Andrew Mitchell from NBT takes a look into this insulation option

Andrew Mitchell from NBT discusses the benefits of woodfibre insulation and why it’s moving beyond the specialist timber and ‘eco’ construction market and into the mainstream.



mongst those who champion sustainable construction, natural materials and renewable resources, the benefits of woodfibre insulation are a given. Manufactured from the off-cuts of felled timber grown in managed forests, woodfibre ticks all the environmentally-friendly boxes of preserving resources and creating a built environment that does not damage our natural world. And, like all timber used in construction, every tonne of woodfibre insulation manufactured locks up carbon for at least 100 years, off-setting any associated CO2 emissions, including transport, entirely. This could make a significant contribution to the Government’s eco targets.

All of this makes a compelling case for environmental projects, Passivhaus builds and timber construction. Indeed, the Structural Timber Association has recently advised that only ‘breathable’ insulation, such as woodfibre, should be used for projects of solid wood construction, such as CLT.

Despite its many environmental benefits, however, it would be a mistake to think that ‘eco-friendly’ is woodfibre’s only USP. Far from it. In fact, it’s the performance, ease of use and installed cost benefits of woodfibre insulation that are really making specifiers sit up and take notice, supporting a transition from niche solution to mainstream option.

Improved performance

Let’s leave woodfibre insulation’s environmental credentials to one side for a moment and look at building performance. Increasingly stringent Part L regulations may have placed greater focus on better insulated buildings that waste less energy, but there remains a worrying disparity between buildings’ designed performance and what they actually achieve post-occupation.

Many buildings simply do not deliver their designed U-values post-completion – despite being heavily specified with ample insulation – because the structure is not airtight. If thermal bridging occurs at the joints between the insulation panels (Y-values), the designed U-value is eroded resulting in a finished building with poor thermal performance.

Woodfibre insulation provides a solution to the issue of thermal bridging as it is applied as an external ‘wrap’ to the building. This solution is not possible with synthetic insulations on timber buildings due in part to their low density but, more critically, because they can trap moisture which in turn can compromise the integrity of the building, or the health of the occupants.

Offering excellent thermal performance thanks to timber’s inherent properties as a natural insulator, Pavatex panels are manufactured with tongue and groove edges for a neat, secure and windtight fit. Alongside woodfibre’s performance benefits as an insulator, it also offers excellent breathability.

The result is not only a more thermally-efficient building, but also an extended lifecycle for the building fabric and significantly increased comfort levels for the occupier.

Reduced costs

While the cost of heating a building continues to rise and energy wastage comes at a high monetary and environmental price, the over-specification and under-performance of conventional insulation continues. Why? Because most specifiers would rather use what they know than try something new; particularly when they expect its natural and renewable credentials to be accompanied by a premium price tag.

In reality, however, woodfibre insulation’s performance enables a simpler roof or wall build up, significantly reducing the cost of both materials and labour. Consequently, switching to woodfibre insulation can deliver both savings and performance during the build and throughout the lifecycle of the building.

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