Pavatex Wood Fibre Insulation

What is Pavatex Wood Fibre Insulation and Why is it Unique?

Pavatex wood fibre insulation is a natural and ecological insulation material which provides a high level of thermal resistance in walls (both internally and externally), roofs, attic floors and suspended floors. Pavatex wood fibre insulation is breathable and offers excellent protection against cold, humidity, noise and summer overheating, ensuring that our homes and workplaces are comfortable and healthy. Save money on your energy bills with this carbon-negative insulation.

Pavatex Wood Fibre Solutions

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Pavatex Wood Fibre Insulation Product Range

We provide a wide range of Pavatex Wood Fibre Insulation products, including the renders, plasters, membranes, tapes, fixings and other accessories required for its installation.

Pavatex Wood Fibre Insulation Benefits

Pavatex Wood Fibre Insulation Performance

Pavatex wood fibre provides excellent thermal insulation

Pavatex wood fibre insulation has thermal conductivity values varying from 0.038 to 0.043 W/mK depending on the product, its density and its thickness. The Isolair Multi wood fibre board has tongue and groove joints, so this greatly reduces thermal leakage through the junctions. Isolair Multi is water resistant so it can be left exposed on roofs or walls for up to 3 months without compromising its thermal qualities or the product itself. Pavaflex flexible insulation is very dense at 50 kg/m³ so this fits very snugly between rafters, studs and joists which means that there will be no air leakage around the sides. It will not slump over time, unlike many other flexible insulation materials.  

Breathable, vapour-open, hygroscopic and capillary-active insulation allowing moisture to escape

So what do these terms actually mean?

Breathability in buildings refers to water (both in gas and liquid forms) inside our buildings, outside our buildings and in the actual building fabric itself – in the walls, roof and floor. It has nothing to with air passing through our buildings!

Water Vapour Permeability in terms of buildings, refers to the rate at which water vapour passes through structures, if it can pass through at all.

Hygroscopicity refers to the absorption and release of water as a vapour or gas, as relative humidities (RH) change. Usually there is more moisture internally from cooking, showering, breathing etc so the moisture tends to move from inside to outside, but not always. Also, warmer air holds more water vapour than colder air.

Capillarity refers to the absorption and release of water as a liquid.

These characteristics mean that water in the form of water vapour, or even small water droplets, can pass completely through the insulation and the building structure at a controlled rate, so that it can evaporate away. This means that the insulation and building remain dry, and therefore warmer. It also improves the air quality of the internal microclimate as the relative humidity will be lower.  Vapour-closed insulation materials can result in moisture being trapped between the structure and the insulation which may lead to interstitial condensation, mould and rot. Moisture Content in timber must remain below 20% to prevent wet and dry rot so it is very important to ensure that timbers do not sweat.  

Breathable or vapour-open insulation is particularly critical on the walls of historic or traditional buildings as these were designed to be totally breathable structures. It is a balancing act to keep airtightness, thermal performance and indoor air quality of our buildings in equilibrium, so breathability is absolutely crucial to observe in both new and old buildings.

Suitable for insulating solid walls on traditional and historic buildings

Solid walls in traditional buildings are generally constructed from stone, brick, clay or cob. These materials readily absorb water vapour, and even water droplets, so it is imperative to only use vapour-open materials on their structure to allow all this moisture to pass through and evaporate to the driest side. Pavatex breathable wood fibre insulation boards can be safely installed onto the inside or outside of these walls and can be finished with vapour-open plaster / render or ventilated cladding. This ensures that moisture in the wall can dry out when the weather conditions are favourable. A dry wall is a warm wall. Critically this also means that timbers embedded in the wall, such as floor joists and roof rafters, will stay dry and will not get wet rot or dry rot. For more information see Insulating Historic Buildings.

Perfect for timber frame and CLT buildings as timber will be able to dry out

Timber must have a Moisture Content of less than 20% throughout the year to ensure that wet rot and dry rot do not occur. Insulation materials should be chosen with consideration for their breathability and interaction with the timber frame. If vapour-closed insulation materials are placed on timber frame or CLT structures, the timber may get damp due to high humidity in the air – both inside and outside – and this may not be able to evaporate away. Instead, the water vapour might get trapped within the structure which can result in unintended consequences.

On timber frame structures, we recommend filling the studs with Pavaflex or Pavatextil P flexible insulation and then installing the Isolair Multi T&G wood fibre insulation board on the outside of the frame. This board is water-resistant so will prevent rain entering the structure. However, very importantly, wood fibre is also vapour-open so will allow moisture within the structure to escape through it so that the moisture content in the timber frame will remain low. The wood fibre insulation boards will also reduce thermal bridging through the studs.  

On CLT structures, we recommend insulating them externally with Pavatherm square edged boards first and then overlaying these with the water-resistant Isolair Multi T&G insulation boards which can be rendered or finished with ventilated cladding.

Please see our Products page for more information on the products mentioned above.

Natural and eco-friendly product made from new timber off-cuts from local sawmills

For our added health and well-being, wood fibre softboards are a totally natural, sustainable and eco-friendly product made from new timber off-cuts from local sawmills. Pavatex receive this material as chippings, splinters and slabs and then further process it to create wood fibre thermal insulation boards that form part of the ecological lifecycle. Trees absorb and lock up carbon dioxide while growing, and so will significantly help reduce our carbon emissions. This contrasts with most man-made insulation materials which produce carbon dioxide during the manufacturing process. Pavatex insulation boards are safe to handle and there is no requirement to wear any protective clothing when installing these wood fibre boards. They are completely recyclable and compostable after their useful life.

Carbon-negative products to greatly benefit our environment

Pavatex insulation materials have Environmental Product Declarations (EPDs) which are third-party verified documents prepared by Pavatex, setting out the various environmental impacts of their products clearly and transparently. Pavatex wood fibre insulation is a carbon-negative product because trees remove more carbon dioxide from the atmosphere during their growth than what is required to process the timber into insulation, once harvested. In addition, the wood fibre insulation reduces heat escaping into the atmosphere during its use, so this is further combating climate change. The densest Pavatex wood fibre boards have a negative Global Warming Potential of -255.90 (kg CO2-Eq) in its production stage due to its low energy intensity in manufacturing plus credit for storing carbon in the product itself-

Enhances our internal air quality

It has been scientifically proven that the internal environment of a building is often polluted by emissions from the materials used in its construction. As an example, products containing formaldehyde and volatile organic compounds (VOCs) have been shown to emit higher emissions as temperature rises. Also, the wood fibre’s ability to absorb excess moisture from the air means that there will be a healthy relative humidity level of 40 to 60%, where bacterial and viral infections are least likely to spread. As houses are mainly built or renovated to provide a comfortable and healthy living environment, natural building materials should be used in the construction, and Pavatex wood fibre insulation boards meet this requirement.

Below is a plot that shows the optimal indoor humidity levels to inhibit the growth of various indoor health-harming sources. At 80% Relative Humidity (RH), mould can grow on surfaces if the surface temperature drops below 15C.

Source: ASHRAE HVAC Systems and Equipment Handbook, Chapter 22. 2016.

Provides thermal mass to lightweight structure meaning a reduction in summertime overheating

Thermal insulation must keep buildings warm during the cold winter months, but it is also important to keep buildings cooler during hot summer days. Contemporary buildings often have a lot of south-facing glazing, which enables excess solar heat gain during summer. Also, converted loft spaces and timber frame buildings regularly overheat due to their lightweight construction. This excess heat can be stored in the wood fibre natural insulation boards for as much as 10 to 12 hours due to their excellent thermal mass properties.  This means that properties will be several degrees cooler in the summer than would be possible with lightweight insulation, which generally has a phase shift of only 5 to 8 hours. Wood fibre contributes to an ambient and comfortable temperature in the building all year round.

Improves acoustic insulation in roofs and walls to enhance our comfort

The high density and fibrous absorbing structure of the Pavatex wood fibre natural insulation means that it is very effective at reducing both airborne sound (e.g. talking, music, traffic noise) and impact sound (e.g. footstep, moving furniture, rain noise) through walls, floors, ceilings and roofs. Timber and metal frame buildings, as well as roofs, are especially prone to external noise transmission from road noise, airplane noise and even rain hitting the roof. Pavatex wood fibre insulation will significantly reduce this noise and so will enhance our quality of life.

Thermal bridging is greatly reduced as wood fibre boards are fitted to studs or rafters rather than only between them

Pavatex by Soprema wood fibre natural insulation greatly reduces thermal bridging because the insulation boards are placed onto the face of the rafters or stud work, rather than only in between them, and so this eliminates a significant amount of heat being lost through the timber elements. This bridging accounts for anywhere between 10 and 15% of the structure, so that leads to a significant amount of leakage if not insulated. We also recommend that Pavaflex or Pavatextil P flexible insulation is placed between the studs, joists or rafters for a better (lower) U-value. The best possible solution is to externally insulate the structure so that the complete building is enclosed in insulation and thermal leakages through junctions are eliminated. Please see our Products page for more information on Pavaflex and Pavatextil P.

We provide complete systems – not just products – and we provide technical advice on these systems

We supply the insulation, renders, plasters, fixings, membranes etc and advise on the complete systems. We are passionate about preserving older buildings by working with their special structure, rather than against them. These buildings cannot be sealed up with vapour-closed materials because they will just sweat and then decay. We have Technical Manuals for all the systems.

Do not emit harmful toxins in the event of a fire

In the unlikely event of a fire, the wood fibre board surface chars and slows down the speed of the fire spreading through the structure – it has Class E flammability. This results in an above-standard fire resistance for the entire building structure when used alongside plasterboard. Pavatex wood fibre insulating boards release virtually no harmful emissions in the event of a fire.

A good long-term investment

Pavatex wood fibre natural insulation boards do not lose their insulation characteristics throughout their lifetime. Their special composition, high density and breathability are the reasons why they do not change their shape and are therefore able to effectively insulate buildings for many years as they have been doing successfully throughout Europe for more than 80 years.


Quality Assured Products from Pavatex by Soprema