Wood fibre insulation may have a small market share in the UK, but it is a growing share and what is even more positive is the increasing number of applications.
“The wood fibre insulation sector is showing good year-on-year growth and this is to be expected when considering this is from a low base,” said Steico. “More encouraging is the wide-ranging applications that it’s now being used in. From typical applications in roofing between rafters or joists and timber frame studwork, wood fibre is now gaining ground in external and internal wall insulations.”
Wood fibre’s profile could be raised further by the Natural Fibre Insulation Group, which was set up recently by the Alliance for Sustainable Building Materials. Its aim is to improve natural materials’ market share by educating architects, specifiers, local and central government, contractors and builders. Steico added that timber sector bodies, such as TRADA and the Structural Timber Association, were also starting to recognise the benefit of wood fibre insulation, particularly when used with timber construction.
“We anticipate that drives to reduce the so-called performance gap between designed and as-built performance, as well as the rise of the healthy building agenda, will help increase wood fibre insulation’s market share,” said Steico.
“There is increasing evidence that the use of non-breathable insulation systems in the retrofit market is causing a build-up of moisture within walls and ultimately leading to failure. Wood fibre does not compromise the breathability of solid walls and we expect this market to grow rapidly as the UK slowly but surely gets to grips with the monumental challenge of improving the energy performance of our stock of old buildings.”
In the new build market, although wood fibre insulation was not a material of choice for volume housebuilding, it was gaining acceptance and increased use in commercial and public buildings, said Steico.
“The self-build market is also growing, where there’s a defined desire to construct with a vapour open fully breathable natural material that promotes a healthy building and offers excellent thermal and sound insulation, and long-term health benefits for the occupants,” said Steico.
The company’s STEICOflex is the volume sales item. It can be fitted between rafters, joists and studs, and causes less irritation in handling than some other insulations. Use of STEICOunderfloor below laminate and real wood flooring is also increasing.
Ecological Building Systems UK Ltd, which distributes the German brand, Gutex, identifies new build timber frame and roofing as the two biggest growth areas, in particular single builds and social housing.
“Commercial projects are small in number, but large quantities of wood fibre insulation may be used per individual project,” said director Penny Randell.
The UK wood-based insulation market was relatively small and finite, although the increasing interest in timber frame meant more people were receptive to using wood fibre and embracing diffusion open buildings, said Ms Randell.
It was important, however, to continue to raise awareness of the product and so training and strong technical and on-site support were vital, she said.
There were also other challenges. “Wood fibreboards are all imported and we are challenged with the impact of exchange rates post-Brexit, which can make our sector less competitive,” said Ms Randell.
“Another factor is competition from other natural materials, such as cellulose and sheep’s wool. We hope that with the increased importance of life cycle analysis of materials and embodied energy that specifiers, particularly for government and multinational buildings, fully research the benefits when considering how to insulate.”
While wood fibre’s share of the market may be small, once specifiers appreciated the technical benefits compared with mineral fibre or petrochemical-based products – acoustic, diffusion open, low thermal diffusivity, fire, sustainability, ease of installation, higher thermal mass and high levels of stored carbon – they tended to repeat specifications on future projects, said Ms Randell. “With a move to nearly zero energy/Passivhaus standards, combined with increased awareness of the environmental impact of building materials, there is significant potential for increased growth in the use of wood fibreboard insulation systems,” she said.
At Ecological Building Systems, the wood fibre products in biggest demand are those used as a wrap around on the exterior of a timber frame structure to provide thermal continuity and optimum levels of breathability. There has also been growth in the retrofit market and the application of wood fibre as internal insulation on masonry walls, said Ms Randell.
Another area of demand, she added, was internal retrofitting of wood fibre insulation in combination with lime plaster finishes. In this market, Lime Green Products has partnered with Steico to produce its Warmshell wall insulation system. While it can be used externally on masonry and stone, it can be applied internally and externally on timber frame.
“The entire insulation system can be mounted externally onto the studwork to provide a complete insulation envelope around the building,” said Lime Green Products head of marketing Dominic Putnam. The bulk of sales is for retrofit, and mainly individual projects, and is often used when a Passivhaus solution is required.
Warmshell has also been adopted in the social housing market. It was used recently on an upgrade of social housing in the London Borough of Lambeth to improve the energy efficiency.
Mr Putnam expects the growth in new build timber frame and CLT, in particular, will also drive demand. “If the option is for a completely or part-rendered solution then Warmshell can be used very successfully on CLT construction,” he said.
Steico agrees that CLT offers huge potential. “CLT coupled with wood fibre is a future-proof solution, the vapour open construction ensuring there is no risk of condensation within the structure and, in the case of direct rendered dwellings, eliminating the all-too-common problem with nonbreathable insulations of green algae on north and north-east elevations,” the company said.
Jobs are already being specified in the UK, but there is some way to catch up with other European markets. Steico believes timber frame offers opportunities, but a step change is needed in wall and roof construction.
“For wood fibre to make any headway in the volume building market, construction has to move to wider studs of around 220- 240mm. With Steico able to offer wall studs up to 500mm there is no limitation in the scope of insulation that could be supplied,” the company said. Ecological Building Systems expects wood fibre sales to benefit from timber frame growth.
“While there are alternative natural materials on the market, which are suitable for internal use, wood fibreboards are rigid or semi-rigid so they can be applied internally or externally,” said Ms Randell.
Wood fibre insulation is more expensive than many other products so it’s important the industry markets its advantages. “Savings can be made in the construction make-up,” said Steico. “In many other wall and roof details, breathable membranes and vapour barriers are required and these can be expensive to buy and incur extra labour to fit.”
Mr Putnam agrees. “Historically it has not been used for mass market application. It tends to be adopted by people who want to achieve a low environmental impact. The Warmshell insulation system is made from almost entirely sustainable products and the materials can be recycled,” he said. “People are also buying into the longer-term benefits of a property that is thermally efficient.”
There are also health and quality of life benefits, he added. “Wood fibre and render wall insulation provides quiet living spaces with excellent air quality. The property is not affected by condensation and wood fibre insulation provides considerable soundproofing, too. Another important benefit to occupiers is the considerable temperature buffering capacity of wood fibre boards, keeping the interior of the building at a more constant temperature irrespective of outdoor temperatures,” said Mr Putnam. It is also important, said Steico, to educate architects and specifiers about wood fibre’s fire performance, especially in the wake of the Grenfell Tower fire.
“For all the wrong reasons, insulation is in the news and quite rightly there is bound to be more scrutiny regarding the use of some materials in construction. Wood and woodbased products have a positive message in relation to fire and tests on wood fibre show its behaviour is both controlled and predictable,” said Steico.
Steico points out that wood fibre accounts for around 10% of the German insulation market, but “a fraction of 1% in the UK”. A change in thinking is required for that market share to grow. “An optimistic vision of the future for wood fibre insulation does require the UK industry to begin to take a more rounded and holistic view of what a good building looks like,” said Steico.
In the immediate future, Steico reports three new developments which should all be completed in the first quarter of next year.
First, at its Czarna Woda plant it is doubling LVL capacity with the installation of a second production line. The investment, which is ahead of schedule because of increased demand, will increase production capacity to around 160,000m3.
At the company’s Czarnkow plant it is installing a second light density fibreboard (LDF) line, providing capacity for an extra 300,000m3 of products. The move is in response to demand across Europe for lighter rigid insulation sarkings and sheathings. It is also investing in a new line for a thin, flexible and rollable wood fibre to be used in underfloor and under carpet applications. Steico has also recently expanded its air-injected insulation offering with a new cellulose product, STEICOfloc.
“As in all our product sectors we are always looking for strong partners to develop these products in their specialised fields of supply,” said Steico.
Ms Randell believes wood fibre insulation will continue to evolve to provide improved thermal and weather-resistant properties.
“For example, Gutex has updated the tongue and groove profile on their primary external roofing board Ultratherm for enhanced weathertightness. “Gutex has also recently launched a semi-rigid wood fibre batt, Thermoflex, with an improved thermal conductivity of only 0.036W/m K.”
