Taking wood outside its comfort zone

During a recent visit to Balcas Sawmill in Enniskillen, director Andrew Kidney placed two split fencing posts on the boardroom table to illustrate how the company extends the service life of fencing material.

This is achieved by mechanically incising posts prior to drying and treatment to allow better penetration of preservatives. This process adds both life and value to fencing posts. What was also impressive was the boardroom table, which was made from laminated sawn Sitka spruce and sanded to a fine finish. Sitka is usually hidden from view in construction but here it looked at home as a design material.

Irish forests currently produce 3.3m cubic metres of timber annually. This is forecast to increase to 8.1m cubic metres by 2035. Sitka spruce will be the main species, so maximising the value of this resource will be a major challenge for foresters, forest owners, timber processors, wood scientists and wood manufacturers over the coming decades.

The current breakdown of sawmill to panelboard production is approximately 70:30, which means that the bulk of timber ends up as sawn timber for construction, packaging and fencing with residue returning to panelboard processing and wood energy.

Ireland’s panelboard mills have shown that we can engineer wood from residue and small logs but Europe’s timber processors are engineering sawn timber to add value by building in wood.

CLT

If Ireland intends to maximise the value of its timber resource, it needs to begin to address the potential of engineered Sitka spruce as a construction and design timber.

Countries such as Austria, Norway, Sweden and Canada have been exploring engineered wood products for rapid multi-storey construction for decades. Buildings up to 50m high are attainable with much more ambitious programmes planned in cities such as Stockholm and Vancouver. These are built using engineered wood, mainly cross-laminated timber (CLT). CLT provides innovative building solutions for single and multi-storey residential and commercial buildings.

Apart from the environmental benefits, CLT offers advantages such as air tightness, fire and earthquake resistance, thermal and acoustic insulation as well as freedom in design.

CLT is also a rapid building method. For example, the 17 timber storeys in the Brock Common student residence in Vancouver, Canada, were erected over the concrete ground floor in nine weeks using a single crane.

The CLT species used in Austria and Sweden is Norway spruce. The challenge in Ireland is to research the suitability of Sitka spruce for manufacture and fabrication of CLT.

CLT research in Ireland is being carried out in NUI Galway as part of the Innovation In Irish Timber Usage project, funded by the Department of Agriculture, Food and the Marine. Researchers here have demonstrated the viability of using Irish Sitka spruce for the manufacture of CLT.

Carbon fibre

The benefits of wood to the bioeconomy extends beyond engineering solid wood. Options are being explored by a University of Limerick-led €4.9m project, which aims to halve the CO2 footprint of carbon fibre production.

This project will see researchers from across Europe produce carbon fibre from forestry by-products. Carbon fibre is a reinforcement which, when added to plastic, improves its mechanical properties thereby forming a composite material. Composites are used in many products including automotive parts and wind-turbine blades. However, carbon fibre is produced from petroleum, which is expensive and detrimental to the environment.

Known as the LIBRE project and led by Dr Maurice Collins of the Stokes Labs, Bernal Institute, UL, it aims to create carbon fibre materials in a cost-effective and environmentally friendly way, by producing them from lignin, a naturally derived wood product. The production of carbon fibre from lignin will allow Ireland and other European countries to move away from a reliance on fossil fuel.

Comfort zone

Ireland has developed an engineered wood capability in its three panelboard mills. It now has an opportunity to develop an engineered wood industry in sawmilling. This means taking Irish wood and the Irish forest industry outside its comfort zone. Other countries have been doing it for decades even with timber not renowned for its structural characteristics such as birch.

Visitors to Seville can see the potential of laminated birch in the 28m high Metropol Parasol construction covering an area of 150m by 70m in Plaza de la Encarnacion. Designed by Jürgen Mayer and built by Arup, the timber was supplied by Finnforest. It is made from 3mm-thick, rotary-peeled wood, which is veneered, glued and eventually sawn to the required thicknesses which can vary from 68mm to 311mm with lengths up to 16.5m. The timber was treated with polyurethane coating which is self-cleaning, and only needs repainting every 20 to 25 years according to the designers.

If Finland, Norway and Austria can fabricate birch and Norway spruce into CLT and deliver it to multi-storey sites around the world, so can Ireland. Supply of raw material shouldn’t be a barrier as timber production will more than double over the next two decades.

The afforestation programme got off to a good start in January with second instalment grants issued for 435ha compared with 377ha for January last year. However, planting dropped to 379ha in February compared with 522ha last year. It is difficult to translate grants to actual performance due to the carryover of payments from month to month, so the sector awaits data for March to get a fuller picture.

However, a number of forestry companies and nurseries have said that planting performance has been extremely disappointing in recent weeks. “Planting has dropped by 46% compared to the comparable period last year,” maintained a spokesperson for None so Hardy Nurseries, the main supplier of plants to the private sector. “If this freefall is not halted and reversed, the level of planting will fall below 6,000ha this season,” he said.

Daragh Little, MD Forestry at Veon Ltd and chair of the IBEC forestry group the Irish Forestry and Forest Products Association, believes there are several reasons for the fall off in planting. “Hurdles to planting land are bigger than other agricultural schemes,” he said. For example, the target audience for forestry is the same audience as GLAS but there is no sufficient difference to the farmer to justify changing to forestry, which is a permanent land use change.”