Tag Archives: insulation boards

Why Use Wood Fibre Insulation?

We’ve added Wood Fibre insulation to our product line-up, and we’re really excited about it because Wood Fibre is a completely renewable material with a very low environmental impact. The insulation can bring down the U-values of your external walls enormously, requiring just 120mm to reach a 0.3w/m2k U-value. We know that many customers who consider external wall insulation are very environmentally aware and are eager to choose materials that do not have a negative impact on the environment – we are keen to encourage environmental friendliness wherever possible, and we think that Wood Fibre insulation is the way to go to achieve this.

Because of its recent addition to our systems we thought we’d talk a bit about the benefits of Wood Fibre insulation, including where it comes from and why it’s so great.

Wood Fibre Insulation is Environmentally Friendly 

We source our Wood Fibre insulation boards from a company called Pavatex, who are dedicated to the notion that using secure and healthy forests for production helps to stabilise and manage the environment. Their Diffutherm Wood Fibre insulation boards serve as complete evidence for this, as they boast the achievement of being absolutely sustainable and environmentally friendly. This achievement has not gone unnoticed; Pavatex are certified by the renowned NaturePlus standard – the European quality standard for building materials set up by the WWF, FSC and Greenpeace.

Not only does the nature of their product contribute positively towards the environment, their manufacturing process is environmentally conscious as well. The Pavatex production locations in Cham and Golbey claim to be dedicated to being efficient and environmentally friendly, which has resulted in the Diffutherm Wood Fibre insulation having an overall positive CO2 balance of around 600kg per tonne of product.

When used as part of an external wall insulation system, Diffutherm Wood Fibre insulation helps to reduce the carbon footprint of property owners by lowering the U-values of the external walls of their property, resulting in reduced energy requirements. Wood Fibre boards are also safe to dispose of due to the fact that they are recyclable and compostable once they have reached the end of their lifespan.

The Diffutherm Wood Fibre boards are therefore eco friendly throughout their entire lifespan, and when used as part of our EWI system they will improve indoor air quality, reduce emissions and enhance the thermal performance of the building.

What Type of Property is Best for Wood Fibre Insulation?

Wood Fibre insulation is compatible for use on masonry, steel frame or timber frame structures and even historic or hard to treat buildings; Pavatex have worked with many organisations such as English Heritage, the National Trust, Scottish Heritage and Cambridge University (to name a few), and Wood Fibre also works really well with our new Heritage range of lime products. However, for the purposes of this article we are going to focus on the use of Wood Fibre insulation for timber frame structures.

Wood Fibre insulation is excellent for EWI on timber frame buildings because timber frames need to be able to breathe in order to resist damp and rotting of the timbers. Air circulation is essential, and because of this it can be incredibly difficult to insulate a timber frame property without increasing the risk of damp. This is where Wood Fibre insulation comes in to its own.

When used with a breathable render, water vapour is able to pass through the existing external walls and out through the many layers of the insulation system. We recommend our Silicone or Silicone Silicate renders for use with Wood Fibre insulation, as the breathability of both materials means that they will work well in conjunction with each other. Wood Fibre insulation boards must also be fixed to the substrate with mechanical fixings and our Premium Basecoat adhesive (our strongest and most breathable adhesive), so it will be able to completely support the weight of the Wood Fibre boards and maintain breathability.

Diffutherm Wood Fibre boards are waterproof so they won’t absorb rainwater or moisture, but they’re also vapour permeable at the same time. This essentially means that the Wood Fibre boards will allow water vapour from within the warm building to pass through walls without becoming trapped behind the insulation.  

Breathable ‘Nature Plus’ Systems with Wood Fibre

In breathable systems, the insulation materials are arranged in such a way that the layers become increasingly more vapour permeable from the inside to the outside so that moisture can safely escape from within the house. This creates a harmonious climate within the house where moisture and the risk of damp is reduced.

To achieve this, we recommend an environmentally friendly ‘Nature Plus system’. This consists of fitting OSB (which can be taped for air-tightness) behind plasterboard on the interior of the timber stud-work, then laying Nature Plus certified Thermafleece insulation in between the stud-work. You would then install our Nature Plus certified Diffutherm Wood Fibre onto the exterior before rendering as a final step.

How are Wood Fibre Insulation boards made?

Pavatex Wood Fibre insulation is made from local, sustainably managed fir and spruce trees from FSC (Forest Stewardship Council) and PEFC (Programme for the Endorsement of Forest Certification) forests. They are manufactured from untreated softwood in the form of sawmill slabs, chippings and splinters which are a byproduct from the manufacture of timber or sustainably built furniture.

The Pavatex Diffutherm Wood Fibre insulation boards are manufactured in Switzerland under tight environmental regulations against high emissions and pollutants. In order to make Wood Fibre insulation boards, the previously mentioned waste wood is ground together to form a pulp. Water is then added and mixed with the pulp, then heated to activate the lignin that the wood naturally contains and which glues the fibres together. The pulp is then pressed into boards, dried and cut to size. Sheets of varying densities are then laminated together to produce optimal strength and stability as well as moisture control and vapour permeability.

Do Wood Fibre Insulation Boards Pose a Fire Risk?

For many, this is the first question that springs to mind when thinking about externally insulating with Wood Fibre. Pavatex Wood Fibre insulation boards are certified as Class E combustible materials. This is the same as many other insulation materials, however there is a key difference with Wood Fibre boards in that because they are made of timber they characteristically char, which actually slows down the spread of fire. To explain this, Pavatex state that:

‘In a fire a layer of ash forms on the surface of Pavatex Wood Fibre insulation boards. This acts as a safety shield, preventing oxygen from reaching the flames and slowing down the spread of the fire. This means the construction can withstand a fire for 90 minutes. In addition Pavatex Wood Fibre insulation systems do not release dangerous gases in case of fire.’ Check out the video below, which demonstrates this further:

We are really excited to be stocking Wood Fibre insulation! If you have any further questions about installation and technical advice, then comment below or give us a call.

We upload a new blog post every Tuesday and Thursday, so stay tuned for more future content about Wood Fibre insulation and EWI!


pebbledash coloured render

Replacing Pebbledash with Coloured Render?

What is Pebbledash?

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

The pebbledash effect is created by applying a layer of mortar (usually sand and cement) to the external wall, and literally throwing pebbles at it to allow them to stick. Pebbledash houses are still dotted all over towns and cities in the UK and can often have a somewhat dilapidated look. As well as this, over time the pebbles can drop, which leaves the mortar exposed to the weather and therefore vulnerable to absorbing water and creating problems with damp. Due to its unpopularity, pebbledash can also reduce the value of a property purely for its lack of aesthetic appeal. This is why coloured render is vastly more popular because it’s nice to look at. Our coloured renders are available in thousands of different colours and can be ordered online or by phone!

We’re not hating on pebbledash (much), but many people want to know how to remove it in order to replace it with a coloured render. For those who have recently moved into a new home, or who are looking to update the look of their property, re-rendering is a popular consideration. However, there is a definite gap in the public knowledge over whether you can apply the render on top of pebbledash, and this is something that we are frequently asked here at EWI Store. So, we thought we would tackle the question for all the pebbledash homeowners out there.

The short answer is that unfortunately, you cannot replace pebbledash with coloured render by applying coloured render directly on top of the pebbledash. However, not all hope is lost, because there are a few ways around this that you may want to consider, which we will elaborate on in this blog post…

Ways to replace pebbledash with coloured render

So, as you may have realised, pebbledash is incredibly difficult to get rid of. You basically have three options when considering how to remove pebbledash…

Option one: removing the pebbledash

The first option is to attempt to hack the pebbledash off, at risk of the brickwork underneath and with no guarantee that you will be able to achieve a smooth finish. If you do decide to go for this option be really careful about who you hire to do this and make sure they are experienced in removing pebbledash. If your pebbledash is forcibly removed by a builder, this can really damage the underlying substrate and can invalidate your house insurance. Even after all of this, you still wouldn’t be free to apply coloured render directly over the wall. Building regulations stipulate that if you strip it right back to the original brick then you’ll need to insulate before rendering with a coloured render.

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

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

Option three: insulate then render over pebbledash

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

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

Which coloured render can I use to replace my pebbledash?

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

Thin Coat Coloured Renders to Replace Pebbledash:

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

They also come in different grain sizes, which determines the textural finish that the coloured render will offer you – the bigger the grain size the more textured the finish that you’ll achieve. If you have simply removed your pebbledash, then you may want to go for a larger grain size because this makes any imperfections in the basecoat less noticeable. Read our blog ‘coloured render cost per m2’ for an idea of pricing!

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

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


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

Thick Coat Coloured Renders to replace pebbledash:

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

  • Monocouche scratch render: Monocouche scratch render is a thick coat, through-coloured render. It is more traditional but does require extra work to install it. This is because the Monocouche needs to be applied in two passes for extra strength and cannot be applied in wet or humid conditions. Monocouche render then needs fibreglass mesh embedded within it to provide extra strength and flexibility (which means it will resist cracking), and then once it’s dried it needs scratching back to achieve the desired texture. Read our blog ‘monocouche scratch render cost per m2′ for an idea of pricing!

To conclude…

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

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

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

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