes in at.

Much like the acrylic, it comes ready to use in a tub – pre-coloured and pre-mixed. It’s highly versatile but also great value, offering the key benefit of breathability. While it does possess less self-cleaning capabilities than our full silicone render and our Premium Bio Silicone Render, Silicone Silicate does offer a long-lasting, aesthetically pleasing finish.

Silicone Render

If you want top-quality and top performance, then you can’t go wrong with our Silicone Render – £57.23 ex. VAT. People tend to pay more for the full silicone render as it is a notoriously high-performance render. It offers breathability, crack resistance and self-cleaning capabilities which provide the reassurance of a long-lasting finish.

Buyers commonly assume that ‘K Rend’ is the only silicone render product, when it’s just one brand of silicone render. Don’t fall into that trap, as there are plenty of other manufacturers of silicone render on the market who all offer a range of finishes and colour choices.

Premium Bio Silicone Render

The Premium Bio Silicone Render is our top of the line, breathable thin coat render, offering advanced self-cleaning capabilities, enhanced impact resistance and increased UV protection. This means that it provides a long-lasting, crack-resistant finish that will remain vibrant in colour for years to come. Because the Premium Bio offers absolutely everything, it’s our most expensive option, coming in at £70.41 ex. VAT per bucket.

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Why Has External Wall Insulation Made My Home Damp?

Damp After External Wall Insulation

External wall insulation is a great way to improve the energy efficiency of your home by reducing the rate of heat loss through your walls. The great thing about EWI is that it wraps around the entire exterior of your home, enveloping the heat inside. 

EWI is much less likely to cause damp than other methods of insulating (such as cavity wall insulation) because there are far fewer breaks within the material – EWI is known as a continuous insulation method. 

However, correct installation is key. External wall insulation consists of rigid insulation boards (as opposed to a foam) that are secured to the exterior walls of the building using adhesive and mechanical fixings. The hugely important part here is that there are no gaps between the boards and no areas where water might penetrate. 

Thermal Bridges

In the context of external wall insulation and damp, the reason we talk about avoiding gaps between the boards and breaks within the insulation is because thermal bridging can occur. During installation, any gaps should be filled using a spray foam adhesive which will act as an insulator.

Thermal bridges are essentially places where there is a higher rate of heat transfer than the surrounding materials, which results in an overall reduction in thermal insulation of construction. Thermal bridges are responsible for up to 35% of thermal losses and increased condensation and mould growth.

Take for example an insulation system where gaps have been left between the boards. The temperature within the gap is going to be a lot colder than the surrounding insulation boards, which means that condensation will gather in that area and damp will occur.

Poor Quality Insulation

Damp insulation means ineffective insulation. Not only this, but moisture gathering behind the insulation boards can lead to erosion of the adhesive, which can cause serious damage to the system.  

If you start to notice damp on your internal walls, then this could be a sign that water is getting behind your EWI system. Signs of damp caused by external wall insulation should be an immediate cause for concern, and a professional should be called out to assess the situation promptly. 

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How to Cover Tyrolean Render

What is Tyrolean Render?

Tyrolean render is a method of applying monocouche or sand and cement render to create a rough textured finish. The render is applied to the substrate in a thick layer, creating an initially smooth surface. This is then left to dry slightly before a second pass is applied using a tyrolean flicker gun. The finished effect looks similar in appearance to a roughcast render; it’s certainly some people’s cup of tea but others may prefer a smooth finish.

The downside to this type of render application is that it is likely to crack because it is applied in a thick layer (usually around 16mm). As we know, buildings tend to expand and contract due to heating and cooling, and thicker renders are much less able to be flexible and withstand this. 

What is OCDC?

OCDC (also known as the One Coat Dash Cover) is our solution to covering over pebbledash and roughcast textured renders. It is a breathable lime basecoat that can be applied up to 50mm thick in two passes. The idea is that it can be applied thick enough to create a smooth surface, without trapping moisture behind it. So for a tyrolean render that is particularly waterlogged, it’ll be easy for the water to gradually evaporate out through the OCDC.

Covering over tyrolean render with OCDC is a fantastic solution if you’re looking to update the look to your property. Once the OCDC is applied, it can be painted or a thin coat silicone render can be applied on top for a high-performance finish.

Applying OCDC onto Tyrolean Render

OCDC is very easy to apply. The product should be mixed with 5 litres of water using an electric paddle mix until it is an even consistency. It can then be sprayed onto the substrate or applied by hand using a trowel; the first pass should be applied at a maximum thickness of 25mm and strips of fibreglass mesh should be embedded within it. The second pass is then applied before the first pass has fully set, taking the total thickness to 50mm.  

Once the OCDC has set, you can then apply your decorative finish. We really recommend using one of our silicone renders for this because they are very high performance and breathable, so they complement the OCDC well. These are available in a range of grain sizes, so you can achieve either a rough or smooth texture to replace the tyrolean render. Silicone-based renders are flexible, crack-resistant, and are self-cleaning so will maintain a clean finish for longer. 

Alternatively, you can sponge up the surface of the basecoat and apply a paint finish instead. This will achieve a perfectly smooth surface and is a more cost-effective solution when compared to the silicone render finish. We recommend using the EWI-005 Silicone Paint, as again it is breathable and hydrophobic so will not hinder the passage of water from the underlying tyrolean render through the OCDC.

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Avoiding Silicone Sealant in EWI Systems

Silicone sealant, often referred to as mastic, is a sealant used in hundreds of different applications. You will probably find it around the house sealing pipes and plumbing, gaps around doors and windows and perhaps around your bath and shower.

Silicone sealant, not to be confused with Silicone Render, is also used to seal solid wall insulation on some properties.

Where is Silicone Sealant used in EWI?

There are several areas where an installer might use silicone. For example, you may see it around windows where the render meets the frame, on oversills where it abuts the wall and around verges where the trim meets the wall or the fascia.


This isn’t ideal because most silicone will not bond with cement very well. On a job where the expected lifespan of the system is 30 years or more, you can be sure that the sealant will need replacing a lot more frequently than that. In an exposed position, this sealant may even perish within a year! That means water ingress behind the insulation and damp inside the property.

How Can I Avoid Using Sealant?

If that sounds like a problem, you might want to consider alternatives to sealant. The best option is to design your project to minimise the use of sealant. Beading is really important around windows, under window sills and at joints. Beading not only creates a good seal, but it also means you get a nice straight edge – and a professional finish. For example, our Reveal Beads come with either a sponge or rubber seal to minimise the use of mastics.

Expanding foam tape is also another option to consider for minimising the use of silicones. The expanding foam tape can be used to create a weather-tight seal in structural and expansion joints in walls and around door and window frames. When installed into a joint, the tape will begin to expand to fill up the gap and smooth over minor imperfections and irregularities.

At the roof line where the verge meets the fascia, it is usually possible to create a joint that is not fully exposed to the elements. You will probably still need to use some sealant, but creating a joint that is protected will mean the sealant lasts a lot longer.

What Sealant Should be Used for EWI?

If you have no choice but to use sealant, we recommend that it is kept to a minimum, and that you use a good quality sealant that will offer a long term solution. One of the best sealants on the market is CT1, which we stock. The difference between CT1 and standard silicone sealants is that this sealant adheres to plastic as well as to brick and cement. This means you will get a quality seal between areas like verge trims and walls.

Whilst we would recommend trying to achieve a sealant-free profile, especially in areas where water is likely to interact with the joint frequently, we understand that this is not always possible, and in these cases a good quality sealant is a good alternative.

Most importantly, don’t be put off insulating a property just because you are worried about sealant. If you are struggling to work out how to seal your job, just get in touch and we would be happy to advise about sealant, beading and verges, and how to create a profile that is protected from the elements.

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Do I Have to Extend my Roof for EWI?

One of the questions that homeowners often have before going ahead with installation is whether or not they will need to extend their roofline to accommodate for the insulation boards. This is often a daunting, expensive-sounding prospect – but it doesn’t have to be.

At EWI Store, we have solutions for all sorts of external wall insulation issues. One of these is our comprehensive range of Verge Trim. 

What is Verge Trim?

Verge Trim is a thin sheet of plastic or metal, designed to tuck up under the fascia board so that it can cap the insulation. All of our Verge Trims are made of powder-coated aluminium and are available in different sizes to house different widths of insulation. 

Why is Verge Trim Necessary?

The point of the Verge Trim is to make sure that rain runs directly off the face of the insulation, rather than running behind the system and causing damage. Insulation boards are sometimes very thick and don’t quite fit underneath the soffit. When this happens, it leaves a real risk of water ingress, which needs to be prevented with Verge Trim.

What are the Different Types of Verge Trim?

Over Sill Verge Trim

The Over Sill, as the name suggests, is used to extend the length of an existing window sill to accommodate the insulation underneath. It’s essential that the window sill overhangs the insulation so that water will run straight off the face of the wall; any water ingress behind the system can lead to erosion of the adhesive and ineffective insulation.

Dropdown Verge Trim 

The Dropdown Verge Trim is designed to go under the soffit board. It is typically used for applications that require fixing from below. Again, this Verge Trim ensures that water falls away from the system while minimising the need for silicone sealants and expanding foam tape. 

Upstand Verge Trim

This type of Verge Trim is most suited to applications where it is fixed from above, for example, the connection to a flat roof or where the upstand can slide up behind the fascia board.

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External Wall Insulation for Homeless Shelter Project

EWI Store is pleased to have recently supplied materials for a charitable organisation, Emmaus Bristol. 

Emmaus Bristol supports homeless people, providing them with shelter and the opportunity to find meaningful work. Their goal is to overcome homelessness and achieve social change within the communities that they operate.

Emmaus Bristol Project – Wood Fibre Insulation System 

We were delighted to supply the materials for the project in Bristol. Our Wood Fibre external wall insulation system was used to renovate the exterior of the property and will ensure the thermal comfort of the residents while improving the energy efficiency of the building. The house will be used to accommodate people who are homeless or at the risk of homelessness. 

The building contractor who was assigned to the job was Nook Housing – they also provided work experience for one of the Emmaus Bristol Companions (a person who is supported by the charity and who was formerly homeless). Thanks to this work experience, he has since gone on to paid work in construction and is living independently. 

Inspirational Mural Painted on EWI Pro System

One of the stand-out features of this project was the mural painted on the side of the EWI Pro system (see pictures below). This was completed by Michele Curtis and depicts Roy Hackett, a Jamaican born co-founder of the Commonwealth Coordinated Committee. 

The mural was carried out as part of the Seven Saints of St Paul’s programme, an artistic movement whereby seven murals are being painted around the St Paul’s area of the city, depicting key people who shaped Bristol’s black community.

Benefits of External Wall Insulation 

  • Increased thermal comfort year-round
  • Reduced energy bills
  • Improved external appearance
  • Environmental benefits
  • External – no internal floor space is required
  • Prolongs the lifespan of the building
  • Low maintenance

Applying Render to a Steel Frame Building

What are the Advantages of Steel Frame Buildings?

Steel frame buildings are, as the name suggests, constructed of heavy-weight steel beams that are used to form the building shape and are then fitted together to create joints. A real benefit of this type of building is that it is extremely strong, durable and easy to assemble. The steel is made-to-measure, prepared off-site and then transported in parts. 

There are many materials that can be used to form the exterior surface of the steel frame, but typically a sheathing board is secured to the frame before a cladding or render is installed on top. For non-residential buildings, Mineral Wool insulation is typically fixed to the sheathing board (with adhesive and fixings) and the thin coat render system is applied on top. For residential projects, Mineral Wool insulation is installed within a cavity, before a render carrier board is secured to the steel frame on the outside. Quite often you can find steel frame buildings with a brick cladding forming the exterior surface as well.

Steel frame properties offer the added value of fire resistance, as steel is non-combustible and will not bend or warp. Combine this with our Mineral Wool external wall insulation system, and you’ve got yourself a building with excellent fire performance. Further to this, unlike timber frame buildings there’s absolutely no risk of rot and termites with a steel-frame – so you’re guaranteed structural integrity throughout its lifespan.

Installing Render Carrier Board onto Steel Frames

Usually, a render carrier board (RCB) will be installed into the steel battens to provide a surface that is ready for rendering. Depending upon the manufacturer’s instructions, a 3-5mm gap should be left between the render carrier board joints. A breathable joint tape should then be applied across each joint to prevent a build-up of condensation in these gaps.

The render carrier board shouldn’t need priming prior to being rendered, as its surface is intended for render anyway. 

Applying the Basecoat Layer to the Render Board

We recommend that you use the EWI-225 Premium Basecoat when rendering a steel frame building. This is because it is breathable, high strength, water-resistant and has high elasticity.  To prepare the basecoat, simply mix each 25kg bag with 6.5 litres of clean, potable water using an electric paddle mix. Once fully combined, leave the mixture for 5 minutes and the re-mix again before it is ready for use. 

The Premium Basecoat should be applied to the substrate using a notched trowel at a maximum thickness of 6mm. Beading should be embedded into the basecoat layer, as well as Fibreglass Mesh strips. Each strip of mesh should overlap its neighbouring strip by 10cm. It’s essential that the mesh is embedded into the middle of the basecoat so that there is no contact with the render carrier board underneath.

Priming the Basecoat

Before applying any render, the basecoat needs to be primed. This is to ensure strong adhesion and create a consistency of colour across the facade (our render primers are tinted to match the render). We recommend the use of EWI-333 which is the ideal topcoat primer for our silicone-based renders. Simply paint the primer onto the substrate using a brush or roller, and then leave for 12 hours to dry.

Applying the Render Topcoat

Technology has greatly improved the breathability of renders; we know that coloured renders are extremely popular these days, but breathability is a really useful characteristic of our thin coat renders, so we recommend the use of EWI-075 Silicone Render for steel frame buildings and render carrier board. The other added benefit is that this type of render can be tinted to create almost any shade, so if you’re really keen on a particular colour we can match it up for you. 

The render should be trowelled onto the substrate at a thickness that matches the chosen grain size, so if you’ve chosen a 1.5mm grain it should go on at 1.5mm thick.  

The trick with our thin coat renders is to rub them up with a plastic render float. Simply use circular movements to bring out the texture of the grain and get a nice even finish across the facade. 

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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What are the Downsides to External Wall Insulation

Is EWI a Fire Hazard? 

The EWI Pro external wall insulation is BBA approved, which means that it is completely safe. If you’re installing EPS boards, they will not burn once they are encased within a cement render, and our Mineral Wool boards are rated as Euroclass A1 non-combustible. 

The system will need to be installed by a qualified installer to make sure that all elements are correctly catered to (i.e. Mineral Wool should be installed around flues and chimney breasts). 

Is External Wall Insulation Unattractive?

External wall insulation boards are professionally decorated using a thin coat render. This provides a waterproof surface to protect the system against the effects of the weather and provide a decorative finish. The renders come in a variety of grain sizes to achieve different textured effects; our most popular is a 1.5mm grain size as this creates a fairly smooth finish.

Our thin coat renders can be tinted to create any shade, so if you’re looking for something very specific then we can arrange it!

Does External Wall Insulation Cause Algae?

If you live in an area where there is a high risk of exposure to organic growth, then we really recommend the use of our Premium Bio Silicone Render. This product actively tackles any signs of vegetation that occur on the surface of the render and it is completely hydrophobic, so water will roll straight off without leaving dirty streaks.

Will External Wall Insulation Cause Mould? 

The insulation boards used for EWI are designed to keep your walls nice and warm. This means that they are more likely to be dry and therefore mould is less likely to grow (mould occurs in damp, dark environments). 

Is it Hard to get Planning Permission for EWI?

External wall cladding is considered to be ‘permitted development’ on the grounds that the new cladding will be similar in appearance to the existing structure. Check out our dedicated post ‘do I need planning permission for EWI’ for a list of instances in which you will need planning permission.

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The Best External Wall Insulation System

If you’re looking to install external wall insulation, it can be difficult to know which system is best, who is qualified to install it and which insulation materials you should use. It’s important to remember that when you choose a quality system, a quality installer is essential to make sure that it all stays in great shape.

The key elements of an external wall insulation system are the insulation boards, the adhesive and the render finish. Let’s take a closer look at the different material choices.

Mineral Wool, EPS, or Wood Fibre?

At EWI Store, we stock lots of different types of insulation board including EPS, Mineral Wool, Wood Fibre and Kingspan K5. These all come in at different price points due to their different insulating capabilities.

Expanded polystyrene insulation is probably the most common material used for external wall insulation. This is because EPS is very cost-effective, easy to install due to how lightweight it is, and it has excellent thermal capabilities. To reach building regulations on a solid wall property, a 90mm board of EPS will bring the building in line with the required U-values.

Mineral Wool is the same material used in lofts and cavity walls, except for external wall insulation it is compressed into a rigid board. Mineral Wool has excellent fire resistance, is completely breathable and also offers acoustic insulating properties. It’s a high-performance material that is incredibly hard-wearing and can be used for most external wall insulation applications.

Wood Fibre is fairly new to our range and is our most breathable and eco-friendly EWI material. Pavatex Wood Fibre is a completely renewable material with very low pollution levels. It is great for installation onto timber frame properties due to its high levels of breathability.

Browse our full range of insulation materials here.

What Type of Render?

External wall insulation boards need to be finished with a protective thin coat render. Thin coat renders are very lightweight, flexible, crack-resistant, and they can be tinted to create any colour. We sell a few types of thin coat renders, each offering varying levels of performance.

  • Silicone Render/Silicone Silicate Render: Silicone 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 box. (Read more about Silicone Render here).
  • Acrylic Render: Acrylic Render is very similar to silicone, except for 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 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).

Finding a Trusted Installer

We work with a range of trusted installers up and down the UK who have undergone the EWI Pro training course. We can recommend you a few experienced installers who are experienced and familiar with our systems, so fill out the form below to get in touch!

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Weber Monocouche Installation Guide

Weberpral Monocouche is a cult classic when it comes to thick coat renders. It’s renowned for creating a crisp, clean finish in a range of natural colours. In terms of installation, this product is highly versatile in the textures that it can create. Whether it’s a scratch finish, tyrolean or a dry dash finish, Weber monocouche can achieve it.

At EWI Store, we’re very excited to have recently started stocking Weberpral Monocouche render, so we’ve put together a basic guide on how to install the render to create a scraped finish!

What is Weberpral M?

Weberpral M is a decorative, through-coloured, thick coat render. It is a very versatile product, as it can be finished in different ways to achieve a range of textures and finishes such as roughcast, scraped, dry dash or ashlar. It is a BBA Approved polymer-modified render that comes as a dry-mix in 25kg bags – a favourable choice when compared to sand and cement.

Substrate Preparation

Prior to application of the Weber Monocouche, you need to ensure that the substrate is stable, clean, suitably dry, sound and free from anything that may affect adhesion. The substrate needs to have the correct amount of suction; too little and the render won’t adhere properly; too much suction and the render will fail. You can test the suction of the substrate by spraying water onto it and visually inspecting the rate at which it is absorbed.

If you find that the substrate has a high suction, it needs to be lightly sprayed with water and then tested again. This should be repeated until it has the correct suction. Be careful not to soak the wall excessively, as this can cause a reduced adhesion of the render.

For very smooth surfaces, we recommend applying Weberend Aid as a key coat. This should be applied using a hawk and trowel, or using an open-hopper spray gun. A tight layer should be applied across the substrate before it is textured using a well-loaded roller.  

Preparation of Weber Monocouche

A 25kg bag of Weberpral M Monocouche should be mixed with 5-5.5 litres of clean, potable water using an electric paddle mix. Weber tends to recommend that you use as little water as possible (erring towards the 5-litre mark) so as to give a workable consistency.

Application of Weber Monocouche

Weberpral M should be applied in either one or two passes using either a spray machine or by hand using a trowel. The typical finish achieved using the Weber monocouche is a scraped finish; for this technique, the minimum thickness that should be achieved is 18mm, with a maximum thickness of 28mm.

Weber recommends the use of Fibreglass Mesh for their monocouche system. The mesh needs to be embedded into the middle of the render – it shouldn’t make contact with the underlying substrate but equally, it needs to be embedded deep enough to avoid becoming visible once the render has been scratched back.

When applying the render in two passes, we recommend applying the first pass and ruling it off to a perfectly flat finish, before going on to apply the next pass 1-2 hours later, before the first has fully hardened. The two layers should fuse together as one coat.

To achieve the textured finish, the render should be scratched back 3mm before it has fully hardened – therefore a 28mm thickness would become 25mm, and an 18mm thickness would be scratched back to 15mm.

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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How to Apply One Coat Render

There are a wide variety of one coat renders available on the market, often chosen by homeowners due to the fact that it is a cost-effective solution while being considerably better than sand and cement render.

We’ve recently started stocking EWI Pro’s EWI-265 OCR, which is a one-coat, cement-lime render, ideal for application using a spray machine. The product is a great solution for creating a smooth surface prior to applying a masonry paint, so have a ready about how to apply it!

OCR Installation Guide: Substrate Preparation

If the original substrate does not have a good key, then we recommend using the EWI-310 Universal Primer, which contains quartz aggregate to provide a rough surface for the render to adhere to.

Once the substrate has been primed, it may need levelling. If it’s particularly uneven, we recommend the use of the EWI-269 Lightweight Basecoat, which can be applied up to 25mm thick in one pass. The product should be mixed with 5 litres of water per 25kg of dry mix. Once combined, the basecoat should be applied at the required thickness to level off the wall. We recommend embedding a layer of Fibreglass Mesh into the basecoat to ensure its stability. Leave to dry completely before applying any further materials.

Applying OCR

If the substrate doesn’t need levelling, you can apply OCR straight off. The bag needs to be mixed with 5.5 litres of water, and it should then be applied at a thickness of 5-15mm (usually this is dependent upon how even your substrate is). If you didn’t apply a levelling layer to begin with then you should embed mesh into the OCR instead.

Choosing your Decorative Finish

OCR is not through-coloured, so a decorative finish will need to be applied on top. Many people opt for a painted finish to achieve a smooth surface texture; we recommend the use of our EWI-005 Silicone Paint, which is a highly hydrophobic masonry paint. This particular paint repels water and is very breathable, so it’s a great choice for ensuring that the render is totally sealed in.

Silicone Paint can be tinted to create any colour, and we can even match to NCS and RAL colours.

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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Cavity Wall Insulation vs. External Wall Insulation

What is a Cavity Wall?

Developed in the early 20th century, cavity walls were introduced into building practices as a means of alleviating problems with damp.

As opposed to traditional solid wall properties, cavity wall properties were made up of two layers of brick with a gap in the middle of around 20-100mm wide. Cavity walls are therefore much wider than solid brick walls, which is one of the ways you can tell whether your property has cavity walls.

Another telltale sign of whether your property has cavity walls is the appearance of the exposed brickwork. If the bricks have been laid lengthways, you probably have a cavity wall.

What is Cavity Wall Insulation?

Cavity wall insulation is the process of filling the gap between the two layers of bricks with different types of materials. It’s fairly cheap to install and on the average house it only takes a few hours. Cavity wall insulation is cheap, easy to install and can save you plenty on your bills. Most properties in the country that are able to install this form of insulation have already had it done. Worth mentioning, however, is that the amount of insulation that you can install, and therefore the energy saving result, is completely dependent upon the size of the cavity.

Cavity wall insulation materials can range in price and vary according to whether they are being retrofit or newly installed. Modern properties will be built with rigid board insulation already in place. When insulation is retrofitted for an older property, usually people go for a fibreglass type insulation which is pretty cheap, or a polystyrene bead insulation, which is more expensive due to its higher insulating capabilities.

What is a Solid Wall?

A solid brick wall is two bricks wide, with each row of bricks interlocking to form a completely solid 9-inch brick wall. There is no gap between the bricks as with cavity walls, so to insulate it you can either add insulation to the inside or outside of the property (i.e. internal wall insulation or external wall insulation).

As with cavity walls, you can identify a solid wall by looking at the brickwork. If the bricks alternate between a mixture of header (short) and stretcher (long) bricks, you have a solid wall. If the property is rendered, check the width of the wall – if it is less than 260mm, chances are that the wall is solid brick. The vast majority of properties built prior to the 30s will be solid brick.

What is External Wall Insulation?

SWI is more expensive than cavity wall insulation, whether it’s internal or external, the price is more within the region of thousands than hundreds. There is some funding available for external wall insulation but unfortunately, it is very limited.

There is a range of options when it comes to external solid wall insulation, however, EWI boards are typically made of EPS, Mineral Wool, Phenolic or Wood Fibre. The insulation boards are secured to the wall using adhesive and screw fixings, and a decorative, weather-proof render is then applied on top.

Choosing external wall insulation is probably the best bet when comparing it with internal wall insulation and even cavity wall insulation. This is because you can gain greater energy saving benefits due to the fact that the thickness of the insulation that you install can be as thick as 200mm – you aren’t restricted by the thickness of the cavity or the loss of internal space.

Mineral Wool external wall insulation prior to the application of the render topcoat.

If you have cavity wall insulation already and you’re looking to increase your thermal performance even further by installing external wall insulation, check out our dedicated blog post ‘Can I Install EWI on a Cavity Wall?’

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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What do I Need to Render my Knauf Aquapanel?

The Knauf Aquapanel is an outdoor cement board, designed for the building and decorating of exterior facades. These render carrier boards are particularly strong and are ideal for withstanding even the most extreme weather conditions. If you’re planning on installing a render system onto the Knauf Aquapanel, then keep reading!

Today’s blog post is an installation and rendering guide for the Aquapanel. We’re going to be talking about how to install the boards and then how to apply the EWI Pro thin coat render system onto them.

Installing the Knauf Aquapanel Boards

To start off, Knauf Aquapanels need to be screwed onto vertical timber battens using 42-60ml self-drilling screws. You should use approximately 23 screws per board, and a 3mm gap needs to be left in between each board.

Once in place, a render carrier board joint tape should be applied to all of the joints, or alternatively, you can cut fibreglass mesh into strips of 10cm and secure these using a thin layer of the EWI-225 Premium Basecoat.  

Applying Render to Knauf Aquapanels

Now that the Knauf Aquapanels are prepared and ready to go, you can go straight into applying the thin coat render system.

First, the EWI-225 Premium Basecoat needs to be mixed with 6 litres of clean, cool water using an electric paddle mix until it is a smooth, workable consistency. This is our strongest basecoat-adhesive, and therefore it’s ideal for applications onto render carrier board as it will help to resist cracking.

Once mixed, the basecoat should be applied directly onto the boards at a thickness of 6mm. At this stage, you should embed the Fibreglass Mesh into the basecoat. It’s important that the mesh is embedded in order to enhance the tensile strength of the system – to do this you need to cut the mesh into strips and ensure that each strip is overlapping by 10cm on all edges.

Remember that you are applying a thin coat render, and therefore the basecoat needs to be perfectly smooth and flat so that any imperfections are not visible through the final render finish.

Once set, the basecoat will need priming with a render primer. This is optional, although we do recommend the use of a render primer if you have chosen an especially bright colour for the topcoat, as the primer can be tinted to match the render and will ensure an even coloured finish. The render primer should be painted onto the basecoat and then left until dry.

The final stage in the render system is the topcoat. Whether you’ve chosen the EWI-010 Acrylic Render or the EWI-076 Premium Bio Silicone render, the application is always the same. The render needs to be applied at a thickness that corresponds with your chosen grain size – so if you’ve chosen a 1.5mm textured finish then the render needs to be applied 1.5mm thick. Once the render itself is on the wall, it needs rubbing up using a plastic render float.

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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lime render

5 Reasons to use Heritage Lime Render

The long-awaited EWI Pro Heritage Range has finally arrived on our shelves! Lime materials have been proven over the centuries to be a reliable, safe building material that will withstand the test of time. In fact, the earliest known use of lime was 4000 years ago.

To celebrate the release of the EWI Pro Heritage Range, we’ve written about our top 5 reasons for why you should use the Heritage Lime Render system.

  1. Breathability

Lime is renowned for being porous and therefore vapour permeable. The effect of lime within renders is very positive; moisture can easily escape from the building fabric rather than remaining trapped behind within the walls (and wreaking havoc!). Breathability is essential for heritage buildings, as trapped moisture can seriously damage the ageing building structure. With Lime renders, water is absorbed into the render but instead of becoming trapped and causing the render to become ‘wet,’ the water is able to slowly evaporate out again.

  1. Environmentally Friendly

Lime is much more environmentally friendly than cement for a couple of reasons. Firstly because the lime is not ‘baked’ beforehand, there is a lesser amount of energy required for its production process.

  1. Strong but Light Adhesion

Lime binds lightly to substrates, so it’s a gentle material to use on a more fragile surface such as a Heritage building. Because lime has a small particle size, it’s a much more ‘sticky’ material; this means that it is able to bond to surfaces very easily and fill minute cracks to provide strong adhesion.

  1. Aesthetically Pleasing

Lime render has a fine texture and therefore offers a smooth render effect. The colour is a natural and traditional off-white shade – a highly aesthetically pleasing finish that is ideal for heritage properties.

  1. Lime is Flexible

Because lime has a very small particle size when compared to cement, it is a much more flexible material. When slight fluctuations within the building structure occur, lime is much more able to withstand this and is therefore much less likely to crack.

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How to Install a Heritage Lime Render System

Those looking to install a Heritage Lime Render system are generally working with older properties that require high levels of breathability and flexibility. Lime is very porous and so it absorbs and releases humidity, allowing for a level of moisture regulation that is extremely important for ensuring structural integrity.

For heritage properties, it’s essential to use the right materials so as not to cause long-term damage; we’ve written before about inappropriate materials on the wrong substrate and the consequences – read the post here.

Our Heritage Lime Render system is highly natural and complements older buildings that would have previously been constructed using natural building technologies. So without further ado, here is how to install a Heritage Lime Render system…

Preparing the Substrate for Heritage Lime Render

Substrate preparation is a key element of any rendering project, but it’s especially important for heritage restoration projects. Often, older substrates are likely to show signs of crumbling mortar or paint, which is why a suitable preparation material, such as the Heritage Lime Harling, is essential. The Lime Harling is ‘harled’ at the wall, creating a roughcast finish which allows the basecoat reinforcement layer to adhere to it strongly.

The Heritage Lime Harling is ideal for substrates with a low/medium salt content or if the substrate is particularly absorptive. It’s best for heritage projects because it works in unison with the rest of the system to maintain breathability. If you’re working with a substrate that has a high salt content, then we recommend the application of the Heritage Lime NaCl which will essentially just stabilise the salts and prevent them coming through to the surface.

Applying the Heritage Lime Mortar

After the Lime Harling has been left to set for a minimum of 3 days, the Heritage Lime Mortar is ready to be applied. To prepare the mortar, mix the 25kg bag is 6 litres of clean cool water and mix thoroughly with an electric paddle mix on a slow rotating setting until the mixture is completely combined. Once everything has been mixed, leave it to sit for 5 minutes and then mix again briefly before it is ready for application.

The Heritage Lime Mortar should be applied using a trowel at a maximum thickness of 2-15mm; bucket life is 2 hours after it has been mixed. You can leave the basecoat like this and apply a breathable paint or lime wash, or you can proceed to rendering. 

Rendering using the Heritage Lime Render

Applying the Heritage Lime Render is very easy. Simply mix with 5 litres of water and apply to the basecoat using a plastering trowel at an approximate thickness of 10-20mm. The render creates a smooth surface and achieves a breathable, aesthetically pleasing and long-lasting finish.

The heritage system ensures that your restoration property receives the care and treatment it needs. Interested in our Heritage range? Call our sales team for technical advice and more product information!

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salt levels external walls

Salt Levels in External Walls

The new EWI Pro Heritage range is a lime-based system, with solutions for varying salt levels in external walls. The Lime Harling is ideal for substrates with low/medium salt levels, and the NaCl (as the name suggests) is best for those with high levels of salt. But how does salt affect a substrate, and why is it necessary to take salt levels into consideration?

Salt Levels in Heritage Buildings

It’s important to take salt levels into account when working with heritage properties. This is because the property has been around much longer, and so the salt will have accumulated to a greater amount than a new build. Heritage properties are also typically made of more natural materials, such as sandstone and limestone, which are more susceptible to salt erosion.

Salt levels in heritage buildings occur as the result of several chemical reactions, however, the most common cause is with the formation of carbonic acid which is formed when rainwater reacts with carbon dioxide.

The result is an acidic rain that breaks down and dissolves the calcium carbonate (salt) in lime-based stones and mortars, disrupting the bind of the material. If a sandstone building was built with a mortar containing calcium-carbonate, the calcium carbonate within the mortar can be dissolved and eroded. Limestone and sandstone are particularly porous materials, so the water containing the calcium carbonate (salt) moves through the external walls by capillary action, depositing the salt in different pore spaces.

Eventually, the pores within the external walls become filled with salt and the cycle of dissolving and depositing puts pressure on the walls. The salt generally makes itself known with the presence of efflorescence on the surface, which is essentially just salt deposits on the face of the wall.  

Cementitious renders and mortars are an inappropriate material to combat the effects of salt because trapping the salt behind the render will just cause further erosion of the building structure. Lime-based renders and mortars are a softer material, allowing the salts to push through. The point of this is that when the salt escapes from the substrate and settles on the surface of the render, it’s imperceptible to the eye and is far less harmful than if it were trapped inside the walls.

Rendering Walls that Contain a High Level of Salt

Rendering a salty substrate requires careful attention. The level of salt first needs to be established before choosing the materials; substrates with a relatively low level of salt require the use of the Heritage Lime Harling. This is a preparation layer before the Heritage Lime Basecoat and Heritage Lime Renders are applied.

Substrates with a medium/high level of salt will need the Heritage NaCl. This acts as a basecoat, so once applied the Heritage Lime Render can go straight on top. The Heritage Lime Plaster would also be an ideal solution for internal walls as a finishing coat on top of the EWI-269 Lightweight Basecoat.  

Salt in Buildings: An Overview

  • Acidic rain causes salt deposits to form in porous building fabrics such as limestone.
  • Excess salt causes erosion and structural damage.
  • Lime-based renders are ideal for heritage buildings because lime is porous and allows the salt to escape rather than trapping it within the structure where it causes more damage.
  • Heritage Lime Harling is ideal for substrate preparation in cases where there is low salt content.
  • Heritage Lime NaCl is for cases where the substrate has a high level of salt, it is essentially a specialist basecoat whereby a lime render is applied directly on top of it.
  • Lime plasters for the internal of buildings are also ideal for heritage buildings.

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lime render

EWI Pro Heritage Lime Renders!

The EWI Pro Heritage range is a set of lime-based products intended for internal and external plastering. The Heritage range is perfect for the restoration of older properties. EWI Pro are all about choosing the right materials for the right substrate, and in older properties, this is completely essential. For example, a sand and cement render would be entirely wrong for a restoration project where materials need to be carefully selected to ensure structural stability, so the lime render range is ideal for these situations.

What are the benefits of using lime-based products?

We’ve previously written about why you would want to use lime render, so for more information on that click here. In terms of the benefits of using a lime-based building material, the real benefit of lime is that it is incredibly lightweight, flexible and breathable.

Older buildings need to breathe to ensure that moisture can escape from the building structure. This is because quite often, old buildings are timber frame and therefore rotting of the timber beams is the number one thing to avoid.

Lime is an incredibly traditional material that goes way back in terms of historic use; it binds gently to substrates, allows for movements within the building structure and allows for the regulation and passage of water vapour. Lime is also considered to be an environmentally friendly building material. So without further ado, here are our new lime-based products!

EWI-291 Heritage Lime Harling

The EWI Pro Heritage Lime Harling is the first step in a renovation project, intended for creating a ‘harl coat’ on an external substrate. The point of the Lime Harling is to provide a mechanical key for the Heritage Lime Basecoat to adhere to and is basically part of the priming stage in order to renovate and prepare the wall before the basecoat is applied.

Typically you would apply the Harling to a brick, block or stone substrate that has been laid using lime mortar, if the substrate has a high absorption or if it has been painted with lime paint.

EWI-292 Heritage Lime Basecoat

The Heritage Lime Basecoat is a mixture of Portland cement and hydrated lime. It’s intended for use where low or medium salt levels are present, can be applied 10-20mm thick and is white in colour. Because of the fact that the basecoat contains lime, it has pores that allow salts and water vapour to escape from its surface. This is the second stage in the renovation process and would usually be applied on top of the Harling coat if present.

EWI-051 Heritage Lime Render

The Heritage Lime Render is completely cement free render, ideally used on top of the Lime Basecoat in order to create a decorative finish. Because the Lime Render is a fine-grain render, it offers a smooth, natural finish that can be applied 10-20mm thick. The render is not suitable for applying directly onto a substrate which has a presence of salt, which is why you’d need to apply it directly to the Heritage Lime Basecoat.

EWI-294 Heritage Lime Mortar

The EWI-294 is a fibre reinforced mortar, which is lime enhanced.  Typically, this would be used for the renovation of decorative features and of the substrate; for example for levelling the substrate, filling cracks/cavities in facades and bricks, and as a putty. The Heritage Lime Mortar is also ideal for repairing and re-creating decorative features on the exterior facade,   

EWI-293 Heritage Lime NaCl

The Heritage Lime NaCl is a specialist basecoat, designed for use on substrates that have a medium/high salt level. It works to absorb and retain crystalline salts from the substrate, while creating a smooth surface for the Heritage Lime Render, or even for internal use with the Heritage Lime Plaster.

EWI-295 Heritage Lime Plaster

The Heritage Lime Plaster is intended for internal use on walls and ceilings as a plaster mortar. Ideally, this works optimally when used on top of the Lightweight Basecoat, as the two are highly breathable and flexible and therefore will resist cracking. Once applied, the Heritage Lime Plaster offers a durable and clean-cut finish while also complementing the building structure.

And there you have it! We are very much looking forward to seeing what people think of the range and seeing it in action. Any further questions or to place an order, contact our sales team who all have excellent technical knowledge of the materials.

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Mineral Wool and Acoustic Insulation

When choosing to install external wall insulation, a lot of people want more than just the standard thermal benefits that these type of systems offer – which is where our Mineral Wool insulation systems come in.

Rockwool Mineral Wool is one insulation material with a multitude of high-performance characteristics; not only does Mineral Wool have a low thermal conductivity, but it’s also breathable, non-combustible and it has acoustic insulation capabilities. This means that when you’re choosing to install our Mineral Wool system, you are getting more than just your average EWI system.

Noisy neighbours, road traffic and harsh weather conditions can be a frustrating source of noise pollution for many homeowners. Being able to control the temperature and sound within our home environment goes hand-in-hand with our wellbeing; acoustic insulation is, therefore, a necessity to ensure comfort.

In today’s blog post we’re going to be discussing how you can achieve acoustic insulation and thermal benefits with Rockwool.

How Does Rockwool Acoustic Insulation Work?

Rockwool Mineral Wool insulation is made from spun volcanic rock. Because stone wool is a dense material with a fibrous structure, it inhibits sound waves and produces a muffling effect. Rockwool insulation therefore absorbs and dampens sound waves; this includes noise pollution not only from airborne sound (noisy neighbours and cars) but also from impact sound (strong winds, heavy rains).

Our Mineral Wool external wall insulation systems create an envelope around the entirety of the property. Because the system is completely seamless and without gaps, this means that your home is protected against both heat loss and external sources of sound.

Acoustic Insulation with a Decorative Finish

Our Mineral Wool insulation systems are installed using adhesive and mechanical fixings to the external walls of a building. A basecoat is then installed to the external facings of the board to create a smooth surface before a decorative render is applied to a) seal the system in against the weather and b) create an attractive finish.

We offer a range of solutions to achieve a decorative finish with our Mineral Wool insulation systems. Our thin coat, silicone-based renders are the topcoat of choice for homeowners. Silicone renders offer self-cleaning capabilities, which means that your external wall insulation system is fully equipped with thermal performance, acoustic performance, breathability, non-combustibility and self-cleaning capabilities.

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self-levelling compound

Types of Self-Levelling Compounds

Our Self-levelling compounds are easy to use and create a strong adhesion to a range of substrates. The finished result is a durable, level and smooth surface that is great for use with different types of flooring.

We have a few different types of self-levelling compounds, all of which are suitable for application at a range of thicknesses. In today’s blog post, we’re going to be outlining the difference between our three self-levellers and then explaining exactly how they should be used.

EWI-250 Ultimate Leveller

The Ultimate Leveller is our standard levelling solution for internal floors. This product is great for levelling floors that require a bit of finesse, as it can be applied up to 20mm thick.

  • Suitable for application using a spray machine
  • 2-20mm
  • Easy to use, self-levelling compound
  • Suitable for under parquet, tiles, carpet and for use with underfloor heating

EWI-251 Deep Fill Self-Levelling Compound

As the name suggests, the Deep Fill Self-Levelling Compound is intended for application on floor surfaces that require a bit more product to achieve a level surface.

  • Suitable for application using a spray machine
  • 5-35mm – greater application thickness
  • Easy to use, self-levelling compound
  • Suitable for under parquet, tiles, carpet and for use with underfloor heating

EWI-254 Quick Set Self-Levelling Compound

If you’re levelling in a hurry, then we highly recommend our Quick Set Self-Levelling Compound. This product is safe for treading after 3 hours and will have fully cured after just 3 days.

  • Suitable for application manually or with a spray machine
  • 2-30mm
  • Easy to use, self-levelling compound
  • Suitable for under parquet, tiles, carpet and for use with underfloor heating
  • Quick setting time of just 3 days

How to Install Self-Levelling Compounds

Our self-levelling compounds are very easy to use, but a lot of preparation needs to go into making sure the substrate is adequately prepared. Cement surfaces that are extremely rough need to be filed down, and any dust, dirt or grease must be removed from the substrate. Cracks within the floor also need to be repaired. If there is no threshold within the doorways, then temporary battens should be installed in these areas to prevent the self-levelling compound from running off into the other room.

You then need to establish exactly how thick you need to pour the product out to. To do this, place your spirit level flat to the floor and lift the lower end until it reads straight. You can then measure the gap between the bottom of the spirit level and the floor, which will enable you to determine the average thickness that you should pour the product out to.

Before application, you will need to mix the product with water (either inside of the spray machine unit or just using a bucket and mixer). Once this has been carried out, the product is simply poured out onto the floor before being spread with a trowel to distribute the product.

We recommend that if you are levelling a particularly large surface area, you should divide the room up with wood battens. This way you can pour the product out to fill the selected area, and then keep moving the batten backwards to create more space to fill.

Once the area is covered in the product it needs to be raked using a spiked roller. This will remove trapped air from the material and therefore prevent air bubbles from affecting the way that the product sets.

For the EWI-250 and EWI-251 you will need to wait 5 days for the product to cure before you can carry out any further works and lay down your chosen flooring. The EWI-254 has a faster curing time of just 3 days, so if you’re in more of a hurry then this is the best product for you.

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thermal conductivity insulation panels

Thermal Conductivity and Insulation Panels

EPS (Expanded Polystyrene Insulation)

Expanded Polystyrene insulation panels are our most popular insulation material, offering great thermal conductivity and performance at a great price. EPS is extremely lightweight, which is what makes it an ideal material for attaching to the external walls to upgrade the thermal performance of the building.

EPS insulation has a thermal conductivity of 0.032W/(m2K), meaning that a 90mm insulation panel will bring a solid wall property in line with building regulations.

XPS (Extruded Polystyrene Insulation)

Much like EPS, Extruded Polystyrene is also a foam insulation panel. This particular foam has a closed-cell structure, which means that it is more waterproof and has greater compressive strength. This type of insulation is typically used for insulating below the DPC, as this area poses a greater risk of water penetration.

XPS insulation has a thermal conductivity of 0.038W/(m2K), which means that 110mm will be required to reach building regulation U-values.

Kingspan K5 Insulation

Kingspan K5 insulation is a high performance, phenolic insulation panel. This product is a premium performance, rigid thermoset insulation which is ideal for refurbishment of solid wall properties. This product has a very high compressive strength and is great for applications where there is a limit to the amount of external space that can be taken up.

The K5 insulation has a thermal conductivity of 0.020W/(m2K), which means that 60mm will be required to reach building regs.

Mineral Wool Insulation

Arguably our most high-performance insulation panels, the Rockwool Duo-Density Slab offers excellent thermal performance, fire performance and acoustic insulating capabilities. This is a premium insulation material that is often used for high rise buildings and for applications where a high level of fire safety is required.

Mineral Wool insulation has a thermal conductivity of 0.038W/(m2K), which means that 110mm would be required for a solid wall to meet building regulations.

Wood Fibre Insulation

If you’re looking for a highly breathable insulation panel, then you can’t go wrong with Wood Fibre. Providing an outstanding level of thermal comfort within the home, Wood Fibre is therefore perfect for use within an EWI system. Not only does the Pavatex Diffutherm insulation offer superlative insulating properties, but it also has the credential of being an environmentally friendly material.

Wood Fibre insulation has a thermal conductivity of 0.038W/(m2K), therefore a 120mm board would be required to reach building regulations.

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monocouche render vs One coat render

Monocouche Render Vs. One Coat Render

Monocouche Render

Monocouche render is a decorative, polymer-modified render that can be applied by hand or spray machine to reach a total thickness of 19mm. Monocouche render is through-coloured, which means that the actual mixture in the bag is in your chosen colour – no need to paint afterwards to achieve a coloured finish.

Monocouche render is a dry-mix render, so it requires mixing with water prior to application. It’s then applied to the substrate, and a Fibreglass Mesh is embedded within it to enhance the crack-resistance and tensile strength of the render. Monocouche is applied in two passes, and once the render has begun to set it is scratched back with a scratch float to achieve a dappled texture effect.

Because this is a through-coloured render, it is virtually maintenance free and due to the fact that it is applied in one go, it has a relatively quick application time compared to our thin coat renders where you have to wait for the basecoat to go off before you can render.

One Coat Render

One Coat Render (OCR) is a cement-lime render, applied in one pass at a thickness of 5-15mm to achieve a smooth flat surface on external walls. OCR is not a through-coloured render in the same way that our Monocouche render is, in fact, it requires painting afterwards with a Silicone Paint or other masonry paint to achieve a decorative finish. Unlike the Monocouche, this render isn’t scratched back to achieve a textured surface – the OCR achieves a different look to the natural, chalky finish of the Monocouche render.

The main appeal of using the One Coat Render is how quickly and effectively you can achieve a smooth finish. It’s applied in one coat directly onto the substrate, and Fibreglass Mesh is embedded within it to enhance tensile strength. Once the OCR has gone off, the paint finish is applied; although you can choose to apply a decorative render on top if you wish.

Key differences:

  • Monocouche is through-coloured
  • It is polymer-modified
  • It is scratched back to achieve a textured effect
  • OCR requires painting to achieve a coloured finish
  • It is mostly used to create a smooth surface
  • Both are sold pre-mixed in 25kg bags

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tyrolean render

3mm Silicone Render vs. Tyrolean Render

When it comes to choosing a render finish, there are endless possibilities. Whether you’re looking to go for a smooth render effect or a rough textured render, we can offer a range of solutions. EWI Pro renders are very customisable, so if there’s a particular look that you really want to achieve then give us a call and we can advise you on the best way to do this!

Today we’re going to be looking at the method of application used to achieve a tyrolean render finish, compared with the application and finish of our 3mm Silicone Render. While no two products will look the same, you may find that the texture that these two renders can achieve is very similar.

Tyrolean Render

Tyrolean render is a traditional rendering technique used to apply a monocouche render to create a rough, textured appearance.

To achieve the tyrolean render finish, the monocouche render needs to be applied in two passes. The first pass is used purely for embedding Fibreglass Mesh and to create a smooth, reinforced surface; this layer will help to prevent cracks further down the line. A second pass of is then applied on top to bring the total thickness up, this is again smoothed over.

To create the tyrolean render finish, the render is then fine-sprayed onto the substrate using a tyrolean flicker gun to achieve a textured surface. The finish is comparable to roughcast, although this method of rendering does not require aggregates to create the texture. The great thing about the finished result is that it looks very natural, although applying render in this method can be time-consuming and therefore costly.

3mm Silicone Render

When compared to the work that goes into a tyrolean render finish, the 3mm Silicone Render looks pretty easy. EWI Pro Silicone Render comes in a range of grain sizes so that you can choose the kind of texture that you want to achieve, whether it’s very smooth or very rough. The added benefit of the silicone is that unlike monocouche, Silicone Render is applied in a very thin layer (between 1-3mm) on top of a reinforced basecoat.

The advantage of this is that the Silicone Render is very flexible (because it’s applied so thinly) and therefore the risk of cracking is significantly reduced. The other advantage of the Silicone Render is that it is through-coloured (like paint) and can be tinted to create almost any shade, so you’re able to choose very natural colours.

Bearing in mind, the monocouche render is a dry-mix render, so the finished result is always going to be slightly different, but you can achieve a very similar texture using a 3mm grain size – the 3mm render looks almost roughcast.

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